Survival rate and treatment success of glass fiber posts cemented with two adhesive cementation strategies after up to 106 months: a randomized clinical trial.

OBJECTIVES: The objective of this study is to evaluate the longevity of two fiber post cementation strategies in a prospective, multicenter, non-inferiority, double-blind randomized controlled trial. METHODS: A total of 152 teeth, with adequate endodontic treatment and loss of coronal structure and bilateral simultaneous posterior occlusal contacts, were randomly allocated to receive glass fiber posts cemented with a conventional cementation strategy (CRC group: adhesive system + resin cement) (Adper Single Bond + RelyX ARC; 3 M-ESPE) or a self-adhesive cementation strategy (SRC group: self-adhesive resin cement; RelyX U100/U200; 3 M-ESPE). The patients were recalled annually for clinical and radiographical evaluation with a 93% recall rate (142 teeth, with 74 at CR groups and 68 at SRC group). The primary outcome was survival rate, considering the fiber post debonding (loss of retention). The secondary outcome included the success rate of the prosthetic treatment with crown debonding, post fracture, and tooth loss (not related to post failure). Both outcomes were evaluated annually. The Kaplan-Meier method and Cox regression with 95% confidence interval were used for the statistical analysis. RESULTS: For the primary outcome (failures directly related to fiber posts cementation strategy), there were 4 fiber post debondings (2 per group), 8 root fractures (3 for SRC group and 5 for CRC group), and one mixed failure (debonding combined with root fracture for CRC), with both strategies presenting similar survival rates (p = 0.331), with 88.9% for the CRC group and 90.9% for the SRC group. For the secondary outcome (failures not related to fiber post cementation strategies), there were 8 crown debondings, 3 post fractures, and 3 tooth losses, with no statistically difference between groups (p = 0.701), with 77% for SRC and 82% for CRC. CONCLUSION: Fiber post cementation strategies with conventional or self-adhesive resin cement presents similar tooth survival and success rates. TRIAL REGISTRATION: NCT01461239 CLINICAL RELEVANCE: Both adhesive cementation strategies led to high survival and success rates and are indicated for fiber post cementation, even after a long follow-up period (up to 106 months).

Longevity of metal-ceramic single crowns cemented onto resin composite prosthetic cores with self-adhesive resin cement: an update of a prospective analysis with up to 106 months of follow-up.

OBJECTIVES: To evaluate the longevity of metal-ceramic single crowns cemented onto resin composite prosthetic cores using a self-adhesive resin cement in a prospective clinical descriptive study. METHODS: A total of 152 teeth were endodontically treated and received resin composite prosthetic cores and metal-ceramic crowns cemented with a self-adhesive resin cement. The patients included in the sample were recalled for clinical and radiography evaluation in an up-to-106-month period after the final cementation procedures, with an average of 62 months of follow-up. 91.5% of the sample (142 teeth) were evaluated regarding the treatment survival rate, analyzed considering the loss of crown retention (crown debonding) and tooth loss as the primary outcome. In addition, post debonding, and root fracture occurrences were also recorded as secondary outcomes to evaluate the success rate of the prosthetic treatment. The aesthetic parameters were also evaluated according to the FDI criteria. The Kaplan-Meier method and Cox regression with 95% confidence interval were applied for the statistical analysis. RESULTS: Regarding the primary outcome, the metal-ceramic crowns cemented with self-adhesive resin cement presented a high survival rate (91.5%), with 8 crown debondings and 3 tooth losses (1 due to caries and 2 due to periodontal disease) occurring after the evaluation period. For secondary outcomes, 9 root fractures and 4 post debondings occurred, generating a success rate of 72%. All crowns had a score 1 on the FDI criteria, indicating that they were clinically excellent or very good regarding the aesthetic parameters. CONCLUSION: The metal-ceramic crowns luted with a self-adhesive resin cement presented a survival rate of 91.5% after an average of 62 months of follow-up. Furthermore, the restorations remained aesthetically satisfactory over time, without changes that would indicate prosthetic retreatment. A success rate of 72% was obtained considering the secondary outcome, mainly related to intraradicular retainer failures (root fractures or post debonding). CLINICAL SIGNIFICANCE: The self-adhesive resin cement is clinically indicated for cementation of metal-ceramic crowns onto resin composite prosthetic cores.

Multidisciplinary Approach for Reestablishing Function and Aesthetic of Unilateral Cleft Lip Defect: A Case Report.

Cleft lip and/or cleft palate defects often result in a functional deficiency in the patient's chewing, speech ability, and aesthetic appearance, usually demanding multidisciplinary effort for addressing the aesthetic and functional patient's requirements. This clinical report describes the planned oral rehabilitation of a 46-year-old woman with unilateral cleft lip defect based on the patient's peculiarities and age. Due to limitations concerning bone grafts and implant procedures, as well as orthodontic treatment, the prosthodontic rehabilitation using the metal-ceramic fixed partial denture was chosen. The treatment adequately reestablished the aesthetic and functional activities, positively impacting the patient's quality of life.

Novel bendable abutments as a solution to correct unfavorable implant inclination. A clinical report.

OBJECTIVE: This clinical case report describes a novel bendable abutment as a prosthetic solution for implants presenting with an unfavorable inclination. CLINICAL CONSIDERATIONS: A metal-ceramic screw-retained single crown was made on this novel bendable abutment in a patient presenting with a pronounced buccal inclination of an implant. A plastic reference guide is used to define the correct inclination and then this inclination is transferred to the abutment using a specific bending device at the same appointment. CONCLUSIONS: Bendable abutments can be used as a solution to correct unfavorable implant inclinations. This abutment can be customized at the same appointment considering a case-specific inclination rather than conventional pre-angled abutments. CLINICAL SIGNIFICANCE: Bendable abutments can be customized according to each case specificities while conventional pre-angled abutments may not be adequate for all patients. Also, the abutment customization could be easily done by dentists at their own practices using a specific bending device with hand pressure only, saving time, and the need to order pre-angled abutments or having it in stock.

Ceramic Repair Without Hydrofluoric Acid.

PURPOSE: To evaluate the bond strength between composite resin and feldspathic ceramic following repair protocols with and without hydrofluoric acid and aging by thermocycling. MATERIALS AND METHODS: Forty-eight glass feldspathic ceramic blocks (8 x 8 x 6 mm) were divided into three groups on the basis of their surface repair treatment: 1. 10% hydrofluoric acid + Signum Ceramic Primer I + Signum Ceramic Primer II (control group); 2. abrasive rubber tips + Signum Ceramic Primer I + Signum Ceramic Primer II (test group); 3. Signum Ceramic Primer I + Signum Ceramic Primer II (negative control group). The treated surface of each block was built up with composite and then sectioned to produce nontrimmed bars (adhesive area = 1 mm²). Half of the bars from each group were aged by 6000 cycles of 30-s immersions in water baths at 5°C and 55°C, with a transfer time of 2 s. The other bars were immediately subjected to microtensile bond strength testing. The mean bond strength for each block was then recorded and submitted to two-way ANOVA and Tukey's test (α = 0.05). RESULTS: The aging protocol influenced the bond strength values of all groups (p = 0.000). The non-aged groups submitted to surface treatment protocols 1 (13.1 ± 2.5 MPa) and 2 (11.5 ± 5.1 MPa) presented the highest bond strength values. CONCLUSIONS: The interface bond strength of all groups was susceptible to aging. Surface treatment protocol 2, with abrasive rubber tips and no hydrofluoric acid, appeared to be the most promising option, as the resulting bond strength values were similar to those of the control group.

Fracture resistance of weakened roots restored with different intracanal retainers.

The purposes of the study were to evaluate the effect of mechanical cycling (MC) on the fracture resistance of endodontically treated weakened roots restored with different intraradicular retainers and to analyze the failure mode. Eighty bovine roots were prepared and restored: 20 roots were reconstructed with cast post-and-cores (CPCs); 20 with fiber posts (FPs); 20 with fiber posts with larger coronal diameter (FPLs); and 20 with anatomic posts (APs). Metal crowns were cemented in all the roots. Half of specimens from each restoration strategy (n = 10) were submitted to MC: CPC-MC, FP-MC, FPL-MC, and AP-MC. The specimens were subjected to a fracture resistance test. The results showed that the type of retainer used was statistically significant (P < 0.0004). The CPC specimens demonstrated a fracture resistance similar to that of the APs, but greater than that of the FPs and FPLs. MC was statistically significant (P < 0.003) and affected AP-MC fracture resistance, which was lower than that of CPC-MC and similar to those of FP-MC and FPL-MC.

Effect of two resin cements and two fiber post surface treatments on push-out bond strength between fiber post and root dentin.

AIM: To evaluate the effect of fiber post surface treatments on push-out bond strength between fiber post and root dentin. MATERIALS AND METHODS: Sixty bovine mandibular teeth (N=60) were sectioned (16 mm), prepared (12 mm), embedded with acrylic resin and then allocated into six groups (n=10): Gr1- Silane coupling agent (Sil)+Conventional resin cement AllC em (Al C); Gr2- Sil+Conventional resin cement RelyX ARC (ARC); Gr3- tribochemical silica coating (TBS)+AlC; Gr4- TBS+ARC; Gr5- No treatment (NT)+AlC; Gr6- NT+ ARC. Specimens were sectioned in four slices (2 mm) and submitted to push-out test. Fracture analyses were executed at x200. The values of the push-out bond strength were submitted to two-way ANOVA and Tukey test (α=0.05). RESULTS: Resincement did not affect the bond strength values (p=0.9674), fiber post surface treatment affected the push-out bond strength (p=0.0353), interaction between factors did not affected the values (p=0.338). Tukey test did not show differences between the groups. Adhesive failure between cement and dentin was predominantly. CONCLUSION: The fiber post surface treatment appears have no Influence on bond strength between fiber post and root dentin. CLINICAL SIGNIFICANCE: The tested fiber posts surface treatment appears do not Influence the fiber post bond behavior.

Microtensile bond strength between indirect composite resin inlays and dentin: effect of cementation strategy and mechanical aging.

PURPOSE: To evaluate the microtensile bond strength of indirect resin composite inlays to dentin using two cementation strategies, before and after mechanical aging. MATERIALS AND METHODS: Standardized inlay cavities (bucco-lingual width: 3 mm; depth: 4 mm) were prepared in 32 human premolars. The teeth were embedded in self-curing acrylic resin up to 3 mm from the cementoenamel junction, impressions were made using a polyvinyl siloxane material, master dies were obtained using type 4 stone, and inlay composite resin restorations were fabricated (Sinfony, 3M ESPE). The teeth were randomly allocated into 4 groups according to the cementation strategy (conventional [C] and simplified [S]) and aging (mechanical cycling [MC] and not aged): C[G1]: Adper SingleBond + RelyX ARC without aging; CMC[G2]: conventional cementation + mechanical cycling (106 cycles, 88 N, 4 Hz, ± 37°C); S[G3]: self-adhesive resin cement (RelyX U-100) without aging; SMC[G4] self-adhesive cementation + mechanical cycling. Intaglio surfaces of composite inlays were treated by tribochemical silica coating in G1 and G2, while G3 and G4 received no surface treatment. Non-aged specimens were stored in a moist environment at ca 37°C for the same period as MC (3 days). Non-trimmed beam specimens (bonding area = 1 mm²) were produced by serial cutting, and microtensile testing was performed (0.5 mm/min). RESULTS: Two-way ANOVA showed that the microtensile bond strength was affected only by cementation strategy (p < 0.0001). Tukey's test showed that groups G1 (35.1 ± 9.1) and G2 (32.7 ± 10.7) presented significantly higher bond strength values than G3 (8.7 ± 6.3) and G4 (5.2 ± 4.6). CONCLUSION: The use of a conventional adhesive technique and tribochemical silica coating resulted in higher µTBS than the one-step simplified cementation, even after mechanical cycling.

Fiber post cementation strategies: effect of mechanical cycling on push-out bond strength and cement polymerization stress.

PURPOSE: To evaluate the effect of mechanical cycling and cementation strategies on the push-out bond strength between fiber posts and root dentin and the polymerization stresses produced using three resin cements. MATERIALS AND METHODS: Eighty bovine mandibular teeth were sectioned to a length of 16 mm, prepared to 12 mm, and embedded in self-curing acrylic resin. The specimens were then distributed into 8 groups (n = 10): Gr1 - Scotchbond Multi Purpose + RelyX ARC; Gr2 - Scotchbond Multi Purpose + RelyX ARC + mechanical cycling; Gr3 - AdheSE + Multilink Automix; Gr4 - AdheSE + Multilink Automix + mechanical cycling; Gr5 - phosphoric acid + RelyX U100 (self-adhesive cement); Gr6 - phosphoric acid+ RelyX U100 + mechanical cycling; Gr7 - RelyX U100; Gr8 - RelyX U100 + mechanical cycling. The values obtained from the push-out bond strength test were submitted to two-way ANOVA and Tukey's test (p = 0.05), while the values obtained from the polymerization stress test were subjected to one-way ANOVA and Tukey's test (α = 0.05). RESULTS: Mechanical cycling did not affect the bond strength values (p = 0.236), while cementation strategies affected the push-out bond strength (p < 0.001). Luting with RelyX U100 and Scotch Bond Multi Purpose + RelyX ARC yielded higher push-out bond strength values. The polymerization stress results were affected by the factor "cement" (p = 0.0104): the self-adhesive cement RelyX U100 exhibited the lowest values, RelyX ARC resulted in the highest values, while Multilink Automix presented values statistically similar to the other two cements. CONCLUSION: The self-adhesive cement appears to be a good alternative for luting fiber posts due to the high push-out bond strengths and lower polymerization stress values.

Assessment of Surgical and Radiographic Parameters for Abutment Height Selection: A Prospective Study with 1-Year Follow-up.

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 peri-implant 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.

Evaluation of four cementation strategies on the push-out bond strength between fiber post and root dentin.

This trial used push-out testing to evaluate four different fiber post cementation strategies. Specimens of bovine mandibular teeth were randomly allocated into four groups according to cementation strategies (n = 10): ScotchBond MultiPurpose and RelyX ARC (Group 1); AdheSE and Multilink Automix (Group 2); phosphoric acid and RelyX U100 (Group 3); and RelyX U100 (Group 4). Four slices from each specimen (2.0 mm thick) were obtained for the push-out test. All slices were analyzed for failure mode after testing. A one-way ANOVA showed differences between the groups (P = 0.002). A Tukey test indicated that Group 1 had the highest bond strength values (13.96 ± 6.41 MPa). Groups 2 (6.58 ± 2.14 MPa), 3 (5.85 ± 2.57 MPa), and 4 (8.19 ± 2.28 MPa) had similar bond strengths, but all of them were lower than Group 1. A three-step total etching adhesive system, associated with a conventional resin cement, might be a good alternative for fiber post cementation.

Influence of cement thickness and mechanical cycling on the push-out bond strength between posts and root dentin.

The aim of this study was to assess the influence of mechanical cycling and cement thickness on the bond strength between fiber posts and root dentin. Forty bovine teeth were sectioned (16 mm) and randomly assigned to four groups (n = 10). Specimens in Groups 1 and 2 were cemented using a thinner cement layer, while specimens in Groups 3 and 4 were cemented using a thicker cement layer. Groups 2 and 4 were submitted to mechanical cycling. Four slices per specimen were produced and submitted to push-out testing. Bond strength values were not affected by mechanical cycling (P = 0.2893), although the thickness of the cement layer did affect bond strengths (P = 0.0059, thinner > thicker). Tukey's test showed that Group 1 (19.27 MPa) had a higher mean bond strength value than Group 3 (12.4 MPa) and Group 4 (13.6 MPa), while Group 2 (15.0 MPa) was statistically similar to all groups. These results indicate that a thicker cement layer negatively affected the push-out bond strength between a fiber post and root dentin, regardless of whether the specimens were subjected to mechanical cycling.

Multi-step adhesive cementation versus one-step adhesive cementation: push-out bond strength between fiber post and root dentin before and after mechanical cycling.

This study evaluated the effects of mechanical cycling on resin push-out bond strength to root dentin, using two strategies for fiber post cementation. Forty bovine roots were embedded in acrylic resin after root canal preparation using a custom drill of the fiber post system. The fiber posts were cemented into root canals using two different strategies (N = 20): a conventional adhesive approach using a three-step etch-and-rinse adhesive system combined with a conventional resin cement (ScotchBond Multi Purpose Plus + RelyX ARC ), or a simplified adhesive approach using a self-adhesive resin cement (RelyX U100). The core was built up with composite resin and half of the specimens from each cementation strategy were submitted to mechanical cycling (45 degree angle; 37 degrees C; 88 N; 4 Hz; 700,000 cycles). Each specimen was cross-sectioned and the disk specimens were pushed-out. The means from every group (n = 10) were statistically analyzed using a two-way ANOVA and a Tukey test (P = 0.05). The cementation strategy affected the push-out results (P < 0.001), while mechanical cycling did not (P = 0.3716). The simplified approach (a self-adhesive resin cement) had better bond performance despite the conditioning. The self-adhesive resin cement appears to be a good option for post cementation. Further trials are needed to confirm these results.

Influence of low-level laser therapy on implant stability in implants placed in healed sites: a randomized controlled trial.

BACKGROUND: The present study aims to assess the influence of low-level laser therapy (LLLT) on stability in implants placed in healed sites. MATERIAL AND METHODS: The present study followed the SPIRIT statement and is reported according to CONSORT. Patients were randomly allocated to LLLT or control groups. LLLT consisted in the application of 808-nm GaAlA laser applied before the preparation of the implant bed and after suturing (80 seconds; 11J/cm2). Implant stability quotient (ISQ) and the distance between the implant platform to the alveolar bone crest (millimeters) were assessed at implant placement (T0) and the abutment selection phase (4-6 months, Ta). RESULTS: A total of 64 implants were placed in 33 patients. The insertion torque ranged from 10 to 70 N.cm (mean 43.23; SD ±16.82). The T0 ISQ ranged from 18 to 95.5 (mean 61.7; SD ±18.23) and the crestal bone radiographic distance was 2.03 mm (SD±1.27). At Ta, the ISQ ranged from 39 to 90 (mean 64.2; SD±9.84), and the mean crestal bone radiographic loss was 1.70mm (SD±1.65). However, no differences were observed when LLLT and control groups were compared with ISQ difference (Ta-T0; p=0.598) or radiographical peri-implant alterations (p=0.531). CONCLUSION: LLLT did not influence the implant stability in implants placed in healed sites compared to a control group. TRIAL REGISTRATION: ReBEC, RBR-35TNJ7 . Registered May 23, 2018.

Randomized controlled trial comparing glass fiber posts and cast metal posts.

OBJECTIVE: This study aimed to assess the survival and success of glass fiber posts compared to cast metal posts in teeth without ferrule. MATERIAL AND METHODS: An equivalency, prospective, double-blind (patient and outcome evaluator) randomized controlled trial (RCT) with parallel groups was designed to compare the clinical performance of cast metal and glass fiber posts cemented in endodontically treated teeth without ferrule (NCT01461239). Teeth were randomly allocated to the glass fiber or cast-metal post groups. All teeth were restored with single metal-ceramic crowns. Kaplan-Meier analysis with the log-rank test was used to test the success and survival between glass fiber and cast metal posts considering a cut-off value of P = 0.05. The annual failure rates were calculated considering the survival data for all restorations and separated by type of post after five years. RESULTS: A hundred and nineteen patients and 183 posts (72 cast metal posts and 111 glass fiber posts) were analyzed. The median follow-up was 62 months (IQR 37-81). The log-rank test for success (P = 0.26) and survival (P = 0.63) analyses did not present statistically significant differences. The AFR of both posts after 5 years was 1.5%. Considering the posts separately and after 5 years, cast metal posts presented AFR of 1.2% and glass fiber posts AFR of 1.7%. Most failures were in posterior teeth (16/23), 10 failures were classified as root fractures and 5 as post debonding. The follow-up rate was 95.3%. CONCLUSIONS: Glass fiber and cast metal posts showed good and similar clinical performance. CLINICAL SIGNIFICANCE: Results of this randomized controlled trial can help dentists to answer how the best technique to rehabilitate endodontically treated teeth with no remaining coronal wall.

Influence of low-level laser therapy on implant stability in implants placed in fresh extraction sockets: A randomized clinical trial.

BACKGROUND: Low-level laser therapy (LLLT) has been suggested to improve primary stability at the early stages of osseointegration in animal models. However, there is still scarce evidence about its influence on implant stability in humans. PURPOSE: To assess the influence of LLLT on implant stability in implants placed in fresh extraction sockets. MATERIAL AND METHODS: A randomized controlled trial was designed according to the SPIRIT guidelines and is reported following the CONSORT. Patients were randomly allocated according to control or LLLT groups. LLLT consisted in the application of GaAlAs laser (808 nm, avg. power density: 50 mW, circular spot diameter and area: 0.71 cm/0.4cm2 ) applied in six points in contact mode with peri-implant soft tissue (1.23 minutes in each point of application; dose per point 11 J) before bone perforation and after suturing. The total dose resulted in 66 J per application moment. This LLLT protocol was applied only in the dental implant placement session. Implant stability was by ISQ at implant placement (T0 ) and the abutment selection (Ta ). Digital radiographs for T0 and Ta were used to assess the distance between the implant platform and alveolar bone crest, in millimeters. T-test and Shapiro-Wilk test were used to analyze data between groups using the implant as a unit of analysis. RESULTS: Fifty implants were placed in 44 patients. The insertion torque ranged from 15 to 60 N.cm (mean 35.64 ± 13.34). Two implants of the LLLT and one of the control groups were lost to follow-up and one implant of the control group failed to osseointegrate (4.3%). ISQ at T0 ranged from 17 to 79 (mean 59.33 ± 13.05) and from 40 to 89 (mean 66.46 SD ± 11.56) at Ta . No differences were observed when comparing the groups with ISQ difference (P = .433) or radiographical peri-implant alterations (P = .261). CONCLUSIONS: LLLT did not influence implant stability in implants placed in fresh extraction sockets when assessed at healing abutment installation.

File-splitting multilayer vs monolithic Y-TZP: Fatigue flexural strength and loading stresses by finite element analysis.

OBJECTIVE: To compare file-splitting multilayer (fused and cemented) with monolithic Y-TZP on the fatigue flexural strength and finite element analysis (FEA) stresses. Additionally, to verify the effect of the material under tension in multilayer Y-TZP. METHODS: Disc-shaped (diameter: 14.4mm; thickness: 1.4mm) monolithic Y-TZP (IPS e.max ZirCAD - Ivoclar Vivadent) and trilayer specimens with Y-TZP framework (IPS e.max ZirCAD), intermediate layer of fusion ceramic (IPS e.max CAD Crystall./Connect) or resin cement (Multilink Automix) and lithium disilicate veneer (IPS e.max CAD) were divided into five groups (n=20): monolithic Y-TZP (M), fused file-splitting with framework under tension (F-FT), cemented file-splitting with framework under tension (C-FT), fused file-splitting with veneer under tension (F-VT) and cemented file-splitting with veneer under tension (C-VT). Fatigue flexural strength was determined (piston-on-three ball) by the staircase approach (750,000 cycles; 20Hz). Mean and confidence intervals (CI) were calculated. FEA was evaluated under the application of the experimental mean fatigue load. RESULTS: The fatigue strength was statistically different for all groups. Means and CI (MPa) were: M - 405.92 (CI 397.58-414.26), F-FT - 377.73 (CI 374.59-380.88), C-FT - 346.54 (CI 340.62-352.46), F-VT - 154.79 (CI 151.86-157.72) and C-VT - 100.34 (CI 97.42-103.26). FEA tensile stresses were similar to the mean experimental values (up to ≅10MPa of variation), with the most discrepant calculated stresses for C-FT (≅20MPa higher than experimental result). SIGNIFICANCE: Monolithic specimens showed the highest flexural fatigue strength and fused file-splitting resulted in higher fatigue strength than cemented file-splitting. Groups with the framework under tension exhibited higher flexural fatigue strength.

Longevity of metal-ceramic crowns cemented with self-adhesive resin cement: a prospective clinical study

Resin cements are often used for single crown cementation due to their physical properties. Self-adhesive resin cements gained widespread due to their simplified technique compared to regular resin cement. However, there is lacking clinical evidence about the long-term behavior of this material. The aim of this prospective clinical trial was to assess the survival rates of metal-ceramic crowns cemented with self-adhesive resin cement up to six years. One hundred and twenty-nine subjects received 152 metal-ceramic crowns. The cementation procedures were standardized and performed by previously trained operators. The crowns were assessed as to primary outcome (debonding) and FDI criteria. Statistical analysis was performed using Kaplan-Meier statistics and descriptive analysis. Three failures occurred (debonding), resulting in a 97.6% survival rate. FDI criteria assessment resulted in scores 1 and 2 (acceptable clinical evaluation) for all surviving crowns. The use of self-adhesive resin cement is a feasible alternative for metal-ceramic crowns cementation, achieving high and adequate survival rates.

Are Stress Associated with Temporomandibular Dysfunction? A Cross-Sectional Study / O Estresse Está Associado à Disfunção Temporomandibular? Um Estudo Transversal

Temporomandibular disorders are frequent in different segments of the population and harm the quality of life of individuals. The present sudy aimed to investigate the association between stress and temporomandibular dysfunction (TMD) in university students in Brazil. All incoming students at the Federal University of Pelotas were invited to participate in this cross-sectional study. A self-administered questionnaire was used with socioeconomic and oral health variables. TMD Fonseca questionnaire "Fonseca's anamnestic index" was used to identify the severity of symptoms of temporomandibular dysfunction. The same was elaborated in the form of Helkimo's anamnestic index. Stress was measured using a modified version of the Perceived Stress Scale and categorized into quartiles. Logistic multivariable regression models were used to analyze the associations of interest controlling for possible confounding variables. A backward stepwise procedure was used to select variables that should be kept in the final model. A total of 2,089 students answered the questionnaires and 82 (3.9%) were classified with the presence of TMD. Adjusted logistic regression shows that chance of presenting temporomandibular dysfunction was higher (OR=2.43; 95%CI=1.04-5.65) when the stress level increased. In conclusion, the mild degree of temporomandibular dysfunction was the most prevalent. Stress was associated with individuals with a higher prevalence of temporomandibular dysfunction. (AU)

As disfunções temporomandibulares são frequentes em diferentes segmentos da população e prejudicam a qualidade de vida dos indivíduos. O presente estudo teve como objetivo investigar a associação entre estresse e disfunção temporomandibular (DTM) em estudantes universitários no Brasil. Todos os alunos ingressantes da Universidade Federal de Pelotas foram convidados a participar deste estudo transversal. Foi utilizado um questionário autoaplicável com variáveis ​​socioeconômicas e de saúde bucal. O questionário TMD Fonseca "Índice anamnésico de Fonseca" foi utilizado para identificar a gravidade dos sintomas da disfunção temporomandibular. O mesmo foi elaborado na forma de índice anamnésico de Helkimo. O estresse foi medido usando uma versão modificada da Perceived Stress Scale e categorizado em quartis. Modelos de regressão logística multivariada foram usados ​​para analisar as associações de interesse controlando possíveis variáveis ​​de confusão. Um procedimento de backward stepwise foi usado para selecionar as variáveis ​​que deveriam ser mantidas no modelo final. Um total de 2.089 alunos responderam aos questionários e 82 (3,9%) foram classificados com presença de DTM. A regressão logística ajustada mostra que a chance de apresentar disfunção temporomandibular foi maior (OR=2,43; IC95%=1,04-5,65) quando o nível de estresse aumentou. Em conclusão, o grau leve de disfunção temporomandibular foi o mais prevalente. O estresse foi associado a indivíduos com maior prevalência de disfunção temporomandibular. (AU)

Fatigue surviving, fracture resistance, shear stress and finite element analysis of glass fiber posts with different diameters.

This study evaluated the shear stress presented in glass fiber posts with parallel fiber (0°) and different coronal diameters under fatigue, fracture resistance and FEA. 160 glass-fiber posts (N=160) with eight different coronal diameters were used (DT=double tapered, number of the post=coronal diameter and W=Wider - fiber post with coronal diameter wider than the conventional): DT1.4; DT1.8W; DT1.6; DT2W; DT1.8; DT2.2W; DT2; DT2.2. Eighty posts were submitted to mechanical cycling (3×10(6) cycles; inclination: 45°; load: 50N; frequency: 4Hz; temperature: 37°C) to assess the surviving under intermittent loading and other eighty posts were submitted to fracture resistance testing (resistance [N] and shear-stress [MPa] values were obtained). The eight posts types were 3D modeled (Rhinoceros 4.0) and the shear-stress (MPa) evaluated using FEA (Ansys 13.0). One-way ANOVA showed statistically differences to fracture resistance (DT2.2W and DT2.2 showed higher values) and shear stress values (DT1.4 showed lower values). Only the DT1.4 fiber posts failed after mechanical cycling. FEA showed similar values of shear stress between the groups and these values were similar to those obtained by shear stress testing. The failure analysis showed that 95% of specimens failed by shear. Posts with parallel fiber (0°) may suffer fractures when an oblique shear load is applied on the structure; except the thinner group, greater coronal diameters promoted the same shear stresses.