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This study aims to assess the mechanical responses of Cast metal post(MP) and Fiber- reinforced composite post(FP) when combined with zirconia crowns supported RPD, with a specific focus on von Mises stress distribution and maximum stress value on abutment teeth and supporting tissue. Linear finite element analysis was used to assess model stress distribution in scenarios featuring MP and FP restored with zirconia crown supporting distal extension base RPD of lower second premolar surrounding by periodontal ligament and alveolar bone. The simulation was conducted with computer software (ANSYS Workbench 2020; ANSYS Inc). A loading force of 40 N of 5 points on artificial teeth of RPD and 100 N of 2 points on abutment tooth paralleled with vertical axis was applied to simulate the mastication. The study demonstrated that both models exhibit similar stress distribution patterns in all components except in post, ferrule and zirconia crown. Stress distribution in model MP (21.83 MPa) was higher than model FP (7.95 MPa) but stress accumulation in root of both models were similar (85.30 MPa for MP, 81.98 MPa for FP) which does not exceed the dentine ultimate tensile strength. Despite the stress distribution at the ferrule was different in pattern which model MP stress accumulated at post ferrule junction while model FP occurred around cervical margin. It was intriguing zirconia crown of model FP (141.21MPa) had higher stress accumulated within crown while model MP (113.87MPa) lower stress distributing from crown to cast metal post. The research findings suggest that cast metal and fiber reinforced composite posts show no significant different stress distribution on abutment teeth in distal extension base RPD. Both posts demonstrated no detrimental effects on the abutments and surrounding periodontal tissues. [ABSTRACT FROM AUTHOR]

Purpose: This narrative review aimed to survey the clinical outcomes of laminate veneers (LVs), including their survival and success rates. Study selection: An electronic search of MEDLINE/PubMed, Web of Science, Cochrane Library, and Google Scholar from 2000 to April 2023 was conducted using the keywords "laminate" OR "veneer" OR "porcelain" OR "feldspathic" OR "lithium disilicate" OR "composite resin" OR "zirconia" OR "survival" OR "success." Case reports, case series, reviews, abstracts, in vitro studies, and observational studies were excluded. Five researchers independently evaluated the titles and abstracts of all identified studies. Results: A total of 55 studies were identified. None of the studies met the criteria for zirconia LVs. According to the studies in this review, LVs fabricated with feldspathic porcelain, leucite-reinforced glass ceramics (LRG), and lithium disilicate ceramics (LDS) exhibited satisfactory survival and success rates. Furthermore, hydrofluoric acid etching followed by silane priming of the surface of ceramic LVs is necessary for improved clinical outcomes. The extent of dentin exposure significantly decreases the success rate of ceramic LVs. An appropriate adhesive luting process is required to achieve the long-term success of ceramic LVs. Dentin exposure should be minimized or sealed during tooth preparation to achieve a reliable and durable bond between LVs and abutment teeth. Conclusions: Based on this narrative review of the literature, the use of silica-based ceramic feldspathic porcelain, LRG, and LDS is recommended for LVs. [ABSTRACT FROM AUTHOR]

Purpose: To describe a novel digital design technique for creating an individualized emergence profile for implant restoration based on the contralateral tooth. Methods: Cone beam computed tomography (CBCT) data were used to accurately obtain a three-dimensional (3D) model of the contralateral tooth, which was mirror-flipped to design the emergence profile. The emergence profile was further divided into critical and subcritical areas; the critical area precisely replicated the mirror-flipped 3D model, whereas the subcritical area featured a slight concavity on the buccal side, flatness on the lingual side, and slight convexity on the mesial and distal surfaces. Subsequently, a milling machine was used to fabricate healing abutments with individualized emergence profiles. The design of the definitive restoration completely duplicated the emergence profile of the individualized healing abutment and was fabricated using a milling machine. Conclusions: This technical procedure presents an alternative novel method for designing the emergence profiles of implant restorations, with the potential to improve esthetics and functions as well as to maintain the long-term stability of peri-implant soft and hard tissues. [ABSTRACT FROM AUTHOR]

Retainer debonding of resin-bonded fixed dental prostheses (RBFDPs) is one of the major reasons for their lower survival rates than fixed dental prostheses (FDPs) with full-coverage crowns. Recent advances in milling technology have enabled the fabrication of RBFDPs with complex retainers (D-shaped designs). This study aimed to assess the marginal fit and retention force of zirconia RBFDPs with inlay-, L-, and D-shaped designs to clarify their clinical applications. Three abutment teeth models without maxillary second premolars were created using inlay-, L-, and D-shaped retainer designs. The zirconia RBFDPs were designed and fabricated according to the manufacturer's instructions (n = 10). The marginal gap was measured using the silicone replica technique. Zirconia frameworks were bonded to the abutment teeth using resin cement. Tensile test was conducted after thermal cycling and dynamic loading tests. The loads during debonding or fracture were recorded. The failure pattern was analyzed by observing the fracture surface using a scanning electron microscope. D-shaped RBFDPs showed a significantly larger marginal gap than inlay- and L-shaped RBFDPs (P < 0.05). However, the mean marginal values were clinically acceptable (<120 μm). The D-shaped model exhibited the highest tensile strength in the tensile tests. The inlay-shaped and most of the D-shaped RBFDPs experienced debonding with cohesive failure, whereas the L-shaped RBFDPs showed fractures near the connector. The D-shaped retainer design was superior to the inlay- and L-shaped designs with respect to the inhibition of retainer debonding. However, the marginal fitness needs to be improved. [ABSTRACT FROM AUTHOR]

Background: The band and loop space maintainer is used to maintain the missing space of deciduous molars which are lost early. When the second deciduous molar is lost prematurely, the stress on the first permanent molar during different degrees of development may vary when it is the abutment. The design and use of the space maintainer may also lead to damage of the loop. The purpose of this article is to use the finite element method to study the stress on the first permanent molar and the loop with or without occlusal contact, with the first permanent molar of four different degrees of development serving as the abutment. We aimed to guide the clinical design and use of the space maintainer. Methods: We developed finite element models of the mandibular first permanent molar and the band and loop space maintainer, and simulated alveolar bone, periodontal ligament (PDL), enamel and dentin. The four developmental stages were 1/2 (I), 2/3 (II), 3/4 (III) and full development (IV). Ansys Workbench was used to analyze the effects of root development and occlusal contact between the loop and the opposite jaw on abutment teeth and the loop. Abutment teeth were statically loaded vertically and obliquely with a force of 70 N. The loop was statically loaded vertically with a force of 14 N. The stress on all structures and the displacement trends of the loop were calculated. Results: The stress on enamel, dentin, PDL and alveolar bone were similar, and the concentration was consistent. But if there was occlusal contact, the loop produced maximum displacement at the near middle edge of contact with the anterior teeth. When the loop was in occlusal contact with the opposing occlusal tooth, the peak value of the equivalent stress on the space maintainer under vertical load was: group I > group IV > group III > group II, and the maximum principal stress peak change was: group I > group III > group II > group IV. The change of the equivalent stress peak value of the loop under oblique load was: group I > group III > group IV > group II, and the maximum principal stress peak change was: group III > group I > group II > group IV. When the loop was not in occlusal contact with the opposing occlusal tooth, the peak value of the equivalent stress on the space maintainer under vertical load was: group IV > group I > group II > group III, and the maximum principal stress peak change was: group IV > group I > group II > group III. The change of the equivalent stress peak value of the space maintainer under oblique load was: group I > group IV > group II > group III, and the maximum principal stress peak change was: group I > group IV > group II > group III. Conclusions: Our results suggested that whenever possible, choosing the teeth with nearly complete root development as the abutment of the space maintainer is advisable. The design and use of the band and loop space maintainer should avoid occlusal contact with the occlusal teeth to prevent deformation of the loop. [ABSTRACT FROM AUTHOR]

Aims: Dental procedures involve intricate techniques that can be challenging to visualize, often hindering imitation and assessment. In this study, the impression-taking performance of abutment teeth was quantitatively analyzed to create objective indexes for dental skill education. Methods: Participants were divided into two groups of different clinical experience levels: 10 dentists and 10 dental students. An aluminum model of abutment teeth was employed to simplify the experiment. An optical motion capture system (VICON, Oxford, UK) measured participants’ movements. The impression accuracy, time length on the analyzed section, impression material pouring speed, total amount of impression material used, and syringe tip trajectory were evaluated. Fisher’s exact test and Mann-Whitney U test were used to compare the two groups’ results (α=0.05). Results: In the dentist group, there were few apparent failures and a high impression accuracy. The amount of impression material dispensed tended to be larger in the dentist group, with longer practice time and slower syringe movement speed. This suggested that the inexperienced participants were sufficiently unable to pour out the impression material. The syringe tip trajectories were not significantly different between the groups. An instructor’s advice is often limited to abstract feedback; therefore, specific suggestions might assist in effective skill education. Conclusion: It is possible to quantitatively analyze impression-taking performance and provide helpful information for dental skill education by using this system. [ABSTRACT FROM AUTHOR]

Telescopic crown-retained dentures (TCDs) are one of the most common types of prosthetic restorations for partially edentulous patients; however, post and core (PC) treatment shows the worst survival probability if the tooth is used as an abutment for the TCD. Due to extra axial forces, abutment tooth fracture is a common cause of failure for TCDs; thus, PC treatment is often needed to refit the existing telescopic crown (TC). However, there are no clinical survival data on whether the PC treatment was used to refit the TC after abutment tooth fracture (PC2) or the PC was already fitted at the time of TCD treatment (PC1). A total of 246 patients with 399 PC treatments were retrospectively evaluated for follow-ups up to 17.33 years. The files were analysed for PC1 and PC2. Furthermore, the influence of the jaw, type of tooth, luting material, PC material, bone attachment, therapist and cause of failure was recorded. For statistical analysis, Kaplan–Meier and Cox regression analyses were conducted. PC2 showed highly significant lower survival probabilities than PC1 (p < 0.001). Moreover, the bone attachment and the age of the patient at the time of fitting the PC crown had an influence on the survival (p < 0.001). Therefore, PC2 should be carefully discussed with the patient and PC1 should be favoured in endodontically treated abutment teeth for TCDs. [ABSTRACT FROM AUTHOR]

Background: Dental implant abutment screw loosening is an increasingly common problem, as evidenced by multiple studies that have investigated its causes. The objective of this study was to compare the screw loosening torque values before and after cyclic loading and to determine whether they are affected by the CAD/CAM abutment manufacturing technique (machined or laser-sintered) and abutment angulation. Materials and Methods: Ninety implants were used and divided into two groups: 45 implants received machined abutments (group A) and 45 implants received laser-sintered abutments (group B). Each group was further divided into three subgroups, with 15 implants each, based on the abutment angulation involved (0°, 15° and 20°). The abutments were tightened to the torque recommended by the manufacturer, and the reverse torque value was measured before and after cyclic loading (300,000 cycles). Data analysis was performed using one-way ANOVA and Wilcoxon signed-rank tests. Results: Statistically significant differences were observed between the laser-sintered and machined groups (p < 0.01). Additionally, differences were observed between subgroups with different angulations for both machined (16.2 ± 1.75, 14.7 ± 1.74 and 13.4 ± 1.08 Ncm) and laser-sintered abutments (14.6 ± 1.25, 12.7 ± 1.2 and 11.1 ± 1.35 Ncm) (0°, 15° and 20°, respectively). Conclusions: The final screw loosening torque after cyclic loading was lower than the initial loosening torque. Both abutment angulation and the CAD/CAM manufacturing method exerted a statistically significant influence on the final loosening torque. The abutment angulation factor was estimated to have an influence of 34.5%, while the abutment manufacturing method was estimated to have an influence of 21%. [ABSTRACT FROM AUTHOR]

Objective: The objective was to assess the one year implant treatment outcome and patient‐related outcome measures (PROMs) following maxillary sinus floor augmentation (MSFA) with autogenous bone graft (ABG) from the zygomatic buttress (control) compared with 1:1 mixture of ABG and anorganic porcine bone mineral (APBM) (Test I) or biphasic bone graft material (BBGM) (Test II). Materials and Methods: Sixty healthy patients (34 females, 26 males) were randomly allocated to either control or test groups. Outcome measures included survival of suprastructures and implants, implant stability quotient, health status of peri‐implant tissue, peri‐implant marginal bone loss, frequency of complications, and PROMs using Oral Health Impact Profile‐14 combined with questionnaire assessing patient perception of peri‐implant soft tissue, prosthetic solution, implant function, and implant treatment outcome using visual analogue scale. Mean differences were expressed with standard deviation and 95% confidence interval. Level of significance was.05. Results: All suprastructures and implants were well‐functioning after one year of functional implant loading. There was no significant difference between control and test groups in any of the applied outcome measures. The implant stability significantly increased from implant placement to abutment connection within all groups (p <.001). High patient satisfaction and significant improvement in oral health‐related quality of life was also reported within all groups. Conclusion: This study demonstrates that MSFA with composite grafts containing minimal amounts of ABG reveals comparable implant treatment outcomes as compared with ABG alone, after one year of functional implant loading. Extensive ABG harvesting in conjunction with MSFA therefore seems not to be needed. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to evaluate the long‐term (5 years) clinical efficacy of the one‐abutment one‐time protocol (test) versus the standard of care by placing the definitive abutment on the day of the prosthetic delivery (control). Materials and Methods: In this study, 39 subjects with 60 implants were randomly allocated to either the test or the control group. Changes in the radiographic interproximal bone levels (DIB), modified sulcus bleeding index, probing depth, modified plaque index, papilla fill (Jemt score), incidence of peri‐implantitis and peri‐implant mucositis as well as patient‐reported outcomes measures (PROMs) were collected and compared at 1, 3 and 5 years. Results: At 5 years, the control group showed a greater, although not statistically significant, change in mean DIB values (0.97 mm vs. 0.53 mm). Regarding the other clinical parameters evaluated, no statistically significant differences were observed between groups at any time point. At 5 years, 51% of the implants presented peri‐implant mucositis (25.5% in the control and 23.5% in the test), and only one implant in the test group developed peri‐implantitis. Conclusions: The connection and disconnection of healing abutments during the healing period was not associated with higher long‐term bone loss. Clinical outcomes and PROMs were similar between groups. [ABSTRACT FROM AUTHOR]

This article examines the potential risks associated with the release of titanium-based particles from dental implants. It acknowledges that while titanium implants are commonly used and have high success rates, complications can occur due to wear and corrosion. The article emphasizes the lack of international standards for evaluating the biological response to implant wear particles and calls for increased awareness among dental implant providers. It also highlights the importance of reliable testing protocols and the availability of testing data to ensure the safety of dental implants. The authors urge manufacturers and clinicians to be mindful of these risks and to take responsibility for the products and treatments they offer. The authors disclose their contributions to the article and state that they have no conflicts of interest. They also note that no datasets were generated or analyzed during the study, so data sharing is not applicable. [Extracted from the article]

Aim: To evaluate site‐related changes in periodontal pocket depth (PPD) after non‐surgical periodontal therapy and to identify predictors for PPD changes in a retrospective patient data analysis. Materials and Methods: PPD, clinical attachment level, bleeding on probing, tooth mobility (TM), furcation involvement (FI), abutment status, adherence to supportive periodontal care (SPC) and SPC follow‐ups were obtained from fully documented patient data before periodontal therapy (baseline, T0), after active periodontal therapy (APT, T1) and during SPC (T2). PPD changes were classified into deteriorated or unchanged/improved at the site level. Multi‐level logistic regression analysis was performed to identify factors influencing PPD changes during SPC. Results: This retrospective study included 51 females and 65 males (mean T0 age: 54.8 ± 10.1 years, 25 smokers, 12 diabetics) suffering from Stage III/IV periodontitis. Evaluation outcome: T0/16,044 sampling sites/2674 teeth; T1/15,636/2606; T2/14,754/2459. During 9.0 ± 2.3 years SPC, PPD decreased (−1.33 ± 0.70 mm) by 21.8% of the sites, remained unchanged by 41.4% and increased (1.40 ± 0.78 mm) by 36.8%. Distopalatal FI (p <.001, odds ratio [OR]: 0.252, 95% confidence interval [CI] for OR: 0.118–0.540), residual pockets (p <.001, OR: 0.503, 95% CI: 0.429–0.590) and TM Degrees I–III (Degree I: p =.002, OR: 0.765, 95% CI: 0.646–0.905; Degree II: p =.006, OR: 0.658, 95% CI: 0.489–0.886; Degree III: p =.023, OR: 0.398, 95% CI: 0.180–0.879) correlated significantly with increasing PPD. Conclusions: Over 75% of PPD remained unchanged or increased during SPC. Distopalatal FI, TM Degrees I–III and residual pockets after APT lead to worsening of periodontal pockets. [ABSTRACT FROM AUTHOR]

Simultaneous avulsion of four or more teeth is a rare event. This case report examines the dental care given to an adult who, during a bicycle accident, experienced the avulsion of a mandibular incisor as well as all of his maxillary incisors. In the immediate aftermath of the accident, four out of the five incisors were located, promptly collected, and stored in a tooth rescue box, all within a 20‐min window. Replantation and splinting were performed on the day of the accident. Endodontic treatment involved sequential intracanal dressing with an antibiotic–corticosteroid paste followed by calcium hydroxide prior to root canal obturation. 3 months post‐accident, signs of external replacement resorption (ERR) began to appear in all the replanted teeth. The gap created by the missing maxillary central incisor was managed with a three‐unit fixed dental prosthesis, despite the onset of ERR in the incisors used as abutment teeth. Regular follow‐ups showed a relatively slow ERR progression rate over a span of nearly 6 years. The patient expressed satisfaction with both the esthetic and functional outcomes. This case, marked by multiple avulsions, underscores the importance of immediate and appropriate intervention alongside the imperative for carefully considered long‐term management strategies. Given the decelerated bone remodeling rate in adults, ERR generally progresses at a slower pace than in children. Accordingly, this case demonstrates the viability of retaining replanted teeth over the long term, even when these teeth have been subjected to nonphysiological storage for extended durations, a factor known to impede periodontal healing. [ABSTRACT FROM AUTHOR]

Background: This pilot study aimed to evaluate the effectiveness of digitally crafted customized healing abutments in stabilizing peri-implant soft tissues following tooth extraction and assess the preservation of peri-implant soft tissue architecture over 5 years. Material and Methods: Forty patients (age ≥ 25 years) were divided into test (n = 20) and control (n = 20) groups. The test group received dental implants with immediate loading after tooth extraction, along with customized healing abutments fabricated using CAD/CAM technology. The control group received dental implants with immediate loading without customized healing abutments. The primary outcome was the change in distance between the peri-implant soft tissue margin and implant fixture surface from baseline to 5 years post implantation. Results: In the test group, there was a significant decrease in the distance between the peri-implant soft tissue margin and fixture surface from baseline to 5 years (p < 0.001), with pairwise comparisons showing significant differences between multiple time points (p < 0.05). The control group showed less pronounced changes over time. Conclusions: Within the limitations of this pilot study, digitally fabricated customized healing abutments appear effective in stabilizing peri-implant soft tissues and preserving soft tissue architecture around dental implants over 5 years following immediate implant placement. Randomized controlled trials are needed to confirm these findings. [ABSTRACT FROM AUTHOR]

Implant-supported-screw-retained prostheses are highly popular. Some of the most frequent complications are connected with the mechanical properties of the fixing elements. These include abutment screw loosening or even screw fracture. Using an intermediate abutment can offer several advantages. However, few studies detail how this affects the mechanical behavior of dental restorations. This study focuses on understanding the mechanical behavior of implant-supported restorations with a transepithelial component compared to direct implant-supported restoration. It was carried out using the finite element method (FEM) and was experimentally validated. The results showed that in the case of transepithelial-supported restoration, the prosthetic screw mounted over the transepithelial component suffered higher stress than the one screwed directly into the implant. After applying a cyclic fatigue load, it was experimentally proven that, in the transepithelial-supported restorations, the fuse changed from being the screw that went into the implant to being the upper one. In conclusion, we can state that the use of an intermediate abutment in dental restoration not only provides better protection for the rest of the dental restoration but also allows for easier repair in the event of a fracture. This can potentially lead to more efficient procedures and improved patient outcomes. [ABSTRACT FROM AUTHOR]

Objective: To assess the reliability of implant stability measurements recorded with the Periotest device and to investigate the differences in values when these measurements were taken on implant retained crowns and healing abutments. Materials and Methods: Fifty‐six implants in eight synthetic bone blocks were used to carry out implant stability measurements using the Periotest device by two different operators. Each block constituted an example of bone of density D1, D2, D3, or D4, and two blocks of each density were used. The healing abutments placed were of a height to allow approximately 6 mm of the implant‐abutment complex to be supracrestal and temporary crowns were made to match the dimensions of an average central incisor. Descriptive statistics were used to describe the perio test values (PTVs) at each of the different heights on the implant abutments and implant crowns. Means for each site were calculated and distribution of data assessed using the Kruskal Wallis test. The interclass correlation coefficient (ICC) was used to determine the relationship between the PTVs recorded on the implant abutments and implant crowns. Results: The mean PTV (±standard devidation) recorded across all sites was 5.57 ± 11.643 on the implant abutments, and 12.27 ± 11.735 on the temporary crowns. Excellent/good inter‐operator ICCs were recorded for the mid‐abutment site in all bone blocks D1–D4 (ICC = 0.814, p < 0.001, ICC = 0.922, p < 0.001, ICC = 0.938, p < 0.001, ICC = 776, p < 0.001). For mid crown sites, ICC between operators was excellent/good only for recordings in D2 bone (ICC = 0.897, p < 0.001). Conclusions: Periotest device seems to be able to reliably measure implant stability across all types of bones when the implant stability is assessed at approximately 3 mm coronal to the implant platform for abutments and 4.5 mm for implant supported single crowns. [ABSTRACT FROM AUTHOR]

Objectives: The stability of the abutment screw is pivotal for successful implant‐supported restorations, yet screw loosening remains a common complication, leading to compromised function and potential implant failure. This study aims to evaluate the effect of different implant‐abutment types and heights on screw loosening in cases with increased crown height space (CHS). Materials and Methods: In this in vitro study, a total of 64 abutments in eight distinct groups based on their type and height were evaluated. These groups included stock, cast, and milled abutments with heights of 4 mm (groups S4, C4, and M4), 7 mm (groups S7, C7, and M7), and 10 mm (groups C10 and M10). Removal torque loss (RTL) was assessed both before and after subjecting the abutments to dynamic cyclic loading. Additionally, the differences between initial RTL and RTL following cyclic loading were analyzed for each group (p <.05). Results: The C10 group demonstrated the highest RTL, whereas the S4 group exhibited the lowest initial RTL percentage (p <.05). Furthermore, the study established significant variations in RTL percentages and the discrepancies between initial and postcyclic loading RTL across different abutment groups (p <.05). Additionally, both abutment types and heights were found to significantly influence the RTL percentage (p <.05). Conclusion: The type and height of the implant abutment affected screw loosening, and in an increased CHS of 12 mm, using a stock abutment with a postheight of 4 mm can be effective in minimizing screw loosening. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this retrospective study was to evaluate the outcomes of a two-piece implant system with a tube-in-tube internal connection after up to 15 years of clinical use. Material and methods: A retrospective follow-up examination of patients treated with internal tube-in-tube implants between 2003 and 2006 was conducted. The implant survival rates, peri-implant conditions (marginal bone loss, bleeding on probing, plaque index, probing depth), and technical complications were determined. Results: In total, 312 dental implants were placed in 152 patients. Of the original 152 patients enrolled, 245 implants in 112 patients were available for a follow-up evaluation after 11 to 15 years (mean observation time, 12.9 ± 1.1 years). The overall implant survival rate was 93.9%. Outcomes for MBL (1.49 ± 1.23 mm), PI (24.3 ± 22.2%), BOP (18.3 ± 28.7%), and PD (2.74 ± 1.21 mm) were observed. Selected parameters (time after implant surgery, smoking habits, bone augmentation (GBR)) showed an influence on MBL and PD. Conclusions: The internal tube-in-tube implant system showed favorable long-term results. The correlation of MBL and PD with the patient-specific factor smoking habit is in accordance with other studies. Clinical relevance: Camlog Root-Line implants with a tube-in-tube implant-abutment connection and a 1.6-mm polished neck configuration have demonstrated favorable long-term outcomes in daily clinical practice. However, it is important to note that these implants are no longer available on the market. [ABSTRACT FROM AUTHOR]

Aim. This study aimed to evaluate the peri-implant soft tissue response to customized healing abutments (CHAs) made of titanium and polyetheretherketone (PEEK). Methods. Titanium and PEEK CHAs were mounted on bone-level dental implants in bilateral edentulous patients in a randomized split-mouth study design. After a three-week healing period, the clinical parameters of the peri-implant soft tissues were assessed. The value of marginal bone resorption was measured by cone-beam computed tomography. In addition, peri-implant crevicular fluid samples were obtained to identify periodontal pathogenic bacteria, cytokine levels, and active neutrophil collagenase (aMMP-8) concentration. Microcirculation and oxygenation parameters were assessed using laser Doppler flowmetry and optical tissue oximetry. In addition, wavelet analysis was conducted to study blood flow control mechanisms. Results. Out of the 23 participants initially recruited, 20 were assessed after titanium and PEEK CHA installation due to losses to follow-up. The peri-implant soft tissue around 27 titanium and 25 PEEK CHAs was evaluated during follow-ups. No differences were found in the values of marginal bone resorption, cytokine levels, or total bacterial load (p>0.05). PEEK CHAs demonstrated lower bleeding on probing values, less plaque accumulation, and faster relief of ischemia and hypoxia. Although aMMP-8 concentration was higher in the PEEK group, the values were within normal limits. Conclusions. The results of this comparative study showed a positive soft tissue response to PEEK CHAs. However, further studies comparing the effectiveness of different materials for CHAs should be carried out, considering their specific physical properties and processing protocols.

Purpose: To evaluate the effect of different treatments applied to titanium implant abutment surfaces on the retention of implant-supported crowns retained using resin cement. Materials and Methods: A total of 72 titanium implant abutments were divided into six groups (n = 12 each) based on the selected surface treatment: (1) untreated; (2) sandblasted; (3) hydrogen peroxide-etched; (4) atmospheric plasma; (5) chemical mechanical polishing; and (6) titanium dioxide nanocoating. After the surface treatments, scanning electron microscopy analyses and roughness measurements of the abutment surfaces were performed. Then, 72 metal copings were fabricated and cemented onto the abutments with dual-curing resin cement. After the thermocycling process, crown retention was measured by using a universal testing machine. The experimental results were statistically evaluated with one-way analysis of variance, Tukey honest significant difference, and Tamhane T2 tests. Results: The highest surface roughness values were obtained in the sandblasted group (1.44 um), which also showed in the highest retention values (828.5 N), followed by the hydrogen peroxide etching group (490.7 N), the atmospheric plasma group (466.5 N), the chemical mechanical polishing group (410.8 N), and the control group (382.6 N). Conclusion: Sandblasting, hydrogen peroxide, etching, and atmospheric plasma treatments significantly increased crown retention, and all alternative treatments, with the exception of TiO2 nanocoating, worked better than the control samples. [ABSTRACT FROM AUTHOR]

Purpose: To provide a 1-year assessment of friction-retention abutments used to retain a single lithium disilicate (LS2) monolithic restoration. Materials and Methods: A total of 522 implants were placed to treat a mandibular or a maxillary single-tooth premolar or molar edentulous site. Three types of implants were used. The tested abutments were connected 3 months after implant placement. A single pressed LS2 monolithic restoration was cemented to a dedicated titanium cap and engaged to the abutment without the use of screws or cement. Any complications affecting the restoration or the opposing dentition, any soft tissue dimensional changes, the distance between the implant platform and the bone peak, and pocket probing depths were recorded at the time of restoration placement (T0), after 6 months of function (T1), and after 1 year of function (T2). Esthetic, functional, and biologic parameters were recorded at T0 and T2. Results: A total of 507 patients (284 women and 223 men) received a restoration at T0, and 504 reached the 1-year follow-up at T2. One restoration fractured after 10 months in function. No statistically significant differences were seen in the soft tissue measurements or in the measurements of the distance between the supporting implant platform and the bone peak. None of the restorations detached during the observation period. Conclusion: The friction retention abutment is a viable option to retain an implantsupported monolithic LS2 glass-ceramic restoration in cases of premolar or molar single-tooth edentulism. [ABSTRACT FROM AUTHOR]

Purpose: To develop, analyze, and optimize a dental implant by considering square threads and varying the thread dimensions to obtain an optimal shape. Materials and Methods: For this study, finite element analysis (FEA) and numerical optimization method were integrated to develop a mathematical model. The critical parameters of dental implants were studied, and an optimized shape was obtained using response surface method (RSM) and design of experiment (DOE). The simulated results were then compared to the predicted values under optimal conditions. Results: Using the one-factor RSM design model for the dental implant and a vertical compressive load of 450 N for testing, the optimal depth to width ratio for the thread was 0.7 in order to achieve the minimum von Mises and shear stress. Conclusion: The buttress thread was found to be the optimal shape for achieving the lowest von Mises and shear stress compared to square threads, and the thread parameters were calculated accordingly, with a thread depth 0.45 times the pitch, a width 0.3 times the pitch, and a thread angle of 17 degrees. Also, due to the constant diameter of the implant, common 4-mm diameter abutments can be used interchangeably. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of cooling on the reverse torque values of different abutments in bone-level and tissue-level implants. The null hypothesis was that there would be no difference in reverse torque values of abutment screws when cooled and uncooled implant abutments were compared. Materials and Methods: Bone-level and tissue-level implants (Straumann, each n = 36) were placed in synthetic bone blocks and subdivided into three groups (each n = 12) based on the abutment type (titanium base, cementable abutment, abutment for screw-retained restorations). All abutment screws were tightened to 35 Ncm torque. In half of the implants, a dry ice rod was applied on the abutments close to the implant-abutment connection for 60 seconds before untightening the abutment screw. The remaining implant-abutment pairs were not cooled. The maximum reverse torque values were recorded using a digital torque meter. The tightening and untightening procedure was repeated three times for each implant including cooling for the test groups, resulting in 18 reverse torque values per group. Two-way analysis of variance (ANOVA) was used to analyze the effect of cooling and abutment type on the measurements. Post hoc t tests were used to make group comparisons (a = .05). The P values of post hoc tests were corrected for multiple testing using the Bonferroni-Holm method. Results: The null hypothesis was rejected. Cooling and abutment type significantly affected the reverse torque values in bone-level implants (P = .004) but not in tissue-level implants (P = .051). The reverse torque values of bone-level implants significantly decreased after cooling (20.31 ± 2.55 Ncm vs 17.61 ± 2.49 Ncm). Overall mean reverse torque values were significantly higher in bonelevel implants compared to tissue-level implants (18.96 ± 2.84 Ncm vs 16.13 ± 3.17 Ncm; P < .001). Conclusion: Cooling of the implant abutment led to a significant decrease in reverse torque values in bone-level implants and may therefore be recommended as a pretreatment before the application of procedures to remove a stuck implant part. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate hard and soft tissue response and mechanical integrity for screw-retained layered zirconia crowns bonded to titanium nitride-coated titanium (TiN) CAD/CAM abutments supported by implants at 1- and 2-year followups. Materials and Methods: A total of 46 patients were restored with a total of 102 free-standing implant-supported layered zirconia crowns, which were bonded to their respective abutments in the dental laboratory and delivered as a one-piece screw-retained crown. Baseline, 1-year, and 2-year data were collated on pocket probing depth, bleeding on probing, marginal bone levels, and mechanical complications. Results: Of the 46 patients, 4 patients with one implant each were not followed-up. These patients were not included in the analysis. Of the remaining 98 implants, due to failed appointments during the global pandemic, soft tissue measurements were recorded for 94 implants at year 1 and 86 implants at year 2, with a mean buccal/lingual pocket probing depth of 1.80/1.95 mm and 2.09/2.17 mm, respectively. Mean bleeding on probing was 0.50 and 0.53 at 1 and 2 years, which represents somewhere between no bleeding and a spot bleed according to the study protocol. Radiographic data were available for 74 implants at year 1 and 86 implants at year 2. The mean marginal bone change from baseline was +0.11 mm mesially and +0.19 mm distally at 1 year and +0.24 mm mesially and +0.16 mm distally at 2 years. The final bone level with respect to the reference point was +0.49 mm mesially and +0.19 mm distally at the end of the study period. Mechanical complications involving a slight misfit of the crown margin were recorded for one unit (1%), porcelain fracture for 16 units (16%), and a loss of preload for 12 units (12%) of < 5 Ncm (< 20% of initial preload). Conclusion: The biologic and mechanical stability of ceramic crowns bonded to CAD/CAM screw-retained abutments using angulated screw access was considered to be high, with overall bone gain, excellent soft tissue health, and only limited mechanical complications related to generally small fractures of the porcelain and a clinically insignificant loss of preload. [ABSTRACT FROM AUTHOR]

Purpose: To investigate and assess the differences in crestal bone loss (CBL) between wide-diameter, external-hexagon-connection implants restored with platform-switching (PS) and platform-matching (PM) restorations with a follow-up of 10 years. Materials and Methods: This study retrospectively analyzed the updated and enlarged dataset of a 5-year prospective clinical study at 10-year follow-up. The data concerns 182 healthy adult subjects treated in a private dental practice who received a single wide-diameter implant with an external hexagon connection in the molar area, restored with either a PS restoration (test) or PM restoration (control). The amount of CBL was radiographically measured at each annual follow-up, as well as after 5 and 10 years of implant loading. In evaluating the association between the two types of abutments and bone loss (including change over time), a linear mixed effects model was run for longitudinal data. Results: Implants connected with PS restorations exhibited significantly lower reduction (0.25 mm) in CBL than those joined to PM restorations (P < .001; 95% CI from 0.22 to 0.29). However, both groups presented a higher increase in bone loss during the first year (0.58 mm in PS and 0.83 mm in PM) and a linear increment thereafter until the 10-year followup (0.046 mm/year; P < .001; 95% CI from .042 to .049). Conclusion: Notwithstanding the limitations of this study, it can be concluded that after 10 years of follow-up, the implant with a wide diameter and external-hexagon connection restored with a PS abutment seems to be more effective in reducing bone loss compared with the PM abutment. [ABSTRACT FROM AUTHOR]

This prospective longitudinal study evaluated the peri-implant soft tissue remodeling, marginal bone levels, and implant success rate of immediately placed single implants--which received a definitive zirconia abutment and provisional restoration at implant placement--in the maxillary esthetic zone. The final crown was delivered 7 days later. Patients (n = 26) presenting a single extraction-indicated lateral or central incisor with adequate bone volume were eligible for this study. Mesial and distal papilla levels (MPL and DPL, respectively), facial gingival level (FGL), and mesial and distal marginal bone levels (MMBL and DMBL, respectively) were assessed after 7 days and at 1, 2, 3, 6, and 12 months. Patients were classified according to gingival phenotype: thin (= 2 mm) or thick (> 2 mm). After 1 year, the implant success rate was 100%. Mean soft tissue recession was -0.04 ± 0.15 mm (MPL), -0.09 ± 0.02 mm (DPL), and -0.13 ± 0.18 mm (FGL). Mean bone remodeling at 1 year was 0.12 ± 0.17 mm (MMBL) and 0.13 ± 0.18 mm (DMBL). The marginal interproximal bone was above the implant platform in 100% of sites. Patients with thick phenotype showed significantly less papillary recession than thin-phenotype patients. Minimal periimplant hard and soft tissue changes were observed at the 1-year follow-up. [ABSTRACT FROM AUTHOR]

Following the extraction of a compromised tooth, the edentulous alveolar ridge undergoes physiologic bone remodeling, which may create a bone volume too deficient for implant placement. Guided bone regeneration (GBR) provides a predictable treatment option to increase the alveolar bone volume for implant placement, but a soft or hard tissue deficiency may remain even after this augmentation procedure has been completed. These deficiencies can be especially challenging in the esthetic zone, where patient expectations and esthetics often determine the satisfaction of the treatment outcome. This paper presents a case report of a xenograft bone substitute used at the secondstage surgery and abutment insertion to provide a solution to these deficiencies even after the patient had undergone a GBR procedure, thus improving the esthetic and functional outcomes of the final implant-supported restoration. [ABSTRACT FROM AUTHOR]

Abstract Background While the concept of angled screw channels has gained popularity, there remains a scarcity of research concerning the torque loss and fracture strength of monolithic zirconia restorations with various screw channel angulations when exposed to thermomechanical cycling. This in-vitro study aimed to evaluate the reverse torque value and fracture resistance of one-piece screw-retained hybrid monolithic zirconia restorations with angulated screw channels after thermomechanical cycling. Methods One-piece monolithic zirconia restorations, with angulated screw channels set at 0°, 15°, and 25° (n = 6 per angulation) were fabricated and bonded to titanium inserts using a dual-cure adhesive resin cement. These assemblies were then screwed to implant fixtures embedded in acrylic resin using an omnigrip screwdriver, and reverse torque values were recorded before and after thermomechanical cycles. Additionally, fracture modes were assessed subsequent to the application of compressive load. One-way ANOVA and Bonferroni post hoc test were used to compare the groups (α = 0.05). Results The study groups were significantly different regarding the fracture resistance (P = 0.0015), but only insignificantly different in the mean percentage torque loss (P = 0.4400). Specifically, the fracture resistance of the 15° group was insignificantly higher compared to the 0° group (P = 0.9037), but significantly higher compared to the 25° group (P = 0.0051). Furthermore, the fracture resistance of the 0° group was significantly higher than that of the 25° group (P = 0.0114). Conclusions One-piece hybrid monolithic zirconia restorations with angulated screw channels can be considered an acceptable choice for angulated implants in esthetic areas, providing satisfactory fracture strength and torque loss.

Purpose: To test a newly introduced implant-abutment material combination against bacterial endotoxin leakage in a human whole blood assay. Materials and Methods: Two dental implant systems with internal connections and the following material combinations at the implant-abutment interface (IAI) were used (implant material/abutment material): yttrium-stabilized tetragonal zirconium dioxide (Y-TZP)/ polyetherketoneketone (PEKK), and titanium (Ti/Ti). Test implants were inoculated with lipopolysaccharide (LPS) and sealed and submerged in human whole blood. Untreated implants served as the control groups. Changes in gene expression levels of inflammatory markers indicating LPS leakage were assessed after 1, 8, and 24 hours using quantitative real-time polymerase chain reaction. Results: In the Y-TZP/PEKK test group, a significant influence of the implant system (P < .001) on increases in gene expression indicating leakage were detected after 8 hours for TLR-4 and after 24 hours for interleukin 1-β and nuclear factor kappa-lightchain-enhancer of activated B-cells (NF-κB), indicating microleakage of LPS at the IAI. In the Ti/Ti test group, differences in gene expression were found only for NF-κB after 8 hours. Conclusion: The internal hexalobe IAI of two-piece dental implants fabricated from Y-TZP and PEKK do not prevent LPS molecular microleakage. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the fracture load of monolithic, single-tooth implant-supported crowns cemented on solid or Ti-base (Variobase C) abutments. Materials and Methods: Besides abutment types (solid and Ti-base abutments), two ceramic systems (IPS e.max CAD and Zirconia inCoris ZI) and two occlusal thicknesses (0.5 and 1.5 mm) were also investigated in this study. In total, eight groups (n = 8) with 64 maxillary second premolar crowns were fabricated. All the crowns were cemented with resin cement, and the screw accesses in Ti-base groups were sealed with composite resin. After mechanical cycling, the specimens were submitted to fracture load test with the maximum force recorded in Newtons (N). Three-way analysis of variance (ANOVA) and Tukey post hoc test were used for statistical analyses (α = .05). Results: Both the abutment type (P = .0001) and the ceramic system (P = .0001) significantly affected the results. Screw-access channels reduced the fracture load of crowns by half compared to those cemented on solid abutments. The 1.5-mm and 0.5-mm zirconia crowns placed on solid abutments had similar highest fracture loads, while the e.max CAD groups positioned on Ti-base abutments showed significantly lower values compared with other groups. Conclusion: The screw access reduces the resistance of crowns supported by Ti-base abutments compared to crowns cemented on solid abutments. The inCoris ZI showed a higher fracture load than the IPS e.max CAD regardless of the abutment type and thickness. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effects of ultraviolet (UV) treatment and alendronate immersion on the osseointegration of dental implants and mucosal attachment of dental implant abutments using a mongrel dog model. Materials and Methods: A total of 48 sandblasted, large-grit, acid-etched (SLA) titanium dental implants and 48 machined surface healing abutments in four male mongrel dogs were prepared. Implants and healing abutments were divided into four groups (n = 12 per group). The control (CON) group did not undergo additional surface treatments. The UV group was treated with UV for 15 minutes, and the alendronate-immersed (AN) group was soaked in 10-3 M alendronate for 24 hours. The UV treatment and alendronate soaking (UVAN) group was treated with alendronate, followed by UV irradiation. All implants were placed in the mandible of mongrel dogs, and the animals were sacrificed at 4 and 8 weeks postoperatively. Bone-to-implant contact (BIC), bone density, and connective tissue attachment were measured. Results: In cortical bone, the UV group exhibited significantly higher BIC compared to the CON and AN groups (P < .05). In contrast, the AN and UVAN groups did not have significantly higher BIC. In the trabecular bone, there was no statistical difference between the groups. No significant increase in bone density and connective tissue attachment was shown in any group. Conclusion: UV treatment of SLA surface implants significantly increased osseointegration in cortical bone. The alendronate immersion did not increase osseointegration, and there was no synergic effect with UV treatment. Further, UV treatment and alendronate immersion of machined healing abutments did not significantly increase connective tissue attachment. [ABSTRACT FROM AUTHOR]

Implant bone loss and implant failure are growing concerns. In some cases, a possible factor leading to bone loss may be an allergy to titanium (Ti). In this report, the existing literature on Ti allergy as a factor in implant loss is reviewed, and the current views on its potential role in implant bone loss are discussed. A case report of implant loss and retreatment in a patient with a potential Ti allergy or intolerance is presented and clinically analyzed. The subsequent success of a ceramic implant may support the finding of a Ti allergy or intolerance. Unfortunately, the lack of prospective clinical trials and lack of a reliable test for Ti allergy makes it impossible to clinically verify whether Ti allergy plays a part in implant bone loss. [ABSTRACT FROM AUTHOR]

Objectives: Doxycycline hyclate is a controlled-release doxycycline polymer which can locally be applied. This study aimed to assess the effects of the prophylactic application of doxycycline hyclate at the implant-abutment interface on the shortterm outcomes of implant therapy. Method and materials: The present split-mouth randomized clinical trial included 20 subjects who received two mandibular implants bilaterally (40 implants in total). In the test side (n = 20), doxycycline hyclate was injected at the implant-abutment interface at the time of delivery of final prosthesis. No intervention was performed for the control side (n = 20). The marginal bone level on mesial and distal implant surfaces, bleeding on probing, pocket probing depth, and incidence of peri-implant mucositis were recorded at baseline and after 3, 6, and 12 months. Results: Significant differences were found between the test and control sites, all favoring the test group, for marginal bone level changes at mesial and distal implant surfaces as well as for changes in pocket probing depth after 6 and 12 months. Furthermore, the numbers of implants with bleeding on probing and risk of developing peri-implant mucositis were significantly greater in the control group compared to the test group at 3-months, 6-months, and 12-months following baseline. Conclusions: Within the limitations of this study, it can be concluded that prophylactic application of doxycycline hyclate at the implant-abutment interface results in reduced crestal bone resorption and pocket probing depth levels. In addition, it reduces the risk of developing peri-implant mucositis. [ABSTRACT FROM AUTHOR]

Purpose: To compare the effect of thermomechanical aging on implant abutment color change when using different abutment backgrounds. Materials and Methods: In this study, three separate experimental groups (n = 10) with different implant abutment materials were used: zirconia, modified polyether ether ketone (MPEEK), and polyether ketone ketone (PEKK). Equal-sized glass-ceramic incisor crowns were cemented to the abutments using transparent dual-curing resin cement. The specimens were then subjected to the thermomechanical aging process for the clinical equivalent of 5 years of use. The color values of each specimen in the middle third and the incisal third were recorded by a digital spectrophotometer in the CIE L*a*b* color coordinates both before and after the aging process. Color differences between groups were compared using one-way analysis of variance (ANOVA), while Tukey test was used to compare differences within the groups (P = .05). Results: In terms of color change (Î"E00) values, the zirconia group was found to show statistically more color changes only in the middle third (P < .000), but there was no significant difference between the the MPEEK and PEKK groups. In all groups, the Î"E00 value was clinically acceptable (Î"E00 < 1.8). Conclusion: After the aging process, high-performance polymer abutments caused less color change than zirconia. Therefore, esthetically satisfying results can be obtained in the anterior region, especially when highly translucent crown materials are used. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the risk factors related to failure of removable partial dentures (RPDs) and to compare the survival of RPDs when abutment teeth have good vs reduced bone support. Materials and Methods: In this longitudinal patient record-based cohort study with a mean follow-up of 44.9 months, Cox regression models were used to evaluate the associations between clinical covariates and abutment tooth failure, as well as prosthesis failure. Results: A total of 142 patients and 172 RPDs were included. Of the 172 prostheses, 64 (nearly 40%) failed after a mean time of about 4 years. Loss of abutment teeth was the main reason leading to RPD failure, followed closely by poor fit and adaptation. No factor was shown to be statistically significant at the prosthesis level. Women (Hazard Ratio [HR] = 0.542), endodontic treatment (HR = 3.460), presence of post and core (HR = 0.302), presence of a prosthetic crown (HR = 3.403), and abutment tooth type (in relation to incisor: canine HR = 0.196, premolar HR = 0.449) were the risk factors statistically significantly associated with the loss of abutment teeth. The pre-prosthesis amount of bone support of the teeth did not affect their prognosis as abutments for RPDs. Conclusion: RPD treatment modality presented a high failure rate after a mean follow-up of 4 years. Vital abutment teeth had a better survival rate than the ones treated endodontically (whether restored with or without a post and core); nevertheless, the amount of bone support did not affect their survival. [ABSTRACT FROM AUTHOR]

Purpose: To observe the effect of different prosthetic materials (polymethyl methacrylate [PMMA] and flowable composite [FC]) on marginal bone loss, pink esthetic score (PES), and cytokine levels (receptor activator of nuclear factor kappa-B ligand [RANKL] and osteoprotegerin [OPG]). Materials and Methods: A total of 46 patients (31 women, 15 men) were treated with immediate implant therapy after tooth extraction. For standardization, only the maxillary premolar tooth of each patient was restored, and also, both of the adjacent teeth were present in the dental arch. Provisional crowns were prepared before the surgery on patient models with two different materials (24 PMMA, 22 FC). Following the surgical procedure, provisional crowns were adjusted on polyetheretherketone (PEEK) abutments as nonfunctional in centric and eccentric movements. After the surgery, patients were evaluated monthly for 3 months. At each follow-up, periapical radiography was obtained by the parallel technique, and peri-implant crevicular fluid (PICF) was collected. Pink esthetic scoring was done. MBL was calculated for the mesial and distal sides separately. Cytokine levels were analyzed from PICF. Statistical analyses (Shapiro-Wilk, Mann-Whitney U, independent-samples t test, Wilcoxon t test, paired-samples t test, and Friedman two-way analysis of variance with Bonferroni correction) were completed (α = .05). Results: PES was increased significantly within groups (P < .01). However, there was no statistically significant difference between groups. According to the Mann-Whitney U test, no significant difference was found for the MBL (P > .05). When the RANKL/OPG values were evaluated within the group by using the Friedmann two-way analysis of variance test, no significant difference was found (P > .05). Conclusion: Similar pink esthetics, cytokine levels, and bone loss can be achieved using a protocol including immediate implants, particle grafts, soft tissue graft, PEEK abutments, and provisional restorations fabricated using PMMA and FC. [ABSTRACT FROM AUTHOR]

Purpose: Restoring the esthetics of anterior teeth with implants is challenging. This study aimed to evaluate the esthetic outcome of interproximal papilla between implant-restored unilateral and bilateral maxillary central incisors. Materials and Methods: A total of 56 adults with implant restorations in the maxillary central incisors were enrolled, including 40 cases of unilateral incisors and 16 cases of bilateral incisors. Photographic and radiographic assessments were performed, and patient-reported esthetic satisfaction was collected. Results: The papilla index (PI) in the unilateral group was superior to that in the bilateral group (P = .002). Patients in the two groups reported equal satisfaction regarding the final esthetic outcome (P = .470). Statistically significant differences were noted between the two groups in papilla height (P = .000), implant-implant or implant-tooth distance (P = .002), and vertical distance from the implant platform to the bone crest (P = .000). In the bilateral group, tested variables were not correlated with PI by nonparametric Spearman correlation. In the unilateral group, the multivariate binary logistic regression model showed that incomplete papilla fill was associated with abutment type (OR = 0.019), implant-tooth distance (range, 2.1 to 6.2 mm; OR = 6.435), and distance from the bone crest to the contact point (range: 3.5 to 6.9 mm; OR = 4.589). Conclusion: In implant-restored maxillary central incisors, PI in the unilateral group was superior to that in the bilateral group. In the bilateral group, no clinical variable was correlated with PI. In the unilateral group, the risk of incomplete papilla fill was reduced by the customized zirconia abutment and was increased by the larger implant-tooth distance and higher distance from the bone crest to the contact point. [ABSTRACT FROM AUTHOR]

Purpose: The "one-abutment, one-time" concept entails the placement of a definitive abutment at the time of implant placement, without removal during prosthesis manufacture, with the aim to promote a safer environment for the periimplant tissues. Identifying surgical and radiographic parameters that can assist with the abutment height selection would facilitate the adoption of the one-abutment, one-time concept. Therefore, the aim of this study was to assess the role of surgical and radiographic parameters as predictive factors for abutment height selection in implant-retained single crowns. Materials and Methods: This prospective study assessed the role of surgical and radiographic measurements in the implant survival and success rates and marginal bone loss in implant-retained single crowns. Implants were placed in both healed sites and extraction sockets, and the distances between the implant platform and alveolar bone crest, implant platform and gingival margin, and buccal gap (when present) were recorded using a straight periodontal probe. Digital radiographs were made at implant placement (T0), abutment height selection (Ta), and 1-year follow-up (Tf), and the distance between the implant platform and the alveolar bone crest (mm) was assessed. Linear regression models and Pearson correlation were used to assess the influence of primary and secondary outcomes on abutment height. Results: A total of 130 implants were placed in 68 patients. The mean surgical distance between the bone crest and the implant platform was 1.71 ± 1.01 mm, and the mean distance from the gingival margin to the implant platform was 3.94 ± 1.90 mm, while at the abutment selection appointment, the mean transmucosal height was 3.58 ± 1.50 mm. A high linear correlation was found between the selected abutment height and two primary outcomes: the radiographic implant platform to alveolar bone crest distance at T0 (r² = 0.66; P < .001) and the transmucosal height at Ta (r² = 0.81; P < .001). Conclusion: Radiographic measurements of the distance between the implant platform and the alveolar bone crest at implant placement can serve as an important parameter to select the abutment height for definitive restorations. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the role of different healing abutment designs in compensating for the buccolingual volumetric tissue change that occurs following flapless single-tooth immediate extraction placement in the molar area. Materials and Methods: Patients in need of extraction and replacement of a first or second molar in the mandible or maxilla were consecutively recruited. Immediately after extraction and implant placement, an abutment was connected. Five different types of abutments were randomly selected to be used for each case. The study population was divided into five categories according to abutment design: 5-mm diameter healing abutment (group 1); 6-mm diameter healing abutment (group 2); 7.5-mm diameter healing abutment (group 3); provisional restoration (group 4); and customized healing abutment (group 5). The buccopalatal dimension (BPD) was measured on the study casts at 1, 3, and 5 mm apical to the free gingival margin, and horizontal volumetric changes were compared between baseline and 2, 4, and 6 months. Results: A total of 267 implants were inserted in 246 patients. The breakdown of placed implants for each group was as follows: 67 implants in group 1; 64 in group 2; 71 in group 3; 33 in group 4; and 32 in group 5. Changes in the mean horizontal ridge dimension were as follows. After 6 months in group 1, BPD diminished at 1-, 3-, and 5-mm distance from the free gingival margin, respectively, by 4.21 ± 0.158, 3.38 ± 0. 178 and 2.35 ± 0.178 mm. In group 2, BPD diminished at 1-, 3-, and 5-mm distance from the free gingival margin, respectively, by 3.16 ± 0.198, 2.56 ± 0.198, and 1.62 ± 0.198 mm. In group 3, BPD diminished at 1-, 3-, and 5-mm distance from the free gingival margin, respectively, by 2.53 ± 0.138, 2.16 ± 0.144, and 1.56 ± 0.144 mm. In group 4, BPD diminished at 1-, 3-, and 5-mm distance from the free gingival margin, respectively, by 1.11 ± 0.179, 1.23 ± 0.179, and 1.12 ± 0.179 mm. In group 5, BPD diminished at 1-, 3-, and 5-mm distance from the free gingival margin, respectively, by 0.25 ± 0.225, 0.30 ± 0.225, and 0.19 ± 0.225 mm. Mixed-effect regression and post hoc means comparisons were used to model the impact of the restoration technique, height of measurement, and time on BPD using a significance reference level of .05. Statistical analysis showed that the type of abutment, the height of measurement, and the time significantly influenced the BPD and that there were complex interaction effects between these variables. Conclusion: The observed volumetric soft tissue changes in the 6-month short-term follow-up appeared to vary based on the use of different healing abutment sizes that were connected to implants placed immediately after tooth extraction in the molar area. In particular, the use of a customized healing abutment resulted in preservation of the original horizontal dimension of the molar soft tissue. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effects of various titanium and zirconia polishing protocols on the colonization of oral bacteria. Titanium and zirconia discs were divided into five groups: unpolished (control, UNP) and polished with Brownie only (BRO), Brownie plus Greenie (BPG), Brownie plus Greenie plus Supergreenie (BGS), and CeraMaster Coarse plus CeraMaster polishing tips (CER). The samples were sterilized and immersed in unstimulated saliva, then incubated in a liquid suspension of Streptococcus gordonii (S gordonii). The number of attached bacteria were counted 48 hours after the diluted suspensions were inoculated. Data were analyzed with ANOVA and Tukey test (P < .05). For titanium discs, the average number of bacteria from each group (CFU/mm2) was 1.51 x 103 for UNP; 3.71 x 103 for BRO; 5.65 x 103 for BPG; 8.99 x 102 for BGS; and 8.49 x 102 for CER. For zirconia, the averages were 2.87 x 102 for UNP; 3.16 x 102 for BRO; 3.50 x 102 for BPG; 1.83 x 102 for BGS; and 8.73 x 101 for CER. Inadequate polishing roughens surfaces and promotes microbial adhesion to titanium and zirconia. Sequential polishing to the finest-finish polishing tips minimizes bacterial adherence to abutment surfaces. Zirconia exhibited less bacterial adhesion than titanium. [ABSTRACT FROM AUTHOR]

The high biomechanical loads in molar region wounds challenge the indication for short implants to be used as a single-unit implant. This study reports on the outcomes of single-unit short implants (= 8.0 mm) in the maxillary and mandibular molar regions. Forty-nine short implants were placed in 48 patients to replace a missing molar tooth. Two-piece restorations with screw retention were fabricated. During the follow-up, implant survival and marginal bone loss (MBL) were assessed. The known implant length was used as a reference to calibrate the linear measurements on digital periapical radiographs, and descriptive statistical analysis was performed. The implants were followed over a period of 47 ± 12 months. No implant failure was recorded, and no prosthesis failure was observed. The average MBL was 0.15 ± 0.5 mm. The mean crown height space was 13 ± 3 mm. The overall crown-to-implant ratio was 1.7 ± 0.4. Two technical complications occurred due to the loosening of the unit abutment. After screw re-tightening, no more screw loosening was observed. This study supports the use of short implants as a single-unit implant in the maxillary and mandibular molar regions. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of this in vitro study was to evaluate the influence of the ceramic thickness, cement shade, and airborne-particle abrasion of the titanium on the final color of titanium base cemented lithium disilicate glass-ceramic restorations. Method and materials: In total, 144 lithium disilicate glass-ceramic disks of three thicknesses (0.5, 1.0, and 1.5 mm) were cemented to airborne-particle-abraded and non-airborne-particle-abraded titanium disks with six adhesive resin cements. The color measurements were performed with a clinical spectrophotometer. The mean and standard deviation of evaluated ΔE values were calculated. A three-way analysis of variance (ANOVA) was used for analyzing the data. Statistical analyses were computed with a significance level of α = .05 using a statistical software program (Minitab 17, Minitab). Results: The 0.5- and 1-mm-thick ceramic specimens cemented with Panavia V5 Opaque showed the lowest ΔE values when cemented on both non-airborne-particle-abraded (5.62 ± 1.66, 3.15 ± 1.28) and airborne-particle-abraded (5.55 ± 0.86, 3.16 ± 0.49) surfaces, while the highest values were seen in the groups cemented with RelyX U200 A2 (29.22 ± 0.83, 17.23 ± 0.45) and Panavia V5 A2 (29.94 ± 1.17, 16.71 ± 0.44) on airborne-particle-abraded surfaces. For the 1.5-mm-thick ceramics, the lowest ΔE values were seen when Multilink MO 0 cement was used on non-airborne-particle-abraded surfaces (1.56 ± 0.29) and when Panavia V5 Opaque was used on airborne-particle-abraded surfaces (1.56 ± 0.66). The highest values were seen when RelyX U200 A2 (9.77 ± 1.13), PA2 (9.24 ± 0.25), and Multilink HO 0 (9.19 ± 1.33) were used on airborne-particle-abraded surfaces, and when Multilink HO 0 (9.61 ± 1.70) was used on non-airborne-particle-abraded surfaces. The 1-mm-thick ceramics cemented with Multilink HO 0 showed higher ΔE values (12.05 ± 1.99) for airborne-particle-abraded and non-airborne-particle-abraded (12.58 ± 1.06) than thinner (0.5 mm) or thicker (1.5 mm) ceramics. Conclusion: Thinnest ceramic superstructures resulted in the highest ΔE values. Cements that mask the underlying color reflect their own shade under thin superstructures. Airborne-particle abrasion of titanium surfaces increases the grayish reflectance if cement shade does not have the color masking ability. [ABSTRACT FROM AUTHOR]

Background: Retrieval of cement-retained implant-supported restorations is intriguing in cases of screw loosening. Detecting the estimated size of the screw access hole (SAH) could decrease destruction to the prosthesis and preserve the crown. Objectives: To precisely localize loose implant screws through cemented crowns to reduce crown damage after screw loosening. Materials and methods: In this in vitro study, 60 cement-retained implants supported 30 zirconia-based, and 30 ceramics fused to metal (CFM) lower molar crowns were invented, and each was subdivided into three subgroups (10 each). In group I (AI/BI) (control), SAH was created with the aid of orthopantomography (OPG). In contrast, in group II (zirconia-crown), SAH was created with the aid of CBCT + 3D printed surgical guide with a 2 mm metal sleeve in subgroups IIA/IIIA and CBCT + MAR was used to develop SAH in subgroups IIB/IIIB. SEM and Micro-CT scanned the SAH openings to determine the diameter of the hole, cracking, chipping, and chipping volume. Results: Regarding the effect of plane CBCT and CBCT + MAR on prepared crowns, a highly significant association between group I with group II (p = 0.001) and group III (p = 0.002) was detected. Regarding the cracking of SAH, significant differences between the zirconium crown and CFM restoration (p = 0.009) were found, while for the chipping, no significant association was seen between groups (p = 0.19). Conclusions: CBCT, either as a plane CBCT or with MAR, significantly improved the accuracy of drilling the screw channel and decreased injury to the existing restoration and abutment, aiding in better localization of SAH in loosened implant abutment screws. [ABSTRACT FROM AUTHOR]

The marginal accuracy of fit between prosthetic restorations and abutment teeth represents an essential aspect with regard to long-term clinical success. Since the final gap is also influenced by the luting techniques and materials applied, this study analyzed the accuracy of the fit of single-tooth zirconia copings before and after cementation using different luting materials. Forty plaster dies with a corresponding zirconia coping were manufactured based on a single tooth chamfer preparation. The copings were luted on the plaster dies (n = 10 per luting material) with a zinc phosphate (A), glass–ionomer (B), self-adhesive resin (C), or resin-modified glass–ionomer cement (D). The accuracy of fit for each coping was assessed using a non-destructive digital method. Intragroup statistical analysis was conducted using Wilcoxon signed rank tests and intergroup analysis by Kruskal–Wallis and Mann–Whitney U tests (α = 0.05). Accuracy of fit was significantly different before/after cementation within A (0.033/0.110 µm) and B (0.035/0.118 µm; p = 0.002). A had a significantly increased marginal gap compared to C and D, and B compared to C and D (p ≤ 0.001). Significantly increased vertical discrepancies between A and B versus C and D (p < 0.001) were assessed. Of the materials under investigation, the zinc phosphate cement led to increased vertical marginal discrepancies, whereas the self-adhesive resin cement did not influence the restoration fit. [ABSTRACT FROM AUTHOR]

The aim of this paper was to evaluate the fracture resistance of 3D-printed zirconia occlusal veneers (OVs) of different thicknesses and supported by different abutment materials. Materials and Methods: The standard OV of a natural molar was prepared and digitized using a laboratory 3D scanner. The resulting digital tooth abutment was milled either using cobalt–chromium (CoCr) or a fiber-reinforced composite (FRC). All the abutments were digitized and standardized OVs (30° tilt of all the cusps) designed with 0.4 mm, 0.6 mm, or 0.8 mm wall thicknesses. The OVs were fabricated using either the Programill PM7 milling device (Ivoclar Vivadent, PM) or one of two 3D zirconia printers, Cerafab 7500 (Lithoz, LC) or Zipro-D (AON, ZD). The ZD samples were only tested on CoCr abutments. The completed OVs were luted to their abutments and subjected to artificial aging, consisting of thermocycling and chewing simulation before fracture testing with a steel sphere (d = 8 mm) as an antagonist with three contact points on the occlusal OV surface. Besides the total fracture resistance Fu,tot, the lowest contact force Fu,cont leading to the local fracture of a cusp was of interest. The possible effects of the factors fabrication approach, wall thickness, and abutment material were evaluated using ANOVA (α = 0.05; SPSS Ver.28). Results: The total fracture resistance/contact forces leading to failure ranged from Fu,tot = 416 ± 83 N/Fu,cont = 140 ± 22 N for the 0.4 mm OVs fabricated using LC placed on the FRC abutments to Fu,tot = 3309 ± 394 N (ZD)/Fu,cont = 1206 ± 184 N (PM) for the 0.8 mm thick OVs on the CoCr abutments. All the factors (the fabrication approach, abutment material, and OV wall thickness) had an independent effect on Fu,tot as well as Fu,cont (p < 0.032). In pairwise comparisons for Fu,tot of the OVs luted to the CoCr abutments, the ZD samples statistically outperformed the LC- and PM-fabricated teeth irrespective of the thickness (p < 0.001). Conclusions: Within the limitations of this study, the printed occlusal veneers exhibited comparable fracture resistances to those of the milled variants. However, more resilient abutments (FRC as a simulation of dentine) as well as a thinner wall thickness led to reduced OV fracture resistance, suggesting that 0.4 mm thick zirconia OVs should not be unreservedly used in every clinical situation. [ABSTRACT FROM AUTHOR]

Introduction: The longevity of cement-retained implant-supported restorations depends upon a strong and durable bond at the metal/cement interface. Various forms of surface treatments of implant abutments have been shown to enhance the retention of cement-retained restorations. The present study was undertaken to comparatively evaluate the tensile bond strength of metal copings luted onto implant abutments subjected to different surface treatments and determine the most effective surface treatment for long-term retention. Materials and Methods: Forty acrylic blocks were prepared, each with an implant analogue placed vertically inside the block and straight abutments tightened optimally onto implant analogues. The samples were divided into four Groups (n = 10) according to surface treatment of implant abutments: Group A – no surface treatment, Group B – sandblasting, Group C – metal primer application and Group D – acid etching. Metal copings were luted onto implant abutments, and the tensile force necessary to debond each metal coping was measured using a universal testing machine. Data were summarised in Mean ± Standard deviation. Groups were compared by one factor analysis of variance (ANOVA) and significance of mean difference between the groups was done by Tukey's honestly significant difference post hoc test after ascertaining normality by Shapiro-Wilk's test and homogeneity of variance between groups by Levene's test. A two-tailed (α = 2) P < 0.05 was considered statistically significant. Results: The highest mean tensile bond strength was recorded for Group C (metal primer application), followed by Groups B, D and A, respectively. Conclusion: Amongst the surface treatments used in the study, metal primer application was found to be most effective in improving the retention of cement-retained prostheses. [ABSTRACT FROM AUTHOR]

Background: In recent years, the use of conometric systems to connect dental implant abutments and prosthetic caps has been advocated because they seem to eliminate the side effects reported when using screw- and cement-connected prosthetic restorations. Objectives: The present case study is focused on conometric connection characterization and its performance in terms of the microarchitecture of peri-implant soft tissues by using a cross-linked approach based on optical microscopy and three-dimensional imaging. Methods: Two dental implants were characterized using micro-CT and another identical one was implanted into a patient; the latter was retrieved 45 days later due to changes in prosthetic needs. Afterward, the peri-implant soft tissues were investigated using synchrotron-based phase contrast imaging, histology, and polarized light microscopy. Results: Micro-CT analysis showed perfect adhesion between the abutment and prosthetic cap; histology and polarized light microscopy showed that connective tissue was richly present around the abutment retrieved from the patient. Moreover, the quantitative evaluation of connective tissues using synchrotron imaging, supported by artificial intelligence, revealed that this tissue was rich in mature collagen, with longitudinal and transverse collagen bundles intertwined. The number and connectivity of transverse bundles were consistently greater than those of the longitudinal bundles. Conclusion: It was found that the peri-implant soft tissue was already mature and well organized after only 45 days of implantation, supporting the hypothesis that conometric connections contribute to the significant stabilization of peri-implant soft tissues. [ABSTRACT FROM AUTHOR]