Influence of Abutment Color and Mucosal Thickness on Soft Tissue Color.

PURPOSE: Zirconia (ZrO2) and titanium nitride (TiN) implant abutments were introduced mainly for esthetic purposes, as titanium's gray color can be visible through mucosal tissues. This study was aimed at assessing whether ZrO2 and TiN abutments could achieve better esthetics in comparison with titanium (Ti) abutments, regarding the appearance of soft tissues. MATERIALS AND METHODS: Ninety patients were included in the study. Each patient was provided with an implant (OsseoSpeed, Dentsply Implant System). A two-stage surgical technique was performed. Six months later, surgical reentry was performed. After 1 week, provisional restorations were screwed onto the implants. After 8 weeks, implant-level impressions were taken and soft tissue thickness was recorded, ranking thin (≤ 2 mm) or thick (≥ 2 mm). Patients were randomly allocated to three experimental groups, based on abutment type: (1) Ti, (2) TiN, and (3) ZrO2. After 15 weeks, the final restorations were delivered. The mucosal area referring to each abutment was measured for color using a clinical spectrophotometer (Easyshade, VITA); color measurements of the contralateral areas referring to natural teeth were performed at the same time. The data were collected using the Commission Internationale de l'Eclairage (CIE) L*a*b* color system, and ΔE was calculated between peri-implant and contralateral soft tissues. A critical threshold of ΔE = 3.7 was selected. The chi-square test was used to identify statistically significant differences in ΔE between thin and thick mucosal tissues and among the abutment types. RESULTS: Three patients were lost at follow-up. No statistically significant differences were noticed as to the abutment type (P = .966). Statistically significant differences in ΔE were recorded between thick and thin peri-implant soft tissues (P < .001). Only 2 out of 64 patients with thick soft tissues showed a ΔE higher than 3.7: 1 in the TiN group and 1 in the ZrO2 group. All the patients with thin soft tissues reported color changes that exceeded the critical threshold. CONCLUSION: The different abutment materials showed comparable results in terms of influence on soft tissue color. Regarding peri-implant soft tissue thickness, the influence of the tested abutments on soft tissue color became clinically relevant for values ≤ 2 mm.

3-Year Randomized Controlled Prospective Clinical Trial on Different CAD-CAM Implant Abutments.

BACKGROUND: Zirconia abutments were introduced to restore esthetic regions and showed sufficient stability to support implant restorations. Nonetheless, to date the observation periods are shorter than those of titanium abutments. PURPOSE: To assess the survival of implant crowns supported by computer aided design-computer aided manufacturing (CAD-CAM) abutments after 3 years. MATERIALS AND METHODS: Fifty-six patients were selected for this prospective clinical study. Each patient received at least 1 titanium implant for a total of 89 fixtures. A two-stage surgical technique and no additional soft or hard tissue graft were used. The implants were randomly divided into 3 groups receiving different CAD-CAM abutments: titanium, titanium nitride, and zirconia. Zirconia or metal-ceramic crowns were used as final restorations. Cementation was the baseline and the restorations were checked after 6 months, 1, 2, and 3 years, assessing any mechanical complication. Statistical analyses were performed to evaluate the 3-year success rates. RESULTS: Five failures were reported in the zirconia group; all the failed restorations showed fractures of the abutment connection. Four failures occurred in posterior regions and one more occurred while screwing the abutment. Titanium and titanium nitride abutments had significantly higher 3-year success rates than zirconia abutments (p < .05). CONCLUSIONS: Atlantis titanium and titanium nitride abutments showed optimal clinical performances after 3 years. Conversely, Atlantis zirconia abutments should be avoided to restore posterior regions.

Effect of different prosthetic abutments on peri-implant soft tissue. A randomized controlled clinical trial.

PURPOSE: This randomized clinical trial assessed the effect of three different prosthetic abutments (titanium, gold-hue titanium and zirconia) on peri-implant soft tissue 2 years after treatment in partially edentulous subjects. METHODS: Baseline data concerning (1) thickness of the buccal peri-implant soft tissue, (2) soft tissue thickness above the bone crest, (3) depth/length of transmucosal pathway, and (4) periodontal biotype at adjacent teeth were collected. The final sample consisted of 47 subjects (21 males, 26 females) with a total of 97 implants. A two-level (patient, implant) statistical model was applied. RESULTS: At the 2-year clinical observation, recession of the gingival margin was observed only at 13% of implants irrespective of the type of abutment. No significant correlation between periodontal biotype at adjacent teeth and peri-implant biotype was observed. Furthermore, none of the investigated variables at patient level (age, gender, implant type, periodontal biotype) or at implant level (keratinized tissue thickness, probing depth, soft tissue thickness) was identified as a significant predictor of recession. In conclusion, this study pointed out that (1) abutment type was not able to influence peri-implant variables after 2 years, and (2) caution should be used in considering periodontal biotype at patient level as a possible indicator of the future peri-implant biotype.

Fatigue resistance and structural integrity of different types of fiber posts.

The study aimed at assessing and estimating the fatigue resistance of different fiber posts and to observe their ultrastructures through SEM. Six types of fiber posts were used: GC Fiber Post (Group 1), ParaPost Fiber White (Group 2), FibreKor (Group 3), DT Light-Post radiopaque (Group 4), FRC Postec (Group 5), and Luscent Anchors (Group 6). Ten out of 15 posts within each group were used for the fatigue test, and the other five were processed for SEM evaluation. The fatigue test revealed that Groups 1, 4, and 5 performed better than all the other groups, and that their performance differed significantly from the other tested groups from a statistical standpoint. For SEM analysis, Groups 1, 4, and 5 also obtained better results. Through correlation analysis, an absence of correlation between fatigue resistance and structural characteristics suggested that the latter reflected more of the divergence inherent in the manufacturing process of fiber posts.

Placement of fiber prefabricated or custom made posts affects the 3-year survival of endodontically treated premolars.

PURPOSE: To assess whether the amount of residual coronal dentin and the placement of a prefabricated (DT Light Post) (LP) or a customized fiber post (Ever Stick Post) (ES) have a significant influence on the 3-year survival of endodontically treated premolars. METHODS: A sample of 345 patients provided six groups of 60 premolars in need of endodontic treatment. Groups were defined based on the amount of dentin left at the coronal level after endodontic treatment and before abutment build-up. Within each group teeth were randomly divided into three subgroups (n = 20). In Subgroup A, no root canal retention was provided for the coronal restoration. In Subgroups B and C, LP and ES, respectively, were placed inside the root canal. All the teeth were finally restored with a single unit metal-ceramic crown. RESULTS: Data were not affected by any loss to follow-up. The overall 36-month survival rate of crowned endodontically treated premolars was 76.7%. The lowest survival rate was recorded for teeth restored without any root canal retention (62.5%). Teeth restored with LP had a survival rate higher (90.9%) than those restored with ES (76.7%). The Cox regression analysis showed that the presence of root canal retention was a significant factor for survival (P < 0.05). The decrease in failure risk was higher in teeth restored with LP (HR = 0.1; 95% CI for HR = 0.09 to 0.34; P < 0.001) than when using ES (HR = 0.5; 95% CI for HR = 0.3 to 0.7; P = 0.003). Teeth retaining one (HR = 0.3; 95% CI for HR = 0.2 to 0.7; P = 0.003), two (HR = 0.2; 95% CI for HR = 0.1 to 0.5; P < 0.001), or three coronal walls (HR = 0.1; 95% CI for HR = 0.05 to 0.3; P < 0.001) had a significantly lower failure risk than teeth deprived even of the ferrule effect. Similar failure risks existed for teeth missing all the coronal walls regardless of the presence or absence of a ferrule effect (P > 0.05). Interaction terms were not significant (P > 0.05). Post placement and the amount of residual coronal dentin affected the 3-year survival of endodontically treated premolars.

How can droplet formation occur in endodontically treated teeth during bonding procedures?

PURPOSE: The aim of this in vivo study was to clarify how blistering formation occurs along intraradicular dentin bonded interfaces. MATERIALS AND METHODS: Patients were selected and post space was prepared in vivo in endodontically treated teeth. Post space was etched, dried with ethanol, and bonded with one of the following adhesive systems: All Bond 2, XP-Bond, Clearfil SE Bond, Xeno III. The four adhesives were considered as representative of each bonding system class. An additional group was prepared with phosphoric acid treatment + application of Pre-Bond unfilled resin of All Bond 2, without the use of the primer agent. Etching was avoided for self-etching materials. Replicas of the post space were taken (1) after post space preparation; (2) after etching, rinsing, and drying; (3) after ethanol drying, and (4) after adhesive application. Replicas were analyzed with SEM and blisters were counted by independent observers. Statistical analysis was performed with Kruskal-Wallis ANOVA and Dunn's multiple comparison tests at p = 0.05. RESULTS: No blister formation occurred on replicas taken prior to adhesive application, while blister formation was evident in all replicas of bonded interfaces, irrespective of the adhesive system. No statistical difference in the number of droplets was found between All Bond 2, XP-Bond, and Clearfil SE Bond. Xeno III exhibited the highest number of blisters. Specimens bonded with Pre-Bond unfilled resin of All Bond 2 without primer application showed no blister formation. CONCLUSION: This study revealed that blister formation occurs only if the priming agent of the adhesive system was applied, thus supporting the hypothesis that blistering occurs due to adhesive phase separation or insufficient solvent evaporation.

Long-term retrospective study of the clinical performance of fiber posts.

PURPOSE: To retrospectively evaluate the long-term clinical performance of three types of fiber posts after a service period of 7-11 years. METHODS: 985 posts were included in the study: 615 Composiposts, 160 AEstethic Posts and 210 AEsthetic Plus Posts were placed into endodontically treated teeth. Four combinations of dentin adhesives/luting materials were used. Endodontic and prosthodontic results were recorded. RESULTS: A 7-11% failure rate was recorded for the three types of posts. A total of 79 failures were recorded: 39 due to endodontic reasons, one root fracture, one fiber post fracture, 17 crown dislodgements and 21 due to post debonding. The mechanical failures were always related to the lack of coronal tooth structure. The results indicated that fiber posts in combination with bonding/luting materials may be used routinely for restoring endodontically treated teeth. Mechanical failure of restored teeth with fiber posts can be related to the amount of residual coronal structure.

Clinical performance of fiber post restorations in endodontically treated teeth: 2-year results.

PURPOSE: This study evaluated the 2-year outcome of post-and-core restorative procedures in endodontically treated teeth. The effect of baseline factors (tooth type, number of residual coronal walls, and type of definitive restoration) on restoration failure was assessed. MATERIALS AND METHODS: The consecutive sample design included 150 patients. A total of 162 teeth (57 anterior and 105 posterior) were restored. Sixty-nine teeth had 3 or 4 residual coronal walls, while 93 teeth had 2 or fewer walls. Crowns and direct resin composite restorations were placed in 121 and 41 teeth, respectively. After 23 to 25 months, all patients were evaluated. Logistic regression was used to identify the joint effect of variables recorded at baseline (P < .05). RESULTS: The only failure modes observed were post debonding (4.3%, 2 in anterior teeth and 5 in posterior teeth) and endodontic failure (3.0%, 2 in anterior teeth and 3 in posterior teeth). All post debondings occurred in teeth with 2 or fewer coronal walls that were crown covered. All endodontic failures occurred in crown-covered teeth (1 failure in a tooth with 3 walls and the remaining 4 failures in teeth with 2 or fewer walls). Logistic regression found no statistical significance for any of the variables recorded at baseline. CONCLUSION: Restorations placed with the use of a fiber post and core resulted in 4.3% post debondings and 3.0% endodontic failures after 2 years of clinical service.

XP BOND in self-curing mode used for luting porcelain restorations. Part A: Microtensile test.

PURPOSE: To assess the bond strength to dentin of an experimental adhesive and the proprietary resin cement used in different curing modes to lute ceramic disks of different thicknesses. MATERIALS AND METHODS: Empress II disks (Ivoclar-Vivadent) were luted to dentin using XP BOND (Dentsply [XP]) in combination with the proprietary self-curing activator (SCA) and cement Calibra (Dentsply [C]). Curing of the adhesive was induced either by mixing with the activator (activator, groups 3 to 6) or by light irradiation for 20 s (group 2). The cement was either light cured for 40 s through the ceramic onlay (groups 1 to 5) or cured chemically (groups 6 and 7). Groups 2 and 4 were compared with group 1, in which Prime & Bond NT (Dentsply DeTrey) was tested as control. In groups 3 and 6, 2-mm-thick onlays were luted with XP+SCA, and the cement was light cured for 40 s or autocured for 5 min, respectively. These groups were compared with group 7, in which Syntac (Ivoclar Vivadent) was applied with C and, in order to reproduce the handling procedures of group 6 (although contrary to manufacturer's instructions), no light irradiation was provided for the adhesive or the cement. The influence of onlay thickness (2, 3, 4 mm) on the bond strength developed by XP+SCA/C was assessed by comparing groups 3, 4, 5. In these groups, C was light cured for 40 s through the onlay. Microtensile beams were obtained from the luted teeth. RESULTS: Bond strengths not including pretest failures (in parentheses: value including pretest failures as 0 MPa) were 21.0 (17.5) MPa in group 1, 24.9 (21.2) MPa in group 2, 23.7 (21.3) MPa in group 3, 29.9 (26.7) MPa in group 4, 30.3 (24.6) MPa in group 5, 28.6 (24.6) MPa in group 6, and 17.1 (9.2) MPa in group 7. Statistically significant differences were found between groups 1 and 4, groups 3 and 5, and groups 6 and 7. CONCLUSION: The bonding potential of XP BOND used with the activator or light cured in combination with Calibra in self- or dual-curing mode outperformed that of a control adhesive-cement system. The bond strength of XP+ SCA + Calibra was not negatively affected by the onlay thickness.

XP BOND in self-curing mode used for luting porcelain restorations. Part B: Placement and 6-month report.

PURPOSE: The aim of this clinical study was to evaluate the postoperative hypersensitivity of Empress II inlays/onlays luted under clinical conditions with XP BOND in combination with SCA and Calibra cured in self-curing mode. MATERIALS AND METHODS: Fifty-three restorations were placed in 38 patients in March and April 2006. No patient received more than two restorations. Luting procedures were performed following manufacturers' instructions. The restorations were evaluated after 2 weeks and 6 months for postoperative hypersensitivity, marginal discoloration, marginal integrity, secondary caries, maintenance of interproximal contact, and fracture. RESULTS: At the 2-week recall, the postoperative hypersensitivity was reported in only 10 and after 6 months in only 3 patients. All other parameters showed alpha scores. CONCLUSION: All the evaluated restorations were in place and acceptable. The postoperative hypersensitivity recorded after using XP BOND and Calibra in self-curing mode was clinically acceptable.

Daytime use of a custom bleaching tray or whitening strips: initial and sustained color improvement.

PURPOSE: To compare the clinical response of 6% hydrogen peroxide whitening strips and a 10% carbamide peroxide custom tray system under common daytime usage conditions, in an Italian dental research center. METHODS: Informed consent and baseline measurements were collected, and 43 healthy adults were randomly assigned to 6% hydrogen peroxide whitening strips (Crest Whitestrips) or the 10% carbamide peroxide custom tray (Opalescence 10%). The maxillary arch was treated twice daily for 30 minutes at-home. Treatment was discontinued after 2 weeks, and subjects were monitored for an additional 4 weeks. Efficacy (initial and sustained) was measured objectively from standard digital images of the maxillary facial tooth surfaces using the international CIELAB system. Safety was assessed from interview and examination. Treatments were compared after 2 weeks (end-of-treatment) and 6 weeks (4 weeks post-treatment) using analysis of covariance methods. RESULTS: Both groups exhibited color improvement at the Week 2 end-of-treatment visit. For yellowness, mean (SD) Deltab* at Week 2 was -2.10 (0.70) for the strip group and -1.61 (1.03) for the tray group. For lightness, mean (SD) DeltaL* at Week 2 was 1.25 (0.92) for the strip group and 1.17 (1.19) for the tray group. Compared to Week 2, the strip group retained 89-92% of the initial Deltab* and DeltaL* color improvement at Week 6 (4 weeks post-treatment), while the tray group had 80-90%. Groups differed significantly (P< 0.05) on end-of-treatment and post-treatment Deltab*, favoring the strips. Both daytime treatments were well-tolerated, with minor tooth sensitivity and oral irritation representing the most common findings.

Clinical trial evaluating the peroxide concentration response of whitening strips over 28 days.

PURPOSE: The research evaluated the peroxide concentration whitening response following self-directed use of whitening strips over a 28-day period. METHODS: A randomized, double-blind, parallel group clinical study was conducted. 37 healthy adult volunteers were randomly assigned to one of three groups based on tooth color at screening: 1.8% hydrogen peroxide strips (HPS), 3.3% HPS or 5.3% HPS. Subjects applied the assigned maxillary strips twice per day for 30 minutes over 28 days. Tooth color was evaluated at day 7, 14 and 28 from digital images of the maxillary six anterior teeth using a standard method. Treatments were compared using analysis of covariance (adjusting for baseline) at a 0.05 level of significance. RESULTS: Hydrogen peroxide at concentrations ranging from 1.8-5.3% resulted in significant (P< 0.05) color improvement versus baseline as early as Day 7. There was a concentration-response for reduction in yellowness (deltab*) and lightness improvement (deltaL*) at all timepoints, favoring the higher concentrations. While the concentration-whitening relationship approached a linear response at Day 7, continued treatment resulted in incremental color improvement. All three peroxide concentrations were well tolerated, and no subjects discontinued early due to a treatment-related adverse event.