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Purpose: This study investigated the influence of different palatal morphologies on the accuracy of intraoral scanning (TRIOS 4) of edentulous maxillae., Methods: Six typodonts were fabricated for different palatal morphologies with flat (F), medium (M), and deep (D) palates, with palatal wrinkles (W), or smooth palates (S), resulting in six groups: WF, WM, WD and SF, SM, SD. Ten scans were performed for each group; standard tessellation language files obtained were imported into a software to measure trueness and precision in micrometer. Trueness was calculated as the mean of the standard deviation values obtained by superimposing each scan onto the reference scan. Precision was achieved by overlapping each scan with that with the best trueness in the group. Descriptive and post-hoc analyses were conducted., Results: The mean values for trueness were as follows: WM=48.7±4.7, WD=161.7±18.4, WF=85.9±16, SM=48.1±2.4, SD=349.9±8.8, and SF=349.1±25.5. The precision values were as follows: WM=46.7±7.3, WD=46.9±9, WF=48.9±6.7, SM=46±2.7, SD=105.9±17.4, SF=72.6±10.8. Significant differences were observed for trueness between SM and SD (P < 0.001), SM and SF (P < 0.001), and WF and SF (P = 0.003); whereas for precision, significant differences were reported between WD and SD (P = 0.015). Regarding trueness and precision, no difference was found between WM and SM (P = 1.0)., Conclusions: Medium palatal depth showed the best accuracy. The mean accuracy values were within the clinical acceptability thresholds for all palatal morphologies. The presence of rugae improved the precision of deeper palates and the trueness of flat palates. No differences were observed in the medium palates with or without rugae.

Background: In edentulous jaws, factors such as the number of implants, cross-arch distribution, and the angle among implants may affect the accuracy of the implant impression. This study explored factors influencing the accuracy of implant abutment-level digital impressions using stereophotogrammetry in edentulous jaws., Methods: Two standard all-on-4 and all-on-6 models of edentulous jaws were constructed in vitro. In the stereophotogrammetry group (PG), the implant digital impression was made using stereophotogrammetry and saved as an STL file. In the conventional group (CNV), the impression was made using the open-tray splint impression technique. An electronic and optical 3D measuring instrument was used to scan the standard model and the conventional plaster model to obtain STL files. Using 3D data processing software (GOM Inspect Pro, Zeiss), the distance and angle between the abutments in the CNV impression and the PG impression were measured and compared with the data from the standard model., Results: The distance deviation in the PG and the CNV was 145 ± 196 μm and 96 ± 150 μm, respectively, with a significant difference (P < 0.001). The angle deviation in the PG and the CNV was 0.82 ± 0.88° and 0.74 ± 0.62°, respectively, with no significant difference (P = 0.267). In the PG, the distance deviation was negatively correlated with the distance between implants (r = -0.145, P = 0.028) and positively correlated with the angle of implants (r = 0.205, P = 0.002). The angle deviation was negatively correlated with the distance between implants (r = -0.198, P = 0.003) and positively correlated with the angle of implants (r = 0.172, P = 0.009). In the CNV, the effect of inter-implant distance on impression accuracy was also shown by Spearman correlation analysis: r = 0.347 (P < 0.001) for distance deviation and r = -0.012 (P = 0.859) for angle deviation. The effect of inter-implant angulation on impression accuracy deviation was r = -0.026 (P = 0.698) for distance deviation and r = 0.056 (P = 0.399) for angle deviation., Conclusions: The CNV method is closer to the real value of the original model. The distance between implants and the distribution angle had a weak correlation with the accuracy of digital impressions but no significant correlation with the accuracy of traditional impressions., (© 2024. The Author(s).)

Aims: This cross-sectional retrospective study was conducted to assess the differences in the microarchitecture of the trabecular bone of the posterior mandibular region at dentulous and edentulous sites with the help of fractal dimension (FD) and lacunarity using cone-beam computed tomography (CBCT)., Materials and Methods: Ninety CBCT scans were analyzed for the purpose of the present study. Inclusion criteria included subjects with unilaterally missing mandibular molars or premolars and an with intact contralateral opposing tooth. The coronal view of the dentulous and edentulous sites was used, and the region of interest (ROI) was selected 2.6 mm below the apex of the tooth present. These images were then transferred to ImageJ Software, and fractal analysis was done using the box-counting method of the FracLac plug-in. A paired samples t -test was performed to compare the means of FD and lacunarity, and a Kendall correlation was performed to check correlations. A p -value less than 0.05 was considered to indicate statistical significance., Results: Statistical analysis revealed that the mean FD of the edentulous side was significantly greater than that of the dentulous side ( p -value = 0.011). Additionally, the mean lacunarity of the edentulous side was marginally significantly greater than that of the dentulous side ( p -value = 0.089). A significant negative correlation was detected between the FD and lacunarity of the edentulous region ( p -value = 0.017), and a marginally significant negative correlation was detected between edentulous lacunarity and dentulous lacunarity ( p -value = 0.081)., Conclusion: The differences in occlusal forces exerted in dentulous and edentulous regions can lead to a change in the trabecular pattern of the bone in these regions. This change in the microarchitecture of bones can be detected by FD and lacunarity, which can further help us assess changes pre- and post-implant., Clinical Significance: The advanced technology, the assessment of microarchitecture of the bone has been made easy, using FD and lacunarity, as done in the present study. This analysis can further aid us in both pre- and post-implant analysis to prevent failure of the implant. How to cite this article: Bhoraskar M, Denny C, Srikant N, et al. Fractal Dimension and Lacunarity Analysis in the Dentulous and Edentulous Mandibular Posterior Region Using Cone-beam Computed Tomography: A Cross-sectional Retrospective Study. J Contemp Dent Pract 2024;25(6):581-587.

Objectives: To evaluate in the absence of teeth the variability of the mylohyoid line (ML), the microarchitecture of the adjacent bone, and whether the variable prominence/width of the ML is associated with the quality of the adjacent bone., Methods: µCT scans of 28 human mandibles from anatomical specimens were analyzed. The following parameters were assessed in four edentulous areas (first and second premolar (PM), first, second, and third molar (M1/2/3)): ML width, cortical thickness (CtTh), average cortical- (Avg.Ct.BV/TV), and trabecular bone volume fraction (Avg.Tb.BV/TV)., Results: The ML width increased from the PM towards the M2 region, which also showed the highest variance (range: 0.4-10.2 mm). The CtTh showed a decrease in the M3 region, while Avg.Ct.BV/TV and Avg.Tb.BV/TV hardly differed among the regions. In the multivariable model on the effect of the various parameters on the ML width, only gender and tooth region were significant. Specifically, male specimens were associated with a wider ML width compared to female specimens and the M2 region was associated with a wider ML width compared to the other tooth regions., Conclusion: The ML width was not associated with the cortical and trabecular bone quality in the adjacent bone, while gender and tooth region had a significant effect. Specifically, the ML width was lower in female, but peaked in the M2 region with a median width of 3-4 mm., Clinical Relevance: From a clinical point of view, it was confirmed that the ML is in general a highly variable structure, especially in the M2 region, but the ML width does not allow any conclusions on the bone quality. Altogether, this underlines the need for an individual and accurate diagnostic prior to any surgical intervention., (© 2024. The Author(s).)

The purpose of this systematic review was to define the effectiveness of palatally positioned dental implants placed in atrophic maxillae. Searches were performed in five databases including the gray literature, up to August 2021, by 2 independent reviewers, in order to answer the following research question: Is the palatal approach technique effective in the rehabilitation of atrophic maxillae? In the initial search, 1948 articles were found and after applying the inclusion and exclusion criteria, five studies were selected, none of which was a randomized clinical trial. A total of 681 implants were placed, 549 of them with a palatal approach and 132 at the alveolar crest, with an effectiveness of 98.38% and 99.5%, respectively, with no statistically significant difference between the groups. In assessing the risk of bias, only one of the studies had a low risk of bias. Implants installed with the palatal approach technique showed high effectiveness for rehabilitation of atrophic maxilla; however, few studies in the literature report this technique, requiring more controlled studies, and with less risk of bias, to confirm the results obtained in this systematic review., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Introduction and Objective: Zygomatic implants (ZI) offer a good and predictable alternative to reconstructive procedures of atrophic maxillae. The main objetive of this systematic review was to assess the effect of rehabilitation with zygomatic implants on patient's quality of life (QLP) using Patient Reported Outcomes Measures (PROMs). Materials and Methods: This review followed PRISMA guidelines. An automated electronic search was conducted in four databases supplemented by a manual search for relevant articles published until the end of January 2021. The Cochrane Collaboration Risk of Bias tool and the Newcastle-Ottawa Quality Assessment Scale were used to assess the quality of evidence in the studies reviewed. Results: General findings of this systematic review showed substantial increases in Oral health-related quality of life (OHRQoL) among patients restored with ZI and high scores in terms of general satisfaction, especially in chewing ability and esthetics. An overall survival rate of ZI was 98.3% after a mean follow-up time of 46.5 months was observed. Occurrence of 13.1% biological complications and 1.8% technical complications were reported. Conclusions: Patients rehabilitated with zygomatic implant-supported complete dental prostheses showed substantial improvements in OHRQoL and general satisfaction with the treatment received.

Purpose: Implant-supported prosthetic rehabilitation in the resorbed maxilla is a great challenge. The aim of this study was to determine the survival rate of conventional anterior implants placed in combination with zygomatic implants according to the Brånemark technique, and to identify risk factors for implant failure., Methods: We collected data retrospectively from 72 consecutive patients who received treatment from 1998 to 2018 at our center, according to Brånemark's original technique. Kaplan-Meier analysis was conducted to assess survival rate, and a survival regression model was used with the patient as the random factor, applying the Weibull distribution., Results: A total of 236 maxillary anterior implants were included, with a mean follow-up of 12.1 years. Kaplan-Meier analysis showed overall cumulative survival rates of 95.3% at 1 year, 94.8% at 2 years, 93.0% at 5 years, 90.5% at 10 years, 81.6% at 15 years, and 67.7% at 20 years. Survival regression showed an association between bruxism and implant failure as well as implants bearing an overdenture. Implants with length ≤ 10 mm had a significantly lower survival time. No significant association was found between the number of anterior implants and survival rate., Conclusions: We found acceptable long-term anterior conventional implant survival. Significant risk factors for failure were bruxism, overdentures, and implants shorter than 10 mm., (© 2022. The Author(s).)

Subperiosteal implants represent an alternative implant approach for cases with severe bone atrophy. Although some successful clinical cases have been reported, the biomechanical stability of subperiosteal implants remains unclear, and more data are needed to confirm the feasibility of this approach. Therefore, this study investigated the biomechanical characteristics of subperiosteal implants based on histological observation, clinical cases, and finite element analysis. Finite element analysis indicated that subperiosteal implants with a lattice-like structure could better disperse the stress to the underlying bone surface. A novel customized subperiosteal implant was then digitally designed and fabricated using an additive manufacturing technology. Six beagle dogs received such customized subperiosteal implants. Histological and microcomputed tomography examination showed new bone growth into and around the implant. Patient-specific subperiosteal implants were placed into the edentulous mandibular bone, with immediate loading. The implant was functional, without pain or infection, over a 12 month observation period. Images taken 12 months post-operatively showed new bone formation and osseointegration of the device. This indicated that 3D-printed lattice-like subperiosteal implants have sufficient stability for the rehabilitation of severely atrophic ridges.

Aim: Bone quality is evaluated using bone density for qualitative classification, a characteristic that may be delicate to evaluate. Contemporary implantology that relies on modern measurement techniques, needs a more quantitative estimate of the bone quality., Materials and Methods: PubMed and EMBASE databases were searched with no time restriction. Clinical and radiographic studies reporting on alveolar ridge dimensions and its parameters in different areas of the dentate and edentulous jaws were included. A meta-analysis was performed using random effect models to report a combined mean for alveolar ridge and its parameters. Meta regression statistical tests were performed in order to identify differences in those outcome parameters., Results: 30 studies were included. The majority of the selected studies (total of 27) used live human subjects and CBCT to analyze alveolar ridge dimensions and its parameters. Using the combined mean obtained from the meta-analysis, a typical portrait of the alveolar ridge was constructed, and a geometrically based quantitative bone classification proposed. The quantitative classification was found to match the existing qualitative classification., Conclusion: A geometry-based analysis was constructed that yields valuable insights on the bone type based on its components and on the dynamics of the dentate / edentulous states., Competing Interests: The authors have declared that no competing interests exist.

Objectives: This study aims to evaluate the short-term clinical outcomes and patient satisfaction of anterior and pterygoid implants in the rehabilitation of edentulous maxilla with posterior atrophy., Methods: Given a minimum follow-up of 1 year, 25 patients with fixed maxillary rehabilitation over anterior and pterygoid implants were enrolled in this retrospective study. The implant survival rates, peri-implant soft tissue status (including probing depth, modified sulcus bleeding index, and plaque index), marginal bone loss, and patient satisfaction were measured., Results: The survival rates for anterior and pterygoid implants at 1-year follow-up were 96.5% and 97.8%, respectively ( P >0.05). No statistically significant difference in probing depth, modified sulcus bleeding index, and plaque index was observed between the two types of implants ( P >0.05). The marginal bone losses of anterior implants were 0.62 mm± 0.44 mm (mesial) and 0.61 mm± 0.40 mm (distal), and those of pterygoid implants were 0.64 mm± 0.46 mm (mesial) and 0.68 mm± 0.41 mm (distal) mm. These results showed no statistical difference in mesial and distal sites ( P >0.05). Patients indicated a high degree of satisfaction with the full-arch prostheses supported by anterior and pterygoid implants., Conclusions: For the edentulous maxilla with posterior atrophy, full-arch fixed prostheses supported by anterior and pterygoid implants has an acceptable short-term clinical outcome and excellent patient satisfaction. It may be considered as a predictable and feasible method for maxillary rehabilitation.

Purpose: It is necessary to correlate cancellous bone patterns with cone beam computed tomography (CBCT) images, but this has not been done to date. The goal of this study was to establish how the superior wall of the mandibular canal (MC) on CBCT images correlates with the cancellous bone around the MC on gross anatomical findings., Methods: Twenty sides from 10 dry mandibles derived from six females and four males were used for this study. In order to observe the MC distally, the specimen was prepared by the method used in our previous study. The cancellous bone around the MC was observed and classified into three types: type I (trabecular pattern), type II (osteoporotic pattern), and type III (dense/irregular pattern). The mandibles were examined with CBCT and the superior wall of the MC on CBCT was scored as visible or non-visible. Finally, the scores (visible or non-visible) were compared to the type by gross observation., Results: For gross observation, a total of 80 areas were available for this study. The data were added to those from our previous study. As a result, 155 areas on 40 sides were analyzed. In dentulous sections, types I, II, and III were found in 55.8%, 20.9%, and 23.3%, respectively. In edentulous sections, the corresponding percentages were 25.0%, 41.1%, and 33.9%, respectively. The dentulous sections was more likely than edentulous to have a type I mandible in both sexes. More females than males had type II (osteoporotic) mandibles. When the superior wall of the MC was non-visible on CBCT, the cancellous bone was type II in 80%., Conclusions: We believe the results can easily be applied to preoperative diagnosis with not only radiological but also anatomical evidence. This classification now necessitates clinical trials for further evidence., (Copyright © 2020 Elsevier GmbH. All rights reserved.)

Introduction: Previous studies of the mandibular canal (MC) have raised questions about the structure of its superior wall that have not been answered. The goal of this anatomical and radiological study was to investigate how CBCT imaging could predict the structure of the superior wall of the MC., Methods: Twenty sides from ten dry mandibles derived from six females and four males were used for this study. The mandibles were examined with CBCT. The specimens were then prepared by the methods of our previous study and observed inferiorly. The inferior views were classified into four groups by gross observation of the surface of the superior wall of the MC: class I (trabecular pattern), class II (osteoporotic pattern), class III (dense/irregular pattern), and class IV (smooth pattern). Coronal section CBCT images were classed according to whether the superior wall of the MC was visible., Results: Class I was most common in dentulous sections in both genders, and class IV was most common class in edentulous sections in both genders. The superior wall was visible in 59.1% in dentulous and 84.9% in edentulous sections, and non-visible in the remainder., Conclusion: Tooth presence and sex are important factors influencing the superior wall of the MC. When the superior wall cannot be seen on CBCT, it is more likely to belong to class II (osteoporotic) than other classes., (Copyright © 2020 Elsevier GmbH. All rights reserved.)

The purpose was to predict the crown-to-implant ratio variation in the edentulous posterior mandibles rehabilitated with short dental implants. Hence, vertical and horizontal dimensions of dentulous posterior mandibles in a sample of 18- to 25-year-olds were measured, and correlations of these dimensions with sex and site were investigated. Mandibular computed tomography scans from 100 subjects were considered. Vertical and horizontal bone and tooth measurements were taken at the sites of the second premolar (PM), and the mesial and distal roots of the first and second molars (M1m, M1d, M2m and M2d, respectively). A hypothetical crown-to-implant ratio (C/I R) was calculated assuming the insertion of short and extra short implants (5, 6 or 7 mm), at 1.5 mm from the inferior alveolar canal, maintaining the position of the existing occlusal plane. All vertical bone dimensions decreased from the PM to the M2d. Width measurements increased from the mesial (PM) to the distal sites (M1m, M1d, M2m and M2d). Males had significantly greater vertical and horizontal measurements than females at all sites. The mean C/I R was higher than 2 for all sizes of implant. The C/I R was lower for the second molar than for the second premolar, while it was similar for the first molar and the second premolar. Males had a higher C/I R than females. Computed tomography can be used to study the anatomical features of alveolar bone, and to predict some clinical aspects of prosthetic rehabilitation with implants, such as the crown-to-implant ratio in conditions of serious bone atrophy.

Introduction: Border molding of the custom tray's edge is an important stage in the treatment of an edentulous jaw that determines the stability of prosthesis at rest and function. Solid, thermoplastic and silicon impression materials may be used in border molding. After bolder molding procedure, the negative pressure between the custom tray and the prosthetic field is created. This is an informal indication for a good impression., Aim: To compare the negative pressure created after border molding procedure with different impression materials., Materials and Methods: 35 patients (17 men and 18 women) aged 51 to 87 years with a complete edentulous upper jaw were examined. New clinical method for negative pressure measurement was created.  We used a special custom tray with palatal adaptor and a pump. Two groups of impression materials were tested:  thermoplastic (Kerr impression compound green sticks, GC Iso functional sticks) and silicones (Detaseal function, Sta-seal f). Statistical analysis was performed using ANOVA, confirmed by the absolute value analysis used to compare negative results, and a log transformation analysis for greater precision and also for negative data comparison., Results: A statistically significant difference was found between the two thermoplastic materials - GC Iso functional sticks and Impression compound green sticks. The mean group difference between these materials was 0.049 bars. There was no statistically significant difference between the other groups of materials., Conclusion: Quantitative measurement of negative pressure, created between the custom tray and the prosthetic field is entirely possible under clinical conditions., (This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Objective: This study evaluates the mandibular lingual foramina (LF) using computed tomographic imaging data from a large Central European cohort, focusing on the most relevant anatomical parameters. We aimed to examine whether there are differences in key parameters between ethnic groups, or based on age and gender. Additionally, we analyze the potential effect of tooth loss on the LF and discuss risk management options before and during surgery., Methods: 460 CT scans of adults (273 females and 186 males) were examined. The number, the location and the diameter of the median and lateral LF were assessed for each patient. The data was analyzed statistically, whereby a p-value lower than 0.05 was considered as significant., Results: Median and lateral LF were present in 95,9%, and 38,9% of patients, respectively. Male patients had a greater number of LF than females. While the majority of median LF (62%) was located above the mental spine, the majority of lateral LF was located below (84%). The diameter of lateral LF (1,15 mm ± 0,33) was smaller than for median LF (1,22 mm ± 0,35), as well the lateral canals (4,8 mm ± 1,28) were shorter than the median canals (5,32 mm ± 1,74). Lateral LF were equidistant to the symphysis (13,89 ± 3,63 mm) on either side. Critical diameter size >1 mm was found in about 2/3 of our cases. The distance from the foramen to the residual ridge was ∼7 mm less in edentulous patients compared to dentulous patients., Conclusion: The median LF is a near-obligatory structure of the mandible, while the lateral LF is a frequently encountered structure. Age does not seem to affect the frequency of LF. Edentulous patients did not show differences regarding the presence of the LF, but their vertical osseous dimension was diminished by 7 mm and they may, therefore, be at an increased risk of adverse surgical incidents. The main findings of this study relate to the substantial variability in the anatomy and location of the LF and confirm with previous studies. As the LF can be reliably detected using CT/CBCT, the use of three-dimensional-imaging is recommended prior to conducting oral surgery. Careful pre-operative planning and accurate anatomical information may help to avoid surgical complications. To ascertain the potential significance of ethnicity on LF, more data need to be collected using standardized methodologies. A definitive conclusion on the impact of ethnicity on LF thus cannot currently be drawn based on the results of our study and those available from the published medical literature., (Copyright © 2020 Elsevier GmbH. All rights reserved.)

Background: In some treatments using multiple dental implants, the implants are inserted in the bone with splinted or non-splinted implant prostheses. There are some reports about the influence of the splinted and non-splinted implants on stress distribution in the bone using the finite element method (FEM), and there is a controversy in the literature regarding whether the splinted or non-splinted implants prostheses reduce the stress generated on the implant-surrounding bone more efficiently. Additionally, the simple shape of the jaw bones with limited bone area was used for FEM analysis in many studies at the expense of accurate analysis., Objective: The aim of this study was to evaluate the difference in stress distribution in the bone between the splinted and non-splinted implants, and between completely and partially edentulous mandibles., Methods: The implants were inserted in the first premolar, second premolar, and first molar regions of the partial and complete mandibles, and the splinted and non-splinted crowns were attached to the implants. Vertical load (100 N) or oblique load (70 N, 30° from its long axis towards the lingual) was applied on the first premolar., Results: When vertical load was applied to the partially edentulous mandible model, the stress was concentrated intensively on the cortical bone around the first premolar regardless of whether splinted or non-splinted implants were used. On the other hand, the vertical load applied to the completely edentulous mandible model caused the stress to be concentrated intensively on the cortical bone around the first premolar with non-splinted implants. With respect to the oblique load, the stress was concentrated intensively on the cortical bone around the first premolar only with the non-splinted implants, in both the partial and complete mandibles., Conclusion: This study shows the different stress distributions of the cortical bone around the implants between the partial and complete mandible. This indicates that the complete mandible should be used for the analysis of bone stress distribution around the implants using FEM.

Purpose: To present a digital method that combines intraoral and face scanning for the computer-assisted design/computer-assisted manufacturing (CAD/CAM) fabrication of implant-supported bars for maxillary overdentures., Methods: Over a 2-year period, all patients presenting to a private dental clinic with a removable complete denture in the maxilla, seeking rehabilitation with implants, were considered for inclusion in this study. Inclusion criteria were fully edentulous maxilla, functional problems with the preexisting denture, opposing dentition, and sufficient bone volume to insert four implants. Exclusion criteria were age < 55 years, need for bone augmentation, uncompensated diabetes mellitus, immunocompromised status, radio- and/or chemotherapy, and previous treatment with oral and/or intravenous aminobisphosphonates. All patients were rehabilitated with a maxillary overdenture supported by a CAD/CAM polyether-ether-ketone (PEEK) implant-supported bar. The outcomes of the study were the passive fit/adaptation of the bar, the 1-year implant survival, and the success rates of the implant-supported overdentures., Results: 15 patients (6 males, 9 females; mean age 68.8 ± 4.7 years) received 60 implants and were rehabilitated with a maxillary overdenture supported by a PEEK bar, designed and milled from an intraoral digital impression. The intraoral scans were integrated with face scans, in order to design each bar with all available patient data (soft tissues, prosthesis, implants, and face) in the correct spatial position. When testing the 3D-printed resin bar, 12 bars out of 15 (80%) had a perfect passive adaptation and fit; in contrast, 3 out of 15 (20%) did not have a sufficient passive fit or adaptation. No implants were lost, for a 1-year survival of 100% (60/60 surviving implants). However, some complications (two fixtures with peri-implantitis in the same patient and two repaired overdentures in two different patients) occurred. This determined a 1-year success rate of 80% for the implant-supported overdenture., Conclusions: In this study, the combination of intraoral and face scans allowed to successfully restore fully edentulous patients with maxillary overdentures supported by 4 implants and a CAD/CAM PEEK bar. Further studies are needed to confirm these outcomes., Competing Interests: The authors report no conflict of interest related to the preparation of the present study.

The edentulous posterior maxilla poses challenges to reconstruction. Posterior forces are great, yet bone quality and quantity are diminished. There is frequent loss of bone resulting from ridge resorption as well as sinus pneumatization. There are also advantages of placing implants in the posterior maxilla compared with the anterior maxilla, such as improved hygiene, esthetics and phonetics, and biomechanical load distribution. This article will present strategies and techniques for improving implant support in the posterior maxilla through various grafting techniques., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The surgical treatment of dentofacial deformities is performed routinely and predictably in dentate patients. However, when dealing with the edentulous maxilla, treatment becomes more challenging and less predictable. In these cases, the combination of orthognathic surgery and osseointegrated implants could be a viable alternative to enable fixed rehabilitation. A patient with an edentulous and atrophic maxilla with maxillomandibular discrepancy and high esthetic requirement was treated with a combination of osseointegrated implants and orthognathic surgery. The rehabilitative sequence was composed of maxillary grafting procedures, installation of dental implants, placement of a fixed implant-supported prosthesis, and bimaxillary orthognathic surgery. During provisional restoration before orthognathic surgery, smaller teeth were used, allowing achievement of appropriate tooth length for the final restoration, even after natural and expected postoperative relapse. This restorative approach provided an implant-supported fixed prosthesis without prosthetic compensation and with optimum esthetics and biomechanics., (Copyright © 2018 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Purpose: The aim of this study was to describe the surgical technique of immediate dental implant placement in calvarial grafts for augmentation of the severely resorbed maxilla and to assess the treatment results., Methods: In 13 patients the maxilla was augmented with calvarial bone followed by simultaneous dental implant placement (total: 68 implants). In the frontal "knife edge" region, implants were inserted in the buccal plated area. In the maxillary sinus area, implants were inserted into alveolar bone that was plated buccally or palatally through the sinus window. After 4 months, the implants were retrieved and subsequently loaded. Per-operative and post-operative variables were scored. One bone biopsy sample was taken for histological analysis., Results: The surgical procedure and wound healing was uneventful. During abutment connection after 4 months, all implants were fully osseointegrated with no signs of graft resorption. Radiographically, the mean (±SD) peri-implant bone loss after 1 year of functional loading was 0.23 ± 0.44 mm. No implants were lost. Histological examination revealed vital calvarial and maxillary bone with active remodeling., Conclusion: Immediate dental implant placement in calvarial bone grafts to rehabilitate severely resorbed maxilla is technically feasible and seems to have a high success rate., (Copyright © 2018 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.)

Purpose: The aim of this study was to perform an exploratory analysis of the morphological variations of mandibles at diverse states of edentulousness using tridimensional geometric morphometrics., Methods: Twelve cadaveric mandibles were selected and divided in three groups: dentate (G1), partially edentate (G2) and totally edentate (G3). CT scans, segmentation and digital reconstruction of 3D surfaces of each specimen was made. Thirteen landmarks were defined; the measurement error was determined and 3D morphometrics exploratory analysis by principal components (PCs) and PC scores was performed., Results: The principal shape variations in G2 and G3 compared to G1 can be summarized as follows: (1) decrease in the mid body mandibular height of 24% in G2 and 41% in G3, (2) decrease of symphysis height of 16% in G2 and 37% in G3, (3) a decrease in posterior mandibular height of 30% in both G1 and G2, (4) a deeper sigmoid notch also in both groups and finally (5) a widening of 7.7% in the cross sectional morphology on the symphysis in G3., Conclusions: The 3D morphometric methods, combined with surface morphing tools confirmed the main patterns of bone changes in edentulous mandibles, referenced in the literature. The average 3D mandibular morphologies of each edentulousness state group was also defined. These methods could offer more accurate definition of shape variations, which is critical in a clinical context. This study provides clinicians with highlights of 3D morphological mandibular variations at different states of edentulism and not only in 2D projections as they are currently described. The 3D surface model for each group in PDF3D file format, are include in supplementary material., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Aim: Analyse the correlation between the measurements made from the landmarks on the cast and the width of the anterior teeth in dentulous study subjects and assessed whether a similar correlation exists in edentulous condition., Materials and Methods: Measurements were made on the cast of dentulous and edentulous subjects. The measurements made were, from incisive papilla to the right hamular notch, from incisiv e papilla to left hamular notch and distance between two hamular notches. After measuring these distances, the predicted value was calculated by taking mean of these three distances. The actual value in both the groups was measured with a flexible ruler. The mean and standard deviation of both groups were calculated. Results were analyzed with correlation and regression analysis., Results: The analysis showed that there was a positive correlation between actual and predicted values in both dentulous and edentulous group of study subjects (p-value <0.01). As the actual value increased in both the groups, the predicted value also increased. So the actual value can be derived with the help of predicted value which will be useful in selecting the proper tooth mold size of the maxillary teeth for edentulous patients., Conclusion: A positive correlation exists between the width of the maxillary teeth (actual value) and mean of the distance (predicted value) between the right hamular notch and incisive papilla, left hamular notch and incisive papilla and interhamular distance in dentate subjects., Clinical Significance: The results obtained from the present study will be helpful for selecting the proper teeth mold size along with other teeth selection methods. Further studies are required to derive a more scientific and reliable method for anterior teeth selection.

Aim: The accurate placement of implants in mandible requires consideration for angulations of the bone along with the vertical dimensions. The aim of this present study was to assess the variation of mandibular anatomy using computed tomography (CT) radiography and to evaluate the effect of presence and absence of teeth on the mandibular anatomy before planning an implant surgery., Materials and Methods: The present population-based retrospective study was conducted using 167 digital CT scan images those selected from departmental archives. The samples were sub-divided two groups: group 1included digital CT of edentulous mandible while group 2 included digital CT of edentulous mandible. The axial height, vertical height, and angulations were recorded separately for each group., Results: The results of the present study showed a gradual increase in mandibular angle in both the groups with a statistically significant difference only in the canine-premolar area. The axial height showed a significant difference at canine and first premolar area and a second premolar and the first molar area. However, available height showed a significant difference in canine and first premolar area and distal to the second molar area. When both the sides were compared, no statistically significant difference was observed between right and left sides., Conclusion: It was concluded that due to the variability of the mandibular anatomy and because of the effects of various imperative factors, 3D imaging like CT scans should be recommended for safer and secure presurgical planning., Clinical Significance: In surgical osteotomies and implant placement especially in post-extraction sockets, two-dimensional (2D) image of panoramic radiographs should not be considered that reliable as these three-dimensional (3D) imaging radiographs. Therefore CT scans of various angulations and sections must be considered by the clinicians to rationally study the mandibular anatomy and their risk associated areas.

Treatment of severely resorbed partially or completely edentulous maxillae can include the utilization of the zygomatic process for immediate implant fixation and stabilization with immediate function. This approach may alleviate the need for significant grafting to enable implant placement in the posterior maxilla and allow implants to be placed into denser, more stable bone. Zygomatic implants, which have been used clinically for the past 20 years in the treatment of the severely resorbed maxilla, allow implant placement to support fixed prosthetics. Their usage can potentially shorten treatment time and reduce costs, as the need to wait for osseous graft maturation is eliminated. Guided surgical approaches are being utilized to maximize placement of the prosthetic platform of these implants.

Objective: To examine the nasopalatine canal (NPC) anatomical and volumetric measurements in anterior edentulous (AE) and anterior dentate (AD) individuals and to compare these findings according to sex, age, shape, and severity of resorption in the premaxilla., Methods: Two hundred cone beam computed tomography images were divided into 2 groups: AE and AD. The diameter, the length of the NPC and the width, the length of the buccal bone anterior to the NPC were measured and recorded. Linear and volumetric measurement results were evaluated in terms of age, sex, dental status, shape, and severity of resorption., Results: No significant differences were observed between the AE and AD groups in terms of the NPC volume (P = 0.289). In the AE group, the spindle shape had the highest volume, and in the same group, with aging, the volume significantly increased (P = 0.00). The mean NPC volume was found to be statistically significantly larger in males than females (P = 0.02). A statistically significant relation was observed between NPC volume and resorption status., Conclusion: Severe bone resorption due to sustained edentation complicated implant surgery because of the increase in incisive and nasal foramen diameters and decrease in buccal residual bone dimensions. The NPC volume was found fewer in edentulous patients, and by the resorption, the volume was decreased.

The technique of inferior alveolar nerve (IAN) block must be based on precise anatomical knowledge regarding the correct position of the mandibular foramen (MF). The aim of the investigation reported here was to determine the anatomic and topographic localization of the MF according to mandibular ramus anatomic landmarks and to identify morphological alterations in the position of the MF and size and shape of the ramus in terms of the impact of tooth socket loss in the molar and premolar region. Seventy-three dry human adult mandibles were divided into two groups according to dental status. These were measured to determine the distances from the anterior and posterior ramus border (AB, PB) to the midpoint of the MF fossa, and from the mandibular notch (MN) and inferior ramus border (IB) to the MF entering point. A number of relevant ramus anatomic features were analyzed, such as ramus width (RW), height (RH), and thickness (RT). The MF was closer to the PB and IB in edentate mandibles (right/left mean PB-MF 10.66 ± 1.84/11.06 ± 2.05 mm; right/left mean IB-MF 21.77 ± 3.23/21.8 ± 2.27 mm) compared to dentate mandibles (right/left mean PB-MF 11.87 ± 2.08/12.04 ± 1.94 mm; right/left mean IB-MF 22.94 ± 3.09/22.74 ± 3.74 mm). Edentate mandibles demonstrated reduced RW (right/left mean RW 26.03 ± 3.53/26.49 ± 3.90 mm), significantly reduced (p = 0.03) right RH (right/left mean RH 43.56 ± 4.74/45.43 ± 4.86 mm), and significantly reduced (p < 0.05) RT in the area of the MF fossa depression (right/left mean RT 5.52 ± 1.21/5.21 ± 0.91 mm) compared to dentate mandibles (right/left mean RW 27.34 ± 3.84/27.48 ± 3.80 mm; right/left mean RH 46.33 ± 4.52/47.40 ± 4.20 mm; right/left mean RT 7.86 ± 1.98/8.10 ± 1.92 mm). Alterations in MF position and mandibular ramus anatomic features in edentate mandibles increase the potential risk of complications and failure of IAN block.

Purpose: The aim of this study was to investigate the correlation between bone density of the edentulous mandibular ridge crest and residual bone height in edentulous subjects using multidetector computed tomography (MDCT) images., Methods: A total of 194 bilateral MDCT images from 97 individuals with an edentulous mandible were selected for analysis. The residual ridge ratio (RRR), the CT values at the residual ridge crest, and the CT values at the lowest point of the mandible measured from MDCT images at molar region. RRR was classified into the three groups (Group 1: >2.0, Group 2: 1.5-2.0, Group 3: <1.5). Bone density at the residual ridge crest was evaluated by calculating the ratio of the CT value at the lowest point of the mandible and the CT value of the residual ridge crest ("ratio of CT values"). The relationship between the height of the residual ridge and the bone density of the residual ridge crest was evaluated by ratio of CT values., Results: Median ratio of CT values was 0.62 in Group 1, 0.70 in Group 2, and 0.84 in Group 3, indicating significant differences between all 3 groups (p<0.05). The correlation coefficient for RRR and residual ridge crest bone density was -0.54 in males and -0.55 in females, implying a moderate correlation for both males and females., Conclusions: The present results suggest a negative correlation between residual bone height and the bone density of the edentulous mandibular ridge crest., (Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.)

Data on the bone trabecular structure and density of the edentulous regions of the first upper molars are important for designing successful dental treatments, especially dental implants. However, no detailed defined morphometric properties on the human maxilla are available at the immunohistochemical and radiographic levels. Cone-beam computed tomography analysis and immunohistochemical observation were applied to the maxillary first molar region of 91 cadavers (46 males and 45 females). The edentulous maxilla can be classified into the following three forms: fully edentulous (FE), partially edentulous (PE), and immediately edentulous (IE). Compared with the first molar dentulous (FMD) specimens, significant differences in cortical bone structure and bone density exist among IE, PE, and FE in maxilla (P < 0.001). According to histochemical observations, the positive CD31 reaction clearly described a large vessel of the PE and small vessels of FMD and IE in maxillary sinus connective tissue. These structural issues were clearly related to tooth extraction. These morphological and radiographic data describing the edentulous region of the maxillary first molar might be useful for improving dental treatments.

Background: The aim of the study is to determine if bone quality evaluation of surgically obtained bone core specimens using a stereomicroscope is reliable for determining bone quality at implant recipient sites., Methods: Bone quality was presurgically assessed in 122 edentulous ridges obtained from 62 patients using periapical radiographs and categorized according to the Lekholm and Zarb classification. During surgery, bone specimens were trephined, and bone types were immediately classified using a stereomicroscope. Microarchitectural characteristics of bone cores were evaluated after being scanned using microcomputed tomography (micro-CT)., Results: Bone types of implant sites categorized from radiography and stereomicroscope had statistically similar distribution but poor interrater agreement. Using micro-CT, maxillae and mandibles showed significant differences in microarchitectural characteristics of bone cores. Bone volume (BV), total volume (TV), and trabecular thickness (Tb.Th) increased, whereas bone surface density (BS/BV) and open porosity (Po.[Op]) decreased in mandibular bone cores compared with those in maxillary bone cores. Moreover, micro-CT values of BV/TV and Po.(Op) statistically correlated with bone types assessed by stereomicroscopy, particularly in mandibles (adjusted means of BV/TV of Type 2 to 4 versus Type 1 decreasing from -9.88%, -15.09%, -29.31%; those of Po.(Op) ranged from 9.77%, 15.06%, 29.52% in an upward trend). However, such correlations were not found in maxillae or when bone types were classified using periapical radiographs., Conclusions: Caution is needed when using presurgical periapical radiographs to predict bone quality at implant recipient sites. Surgically preserved bone core specimens, whenever obtainable, might offer additional information to accurately assess bone quality, particularly at mandibular implant sites.

Background: Rehabilitation using an implant supported overdenture with two implants inserted in the interforaminal region is the easiest and currently accepted treatment modality to increase prosthetic stabilization and patient satisfaction in edentulous patients. The insertion of implants to the weakend mandibular bone decreases the strength of the bone and may lead to fractures either during or after implant placement. The aim of this three dimensional finite element analysis (3D FEA) study was to evaluate the biomechanical effects of implant diameter in case of facial trauma (2000 N) to an edentulous atrophic mandible with two implant supported overdenture., Methods: Three 3D FEA models were simulated; Model 1 (M1) is edentulous atrophic mandible, Model 2 (M2), 3.5x11.5 mm implants were inserted into lateral incisors area of same edentulous atrophic mandible, Model 3 (M3), 4.3x11.5 mm implants were inserted into lateral incisors area of same edentulous atrophic mandible., Results: In M1 and M2 highest stress levels were observed in condylar neck, whereas highest stress values in M3 were calculated in symphyseal area., Conclusions: To reduce the risk of bone fracture and to preserve biomechanical behavior of the atrophic mandible from frontal traumatic loads, implants should be inserted monocortically into spongious bone of lateral incisors area.

Background: The purpose of the study was to validate a newly proposed therapeutic anatomically based clinical and radiological classification for dental implant treatment., Methods: Eighty-one patients with at least 1 edentulous jaw segment (EJS) from 2 dental clinics were included in this study. Both clinical and radiological parameters were assessed in aesthetic and nonaesthetic zones. The data were then compared at preoperative, intraoperative, and postoperative (subdivided into early and late stage) study stages., Results: Based on the hard and soft tissue support, EJSs were divided into 3 types. The outcomes were then validated at preoperative, intraoperative, and early postoperative stages. Data were then analyzed using paired sample t test and the Wilcoxon signed ranks test. No statistically significant difference (P > 0.05) was identified between any the measurements., Conclusions: The proposed therapeutic anatomically based clinical and radiological classification for the dental implant treatment seems to be reproducible, objective, and helpful in planning dental implant treatment. Future studies with a larger sample size are needed to further validate the outcome obtained in this pilot study.

Aims: To evaluate the ridge dimensions of posterior sextant in totally edentulous mandibles., Material and Methods: Cone beam computed tomography scans of 136 patients were retrospectively included for analysis. At sites corresponding to the second premolar (site a) and the mesial and distal root of first molar (sites b and c, respectively), bone height (BH) and bone width (BW) were measured., Results: BH significantly decreased from site a (11.20 ± 4.03 mm) to site c (10.28 ± 3.33 mm). Males showed a significantly higher BH compared with females at all sites (P < 0.001), No significant impact of age on BH was found. BW increased from coronal to apical at all sites. At all height levels, BW increased from mesial to distal (BWc > BWb > BWa)., Conclusions: BH decreased from mesial to distal, whereas BW showed an increase. Sex showed a significant impact on BH, with males having on average a 2.8 mm greater height than females, but not on BW. Age did not significantly influence the dimensions of the residual bone crest.

Introduction: The present study was undertaken to evaluate the anatomy of the maxillary sinus in relation to its position and the height of its septa, using cone beam computed tomography (CBCT)., Materials and Methods: In this descriptive retrospective study, 300 CBCT images of maxillary sinuses of patients with posterior maxillary edentulism were evaluated. The maxillary sinus septa were evaluated in relation to their prevalence, height, and position; t-test and Mann-Whitney tests were used for the analysis of data., Results: Sinus septa were detected in 44% of the subjects, with equal frequencies in the anterior, middle, and posterior positions. The mean height of the septa was 3.6 ± 1.56 mm., Conclusion: In a population of Iranian subjects, in half of the cases, the sinus septa might be present in the anterior, middle, and posterior positions., Clinical Significance: In order to avoid intraoperative problems during sinus lift procedures, it is necessary to accurately evaluate the sinus, preferably with the use of CBCT Keywords: Cone beam computed tomography, Dental implant, Maxillary sinus septa.

Statement of Problem: After the loss of the natural teeth, the alveolar process and part of the basal bone remodels, resulting in edentulous residual jaws. In edentulous patients, the residual arches provide the vital tissues on which to place the denture bases and the artificial teeth into their selected positions. The residual arches also furnish the foundation of osseo-integrated implants for the planned restorations., Purpose: To examine some characteristics of the edentulous arches, the relations between the occluding jaws and their clinical importance., Material and Methods: 212 stone casts mounted in centric relation, from one hundred and six edentulous patients were examined and surveyed. The measurements included the length, the width of the maxillary and mandibular edentulous arches and the inter jaw distances at anterior and posterior regions., Results: Of the one hundred and six participants, 62.3% were female and 37.7% male subjects. The maximallary arch length and width varied from 36 to 71mm, and between 36 to 58mm, respectively. The mandibular length and width differed from 32 to 55mm, and between 48 to 62mm. Higher width values of maxilla and mandibles were found among males as compared to females (p<0.001). The vertical inter jaw distances varied from 9 to 28mm in both anterior and posterior regions. The horizontal inter jaw distances and relation modes varied widely at both anterior and posterior regions., Conclusions: There is a large disparity in sizes and shapes of the edentulous arches and varied spatial inter arch characteristics., Clinical Implications: Before the placement of osseo integrated implants and rehabilitation of the edentulous patients, it is essential to identify the anatomy and relations of the occluding residual arches to contribute to a successful dental treatment.

Purpose: The aim of this study was to investigate the effect of immediately loaded mini dental implants (MDIs) used to support mandibular overdentures on the peri-implant bone level as well as patients' related levels of satisfaction and quality of life., Materials and Methods: Four MDIs were placed in the interforaminal region of 10 completely edentulous patients, and the implants were loaded immediately (same day) with an overdenture. Radiographic assessment of the bone loss during a period of 18 months was performed by measuring the bone level changes at the mesial and distal aspects of each implant on panoramic radiographs. At the end of this period, patients' satisfaction level on the visual analog scale (VAS) and oral health-related quality of life was assessed by means of questionnaires., Results: A mean bone loss of 1.04 mm on the mesial and distal sides was recorded during the 18-month period after loading of the implants. The score for general satisfaction level was 95.67 ± 5.68. Similarly high VAS scores were given by the patients in all other specific items on patient satisfaction. The total score for the Oral Health Impact Profile-20 (OHIP-20) was 34.07 ± 13.90, which was comparable to that recorded in other studies., Conclusion: The short-term radiographic peri-implant bone level changes of MDIs immediately loaded with overdentures in the edentulous mandible were within the physiologic limits. The patients expressed a high level of satisfaction and oral health-related quality of life with this treatment modality.

A model with simulated flabby tissue was fabricated by modifying the standard maxillary edentulous acrylic resin cast to evaluate the effect of maxillary impression tray design on the displacement of flabby tissue. Seven groups of trays were fabricated using different combinations of relief spaces and escape holes. After impression taking, test and control casts were scanned and three-dimensional digital models were superimposed. Negative deviations were recorded at the point of the alveolar crest, the posterior part of the flabby tissue, and the middle of the palate, while positive deviations were recorded at the point of the anterior part of flabby tissue. The amount and characteristics of tissue displacement differed with tray design and the relief method used.

Background: Prostheses in the edentulous maxilla affect the mucosa., Purpose: To evaluate mucosal alterations with implant supported fixed prostheses (FDP) and overdentures (IOD)., Material and Methods: Patients receiving prostheses during a time period of 10 years were recruited. Maxillary mucosal conditions in relation to FDPs, IODs were analyzed. Peri-implant parameters were measured and the Oral Health Impact Profile (OHIP) was administered., Results: One hundred seven patients wearing 74 IODs and 33 FDPs were identified with a total of 519 implants, the mean observation time was 6.5 ± 2.7. Cumulative implant survival was 93%. Erythema and hyperplastic tissue were identified in 71% of the IOD wearers, but were mostly absent with FDPs. The peri-implant parameters demonstrated healthy peri-implant mucosa. Medication and smoking had no effect on mucosal alteration (OR = 1.065 and 1.568). The average OHIP value was 3.73 ± 4.12. A lower value (p < 0.0048) was found for FDPs and one type of IOD., Conclusions: A rigorous maintenance program did not prevent IOD mucosal alterations in IOD wearers, but the health of the peri-implant mucosa was maintained and was comparable for all types of prostheses., (© 2015 Wiley Periodicals, Inc.)

Purpose: The objective of this study was to assess the stress distribution generated by a simulated loading (100 N) in the area of the cantilever in three different five-implant mandibular protocol prosthesis models., Materials and Methods: The finite element analysis was carried out in three-dimensional models simulating: (1) a temporary all acrylic resin mandibular protocol prosthesis; (2) a metal-acrylic mandibular protocol prosthesis; and (3) a metal-ceramic mandibular protocol prosthesis., Results: The all acrylic model promoted the highest stress values on the implant closest to the cantilever loading point., Conclusion: This study supports the need for a metallic bar reinforcement in the denture base.

Purpose: The aim of this in vitro study was to compare the accuracy of two different impression techniques for the All-on-Four implant therapy protocol., Materials and Methods: An acrylic resin analog for an edentulous maxilla with four internal connection implants (Replace Select, Nobel Biocare) was fabricated according to the All-on-Four protocol. A total of 40 impressions were made with different techniques (open and closed tray) at abutment and implant levels and poured in type IV dental stone. A coordinate measuring machine was used to record the x, y, and z coordinates and angular displacement. The measurements were compared with those obtained from the reference model. Data were analyzed with analysis of variance and t test at α = .05., Results: There was less linear and rotational displacement for the open-tray technique when compared with the closed-tray technique (P = .02 and P < .001, respectively). Impressions made at abutment level produced fewer linear and rotational displacements when compared with implant level impressions using the open-tray technique for straight and angulated implants (P = .04 and P < .001, respectively). However, less rotational dislocation was observed for impressions made with the closed-tray technique when compared with the open-tray technique at implant level (P < .001)., Conclusion: Choice of impression technique affected the accuracy of impressions, and less displacement was observed with the open-tray method. Abutment-level impressions with an open-tray technique were more accurate, while implant-level impressions were more accurate when a closed-tray technique was used.

Objectives: Osteocytes have emerged as key regulators of skeletal and mineral homeostasis. The number of these cells could be influenced by the presence of osteoporosis and osteopenia. Hence, the aim this study was to evaluate the osteocyte density in patients with osteopenia, and in patients with osteoporosis treated with bisphosphonates., Materials and Methods: Thirty-nine patients were selected for this study and divided into three groups: (A) nine healthy patients (control), (B) 15 patients with osteopenia, and (C) 15 patients with osteoporosis. During the surgical insertion of dental implants in the lower jaw, bone samples were retrieved and processed for histological analysis of osteocyte density, measured as number of osteocytes/bone tissue area (μm(2) )., Results: Patients with osteopenia showed statistically higher values of osteocyte density than patients with osteoporosis (P < 0.05) No significant differences were detected between osteopenia and osteoporosis subjects vs. healthy patients (P > 0.05)., Conclusions: Bone metabolism diseases (osteoporosis and osteopenia) do not seem to influence the osteocyte density; this could be due to the administration of bisphosphonates in patients with osteoporosis. This information could play a fundamental role in the diagnosis and treatment of patients in a postmenopausal stage., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Purpose: The aim of this cohort study was to evaluate the width of keratinized mucosa at implant sites of partially edentulous patients who were treated for generalized aggressive periodontitis., Materials and Methods: Dental implants were placed in 35 patients who were treated for generalized aggressive periodontitis and 18 periodontally healthy individuals (controls). At baseline, the keratinized mucosa of all implants was ≥ 2 mm. Follow-up examinations were conducted every 3 months over a 4-year period., Results: The implant survival rate was 97.3% in patients with generalized aggressive periodontitis and 100% in the control group. Four years after implant insertion, patients with generalized aggressive periodontitis had significantly higher clinical attachment levels at the teeth and implants compared with the controls. At all time points, in both groups the mean probing depth at the implants was significantly larger than at the teeth. The mean widths of keratinized mucosa and keratinized gingiva were not significantly different between the two groups. In both groups, the widths of keratinized mucosa and keratinized gingiva were significantly higher at the maxilla than at the mandible. Four years after baseline, the implants in the mandible showed the smallest keratinized mucosa (mean: ≤ 1 mm)., Conclusion: During the first 4 years after implant placement, no significant changes in the keratinized mucosa at implants could be shown, either in periodontally healthy patients or in patients treated for generalized aggressive periodontitis. The keratinized gingiva at the teeth was generally significantly wider than the keratinized mucosa at the implants.

Purpose: This study compared tissue three-dimensional (3D) displacements during the material setting phase of two maxillary impression tray-holding techniques: clinician manual pressure and patient occlusal pressure., Materials and Methods: The resultant two maxillary casts for each of 10 edentulous patients were compared using an optical 3D measurement system., Results: The junction between the hard and soft palates acted like a rotation center during impression making. The vertical displacements were significantly lower and posteriorly set when the impression was taken with the patient's occlusion, in contrast to being located at the anterior two-thirds during the manual impression technique., Conclusion: Use of patient's occlusion as a tray-holding technique may be preferred during the material setting phase of maxillary impressions.

The treatment of patients having a completely edentulous maxillary arch and lower anterior teeth present is frequent in the dental practice. In these cases some specific changes can be detected in the oral cavity and on orthopantomograms. These signs were summarized and described first by Kelly (1972). Aim of the study was to examine the presence of the specific signs of the combination syndrome among the patients between 2009 and 2014. With the help of the electronic patient registry system used by the University of Pécs, 319 patients were filtered who were diagnosed with anodontia code (K0000 International Classification of Diseases (ICD)) in the examined period. 220 patients' orthopantomograms were evaluated searching for specific symptoms of the combination syndrome. 34 patients had complete edentulous maxilla and anterior teeth in the mandible. 4 patients (11.7%) showed the main sign of the combination syndrome, i.e. the maxillary anterior bone loss. Hypertrophy of maxillary tuberosity (9 cases, 26.4%), extrusion of the lower anterior teeth (6 cases, 17.6%) and great resorption of the distal mandibular ridge (16 cases, 47%) was diagnosed on the X-rays. The clinical examination of three patients supported the radiological findings. The combination syndrome was detectable, but the incidence rate was lower in this population in comparison with the data available in dental scientific publications.

Objectives: We developed an innovative procedure for digitizing maxillary edentulous residual ridges with a photogrammetric system capable of estimating three-dimensional (3D) digital forms from multiple two-dimensional (2D) digital images. The aim of this study was to validate the effectiveness of the photogrammetric system., Materials and Methods: Impressions of the maxillary residual ridges of five edentulous patients were taken with four kinds of procedures: three conventional impression procedures and the photogrammetric system. Plaster models were fabricated from conventional impressions and digitized with a 3D scanner. Two 3D forms out of four forms were superimposed with 3D inspection software, and differences were evaluated using a least squares best fit algorithm., Results: The in vitro experiment suggested that better imaging conditions were in the horizontal range of ± 15 degrees and at a vertical angle of 45 degrees. The mean difference between the photogrammetric image (Form A) and the image taken from conventional preliminarily impression (Form C) was 0.52 ± 0.22 mm. The mean difference between the image taken of final impression through a special tray (Form B) and Form C was 0.26 ± 0.06 mm. The mean difference between the image taken from conventional final impression (Form D) and Form C was 0.25 ± 0.07 mm. The difference between Forms A and C was significantly larger than the differences between Forms B and C and between Forms D and C., Conclusion: The results of this study suggest that obtaining digital impressions of edentulous residual ridges using a photogrammetric system is feasible and available for clinical use.

Objective: To suggest a technique to prevent trauma of the edentulous ridge from opposing dental implants when prosthesis kept out during night., Background: In modern dentistry, implant-supported overdentures are commonly fabricated to minimise the problems associated particularly with mandibular conventional removable denture such as the lack of retention or stability, decreased chewing efficiency, difficulties in speech and soft tissue abrasion. The patients wearing two implant-retained overdentures that are mainly soft tissues supported-implant-retained overdentures are advised to keep prosthesis out of the oral cavity during night to allow the tissues to rest and remain healthy. Few of such patients might complaint about trauma of the opposing soft tissues by the dental implants when prosthesis is kept out., Materials and Methods: A thermoplastic resin mouthguard was fabricated by adapting the modelling wax over the abutments on the master cast from thermoplastic resin sheets. The wax was removed and guard was filled with chemically cure permanent silicone soft liner and immediately placed in the patient mouth., Conclusion: The trauma caused by dental implants to the opposing edentulous ridge was effectively managed by soft thermoplastic resin mouthguard filled with permanent silicone soft liner., (© 2014 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd.)

Purpose: Many different attachment systems (eg, bars, studs, magnets, telescopic copings) have been used to retain overdentures. The current study aimed to investigate the load transfer characteristics and to compare the stress levels of four attachment designs for mandibular overdentures retained by one central implant and two inclined distal implants., Materials and Methods: Photoelastic mandibular models fabricated with three screw-type implants (Tapered Screw-Vent, 3.75 × 13 mm) were placed in the parasymphyseal area. The center implant was vertically oriented to the midline, and the other implants were embedded in the canine areas with a 20-degree angulation relative to the center implant. Four overdentures with different attachment designs (bar, bar/ball, bar/distally placed Rk-1s, and Locators) were studied in the context of this model. Vertical loads (100 N) were applied to the central fossa of the right first molar area of each overdenture. Stress levels that developed in the denture-bearing areas and around the implants were observed photoelastically and evaluated visually., Results: The studied attachment designs showed low and moderate stress levels. The greatest stress was found with the bar/ball design, while the lowest stress levels were observed with the Locator attachment design., Conclusion: Stresses were concentrated on the loaded side for each design. All tested designs experienced moderate stress around the posterior edentulous area. None of the designs experienced more than moderate stress. The lowest stress was noted with the Locator attachments, which transmitted little discernible stress around the implants.

Objectives: Adaptations of the alveolar ridge after tooth loss have been well described. However, studies on the morphometric characteristics of cortical bone are rare; hence, this study of human atrophic edentulous mandibles was undertaken., Material and Methods: Total cortical area, porosity, and thickness, and the percentage of cortical area in the complete mandibular area as well as in an area (height, 10 mm) starting at the most caudal point of the trabecular compartment and extending in the coronal direction were determined in 185 thin ground sections of edentulous mandibles (incisor region, 49; premolar region, 76; molar region, 60; 95 from females and 90 from males; mean age, 78.2 years, SD ± 7.8 years; Caucasian donors; cause of death: cardiovascular disease). Further, mandibular height and width and degree of residual ridge resorption (RRR) were recorded., Results: The percentage of cortical area in the complete mandibular area increased with increasing RRR. Yet, evaluation of the 10-mm caudal portion corresponding to the basal part of the mandibular body did not confirm these changes in cortical bone. Cortical porosity and thickness decreased from the mesial to the distal region. Cortical porosity was unaffected by RRR, while cortical thickness increased, mainly at lingual aspects., Conclusions: In conclusion, cortical bone remained stable in different degrees of RRR except for some modulations in the lingual aspects. Changes in the relative composition between cortical and trabecular bone are due to loss of height and total area, mainly at expense of trabecular bone area, but not to adaptations of the cortical bone., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objectives: Fractures of the atrophic edentulous mandible are a rare complication that can become severe after the insertion of dental implants. This in vitro study investigated the effects of different implant settings varying in number, diameter, and length. and the influence of a fixed bar., Materials and Methods: In biomechanical experiments on artificial mandibles, an unmodified reference group, four implant settings with two different implants, and the effect of adding a fixed bar to these settings were tested. All specimens were loaded with incisal biting forces until failure due to fracture., Results: Implants weakened all specimens significantly compared with those in the reference group. Without a fixed bar, four short and thick implants showed the best results, with high significance. With a fixed bar, four long and thin implants withstood the highest loads. The addition of fixed bars reduced the differences between the implant settings. Fixed bars did not show increased stability for all groups; however, these groups showed a higher mean strength., Conclusions: Four implants with a short and thick design should be the first choice when implants are placed without a fixed bar in an atrophic mandible. With a fixed bar, four long and thin implants should be used., (Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.)