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Heleocola piceanus, a new, relatively large metatherian from Upper Cretaceous ('Edmontonian') strata of the Williams Fork Formation in northwestern Colorado is described, based on a recently discovered jaw fragment (MWC 9744), in addition to three isolated teeth initially referred by other studies to Aquiladelphis incus and Glasbius piceanus. Although sharing several morphologic characters with the Lancian genus Glasbius, H. piceanus lower molars are considerably larger than those of Glasbius and differ from the latter in lacking a buccal cingulid, possessing carnassiform notches on the cristid obliqua and entocristid, and bearing an entoconulid on m3. To examine the relationship of Heleocola piceanus to other metatherians, H. piceanus was scored into a previously existing taxon-character matrix. Our phylogenetic analysis recovers H. piceanus as the sister taxon to Glasbius, which is consistent with our morphologic comparisons. H. piceanus represents the oldest member of the Glasbiidae. A regression equation for predicting body mass of dentally conservative metatherians that utilizes the length of m1 estimates the mass of H. piceanus at 855–1170 g, which is comparable in mass to today's muskrat (Ondatra zibethicus) and large relative to other Late Cretaceous pediomyoids. Based upon its molar morphology, specifically the low inflated cusps, low height differential between the trigonid and talonid, and near-bunodont morphology, H. piceanus is interpreted as an omnivore with a plant-dominated diet. [ABSTRACT FROM AUTHOR]

Objective: The patterning cascade model of crown morphogenesis has been studied extensively in a variety of organisms to elucidate the evolutionary history surrounding postcanine tooth form. The current research is the first to use a large modern human sample to examine whether the crown configuration of lower deciduous and permanent molars aligns with expectations derived from the model. This study has two main goals: 1) to determine if metameric and antimeric pairs significantly differ in size, accessory trait expression, and relative intercusp spacing, and 2) assess whether the relative distance among early-forming cusps accounts for observed variation in accessory cusp expression. Methods: Tooth size, intercusp distance, and morphological trait expression data were collected from 3D scans of mandibular dental casts representing participants of the Harvard Solomon Islands Project. Paired tests were utilized to compare tooth size, accessory trait expression, and relative intercusp distance between diphyodont metameres and permanent antimeres. Proportional odds logistic regression was implemented to investigate how the odds of greater accessory cusp expression vary as a function of the distance between early-developing cusps. Results/Significance: Comparing paired molars, significant differences were identified for tooth size and cusp 5 expression. Several relative intercusp distances emerged as important predictors of cusp 6 expression, however, results for cusp 5 and cusp 7 did not match expected patterns. These findings support previous quantitative genetic results and suggest the development of neighboring crown structures represents a zero-sum partitioning of cellular territory and resources. As such, this study contributes to a better understanding of the foundations of deciduous and permanent molar crown variation in humans. [ABSTRACT FROM AUTHOR]

Understanding how epigenetic factors impact dental phenotypes can help refine the use of teeth for elucidating biological relationships among human populations. We explored relationships among crown size, principal cusp spacing, and accessory cusp expression in maxillary dental casts of nutritionally supplemented (n = 34) and non-supplemented (n = 39) individuals from Tezonteopan, Mexico. We hypothesized that the non-supplemented group would exhibit smaller molar crowns and reduced intercusp spacing. Since intercusp spacing is thought to be more sensitive to epigenetic influences than crown size, we predicted that the supplemented and non-supplemented groups would differ more in the former than the latter. Previous work suggests that molar accessory cusp expression may be elevated under conditions of stress. We therefore expected evidence of greater Carabelli and Cusp 5 trait expression in the non-supplemented group. We further hypothesized that anterior teeth would be affected by nutritional stress during development, with the non-supplemented group having smaller anterior tooth crowns and therefore limited space to form the tuberculum dentale. Finally, we tested whether the presence of molar accessory traits followed predictions of the Patterning Cascade Model of tooth morphogenesis in the entire sample. Our results supported the expectation that cusp spacing would differ more than molar crown size between the two groups. Carabelli trait showed little evidence of frequency differences between groups, but some evidence of greater trait scores in the non-supplemented group. The non-supplemented group also showed evidence of greater Cusp 5 frequency and expression. In the central incisors and canines, there was strong evidence for smaller crown sizes and reduced tuberculum dentale frequency in the non-supplemented group. With both groups pooled together, there was strong evidence of closer mesiodistal distances among principal cusps in molars with accessory cusps, a finding that is consistent with the PCM. Overall, our findings suggest that nutritional stress may affect accessory cusp expression. [ABSTRACT FROM AUTHOR]

Objectives: The impression technique highly influences the adaptation of ceramic restorations. Not enough information is available to compare the marginal (MF) and internal fit (IF) of endocrowns fabricated with various digitization techniques. Therefore, this in-vitro study aimed to compare the MF and IF of lithium disilicate (LDS) endocrowns fabricated through direct and indirect digital scanning methods. Materials and methods: One extracted maxillary molar was used to fabricate endocrowns. The digitization of the model was performed with (G1) direct scanning (n = 10) utilizing an intraoral scanner (IOS), (G2) indirectly scanning the conventional impression taken from the model using the same IOS (n = 10), (G3) indirectly digitalizing the obtained impression using an extraoral scanner (EOS) (n = 10), and (G4) scanning the poured cast using the same EOS (n = 10). The MF and IF of the endocrowns were measured using the replica method and a digital stereomicroscope. The Kruskal-Wallis test was used to analyze data. Results: The studied groups differed significantly (p<0.001). G2 (130.31±7.87 μm) and G3 (48.43±19.14 μm) showed the largest and smallest mean vertical marginal gap, respectively. G2 and G3 led to the highest and lowest internal gaps in all regions, respectively. With significant differences among the internal regions (p<0.001), the pulpal area demonstrated the most considerable misfit in all groups. Conclusions: Scanning the impression using an extraoral scanner showed smaller marginal and internal gaps. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the effect of glide path and coronal flaring on the dentin volume removal and percentage of touched walls in curved canals using two heat-treated rotary files. The mesiobuccal canal of forty-eight, randomly selected, extracted mandibular molars was divided into two groups of 24 each, according to the type of instrument used (RACE EVO and EdgeSequel rotary files). Each group was further divided into three subgroups; Group (A): Control using one file shaped to 04/30, Group (B) with a glide path (EdgeGlidePath (EGP)), and Group (C): with a glide path and coronal flaring (EGP and EdgeTaper Platinum (ETP) SX file respectively). The root canals were then instrumented using the assigned instruments. The assessment was carried out using micro-CT. The comparison of the mean values of the tested groups about dentin volume removal and percentage of untouched walls did not reach statistical significance (p<0.05). Glide path and coronal flaring had an insignificant effect on the dentin volume removal and percentage of untouched walls in curved canals. [ABSTRACT FROM AUTHOR]

Introduction: Understanding the anatomy of root canal systems and being aware of their variations is crucial for successful endodontic treatment. Specifically, the intricate and diverse nature of the root anatomy in maxillary third molars poses a significant challenge for dental clinicians. The study analyzed the morphology of the root canal system in maxillary third molars among residents of the Lower Silesia region in Poland using cone beam computed tomography (CBCT). Material and methods: This retrospective cross-sectional imaging study was conducted at the X-Ray Diagnostics Laboratory of the Academic Dental Polyclinic of Wroclaw Medical University, Poland. The study evaluated 316 CBCT scans and included 196 maxillary third molars. They were obtained from 118 females and 78 males over the age of 18, in the period from January to April 2022 (three consecutive months). The number of roots, root canals, and root canal configurations according to Vertucci's classification were analyzed. Results: Three-rooted maxillary molars were found most often (64.29%), followed by single-rooted (24.49%), two-rooted (7.65%), and four-rooted (3.57%) teeth. Among all the roots examined, Vertucci Type I root canals were the most prevalent. Our research found that single-rooted forms (40 teeth, 33.89% vs. 8 teeth, 10.26%, p = 0.0013) of maxillary third molars were significantly more common in females than in males. However, three-rooted forms (62 teeth, 79.49% vs. 64 teeth, 54.24%, p = 0.0013) of maxillary third molars were significantly more common in males than in females. Discussion: In the Lower Silesia region, the typical maxillary third molar in the Polish population has a three-rooted structure with Vertucci Type I root canal configuration. We noted a sex-dependent correlation in maxillary third molar morphology, with single-rooted forms more prevalent in women and three-rooted forms in men. [ABSTRACT FROM AUTHOR]

Background: CAD/CAM has considerably transformed the clinical practice of dentistry. In particular, advanced dental materials produced via digital technologies offer unquestionable benefits, such as ideal mechanical stability, outstanding aesthetics and reliable high precision. Additive manufacturing (AM) technology has promoted new innovations, especially in the field of biomedicine. Aims: The aim of this study is to analyze the fracture resistance of implant-supported 3D-printed temporary crowns relative to milled crowns by compression testing. Methods: The study sample included 32 specimens of temporary crowns, which were divided into 16 specimens per group. Each group consisted of eight maxillary central incisor crowns (tooth 11) and eight maxillary molar crowns (tooth 16). The first group (16 specimens) was 3D printed by a mask printer (Varseo, BEGO, Bremen, Germany) with a temporary material (VarseoSmile Temp A3, BEGO, Bremen, Germany). The second group was milled with a millable temporary material (VitaCAD Temp mono-color, Vita, Bad Säckingen, Germany). The two groups were compression tested until failure to estimate their fracture resistance. The loading forces and travel distance until failure were measured. The statistical analysis was performed using SPSS Version 24.0. We performed multiple t tests and considered a significance level of p <0.05. Results: The mean fracture force of the printed molars was 1189.50 N (±250.85) with a deformation of 1.75 mm (±0.25). The milled molars reached a mean fracture force of 1817.50 N (±258.22) with a deformation of 1.750 mm (±0.20). The printed incisors fractured at 321.63 N (±145.90) with a deformation of 1.94 mm (±0.40), while the milled incisors fractured at 443.38 N (±113.63) with a deformation of 2.26 mm (±0.40). The milled molar group revealed significantly higher mechanical fracture strength than the 3D-printed molar group (P<0.001). However, no significant differences between the 3D-printed incisors and the milled incisors were found (p = 0.084). There was no significant difference in the travel distance until fracture for both the molar group (p = 1.000) and the incisor group (p = 0.129). Conclusion: Within the limits of this in vitro investigation, printed and milled temporary crowns withstood masticatory forces and were safe for clinical use. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate if single nucleotide polymorphisms (SNPs) in WNT6 and WNT10A are associated with the risk of dental pulp calcification in orthodontic patients. This cross-sectional study followed the "Strengthening the Reporting of Genetic Association Studies" (STREGA) guidelines. Panoramic radiographs (pre- and post-orthodontic treatment) and genomic DNA from 132 orthodontic patients were studied. Dental pulp calcification (pulp stones and/or pulp space narrowing) was recorded in upper and lower first molars. The SNPs in WNT6 and WNT10A (rs7349332, rs3806557, rs10177996, and rs6754599) were assessed through genotyping analysis using DNA extracted from buccal epithelial cells. The association between pulp calcification and SNPs were analyzed using allelic and genotypic distributions and haplotype frequencies (p<0.05). Prevalence of dental pulp calcification was 42.4% in the 490 studied molars. In the genotypic analysis, the SNPs in WNT10A showed a statistically significant value for molar calcification (p = 0.027 for rs1017799), upper molar calcification (p = 0.040 for rs1017799) (recessive model), and molar calcification (p = 0.046 for rs3806557) (recessive model). In the allelic distribution, the allele C of the SNP rs10177996 in WNT10A was associated with molar calcifications (p = 0.042) and with upper first molar calcification (p = 0.035). Nine combinations of haplotypes showed statistically significant value (p<0.05). The findings of this study indicates that SNPs in WNT10A and WNT6 are associated with dental pulp calcification in molars after orthodontic treatment and may be considered as biomarkers for dental pulp calcification. [ABSTRACT FROM AUTHOR]

Introduction: Molar-incisor hypomineralization (MIH) is a qualitative defect of dental enamel that affects one or more permanent first molars, with or without involvement of the incisor teeth. This condition leads to challenges to dental care and treatment planning. Aim: Based on the hypothesis that children who have MIH possibly present alterations in postural and masticatory activities and considering the absence of studies investigating these parameters, the present study evaluated the functionality of the stomatognathic system considering the mentioned aspects. Materials: The comparison of individuals with (MIHG; n = 32) and without MIH (CG; n = 32) was evaluated by electromyographic activity of the masseter and temporal muscles (right and left), as well as evaluation of the masticatory cycles during habitual mastication. Results: MIHG showed muscle hyperactivity in postural and dynamic conditions compared to the CG; higher electromyographic values for MIHG when compared to CG in the following postural conditions: at rest for the right temporal (p = 0.00) and left temporal muscles (p = 0.03); in the protrusion to the right temporal muscle (p = 0.02); in the right laterality for the right masseter (p = 0.00) and left temporal muscles (p = 0.01); in the left laterality for the right masseter (p = 0.03) and left temporal (p = 0.04) muscles. In dynamic conditions with consistent food, significance was observed for the left temporal (p = 0.01); and with soft food for the right (p = 0.01) and left temporal muscles (p = 0.04). Conclusions: Children with MIH seem to have impaired functionality of the stomatognathic system. Children with MIH have alterations in the stomatognathic system. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the educational value of YouTube as a learning tool for dental students regarding endodontic access cavity preparation. Methods and findings: YouTube search was made for videos related to endodontic access cavity preparation using specific terms. After exclusions, 41 videos were chosen and assessed for tooth type, video length, days since upload, country of origin, number of views and likes, source of authorship, and viewing rate. To grade the content of videos, a usefulness score with seven elements was developed. Each element was given a score of 0 or 1. Statistical tests were run by using Kruskal-Wallis and Mann-Whitney tests (SPSS Inc, Chicago, IL, USA) at a 5% significance level. The videos received a mean of 181198.5 views with a mean duration of 686.1 seconds. The mean number of "likes" was 1047.8. Almost half of the videos covered content related to molar teeth. Most videos were provided by health care professionals with almost 50% uploaded from India. The mean usefulness score was 4.29 (range: 1–7) and the most discussed elements were description, instruments used, access cavity demonstration, and evaluation criteria. About a quarter of the videos were classified as good, while 46.3% as moderate and 29.3% as poor. Among the content usefulness categories, no difference was found in the video demographics (p>0.05) except "days since upload" (p = 0.018) in which good quality videos were found to have the highest median. Moreover, although insignificant, good videos were found to have the longest duration and lowest number of views, likes, and viewing rate. The mean usefulness score of videos released during the COVID-19 pandemic was lower than that for pre-pandemic videos (p = 0.042), and videos uploaded by academic institutions had a higher mean usefulness score than videos uploaded by health care professionals (p<0.001). Conclusions: Information on endodontic access cavity preparation is not comprehensive in most of the reviewed YouTube videos and could be of low educational value. [ABSTRACT FROM AUTHOR]

Dental caries and periodontal disease are very common chronic diseases closely linked to inadequate removal of dental plaque. Powered toothbrushes are viewed as more effective at removing plaque; however, the conflicting evidence and considerable unexplained heterogeneity in their clinical outcomes does not corroborate the relative merits of powered tooth brushing. To explain the heterogeneity of brushing patterns with powered toothbrushes, we conducted a observational study of tooth brushing practices of 12 participants in their naturalistic setting. Integrated brush sensors and a digital data collection platform allowed unobtrusive and accurate capture of habitual brushing patterns. Annotated brushing data from 10 sessions per participant was chosen for scrutiny of brushing patterns. Analysis of brushing patterns from the total 120 sessions revealed substantial between- and within-participant variability in brushing patterns and efficiency. Most participants (91.67%) brushed for less than the generally prescribed two minutes; individual participants were also inconsistent in brushing duration across sessions. The time devoted to brushing different dental regions was also quite unequal. Participants generally brushed their buccal tooth surfaces more than twice as long as the occlusal (2.18 times longer (95% CI 1.42, 3.35; p < 0.001)) and lingual surfaces (2.22 times longer (95% CI 1.62, 3.10; p < 0.001); the lingual surfaces of the maxillary molars were often neglected (p < 0.001). Participants also varied in the epochs of excessive brushing pressure and the regions to which they were applied. In general, the occlusal surfaces were more likely to be brushed with excessive pressure (95% CI 0.10, 0.98; p = 0.015). Our study reveals that users of powered toothbrushes vary substantially in their use of the toothbrushes and diverge from recommended brushing practices. The inconsistent brushing patterns, between and within individuals, can affect effective plaque removal. Our findings underscore the limited uptake of generic oral self-care recommendations and emphasize the need for personalized brushing recommendations that derive from the objective sensor data provided by powered toothbrushes. [ABSTRACT FROM AUTHOR]

Purpose: Evaluation of the clinical performance of computer-aided design/computer-aided manufacturing-produced resin composite crowns (CAD/CAM composite crowns) on molars with a particular focus on placement location. Methods: A retrospective cohort study was performed based on the clinical records of patients with CAD/CAM composite crowns on molars (June 2016 to March 2021). The hazard ratios (HRs) and 95% confidence intervals (95% CIs) were estimated based the Cox proportional hazard model to evaluate the effect of tooth location on complication type and occurrence. Covariates included crown location (maxilla/mandible, distalmost tooth/not distalmost tooth, and first molar/second or third molar) and endodontically treated (nonvital) or untreated (vital) tooth. Results: Overall, 362 crowns were evaluated (mean follow-up: 378 days, median: 286 days), and 106 crowns (29.3%) showed complications, most frequently crown debonding. The cumulative success and survival rates were 70.9% and 93.7%, respectively, after 1 year and 49.5% and 86.5%, respectively, after 3 years. There was no significant difference in the HRs and log-rank tests in the Kaplan–Meier curves based on crown location parameters (P > 0.05). However, placement on vital teeth was associated with higher risks than on nonvital teeth (HR, 1.55; 95% CI, 1.03–2.23). In addition, the cement as a covariate yielded a high HR. Conclusions: The location of CAD/CAM composite molar crowns is unlikely a risk factor for complications; therefore, these crowns can be clinically applied to all molars. However, the application of such molar crowns to vital teeth and the use of a cement other than adhesive resin cement present risks. [ABSTRACT FROM AUTHOR]

Objectives: The objective of this report was to provide a review of the minipig intraoral dental implant model including a meta-analysis to estimate osseointegration and crestal bone remodeling. Methods: A systematic review including PubMed and EMBASE databases through June 2021 was conducted. Two independent examiners screened titles/abstracts and selected full-text articles. Studies evaluating titanium dental implant osseointegration in native alveolar bone were included. A quality assessment of reporting was performed. Random-effects meta-analyses and meta-regressions were produced for bone-implant contact (BIC), first BIC, and crestal bone level. Results: 125 out of 249 full-text articles were reviewed, 55 original studies were included. Quality of reporting was generally low, omissions included animal characteristics, examiner masking/calibration, and sample size calculation. The typical minipig model protocol included surgical extraction of the mandibular premolars and first molar, 12±4 wks post-extraction healing, placement of three narrow regular length dental implants per jaw quadrant, submerged implant healing and 8 wks of osseointegration. Approximately 90% of studies reported undecalcified incandescent light microscopy histometrics. Overall, mean BIC was 59.88% (95%CI: 57.43–62.33). BIC increased significantly over time (p<0.001): 40.93 (95%CI: 34.95–46.90) at 2 wks, 58.37% (95%CI: 54.38–62.36) at 4 wks, and 66.33% (95%CI: 63.45–69.21) beyond 4 wks. Variability among studies was mainly explained by differences in observation interval post-extraction and post-implant placement, and implant surface. Heterogeneity was high for all studies (I2 > 90%, p<0.001). Conclusions: The minipig intraoral dental implant model appears to effectively demonstrate osseointegration and alveolar bone remodeling similar to that observed in humans and canine models. [ABSTRACT FROM AUTHOR]

Background: Forensic dentistry identifies deceased individuals by comparing postmortem dental charts, oral-cavity pictures and dental X-ray images with antemortem records. However, conventional forensic dentistry methods are time-consuming and thus unable to rapidly identify large numbers of victims following a large-scale disaster. Objective: Our goal is to automate the dental filing process by using intraoral scanner images. In this study, we generated and evaluated an artificial intelligence-based algorithm that classified images of individual molar teeth into three categories: (1) full metallic crown (FMC); (2) partial metallic restoration (In); or (3) sound tooth, carious tooth or non-metallic restoration (CNMR). Methods: A pre-trained model was created using oral-cavity pictures from patients. Then, the algorithm was generated through transfer learning and training with images acquired from cadavers by intraoral scanning. Cross-validation was performed to reduce bias. The ability of the model to classify molar teeth into the three categories (FMC, In or CNMR) was evaluated using four criteria: precision, recall, F-measure and overall accuracy. Results: The average value (variance) was 0.952 (0.000140) for recall, 0.957 (0.0000614) for precision, 0.952 (0.000145) for F-measure, and 0.952 (0.000142) for overall accuracy when the algorithm was used to classify images of molar teeth acquired from cadavers by intraoral scanning. Conclusion: We have created an artificial intelligence-based algorithm that analyzes images acquired with an intraoral scanner and classifies molar teeth into one of three types (FMC, In or CNMR) based on the presence/absence of metallic restorations. Furthermore, the accuracy of the algorithm reached about 95%. This algorithm was constructed as a first step toward the development of an automated system that generates dental charts from images acquired by an intraoral scanner. The availability of such a system would greatly increase the efficiency of personal identification in the event of a major disaster. [ABSTRACT FROM AUTHOR]

Clinical studies on the efficacy of sonic toothbrushes show inconsistent results, most studies have been conducted without sufficient supervision of appropriate toothbrush usage. Aims of the explorative clinical trial were therefore to investigate whether the usage of an activated sonic toothbrush reduces plaque more effectively than an inactivated one used as a manual toothbrush, and to which extent the correct use of such toothbrush plays a role in its efficacy. The clinical trial was designed as a video-controlled interventional study. Thirty participants (mean (±SD) age 22.9 (±2.5) years) were included, areas of interest were the buccal surfaces of the upper premolars and the first molar (partial mouth recording). Toothbrushing was performed without toothpaste in a single brushing exercise under four different conditions: switched off, habitually used as manual toothbrush, no instruction; switched on, habitually used as powered toothbrush, no instruction; switched off, used as manual toothbrush, instruction in the Modified Bass Technique; switched on, used as powered toothbrush, instruction in a specific technique for sonic toothbrushes. Brushing performance was controlled by videotaping, plaque was assessed at baseline (after 4 days without toothbrushing) using the Rustogi modified Navy-Plaque-Index and planimetry. Main study results were that plaque decreased distinctly after habitual brushing regardless of using the sonic brush in ON or OFF mode (p for all comparisons < 0.001). After instruction, participants were able to use the sonic brush in ON mode as intended, with only minor impact on efficacy. Using the toothbrush in OFF mode with the Modified Bass Technique was significantly less effective than all other conditions (p for all comparisons < 0.001). Under the conditions used, the sonic toothbrush was not more effective when switched on than when switched off, and there was no evidence that the correct use of the toothbrush was more effective than the habitual use. [ABSTRACT FROM AUTHOR]

Dental caries is one of the most common infectious diseases affecting 6–8-year-old children, especially their first permanent molars (FPMs). This study explored the prevalence of dental caries on FPMs by analyzing the oral health status of 1,423,720 children aged 6–8 years in Zhejiang Province, China. The data were extracted from the dental electronic records of the schoolchildren attending the Oral Health Promotion Project (OHPP), conducted during 2013–2017 in Zhejiang Province. Multiple logistic regression models were used to determine the factors affecting dental caries. Boys and girls accounted for 53.2% and 46.8% of the subjects, respectively. From 2013 to 2017, the prevalence of dental caries on FPMs increased: 2013: 20.4%; 2014: 25.3%; 2015: 24.5%; 2016: 27.0%; and 2017: 29.0%, despite the OHPP conducted. Based on multiple logistic regression model, girls had a significantly higher risk of FPM caries compared to boys (OR = 1.38, 95% CI: 1.37–1.39, p < 0.0001); compared with the caries rates in urban areas, the caries risk was significantly higher in rural areas (OR = 1.15, 95% CI: 1.14–1.16, p < 0.0001). In terms of geographic location in Zhejiang Province, the odds ratios of the caries risk of the east, south, west, and north were 1.35 (1.33–1.36), 1.3 (1.28–1.31), 0.81 (0.8–0.83), and 0.82 (0.81–0.84), respectively (p < 0.0001), by considering the central region as a reference. The caries prevalence of FPMs was high, with an increasing tendency and gender, social, cultural, and environmental factors affecting the caries prevalence. [ABSTRACT FROM AUTHOR]

Background: In adult patients, treatment of skeletal crossbite requires combined treatment by fixed or removable appliances and orthognathic surgery. In cases of dentoalveolar crossbite, expansion can be achieved with fixed multibrackets and removable transparent aligners. Various researchers have already assessed the Invisalign system's predictability for arch expansion. However, most of this research was conducted using older appliances, making it necessary to assess the characteristics of the updated system SmartTrack. Material and methods: A sample of 114 patients with transverse malocclusion were treated with SmartTrack. The predictability of the system's software (Clincheck) was assessed by comparing planned measurements (width of canines, premolars and molars rotations and inclinations) with the real measurements achieved at the end of the first treatment phase. Measurements were imported to Clincheck software to create three data sets; T1: initial measurements at start of treatment; T2: Clincheck predicted measurements at end of first treatment phase; T3: measurements taken at start of the second treatment phase. Results: Widths underwent significant advances as a result of treatment. For all widths, virtual planning obtained prognoses of greater expansion than actually achieved: a mean of 0.63 mm more expansion at the canine level (p<0.001), 0.77 mm at first premolar (p<0.001), 0.81 at second premolar (p<0.001), 0.69 mm at first molar (p<0.001), and 0.25 mm at second molar (p = 0.183). All the treatment plan's estimations, with the exception of the second molar, were significantly higher than the actual outcomes. Conclusions: Aligners are an effective tool for producing arch expansion, being more effective in premolar area and less effective in canine and second molar area. Predictability was reasonable for expansion movement. Overcorrection should be considered at the virtual planning stage in order to obtain the expected outcomes. [ABSTRACT FROM AUTHOR]

A high-performance liquid chromatography (HPLC) method with relative molar sensitivity (RMS) based on 1H quantitative NMR spectroscopy (1H-qNMR) has been developed for food ingredients such as acteoside (verbascoside) and pedaliin (pedalitin-6-O-glucoside) without requiring authentic and identical standards as the reliable analytical methods. This method is used methyl 4-hydroxybenzoate (MHB) as an alternative reference standard. Each RMS is also calculated from the ratio of each analyte's molar absorption coefficient to that of MHB after correcting the purities of the analytes and reference standard by 1H-qNMR. Therefore, this method can quantify several analytes with metrological traceability to the International System of Units (SI) using the RMS and one alternative reference standard. In this study, the content of acteoside and pedaliin in several samples, such as dried sesame leaf powders and commercially processed foods, can be determined by the proposed RMS method and demonstrated in good agreement that obtained by a conventional method. Moreover, the proposed method yields analytical data with SI-traceability without the need for an authentic and identical analyte standard. Thus, the proposed RMS method is a useful and practical tool for determining acteoside and pedaliin in terms of the accuracy of quantitative values, the routine analysis, and the cost of reagents. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study was to evaluate the effects of miniscrew insertion angle and vertical facial type on the interradicular miniscrew–root distance available for molar distalization. Materials and methods: Cone-beam computed tomography images of 60 adults with skeletal Class I occlusion exhibiting hyperdivergent (n = 20), normodivergent (n = 20), and hypodivergent (n = 20) facial types were used. Placement of a 6-mm long, 1.5-mm diameter, tapered miniscrew was simulated at a site 4 mm apical to the cementoenamel junction, with insertion angles of 0°, 30°, 45°, and 60° relative to the transverse occlusal plane. The shortest linear distance between the miniscrew and anterior root at four interradicular sites was measured: maxillary second premolar and first molar (Mx 5–6), maxillary first and second molars (Mx 6–7), mandibular second premolar and first molar (Mn 5–6), and mandibular first and second molars (Mn 6–7). Results: Miniscrew–root distance significantly increased as the insertion angle increased from 0° to 60°. In the mandible, the distances significantly differed among vertical facial types, increasing in the following order: hyperdivergent, normodivergent, and hypodivergent. The minimum mean distance was found in the Mx 6–7 (30°; 0.86±0.35 mm), and the maximum mean distance was found in the Mn 5–6 (60°; 2.64±0.56 mm). The rates of miniscrews located buccally outside the root distalization path were up to 70% and 55% when the miniscrews were placed at 60° insertion angles in the Mx 5–6 and Mn 5–6 regions, respectively. Conclusions: Miniscrew–root distance increased significantly with the increased insertion angle, and the amount of increase was affected by the miniscrew placement site and vertical facial type. To ensure adequate distalization of the posterior segment, the miniscrew should be inserted at an angle in the interradicular area between the second premolar and first molar. [ABSTRACT FROM AUTHOR]

Dental enamel thickness, topography, growth and development vary among hominins. In Homo, the thickness of dental enamel in most Pleistocene hominins display variations from thick to hyper-thick, while Neanderthals exhibit proportionally thinner enamel. The origin of the thin trait remains unclear. In this context, the Middle Pleistocene human dental assemblage from Atapuerca-Sima de los Huesos (SH) provides a unique opportunity to trace the evolution of enamel thickness in European hominins. In this study, we aim to test the hypothesis if the SH molar sample approximates the Neanderthal condition for enamel thickness and/or distribution. This study includes 626 molars, both original and comparative data. We analysed the molar inner structural organization of the original collections (n = 124), belonging to SH(n = 72) and modern humans from Spanish origin (n = 52). We compared the SH estimates to those of extinct and extant populations of the genus Homo from African, Asian and European origin (estimates extracted from literature n = 502). The comparative sample included maxillary and mandibular molars belonging to H. erectus, East and North African Homo, European Middle Pleistocene Homo, Neanderthals, and fossil and extant H. sapiens. We used high-resolution images to investigate the endostructural configuration of SH molars (tissue proportions, enamel thickness and distribution). The SH molars exhibit on average thick absolute and relative enamel in 2D and 3D estimates, both in the complete crown and the lateral enamel. This primitive condition is shared with the majority of extinct and extant hominin sample, except for Neanderthals and some isolated specimens. On the contrary, the SH molar enamel distribution maps reveal a distribution pattern similar to the Neanderthal signal (with thicker enamel on the lingual cusps and more peripherally distributed), compared to H. antecessor and modern humans. Due to the phylogenetic position of the SH population, the thick condition in molars could represent the persistence of the plesiomorphic condition in this group. Still, more data is needed on other Early and Middle Pleistocene populations to fully understand the evolutionary meaning of this trait. [ABSTRACT FROM AUTHOR]

Crown shape variation of the first lower molar in the arctic (Vulpes lagopus) and red foxes (Vulpes vulpes) was analyzed using five groups of morphotypes. Carnassial morphologies were compared between the species and between spatially and temporally distant populations: one Late Pleistocene (n = 45) and seven modern populations of the arctic fox (n = 259), and one Late Pleistocene (n = 35) and eight modern populations of the red fox (n = 606). The dentition of Holocene red foxes had larger morphotype variability than that of arctic foxes. The lower carnassials of the red fox kept have some primitive characters (additional cusps and stylids, complex shape of transverse cristid), whereas the first lower molars of the arctic fox have undergone crown shape simplification, with the occlusal part of the tooth undergoing a more pronounced adaptation to a more carnivorous diet. From the Late Pleistocene of Belgium to the present days, the arctic fox's crown shape has been simplified and some primitive characters have disappeared. In the red fox chronological changes in the morphology of the lower carnassials were not clearly identified. The phyletic tree based on morphotype carnassial characteristics indicated the distinctiveness of both foxes: in the arctic fox line, the ancient population from Belgium and recent Greenland made separate branches, whereas in the red foxes the ancient population from Belgium was most similar to modern red foxes from Belgium and Italy. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the trueness of 5 intraoral scanners (IOSs) for digital impression of simulated implant scan bodies in a partially edentulous model. A 3D printed partially edentulous mandible model made of Co-Cr with a total of 6 bilaterally positioned cylinders in the canine, second premolar, and second molar area served as the study model. Digital scans of the model were made with a reference scanner (steroSCAN neo) and 5 IOSs (CEREC Omnicam, CS3600, i500, iTero Element, and TRIOS 3) (n = 10). For each IOS's dataset, the XYZ coordinates of the cylinders were obtained from the reference point and the deviations from the reference scanner were calculated using a 3D reverse engineering program (Rapidform). The trueness values were analyzed by Kruskal-Wallis test and Mann-Whitney post hoc test. Direction and amount of deviation differed among cylinder position and among IOSs. Regardless of the IOS type, the cylinders positioned on the left second molar, nearest to the scanning start point, showed the smallest deviation. The deviation generally increased further away from scanning start point towards the right second molar. TRIOS 3 and i500 outperformed the other IOSs for partially edentulous digital impression. The accuracy of the CEREC Omnicam, CS3600, and iTero Element were similar on the left side, but they showed more deviations on the right side of the arch when compared to the other IOSs. The accuracy of IOS is still an area that needs to be improved. [ABSTRACT FROM AUTHOR]

Deperetellidae is a clade of peculiar, Asian endemic tapiroids from the early and middle Eocene. The previously published material mainly comprises maxillae, mandibles, and some postcranial elements. However, the absence of cranial materials and primitive representatives of the deperetellids obscures their phylogenetic relationships within Tapiroidea. Furthermore, derived deperetellids have completely molarized premolars, but the pattern of their evolution remains unclear. Here, we report a nearly complete skull and some carpals of a new basal deperetellid tapiroid, Irenolophus qii gen. et sp. nov., from the late early Eocene of the Erlian Basin, Inner Mongolia, China. We suggest that deperetellids (along with Tapiridae) probably also arose from some basal 'helaletids', based on the reduced, flat, lingually depressed metacones on the upper molars, the trend towards the bilophodonty on the lower molars, and a shallow narial notch with the premaxilla in contact with the nasal. The molarization of the premolars in Deperetellidae from Irenolophus through Teleolophus to Deperetella was initiated and gradually enhanced by the separation between the paraconule and the protocone. That pattern differs from the protocone-hypocone separation in helaletids, tapirids, and most rhinoceroses, and the metaconule-derived pseudohypocone in amynodontids. However, the specific relationship of deperetellids within Tapiroidea and the roles of different patterns of premolar molarization in perissodactyl evolution need further and comprehensive study. [ABSTRACT FROM AUTHOR]

The Sthenurinae were a diverse subfamily of short-faced kangaroos that arose in the Miocene and diversified during the Pliocene and Pleistocene. Many species possessed skull morphologies that were relatively structurally reinforced with bone, suggesting that they were adapted to incorporate particularly resistant foods into their diets. However, the functional roles of many unique, robust features of the sthenurine cranium are not yet clearly defined. Here, the finite element method is applied to conduct a comprehensive analysis of unilateral biting along the cheek tooth battery of a well-represented sthenurine, Simosthenurus occidentalis. The results are compared with those of an extant species considered to be of most similar ecology and cranial proportions to this species, the koala (Phascolarctos cinereus). The simulations reveal that the cranium of S. occidentalis could produce and withstand comparatively high forces during unilateral biting. Its greatly expanded zygomatic arches potentially housed enlarged zygomaticomandibularis muscles, shown here to reduce the risk of dislocation of the temporomandibular joint during biting with the rear of a broad, extensive cheek tooth row. This may also be a function of the zygomaticomandibularis in the giant panda (Ailuropoda melanoleuca), another species known to exhibit an enlarged zygomatic arch and hypertrophy of this muscle. Furthermore, the expanded frontal plates of the S. occidentalis cranium form broad arches of bone with the braincase and deepened maxillae that each extend from the anterior tooth rows to their opposing jaw joints. These arches are demonstrated here to be a key feature in resisting high torsional forces during unilateral premolar biting on large, resistant food items. This supports the notion that S. occidentalis fed thick, lignified vegetation directly to the cheek teeth in a similar manner to that described for the giant panda when crushing mature bamboo culms. [ABSTRACT FROM AUTHOR]

In 2016, an extraordinary burial of a young adult individual was discovered at the Late Pre-Pottery Neolithic B (LPPNB, 7,500–6,900 BCE) settlement of Baʻja in southern Jordan. This burial has exceptional grave goods and an elaborate grave construction. It suggests discussing anew reconstructions of early Neolithic social structures. In this article, we will summarize former theories on the emergence of leadership and hierarchies and present a multivariate model according to which anthropological and archaeological data of the burial will be analyzed. In conclusion, we surmise that early Neolithic hierarchization in southern Jordan was based on corporate pathways to power rather than self-interested aggrandizers. However, some aspects of the burial point to regional exchange networks of prestige goods, a trait considered characteristic of network based leadership. In line with anthropological and sociological research, we argue that pathways to power should be considered as relational processes that can be understood only when comparing traits of the outstanding person to her/his social environment. [ABSTRACT FROM AUTHOR]

Recent molecular systematic studies of arvicoline voles of the genera Neodon, Lasiopodomys, Phaiomys, and Microtus from Central Asia suggest the inclusion of Phaiomys leucurus, Microtus clarkei, and Lasiopodomys fuscus into Neodon and moving Neodon juldaschi into Microtus (Blanfordimys). In addition, three new species of Neodon (N. linzhiensis, N. medogensis, and N. nyalamensis) have recently been described from Tibet. Analyses of concatenated mitochondrial (Cytb, COI) and nuclear (Ghr, Rbp3) genes recovered Neodon as a well-supported monophyletic clade including all the recently described and relocated species. Kimura-2-parameter distance between Neodon from western Nepal compared to N. sikimensis (K2P = 13.1) and N. irene (K2P = 13.4) was equivalent to genetic distances observed between recognized species of this genus. The specimens sampled from western Nepal were recovered sister to N. sikimensis in the concatenated analysis. However, analyses conducted exclusively with mitochondrial loci did not support this relationship. The occlusal patterns of the first lower (m1) and third upper (M3) molars were simpler in specimens from western Nepal in comparison to N. sikimensis from eastern Nepal and India. Twelve craniodental characters and four external field measurements were examined from specimens of N. sikimensis from eastern Nepal and India, N. irene, and Neodon from western Nepal. Neodon from western Nepal were significantly different from N. sikimensis from eastern Nepal and India in ten out of 16 characters measured and from N. irene for all characters except ear height. Specimens from western Nepal were smaller in size than N. sikimensis from Eastern Nepal and India and larger than N. irene. Together the results of the molecular and morphological analyses indicate that Neodon from western Nepal are distinct under the phylogenetic, genetic and morpho species concepts. [ABSTRACT FROM AUTHOR]

Orthodontic relapse after orthodontic treatment is a major clinical issue in the dental field. However, the biological mechanism of orthodontic relapse is still unclear. This study aimed to establish a mouse model of orthodontic retention to examine how retention affects the rate and the amount of orthodontic relapse. We also sought to examine the role of osteoclastogenesis in relapse using an antibody to block the activity of M-CSF, an essential factor of osteoclast formation. Mice were treated with a nickel-titanium closed-coil spring that was fixed between the upper incisors and the upper-left first molar to move the first molar in a mesial direction over 12 days. Mice were randomly divided into three groups: group 1, no retention (G1); group 2, retention for 2 weeks (G2); and group 3, retention for 4 weeks (G3). In G2 and G3, a light-cured resin was placed in the space between the first and second molars as a model of retention. Orthodontic relapse was assessed by measuring changes in the dimensions of the gap created between the first and second molars. To assess the activity and role of osteoclasts, mice in G3 were injected with anti-c-Fms antibody or PBS, and assessed for changes in relapse distance and rate. Overall, we found that a longer retention period was associated with a slower rate of relapse and a shorter overall amount of relapse. In addition, inhibiting osteoclast formation using the anti-c-Fms antibody also reduced orthodontic relapse. These results suggest that M-CSF and/or its receptor could be potential therapeutic targets in the prevention and treatment of orthodontic relapse. [ABSTRACT FROM AUTHOR]

Nicotine is known to affect cell proliferation and differentiation, two processes vital to proper development of the mandible. The mandible, the lower jaw in mammals and fish, plays a crucial role in craniofacial development. Malformation of the jaw can precipitate a plethora of complications including disrupting development of the upper jaw, the palate, and or impeding airway function. The purpose of this study was to test the hypothesis that in utero nicotine exposure alters the development of the murine mandible in a dose dependent manner. To test this hypothesis, wild type C57BL6 mice were used to produce in utero nicotine exposed litters by adding nicotine to the drinking water of pregnant dams at concentrations of 0 μg/ml (control), 50 μg/ml (low), 100 μg/ml (medium), 200 μg/ml (high) throughout pregnancy to birth of litters mimicking clinically relevant nicotine exposures. Resultant pups revealed no significant differences in body weight however, cephalometric investigation revealed several dimensions affected by nicotine exposure including mandibular ramus height, mandibular body height, and molar length. Histological investigation of molars revealed an increase in proliferation and a decrease in apoptosis with nicotine exposure. These results demonstrate the direct effects of nicotine on the developing mandible outside the context of tobacco use, indicating that nicotine use including tobacco alternatives, cessation methods, and electronic nicotine delivering products may disrupt normal growth and development of the craniofacial complex. [ABSTRACT FROM AUTHOR]

Despite the high success rates of preformed metal crowns (PMCs) in children no randomized clinical trials compare methods of placement and none describe its use in Africa. Our aim was to compare survival and cost-effectiveness of PMCs placed by conventional techniques (CT) and biological Hall techniques (HT) using a prospective randomized control trial in a general dental practice from Khartoum. One hundred and nine and 103 PMCs were placed in randomly selected children (5-8years) with 1–2 carious primary molars using HT and CT respectively and followed for 2 years. Socioeconomic status, periodontal health, occlusion, anxiety, and procedure time were compared using student t-test. Kaplan–Meier survival rates and incremental cost effectiveness ratio (ICER) were compared between CT and HT. CT and HT groups were similar for age, gender, socio-economic status. Survival rates were high (over 90%) for both study arms and not statistically different (p>0.05). Anxiety scores were significantly higher in CT arm after 12 months compared to HT (p<0.001). Clinically, gingival and plaque indices were similar between groups (p>0.05) but occlusions were raised in nearly all subjects in the HT arm (p<0.05). Periodontal health improved, and occlusions adjusted over time in both arms. There were 3 (2.7%) and 6 (5.8%) minor failures, 7 (6.4%) and 6 (5.8%) major failures in HT and CT arms respectively. Mean procedure time was lower in HT (9.1 min) than CT (33.9 min); p<0.001. Mean PMC cost was US$2.45 and US$7.81 for HT and CT respectively. The ICER was US$136.56 more for each PMC placed by CT per life year. We show that PMCs have high survival outcomes in disadvantaged populations similar to results from developed countries. As HT can be carried out by less experienced dental operators and therapists, this biological approach provides a promising cost-effective option to manage caries in developing countries with limited resources. Trial registration: The trial is registered at clinicaltrials.gov. ClinicalTrial.gov Trial Registration: [ABSTRACT FROM AUTHOR]

Dental topography is a widely used method for quantifying dental morphology and inferring dietary ecology in animals. Differences in methodology have brought into question the comparability of different studies. Using primate mandibular second molars, we investigated the effects of mesh preparation parameters smoothing, cropping, and triangle count/mesh resolution (herein, resolution) on six topographic variables (Dirichlet normal energy, DNE; orientation patch count rotated, OPCR; relief index, RFI; ambient occlusion, portion de ciel visible, PCV; enamel surface area, SA; tooth size) to determine the effects of smoothing, cropping, and triangle count/resolution on topographic values and the relationship between these values and diet. All topographic metrics are sensitive to smoothing, cropping method, and triangle count/resolution. In general, smoothing decreased DNE, OPCR, RFI, and SA, increased PCV, and had no predictable effect on tooth size. Relative to the basin cut off (BCO) cropping method, the entire enamel cap (EEC) method increased RFI, SA, and size, and had no predictable effect on DNE and OPCR. Smoothing and cropping affected DNE/OPCR and surfaces with low triangle counts more than other metrics and surfaces with high triangle counts. There was a positive correlation between DNE/OPCR and triangle count/resolution, and the rate of increase was weakly correlated to diet. PCV tended to converge or decrease with increases in triangle count/resolution, and RFI, SA, and size converged. Finally, there appears to be no optimal triangle count or resolution for predicting diet from this sample, and constant triangle count appeared to perform better than constant resolution for predicting diet. [ABSTRACT FROM AUTHOR]

The loss of Neanderthal groups across Western and Central Europe during Oxygen Isotope Stage (OIS) 3 has held the attention of archaeologists for decades. The role that climatic change, genetic interbreeding, and interspecies competition played in the extinction of Neanderthal groups is still debated. Hohle Fels is one of several important Middle and Upper Paleolithic sites from the Ach Valley in southwestern Germany which documents the presence of Neanderthals and modern humans in the region. Chronological and stratigraphic records indicate that these two groups occupied the site with little to no overlap or interaction. This provides the opportunity to examine the behavioural variability of Swabian Neanderthal populations without the complication of cross-cultural influence. In this study we contribute a terrestrial paleoenvironmental record derived from the small mammal material from Hohle Fels Cave to the ever-growing archaeological record of this period. By reconstructing the climate and landscape of the Ach Valley during this time we can identify the effect that the OIS 3 environment had on the presence of Neanderthals in the region. Based on indicator taxa and the habitat weighing method, the small mammal record, which includes rodents, insectivores, and bats, from Hohle Fels shows that the earliest Neanderthal occupation took place on a landscape characterized by substantial woodland and forest, rivers and ponds, as well as moist meadows and grasslands. A gradual increase in cold tundra and arctic environments is clear towards the end of the Middle Paleolithic, extending to the end of the early Aurignacian which may correlate with the onset of the Heinrich 4 event (~42,000 kya). Our taphonomic analysis indicates the material was accumulated primarily by opportunistic predators such as the great grey owl, snowy owl, and European eagle owl, and therefore reflects the diversity of landscapes present around the site in the past. Importantly, at the time Neanderthals abandoned the Ach Valley we find no indication for dramatic climatic deterioration. Rather, we find evidence of a gradual cooling of the Swabian landscape which may have pushed Neanderthal groups out of the Ach Valley prior to the arrival of modern human Aurignacian groups. [ABSTRACT FROM AUTHOR]

Recently, ambient occlusion, quantified through portion de ciel visible (PCV) was introduced as a method for quantifying dental morphological wear resistance and reconstructing diet in mammals. Despite being used to reconstruct diet and investigate the relationship between dental form and function, no rigorous analysis has investigated the correlation between PCV and diet. Using a sample of platyrrhine and prosimians M2s, we show average PCV was significantly different between most dietary groups. In prosimian, insectivores had the lowest PCV, followed by folivores, omnivores, frugivores, and finally hard-object feeders. In platyrrhines, omnivores had the lowest average PCV, followed by folivores, frugivores, and finally hard-object feeders. PCV was correlated to two topographic variables (Dirichlet normal energy, DNE, and relief index, RFI) but uncorrelated to three others (orientation patch count rotated, OPCR, tooth surface area, and tooth size). The OPCR values here differed greatly from previously published values using the same sample, showing how differences in data acquisition (i.e., using 2.5D vs. 3D surfaces) can lead to drastic differences in results. Compared to other popular topographic variables, PCV performed as well or better at predicting diet in these groups, and when combined with a metric for size, the percent of successful dietary classifications reached 90%. Further, using an ontogenetic series of hominin (Paranthropus robustus) M2s, we show that PCV correlates well with probability of wear, with PCV values being higher on the portions of the occlusal surface that experience more wear (e.g., cusps and crest tips, wear facets) than the portions of the tooth that experience less. This relationship is strongest once wear facets have begun to form on the occlusal surface. These results highlight the usefulness of PCV in quantifying morphological wear resistance and predicting diet in mammals. [ABSTRACT FROM AUTHOR]

Background and objective: Gestational diabetes mellitus (GDM) is associated with short- and long-term maternal and perinatal repercussions. Our objective was to evaluate the long-term consequences of intrauterine exposure to hyperglycemia on Developmental Defects of Enamel (DDE) in offspring. Results: Overall, 50 children of women with GDM and 250 children of normoglycemic women participated, the latter serving as controls. Children were examined at the age between 3 and 12 years. In addition to physical examination, two independent observers examined and rated photographs to identify specific types of DDE in a blinded fashion. Among offspring of mothers with GDM, rates of DDE (all types combined) and hypoplasia (specific type) were significantly higher (p<0.001, p = 0.04), in comparison to offspring of normoglycemic mothers. Considering only the affected teeth (1060 in GDM category; 5499 in controls), rates of DDE (all types combined) were significantly higher for total teeth (p <0.001) and deciduous teeth (p<0.001), but not permanent teeth. In specific types of DDE involving deciduous teeth, rates of demarcate opacity were significantly higher (p<0.001; canine and 2nd mandibular molars) and hypoplasia (p <0.001; 2nd maxillary molars and 2nd mandibular molars). In permanent teeth, the rate of diffuse opacity in association with GDM was significantly higher (p<0.001; maxillary central incisors and 1st maxillary molars). Conclusion: GDM was associated with the adverse effects of DDE on offspring. This study lays the foundation for future studies to determine the impact of GDM on long-term risk of DDE. [ABSTRACT FROM AUTHOR]

Introduction: The study aimed to evaluate, through in vivo tomographic analysis, the prevalence of C-shaped canals in mandibular first and second molars of Brazilian individuals, analyzing its frequency by thirds of the roots, and in contralateral teeth. Methods: Images of 801 mandibular molars (379 first molars and 422 second molars) from 334 Brazilian individuals (142 men and 192 women) were identified through 1544 cone beam computed tomography (CBCT) exams, obtained from a private oral radiologic clinic. The cross-sectional configurations were analyzed to determine the frequency of C-shaped canals at three different axial levels and classified in categories by three experienced endodontists independently. Results: The incidence of C-shaped canals was 181 (23%). Considering the type of tooth, 91 (24.01%) were identified in the first molars, and 90 (21.32%) were found in the second molars. The incidence was significantly higher in female individuals (P < 0.05) for both first and second molars. The most common C-shaped canal configurations were: C1 (89.01% for first molars and 90% second molars), followed by C2 (8.79% for first molars and 6.66% for second molars) and C4 (2.19% for the first molars and 3.33% for the second molars). Bilateral C-shaped canals were significantly higher than unilateral for both first and second molars (P < 0.01). Conclusions: The prevalence of C-shaped canals in mandibular molars of the Brazilian individuals was higher than previously reported for both mandibular first (24.01%) and second molars (21.32%). The incidence was significantly higher in female individuals and the coronal portion of the roots. The classic C-shaped format “C1” was the most frequent anatomical configuration. Furthermore, the prevalence of bilateral C-shaped canals was higher for the first molar (61.70%) and lower for the second molar (38.29%). [ABSTRACT FROM AUTHOR]

Osteonecrosis of the jaw induced by administration of bisphosphonates (BPs), BP-related osteonecrosis (BRONJ), typically develops after tooth extraction and is medically challenging. As BPs inhibit oral mucosal cell growth, we hypothesized that suppression of the wound healing-inhibiting effects could prevent BRONJ onset after tooth extraction. Since basic fibroblast growth factor (bFGF) promotes wound healing, but has a short half-life, we examined whether the initiation of BRONJ could be prevented by applying a bFGF-containing gelatin hydrogel over the extraction sockets of BRONJ model rats. Forty-three rats, received two intravenous injections of zoledronic acid 60 μg/kg, once per week for a period of 2 weeks, underwent extraction of a unilateral lower first molar. The rats here were randomly assigned to the bFGF group (n = 15 rats, gelatin hydrogel sheets with incorporated bFGF applied over the sockets); the phosphate-buffered saline (PBS) group (n = 14 rats, gelatin hydrogel sheets without bFGF applied over the sockets); or the control group (n = 14 rats, nothing applied over the sockets). One rat in the bFGF group was sacrificed immediately after tooth extraction. Twenty-one rats were sacrificed at 3 weeks, and the remaining 21 rats were sacrificed at 8 weeks after tooth extractions. The harvested mandibles were analyzed using micro-computed tomography and sections were evaluated qualitatively for mucosal disruption and osteonecrosis. The incidence of osteonecrosis at 8 weeks after tooth extraction was 0% in the bFGF group, 100% in the PBS group, and 85.7% in the control group. The frequency of complete coverage of the extraction socket by mucosal tissue was significantly greater in the bFGF group than in the other groups. These results suggest that application of bFGF in the extraction socket promoted socket healing, which prevented BRONJ development. The growth-stimulating effects of bFGF may have offset the inhibition of wound healing by BP. [ABSTRACT FROM AUTHOR]

Background: International guidelines on the prevention of caries recommend sealing of the pits and fissures of the permanent molars. There is no evidence on which type of material is most effective on demineralized enamel. Aim: To evaluate the microleakage of a conventional light-cured, resin-based fissure sealant (LCRBS), GrandiO Seal, and a resin-modified glass ionomer sealant (RMGIS), Vitremer, after application of a fluoride varnish, Bifluorid 12, on demineralized enamel. Design: 80 human third molars were divided into eight groups. The groups combined the three study factors (1) type of enamel (intact or demineralized); (2) enamel non-varnished or varnished with Biflourid12; and (3) type of sealant (GrandiO Seal or Vitremer). The percentage of microleakage after thermocycling was measured using imaging analysis software. The Kruskal-Wallis plus Dunn tests were used to compare differences in microleakage in the different groups. Results: The lowest microleakage was in the unvarnished groups, and was the same for GrandiO Seal and Vitremer. When varnish was applied, microleakage was greater in demineralized enamel than in intact enamel for both LCRBS and RMGIS. Conclusion: The application of fluoride varnish on demineralized enamel increases the microleakage of both GrandiO Seal and Vitremer. [ABSTRACT FROM AUTHOR]

Although genes on the human X chromosome reportedly influence tooth crown morphology, little is known about X chromosome activation or inactivation systems relevant to morphological variations. We assessed the relationships between tooth crown size and crown morphological traits in females with Turner syndrome, the variants of which include complete absence of one X chromosome, lack of the short arm (Xp), or duplication of the long arms (Xq), and then estimated the functions of Xp and Xq in the process of unilateral X chromosome inactivation during tooth crown development. The mesiodistal and buccolingual diameters in the maxillary first (M1) and second (M2) permanent molars were compared among X chromosome karyotypes by multiple regression analyses, and their relationships with the development of Carabelli’s cusp and the distolingual cusp were analyzed using logistic regression analysis. The crown sizes increased in the order of the 46,X,i(Xq) karyotype, 45,X and 45,X/46,XX karyotypes, and control group. A lower frequency of Carabelli’s cusp and higher frequency of a reduced distolingual cusp in M1 were characteristics of Turner syndrome. The overall M1 and M2 crown sizes differed among the X chromosome karyotypes, whereas a smaller crown size was associated with a reduced distolingual cusp but not with Carabelli’s cusp. Considering the differences in chromosome arrangement among females with Turner syndrome and the process of unilateral X chromosome inactivation, the observed results can be considered in terms of quantity or number of promoters/inhibitors during tooth crown development. The X chromosome karyotypes have a strong influence on the overall crown sizes of the M1 and M2 molars because those karyotypes with variable numbers of active gene regions directly influence tooth germ development in an early stage of human odontogenesis. The later forming cusps, such as the distolingual cusp and Carabelli’s cusp, may be affected by this developmental prerequisite. [ABSTRACT FROM AUTHOR]

Island biotas have disproportionately influenced the history and development of evolutionary biology, but understanding their genesis and evolution across geological timescales has been hindered by a poor fossil record. Here we augment the insular Eocene (~43 Ma) mammalian fauna known from the Pontide terrane of central Anatolia by describing two new metatherian taxa (stem marsupials) from the Lülük Member of the Uzunçarşıdere Formation in the Orhaniye Basin. Geological and paleontological data indicate that the Pontide terrane was an island on the northern margin of Neotethys during the middle Eocene. Reflecting its geodynamic context in a region of active tectonic convergence, the Eocene Pontide terrane hosted a unique combination of Laurasian and Gondwanan mammals, including an anachronistic radiation of pleuraspidotheriids (archaic ungulates) that went extinct on the European mainland ~13 Ma earlier. Most of the mammalian clades occupying the Pontide terrane colonized it by dispersal across marine barriers rather than being stranded there through vicariance. Endemic radiations of pleuraspidotheriid ungulates and polydolopimorphian metatherians on the Pontide terrane reveal that in situ diversification was an important factor contributing to faunal assembly and evolution. The insular fauna that arose on the Pontide terrane is highly analogous to that of modern Sulawesi, which evolved under strikingly similar geological conditions. Illustrating the ephemeral nature of insular biotas across macroevolutionary timescales, the demise of the Pontide fauna coincided with paleogeographic changes enabling more cosmopolitan taxa to reach it for the first time. The high level of endemism shown by the mammalian fauna of the Uzunçarşıdere Formation eliminates the Pontide terrane as a potential early Eocene dispersal corridor between western Europe and India. [ABSTRACT FROM AUTHOR]

Hominoid remains from Miocene deposits in India and Pakistan have played a pivotal role in understanding the evolution of great apes and humans since they were first described in the 19th Century. We describe here a hominoid maxillary fragment preserving the canine and cheek teeth collected in 2011 from the Kutch (= Kachchh) basin in the Kutch district, Gujarat state, western India. A basal Late Miocene age is proposed based on the associated faunal assemblage that includes Hipparion and other age-diagnostic mammalian taxa. Miocene Hominoidea are known previously from several areas of the Siwalik Group in the outer western Himalayas of India, Pakistan, and Nepal. This is the first record of a hominoid from the Neogene of the Kutch Basin and represents a significant southern range extension of Miocene hominoids in the Indian peninsula. The specimen is assigned to the Genus Sivapithecus, species unspecified. [ABSTRACT FROM AUTHOR]

This study further investigated the mechanisms underlying the rat model of tooth pulp inflammatory pain elicited by complete Freund’s adjuvant (CFA), in comparison to other pulpitis models. Pulps of the left maxillary first molars were accessed. In the CFA group, the pulps were exposed, and CFA application was followed by dental sealing. In the open group, the pulps were left exposed to the oral cavity. For the closed group, the pulps were exposed, and the teeth were immediately sealed. Naïve rats were used as negative controls. Several parameters were evaluated at 1, 2, 3 and 8 days. There was no statistical significant difference among the groups when body weight variation, food or water consumption were compared. Analysis of serum cytokines (IL-1β, TNF or IL-6) or differential blood cell counts did not reveal any evidence of systemic inflammation. The CFA group displayed a significant reduction in the locomotor activity (at 1 and 3 days), associated with an increased activation of satellite glial cells in the ipsilateral trigeminal ganglion (TG; for up to 8 days). Amygdala astrocyte activation was unaffected in any experimental groups. We provide novel evidence indicating that CFA-induced pulp inflammation impaired the locomotor activity, with persistent activation of ipsilateral TG satellite cells surrounding sensory neurons, without any evidence of systemic inflammation or amygdala astrogliosis. [ABSTRACT FROM AUTHOR]

Scholars have debated the taxonomic identity of isolated primate teeth from the Asian Pleistocene for over a century, which is complicated by morphological and metric convergence between orangutan (Pongo) and hominin (Homo) molariform teeth. Like Homo erectus, Pongo once showed considerable dental variation and a wide distribution throughout mainland and insular Asia. In order to clarify the utility of isolated dental remains to document the presence of hominins during Asian prehistory, we examined enamel thickness, enamel-dentine junction shape, and crown development in 33 molars from G. H. R. von Koenigswald's Chinese Apothecary collection (11 Sinanthropus officinalis [= Homo erectus], 21 “Hemanthropus peii,” and 1 “Hemanthropus peii” or Pongo) and 7 molars from Sangiran dome (either Homo erectus or Pongo). All fossil teeth were imaged with non-destructive conventional and/or synchrotron micro-computed tomography. These were compared to H. erectus teeth from Zhoukoudian, Sangiran and Trinil, and a large comparative sample of fossil Pongo, recent Pongo, and recent human teeth. We find that Homo and Pongo molars overlap substantially in relative enamel thickness; molar enamel-dentine junction shape is more distinctive, with Pongo showing relatively shorter dentine horns and wider crowns than Homo. Long-period line periodicity values are significantly greater in Pongo than in H. erectus, leading to longer crown formation times in the former. Most of the sample originally assigned to S. officinalis and H. erectus shows greater affinity to Pongo than to the hominin comparative sample. Moreover, enamel thickness, enamel-dentine junction shape, and a long-period line periodicity value in the “Hemanthropus peii” sample are indistinguishable from fossil Pongo. These results underscore the need for additional recovery and study of associated dentitions prior to erecting new taxa from isolated teeth. [ABSTRACT FROM AUTHOR]

Categorizing the archaeological remains of Sus scrofa as domesticated “pigs” or wild “boars” is often difficult because of their morphological and genetic similarities. For this purpose, we tested whether feeding ecological change of S. scrofa that accompanied their domestication can be detected based on the three-dimensional texture created on the tooth enamel surface by mastication. We scanned the lower tooth surface of one wild and one stall-fed populations of modern S. s. leucomystax and one wild population of S. s. riukiuanus by using a confocal laser microscope. The average body weight of S. s. leucomystax is twice as heavier as that of S. s. riukiuanus. The textures were quantified using the industrial “roughness” standard, ISO 25178, to prevent inter-observer errors and to distinguish small differences that were difficult to detect by two dimensional image observation. The values of parameters related to height and volume were significantly larger in the stall-fed population. Twenty parameters differed significantly between the stall-fed and wild population of S. s. leucomystax, which indicated that the feeding ecological difference affected the ISO parameters of the two boar populations. Six parameters also differed between the wild populations of S. s. leucomystax and S. s. riukiuanus. Surprisingly, no parameter differed between the populations of stall-fed S. s. leucomystax and wild S. s. riukiuanus. Consumption of hard nuts and/or agricultural fruits and crops by the wild population of S. s. riukiuanus may have produced a tooth surface texture similar to that of the stall-fed population of S. s. leucomystax. Further analysis of S. s. riukiuanus with a known diet is necessary to conclude whether ISO parameters reflect the dietary transition accompanying the domestication of Sus (e.g., wild, semi-domestic, and domestic). Until then, caution is needed in discriminating domesticated populations from wild populations that mainly feed on hard objects. [ABSTRACT FROM AUTHOR]

Tooth crown tissue proportions and enamel thickness distribution are considered reliable characters for inferring taxonomic identity, phylogenetic relationships, dietary and behavioural adaptations in fossil and extant hominids. While most Pleistocene hominins display variations from thick to hyper-thick enamel, Neanderthals exhibit relatively thinner. However, the chronological and geographical origin for the appearance of this typical Neanderthal condition is still unknown. The European late Early Pleistocene species Homo antecessor (Gran Dolina-TD6 site, Sierra de Atapuerca) represents an opportunity to investigate the appearance of the thin condition in the fossil record. In this study, we aim to test the hypothesis if H. antecessor molars approximates the Neanderthal condition for tissue proportions and enamel thickness. To do so, for the first time we characterised the molar inner structural organization in this Early Pleistocene hominin taxon (n = 17) and compared it to extinct and extant populations of the genus Homo from African, Asian and European origin (n = 355). The comparative sample includes maxillary and mandibular molars belonging to H. erectus, East and North African Homo, European Middle Pleistocene Homo, Neanderthals, and fossil and extant H. sapiens. We used high-resolution images to investigate the endostructural configuration of TD6 molars (tissue proportions, enamel thickness and distribution). TD6 permanent molars tend to exhibit on average thick absolute and relative enamel in 2D and 3D estimates, both in the complete crown and the lateral enamel. This condition is shared with the majority of extinct and extant hominin sample, except for Neanderthals and some isolated specimens. However, while the total crown percentage of dentine in TD6 globally resembles the low modern values, the lateral crown percentage of dentine tends to be much higher, closer to the Neanderthal signal. Similarly, the H. antecessor molar enamel distribution maps reveal a relative distribution pattern that is more similar to the Neanderthal condition (with the thickest enamel more spread at the periphery of the occlusal basin) rather than that of other fossil specimens and modern humans (with thicker cuspal enamel). Future studies on European Middle Pleistocene populations will provide more insights into the evolutionary trajectory of the typical Neanderthal dental structural organization. [ABSTRACT FROM AUTHOR]

The penecontemporaneous Middle Pleistocene sites of Fontana Ranuccio (Latium) and Visogliano (Friuli-Venezia Giulia), set c. 450 km apart in central and northeastern Italy, respectively, have yielded some among the oldest human fossil remains testifying to a peopling phase of the Italian Peninsula broadly during the glacial MIS 12, a stage associated with one among the harshest climatic conditions in the Northern hemisphere during the entire Quaternary period. Together with the large samples from Atapuerca Sima de los Huesos, Spain, and Caune de l’Arago at Tautavel, France, the remains from Fontana Ranuccio and Visogliano are among the few mid-Middle Pleistocene dental assemblages from Western Europe available for investigating the presence of an early Neanderthal signature in their inner structure. We applied two- three-dimensional techniques of virtual imaging and geometric morphometrics to the high-resolution X-ray microtomography record of the dental remains from these two Italian sites and compared the results to the evidence from a selected number of Pleistocene and extant human specimens/samples from Europe and North Africa. Depending on their preservation quality and on the degree of occlusal wear, we comparatively assessed: (i) the crown enamel and radicular dentine thickness topographic variation of a uniquely represented lower incisor; (ii) the lateral crown tissue proportions of premolars and molars; (iii) the enamel-dentine junction, and (iv) the pulp cavity morphology of all available specimens. Our analyses reveal in both samples a Neanderthal-like inner structural signal, for some aspects also resembling the condition shown by the contemporary assemblage from Atapuerca SH, and clearly distinct from the recent human figures. This study provides additional evidence indicating that an overall Neanderthal morphological dental template was preconfigured in Western Europe at least 430 to 450 ka ago. [ABSTRACT FROM AUTHOR]

Skulls of 1,901 Eastern Atlantic harbor seals (Phoca vitulina vitulina) were systematically studied for externally visible dental anomalies and lesions. The sample comprised 927 males and 974 female individuals, with age at death ranging between 1 week and 25 years. Most of the skulls originated from animals collected in 1988, when the population suffered from a mass mortality event caused by the phocine distemper virus (PDV). Mean age (± SD) of females (6.7 ± 6.4 years) was higher (p = 0.002) than that of males (5.9 ± 5.2 years). In 264 individuals, one or more teeth were missing either congenitally (n = 26 animals, 1.4%) or due to intravital loss (n = 238 animals, 12.5%). One male exhibited congenital absence of all teeth (anodontia). As this animal had been reported to be almost hairless, the condition was tentatively diagnosed as a case of hypohidrotic ectodermal dysplasia. Males were more frequently (p = 0.002) affected by intravital tooth loss (15.0%) than females (10.2%). Supernumerary teeth were found in 3.4% of the skulls, with females (4.7%) showing hyperodontia more frequently (p < 0.001) than males (1.9%). Fifty-nine individuals (3.1%; 28 males, 31 females, p = 0.84) exhibited abnormal tooth morphology. Tooth fractures were noted in 40 seals (2.1%), with males being more frequently affected than females (p = 0.017). Periapical lesions were diagnosed in 143 skulls, with a tendency (p = 0.05) for males (8.7%) to be more frequently affected than females (6.4%). Enamel hypoplasia was not observed in the study sample. Analyzing the occurrence of dental anomalies and lesions in wild mammals can substantially contribute to an assessment of population health and thereby broaden the basis for effective species conservation and informed management decisions. [ABSTRACT FROM AUTHOR]

This methodology permits to simulate the performance of different Poly(D,L-lactide-co-glycolide) copolymer formulations (PDLGA) in the human body, to identify the more influencing variables on hydrolytic degradation and, thus, to estimate biopolymer degradation level. The PDLGA characteristic degradation trends, caused by hydrolysis processes, have been studied to define their future biomedical applications as dental scaffolds. For this purpose, the mass loss, pH, glass transition temperature (Tg) and absorbed water mass of the different biopolymers have been obtained from samples into a phosphate-buffered saline solution (PBS) with initial pH of 7.4, at 37°C (human body conditions). The mass loss has been defined as the variable that characterize the biopolymer degradation level. Its dependence relationship with respect to time, pH and biopolymer formulation has been modelled using statistical learning tools. Namely, generalized additive models (GAM) and nonlinear mixed-effects regression with logistic and asymptotic functions have been applied. GAM model provides information about the relevant variables and the parametric functions that relate mass loss, pH and time. Mixed effects are introduced to model and estimate the degradation properties, and to compare the PDLGA biopolymer populations. The degradation path for each polymer formulation has been estimated and compared with respect to the others for helping to use the proper polymer for each specific medical application, performing selection criteria. It was found that the mass loss differences in PDLGA copolymers are strongly related with the way the pH decay versus time, due to carboxylic acid groups formation. This may occur in those environments in which the degradation products remain relatively confined with the non degraded mass. This is the case emulated with the present experimental procedure. The results show that PDLGA polymers degradation degree, in terms of half life and degradation rate, is increasing when acid termination is included, when DL-lactide molar ratio is reduced, decreasing the midpoint viscosity, or when glycolide is not included. [ABSTRACT FROM AUTHOR]

Statement of problem: Although there are specific and general digital scanning guidelines depending on the system used, it is important to have the necessary flexibility in the acquisition of three-dimensional (3D) images to adapt to any clinical situation without affecting accuracy. Purpose: The purpose of this in vitro study was to identify and compare the scanning strategy with the greatest accuracy, in terms of trueness and precision, of four intraoral scanners in the impression of a complete dental arch. Material and methods: Four digital scanners were evaluated with a 3D measuring software, using a highly accurate reference model obtained from an industrial scanner as a comparator. Four scanning strategies were applied 10 times on a complete maxillary arch cast inside a black methacrylate box. The data were statistically analyzed using one-way analysis of variance (ANOVA) and post hoc comparisons with Tamhane T2 test. Results: The trueness of the Trios and iTero system showed better results with strategy “D,” Omnicam with strategy “B,” and True Definition with strategy “C”. In terms of precision, both iTero and True Definition showed better results with strategy “D”, while Trios showed best results with strategy “A” and Omnicam with strategy “B”. There were significant differences between the scanning strategies (p<0.05) with the iTero scanner, but not with the other scanners (p>0.05). Conclusions: The digital impression systems used in the experiment provided sufficient flexibility for the acquisition of 3D images without this affecting the accuracy of the scanner. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the performance of two different models of smartphone and a conventional camera with that of direct clinical examination in detecting caries lesions at different stages of progression in deciduous molars. The photographic equipment consisted of two smartphones (iPhone and Nexus 4) and a conventional macro camera setup. First, in the laboratory phase of the study, we compared the images of 20 exfoliated primary teeth having caries lesions at different stages. Then, in the clinical phase of the study, the images of 119 primary molars from fifteen children (3 to 6 years old) were used. All of the photographic images were taken using the previously described devices. In both groups, two examiners, blinded to the photographic equipment used, assessed the images independently on a computer screen, and classified them according to the International Caries Detection and Assessment System (ICDAS). The teeth were then examined directly by two other experienced examiners, and the consensus reached was considered the reference standard. Parameters of validity, such as percentage of correct answers, agreement with the reference standard, sensitivity, specificity and inter-examiner agreement (using the weighted kappa test) were calculated. The examiners performed similarly in both in vitro and in vivo studies. Inter-examiner reliability was approximately 0.7 for all the devices in the laboratory setting, and for the macro camera photography system in the clinical setting, but it was approximately 0.9 for the iPhone and Nexus images taken in vivo. With regard to the percentage of correct answers, the highest values were observed for sound and extensive caries lesions in both laboratory and clinical settings. The percentage of correct answers for initial and moderate lesions was particularly low in the clinical evaluation, irrespective of the camera devices used. Therefore, we concluded that photographic diagnosis using smartphone images is feasible and accurate for distinguishing sound tooth surfaces from extensive caries lesions; however, photographic images are not a good method for accurately detecting initial and moderate caries lesions. [ABSTRACT FROM AUTHOR]

Periptychus is the archetypal genus of Periptychidae, a clade of prolific Paleocene ‘condylarth’ mammals from North America that were among the first placental mammals to radiate after the end-Cretaceous extinction, remarkable for their distinctive dental anatomy. A comprehensive understanding of the anatomy of Periptychus has been hindered by a lack of cranial and postcranial material and only cursory description of existing material. We comprehensively describe the cranial, dental and postcranial anatomy of Periptychus carinidens based on new fossil material from the early Paleocene (Torrejonian) of New Mexico, USA. The cranial anatomy of Periptychus is broadly concurrent with the inferred plesiomorphic eutherian condition, albeit more robust in overall construction. The rostrum is moderately elongate with no constriction, the facial region is broad, and the braincase is small with a well-exposed mastoid on the posterolateral corner and tall sagittal and nuchal crests. The dentition of Periptychus is characterized by strongly crenulated enamel, enlarged upper and lower premolars with a tall centralised paracone/protoconid. The postcranial skeleton of Periptychus is that of a robust, medium-sized (~20 Kg) stout-limbed animal that was incipiently mediportal and adopted a plantigrade stance. The structure of the fore- and hindlimb of Periptychus corresponds to that of a typically terrestrial mammal, while morphological features of the forelimb such as the low tubercles of the humerus, long and prominent deltopectoral crest, pronounced medial epicondyle, and hemispherical capitulum indicate some scansorial and/or fossorial ability. Most striking is the strongly dorsoplantarly compressed astragalus of Periptychus, which in combination with the distal crus and calcaneal morphology indicates a moderately mobile cruropedal joint. The anatomy of Periptychus is unique and lacks any extant analogue; it combines a basic early placental body plan with numerous unique specializations in its dental, cranial and postcranial anatomy that exemplify the ability of mammals to adapt and evolve following catastrophic environmental upheaval. [ABSTRACT FROM AUTHOR]

Background: We have synthesized a sustained-release lidocaine sheet (SRLS) using biodegradable polymers and previously demonstrated its safety and long-term analgesic effect in the normal mucous membrane of healthy human volunteers. Objectives: The aim of this clinical study was to evaluate the efficacy, safety, and appropriate dose of the SRLS for pain following tooth extraction. Design: Randomized, single-blind, dose-response, controlled, clinical study (Phase 1/2). Methods: The patients in this trial were enrolled between January 2014 and December 2016. A total of 99 patients were randomly divided into 5 groups as follows: the Non-administration group received the conventional extraction; the Poly Lactic-co-Glycolic Acid (PLGA) 100 mg control group received the PLGA matrix without lidocaine; the SRLS 100 mg group received a single sheet of SRLS 100 mg; the SRLS 200 mg group received double sheets of SRLS 100 mg; and the SRLS 400 mg administration group received four sheets of SRLS 100 mg. A study drug was inserted into the defect socket after the extraction, and postoperative pain intensity, satisfaction with postoperative pain relief, adverse events, and postoperative supplemental analgesic rescue use (time, dose) were investigated by patient self-report. Results: In total, 94 (94.9%) patients completed the study. There were no significant differences in postoperative pain intensity, satisfaction with postoperative pain relief, and postoperative supplemental analgesic rescue use among the 5 groups. There were no serious side effects, including a plasma concentration increase of lidocaine, attributable to the SRLS. Conclusions: Administration of the SRLS at 100 mg may have clinical therapeutic potential for pain relief following tooth extraction. The safety of the SRLS for patients undergoing tooth extraction was demonstrated. Trial registration: The University Hospital Medical Information Network [ABSTRACT FROM AUTHOR]