Recurrence Rate of Proximal Contact Loss Between Implant Restorations and Adjacent Teeth After Proximal Contact Repair: A Retrospective Study.

PURPOSE: Proximal contact loss (PCL) between implant-supported fixed dental prostheses (FDPs) and adjacent teeth has been reported as a common complication of implant therapy. The prevalence of PCL and its potential risk factors have been extensively studied. However, few studies have discussed the recurrent PCL after intervention to restore the proximal contacts. Thus, this retrospective study aimed to evaluate the recurrence rate of PCL and its potential risk factors. MATERIALS AND METHODS: This study included 41 patients (with 45 implants in the posterior region), who had experienced PCL between implant restorations and adjacent teeth and had received contact repair. Recurrent PCL was recorded and evaluated during routine follow-ups with an interval of 6 to 12 months. The recurrence rates and time were measured. The potential influential factors of PCL were also assessed. Fisher exact test, t test, univariate logistic regression analyses, and multivariate logistic regression model were utilized to identify factors influencing PCL. RESULTS: The recurrence rates of mesial PCL were high (> 50%) and the recurrence time became progressively rapid after each repair (5, 3.2, and 2.2 years). Implants with the first PCL recurrence were more likely to be splinted than those implants without recurrence (54.5% vs 18.8%; P = .032). In addition, patients with the first recurrence were slightly older than those without recurrence (55.8 vs 50.1 years; P = .087). Age, implant restoration (splinted vs single), frequent use of interdental brushes, and time to first complaint were the candidate factors associated with recurrent PCL in the univariate logistic regression analysis. The multivariate logistic regression model revealed that only splinted implant restoration was independently associated with a higher risk of recurrence (odds ratio 4.99; 95% confidence interval 1.02-24.31; P = .047). CONCLUSION: The recurrence rates of mesial PCL were high and associated with the splinted-type design. Also, the recurrence time of PCL accelerated after each repair. Therefore, routine follow-up monitoring PCL and carefully assessing patient compliance after implant therapy are recommended.

Comparison of the residual cement on custom computer-aided design and computer-aided manufacturing titanium and zirconia abutments: A preliminary cohort study.

STATEMENT OF PROBLEM: Clinical studies comparing the occurrence and quality of residual cement between custom zirconia and custom titanium abutments with subgingival margins are scarce. PURPOSE: The purpose of this clinical study was to assess the difference in the amount of residual cement between custom zirconia and titanium abutments with a 1-mm subgingival margin. MATERIAL AND METHODS: Eighty participants were randomized to receive either a custom zirconia abutment with a bonded titanium insert or a custom titanium abutment with a 1-mm subgingival margin on a posterior bone-level implant. Monolithic lithium disilicate crowns with a screw-access hole were cemented to abutments randomly with either a resin-modified glass ionomer cement or a resin cement. After cementation, the crown-abutment assemblies were removed and photographed from the mesial, buccal, distal, and lingual of the specimen to record the residual cement. The length along the abutment margin of each aspect of the assembly was measured. The surface area of the residual cement (SA) and the surface area of the residual cement per unit length of margin (SA_P) were calculated. Results for the groups were compared with the Fisher exact test, the Friedman test, and the Mann-Whitney U test (α=.05). RESULTS: The median (lower quartile, upper quartile) of SA and SA_P for the custom zirconia abutment with a bonded titanium insert was 1.9 (0.5, 3.9) mm2 and 0.086 (0.032, 0.02) mm2, respectively, and for the custom titanium abutment, the values were 2.9 (1.3, 5.1) mm2 and 0.138 (0.062, 0.239) mm2, respectively. No significant difference was found between the custom zirconia abutments with bonded titanium inserts and titanium abutments for SA (P=.075) and SA_P (P=.083) with the Mann-Whitney U test. No significant difference was found in residual cement between the 4 aspects of the abutment (SA: P=.852; SA_P: P=.954) with the Friedman test and between the 2 types of cement (SA: P=.447; SA_P: P=.878) with the Mann-Whitney U test. CONCLUSIONS: A similar amount of subgingival residual cement was recorded around the abutment-crown assembly, regardless of the abutment material or cement type used.

Retrospective comparison of posterior fixed dental prostheses supported by two different titanium abutments on tissue level implants.

STATEMENT OF PROBLEM: Clinical studies comparing compatible computer-aided design and computer-aided manufacturing (CAD-CAM) titanium abutments (CAs) and original prefabricated 1-piece titanium abutments (PAs) for posterior fixed dental prostheses (FDPs) on Straumann Tissue Level (STL) implants are sparse. PURPOSE: The purpose of this retrospective clinical study was to compare the performance of posterior FDPs supported by CAs and PAs on STL implants after a mean observation period of 7.2 years. MATERIAL AND METHODS: Patients who received STL implants and posterior FDPs by using CAs or PAs between January 2002 and December 2012 and returned for follow-up between January 2017 and September 2018 were included in this study. Technical and biological complications of FDPs were examined and recorded. Radiographs were used for the measurement of marginal bone loss (MBL) of each implant. Variables, complication rates, and MBL of the 2 groups were analyzed by using a generalized estimating equation and multivariable linear mixed model. RESULTS: Ninety-nine patients with 195 implants in the CA group and 75 patients with 143 implants in the PA group were included. The mean functional time of FDPs was 6.5 ±1.1 years for the CA group and 8.1 ±2.6 years for the PA group. No implant failure was noted in either group. The technical complication rate was 20.8% in the CA group and 26.3% in the PA group. Abutment screw loosening (ASL) was noted in the CA group (8.5%). The decementation rate was significantly higher in the PA group (14.1%) than that in the CA group (3.1%) (adjusted odds ratio=4.40, confidence interval=1.41 to 13.69, P=.011). No significant differences were found between the 2 groups in terms of the rates of ceramic chipping, peri-implantitis, peri-implant mucositis, or mean MBL. CONCLUSIONS: Using CAs or PAs to support posterior FDPs on STL implants has no significant effect on the incidence rate of biological complications. However, a higher ASL rate and a lower decementation rate were noted with CAs than with PAs.

The prevalence and associated factors of proximal contact loss between implant restoration and adjacent tooth after function: A retrospective study.

BACKGROUND: Dental implant is widely used as a treatment for missing teeth. However, proximal contact loss (PCL) between implant-supported fixed dental prostheses (FDP) and adjacent teeth has been reported as one of the common and adverse complications. PURPOSE: We aimed to evaluate the prevalence of PCL up to 18 years after implant prosthesis delivery and to analyze associated factors. MATERIALS AND METHODS: A total of 317 patients who had received implant FDP at the posterior regions were included in this study. Nineteen factors were assessed, including degrees of proximal contact tightness, oral hygiene, periodontal conditions, and food impaction. Chi-square test, univariate generalized estimating equation (GEE), and multivariate GEE were utilized to identify factors influencing PCL. RESULTS: Proximal contacts at both the mesial and distal (if present) sides were evaluated. The mesial contact loss rate (27%) was significantly higher than that of the distal contact loss (5%). Increased PCL rates over functional time were observed at both the mesial and distal sides. Six factors, including patient age, implant functional years, frequent use of interdental brushes, splinting or single implant, plunger cusp, and food impaction, were revealed to be associated with the mesial PCL using the chi-square test and univariate GEE analysis. However, only functional years (>5 years), frequent use of interdental brushes and food impaction showed significance in the multivariate GEE. CONCLUSIONS: Mesial PCL was frequent and increased over functional years. An occlusal retainer and routine follow-up may help prevent PCL. Although oral hygiene conditions contribute little to PCL, food impaction and frequent use of interdental brushes were influential factors.

Clinical evaluation of two-piece zirconia abutments with bonded titanium inserts for implant-supported restorations.

STATEMENT OF PROBLEM: Information about the long-term evaluation of 2-piece zirconia abutments (TPZAs) with bonded titanium inserts for implant-supported restorations is sparse. PURPOSE: The purpose of this clinical study was to evaluate the clinical outcome of TPZAs with bonded titanium inserts for implant-supported restorations. MATERIAL AND METHODS: This study retrospectively evaluated the records of patients who received implant restorations supported by TPZAs with bonded titanium inserts. The patients were recalled between January 2017 and December 2017 so that the restorations could be examined clinically and radiographically for technical and biological complications. RESULTS: A total of 27 patients with 30 restorations and 42 zirconia abutments (ZAs) were included in the study. The patient records revealed that all implants remained integrated. However, 5 restorations supported by seven ZAs in 4 patients had to be refabricated because of abutment failure before the recall. Six of the failed abutments were in the molar area, with a combination of zirconia and titanium as the connection platform. Additional complications included screw loosening (1 patient), ceramic chipping (1 patient), and peri-implantitis (1 patient). The mean observation period was 6.6 ±1.5 years (range: 3.6 to 9.2 years). CONCLUSIONS: After a mean observation period of 6 years after insertion, TPZAs with bonded titanium inserts appear to be a suitable treatment option in the anterior and premolar regions. However, in the molar area, the use of the same type of ZA without a complete metal-to-metal connection platform to support the restoration led to a high incidence of fracture.

Retrospective and Clinical Evaluation of Aftermarket CAD/CAM Titanium Abutments Supporting Posterior Splinted Prostheses and Single Crowns.

PURPOSE: To evaluate the clinical outcomes of aftermarket computer-aided design/computer-assisted manufacturing (CAD/CAM) titanium abutments supporting splinted prostheses and single crowns in the posterior region. MATERIALS AND METHODS: This study retrospectively evaluated the records of patients who received posterior implant-supported splinted restorations and single crowns supported by aftermarket CAD/CAM titanium abutments. Recall and clinical examination of the patients were performed between January 2017 and February 2018. A logistic regression was conducted to evaluate the influence of variables on the occurrence of complications and success rates. Correlations between the bone-level change and variables were calculated using the Spearman correlation. RESULTS: One hundred thirty-five patients with 287 implants (86 crowns and 97 splinted prostheses) were recalled and examined clinically and radiographically after a mean observation period of 6.3 ± 1.2 years (range 4.1 to 9 years). Failure of 3 implants led to a survival rate of 99.0%. Complications included 18 (9.8%) ceramic chippings, 15 (8.2%) screw loosenings, 8 (4.4%) decementations, 52 (38.5%) patients with peri-implant mucositis, and 9 (6.7%) patients with peri-implantitis. A significantly higher incidence of ceramic chipping occurred with bruxers (odds ratio [OR] = 3.939, 95% confidence interval [CI] = 1.28-12.09, P < .05). All screw loosenings occurred in single crowns. All decementations were observed in restorations cemented with temporary cement. Marginal bone loss around implants was significantly correlated with smoking (r = -0.155, P < .05). Hypertension was significantly associated with peri-implant mucositis (OR = 4.7, 95% CI = 1.65-13.39, P < .05). The technical success rate was 80.1%. The biologic success rate was 57%. There was no association between the restoration type and the success rates of the restorations. CONCLUSIONS: Using aftermarket CAD/CAM titanium abutments to support posterior restorations yielded comparable survival and success rates after a mean observation period of 6 years. However, in light of the relatively high incidence of screw loosenings, especially in patients receiving single-implant crowns, informing patients of the additional chairside aftercare with this type of treatment option is recommended.

Compatible CAD-CAM titanium abutments for posterior single-implant tooth replacement: A retrospective case series.

STATEMENT OF PROBLEM: In addition to the original abutments provided by implant companies, compatible computer-aided design and computer-aided manufacturing (CAD-CAM) abutments are also available from different manufacturers. However, the combination of abutments and implant systems from different manufacturers may lead to mechanical problems between components. Little has been reported on the clinical performance of this treatment option. PURPOSE: The purpose of this retrospective case series was to evaluate the outcome of compatible CAD-CAM titanium abutments (TiAs) for posterior single-implant tooth replacement (PSITR) up to 6 years after insertion. MATERIAL AND METHODS: Eighty-one patients (34 men, 47 women) who received PSITR restored with compatible CAD-CAM TiAs and had a final recall examination between May 2014 and April 2015 were included in this study. Clinical and radiographic examinations were documented. Retrospective evaluation of the patient records was also performed. Correlations between bone-level changes and variables were calculated using the Spearman correlation. RESULTS: Implant and prosthesis survival rates were 100%. Twenty technical complications were observed, including 9 decementations of the crown, 6 screw loosenings, and 5 ceramic fractures. Periimplant mucositis was diagnosed in 36 patients (44.4%) and periimplantitis in 6 patients (7.4%). Correlation analysis showed a significant effect of the extent of periodontal bone loss of the remaining teeth on the marginal bone-level changes around implants (r=0.548, P<.001). CONCLUSIONS: Compatible CAD-CAM TiAs provide a viable treatment option for PSITR. However, in light of relatively high screw-loosening and decementation rates, choosing appropriate cements and abutment manufacturers is essential to improve the clinical performance of this treatment option.

SEM evaluation of resin-carious dentin interfaces formed by two dentin adhesive systems.

OBJECTIVES: We investigated the influence of dentin tubule direction and identifiable zone of carious dentin on the microstructure and the thickness of the hybrid-like layer (HL) formed by self-etch and etch-rinse adhesive systems. METHODS: An etch-rinse and a self-etching adhesive were bonded to dentin carious zones divided into groups with parallel or perpendicular orientation relative to the dentin tubules at the resin-carious dentin interface (N=5/variable). Bonds were prepared to each of the four zones of carious dentin apparent after staining with Caries Detector: pink, light pink, transparent and apparently normal; six non-carious third molars were controls. The microstructure and thickness of the HL were determined by SEM and compared using three-way ANOVA and Tukey's multiple comparisons (p<0.05). RESULTS: Etch-rinse controls gave thicker HLs than self-etching systems; orientation did not affect thickness for the self-etch system. Perpendicular orientations gave thicker HLs than parallel for the pink zone bonded with the etch-rinse system. For both adhesives, HL thickness in the pink zone was significantly greater than in light pink for the perpendicular group, but no significant differences were found among other variables. HL microstructure was more granular and rougher for the etch-rinse than for the self-etching system. Pores and cracks were obvious in the more demineralized zones. Resin tags were shorter and irregular in the transparent zone and often were completely absent in the outer demineralized zones (pink, light pink). SIGNIFICANCE: Microstructure of bonded interfaces varies markedly depending on adhesive system, tubule orientation and carious zone.

Multi-factorial retainer design analysis of posterior resin-bonded fixed partial dentures: a finite element study.

OBJECTIVES: Biomechanical aspects related to prosthesis design of RBFPD have been proposed as the predominant contributor to unpredictable clinical retention. The aim of this study was to investigate the biomechanics of multiple posterior retainer designs and their interactions using three-dimensional finite element analysis. METHODS: To understand the interactions among the retainer design factors, three values of retainer thicknesses (1.2, 0.8 and 0.4mm), heights (100, 75 and 50% of the distance from 2mm above the CEJ to the occlusal surface) and angle of the axial surface extensions (150, 180 and 210 degrees ) were selected as the design parameters. Twenty-seven RBFPD FE models with three retainer-design parameters were created by image processing, contour stacking, and mapping mesh procedures. The maximum principal and von Mises stresses in remaining tooth and prosthesis, respectively, were recorded in 54 FE analyses (27 FE models with axial and lateral occlusal loadings). RESULTS: The simulated results showed that the averaged stress values of the remaining tooth and prosthesis decreased with greater retainer thickness and height as a result of increasing prosthesis stiffness and maximizing of the bonding area between the enamel and the retainer, respectively. However, no significant stress differences were found according to the angle of the retainer extension because stress transmission was concentrated at the connectors. CONCLUSIONS: The stress elevation rate (termed as VSR-stress elevation by decreasing one unit volume of the remaining tooth) addresses that the height was the most influential factor for the remaining tooth structure, followed by retainer thickness and extension angle.

Esthetic restoration of infra-occluded retained primary mandibular incisors with all-ceramic crowns in adult dentition.

The prevalence of hypodontia is reported to be between 1.5% to 10% in the permanent dentition. In the anterior teeth, maxillary lateral incisors and mandibular central incisors are the most frequently involved teeth. This causes esthetic problems for the patient. Several reports have focused on restoration of retained maxillary primary anterior teeth, but none have described restoration of retained mandibular primary incisors. This clinical report describes the restoration of infra-occluded retained primary mandibular central incisors of a 17 year-old girl diagnosed with hypodontia. All-ceramic crowns made with computer-aided design/ computer-aided manufacturing technology were used to restore the teeth incisally and interproximally. Due to a relatively short root length and inadequate crown-root ratio, the primary mandibular central incisors were splinted and adjusted to distribute the protrusive force evenly across the maxillary and mandibular incisors. Functional and esthetic results were achieved.

Guided bone regeneration for fenestration defects in dental implants.

Guided bone regeneration has been applied in implant dentistry for increasing the width and height of the alveolar ridge in areas with insufficient bone. Various materials and techniques have been used for this purpose. It refers to a surgical procedure by which utilizing a mechanical barrier to create a secluded space around the defect to permit bone regeneration without the competition of other tissues. This report presents a case with buccal fenestrations on maxillary implant sites observed during a surgical procedure. An allograft and a non-resorbable membrane were concomitantly used to increase the width of the alveolar ridge. Hard tissue regeneration was evident clinically. The implants were restored for functioning and followed for 2 years. Factors affecting outcomes are also discussed. Membrane stability and the space-making effect remain the keys to success.