Outcome measurements and quality of randomized controlled clinical trials of tooth-supported fixed dental prostheses: A systematic review and qualitative analysis.

STATEMENT OF PROBLEM: The lack of consensus regarding a standardized set of outcome measurements and noncompliance with current reporting guidelines in clinical trials of tooth-supported fixed dental prostheses (FDPs) hamper interstudy comparability, compromise scientific evidence, and waste research effort and resources in prosthetic dentistry. PURPOSE: The primary objective of this systematic review was to identify all primary and secondary outcome measurements assessed in randomized controlled trials (RCTs) of tooth-supported FDPs. Secondary objectives were to assess their methodological quality by using the Cochrane Collaboration's risk of bias tool (RoB, v2.0) and their reporting quality by means of a standardized 16-item CONSORT assessment tool through published reports. MATERIAL AND METHODS: An electronic search was conducted in MEDLINE, EMBASE, and Cochrane library to identify all RCT-related articles published in the past 10 years. Differences in RoB were tested with the Pearson chi-square test, and those in CONSORT score with the Student t test. RESULTS: A total of 64 RCTs from 79 publications were deemed eligible. The diversity of outcome measures used in the field is apparent. Twenty percent of the included studies had a low RoB, 79% showed some concerns, and 1% had a high RoB. The mean ±standard deviation CONSORT compliance score was 22.56 ±3.17. Trials adhered to the CONSORT statement reported lower RoB than those that did not adhere (P<.001). RCTs with a low RoB reported more comprehensive adherence to CONSORT guidelines than those with some concerns (MD 4 [95% CI 1.52-6.48]; P=.004). CONCLUSIONS: A standardized core outcome reporting set in clinical research on tooth-supported FDPs remains evident. Adherence to the CONSORT statement continues to be low, with some RoB concerns that can be improved.

Fracture Load Before and After Veneering Zirconia Posterior Fixed Dental Prostheses.

PURPOSE: To evaluate the fracture load of 3-unit zirconia-based posterior fixed dental prostheses (FDPs) before and after veneering the frameworks. MATERIALS AND METHODS: Forty standardized stainless-steel master dies were fabricated (height: 5 mm, convergence: 6º, chamfer: 1 mm) and randomly screwed in pairs onto metal bases. The bases were randomly divided into two groups (n = 20 each) according to the zirconia CAD/CAM system used for constructing 3-unit structures for FDPs: group 1 (L): Lava All-ceramic, group 2 (Z): IPS e.max ZirCAD. Half of the zirconia structures per group were randomly selected and veneered, while the remaining half was left unveneered. The specimens were luted in standard fashion onto the stainless steel master dies using conventional glass ionomer cement. All specimens were tested for fracture load (FL). Specimens were subjected to a three-point bending test until fracture by applying an axial compressive load at the central fossa of the pontics with a universal testing machine at a 0.5 mm/min crosshead speed. Wilcoxon's rank-sum test and Weibull statistics were used for statistical analysis (α = 0.05). RESULTS: L structures recorded significantly higher values of load to fracture than the Z group both before and after veneering. Within each ceramic group, no differences were found between unveneered and veneered frameworks. CONCLUSIONS: Although further studies are necessary to corroborate these findings, both zirconia systems could be recommended for restoring posterior teeth on the basis of the fracture load values recorded in this experiment (>1000 N). The veneering procedure did not affect the overall load to fracture in any group.

Effect of Preoperative Occlusal Matrices on the Vickers Microhardness of Composite Disks Polymerized with QTH and LED Lamps.

PURPOSE: This study aimed to assess the reliability of the preoperative occlusal matrix technique in terms of the surface Vickers microhardness (VMH) of the underlying composite restorative material. MATERIALS AND METHODS: Two hundred microhybrid composite cylinders were built up and light-cured in a single-layer step, forming two experimental groups (N = 100) according to their heights (1.5 mm/2 mm). Each group was divided into five subgroups (N = 20) depending on the matrix thickness (no matrix/0.5 mm/1 mm/2 mm/3 mm). Half the specimens per subgroup (N = 10) were randomly polymerized with a quartz-tungsten-halogen (QTH) light-curing unit (LCU). The remaining half were cured using a light-emitting diode lamp. The top and bottom samples' sides were tested for VMH at 1 hour and 24 hours post-curing using a universal VMH machine. A multiple analysis of variance with repeated measurements for the "surface" factor and the Student-Newman-Keuls test were run (α = 0.05). Bottom/top microhardness ratios were compared with the empirically accepted limit (0.8). Surface topography was analyzed under a scanning electron microscope. RESULTS: The thinnest matrices provided the significantly best VMH values. LCU, disc height, and time also contributed to VMH. At 24 hours, 2-mm high discs polymerized with QTH resulted in inadequate microhardness ratios when 1-mm thick to 3-mm thick matrices were used. CONCLUSION: The thinnest matrices are the most recommendable ones. CLINICAL SIGNIFICANCE: The esthetics and occlusal reproducibility achieved with customized occlusal matrices fabricated before cavity preparation have been widely demonstrated. However, their effect on the physical properties of the restorations deserves further investigation. Although more studies are necessary, the thinnest matrices seem to be the most suitable to preserve the composite surface VMH and the curing depth.

Oral health-related quality of life in complete denture wearers depending on their socio-demographic background, prosthetic-related factors and clinical condition.

OBJECTIVES: To investigate the differences in impact on oral health-related quality of life (OHRQoL) among complete denture wearers depending on their socio-demographic characteristics, prosthetic-related factors and oral status. STUDY DESIGN: 51 patients aged 50-90 years treated, from 2005 to 2010, with at least one complete denture at the Department of Buccofacial Prostheses of the Complutense University (Madrid) were enrolled in this cross-sectional study. All of the participants answered the Oral Health Impact Profile (OHIP-14sp) questionnaire. The additive scoring method was used. The prevalence of impacts was calculated by using the occasional threshold (OHIP-14sp score ≥ 2). Socio-demographic and prosthetic-related variables were gathered. Patients underwent clinical examination to assess their oral condition. Descriptive probes and Chi-Square tests were run (p ≤ 0.05). RESULTS: The predominant participants' profile was that of a man with a mean age of 69 years wearing complete dentures in both the maxilla and the mandible. The prevalence of impact was 23.5%, showing an average score of 19 ± 9.8. The most affected domains were "functional limitation" and "physical pain", followed by "physical disability". Minor impacts were recorded for the psychological and social subscales ("psychological discomfort", "psychological disability", "social disability" and "handicap"). The prosthesis' location significantly influenced the overall patient satisfaction, the lower dentures being the less comfortable. Having a complete removable denture as antagonist significantly hampered the patient satisfaction. Patients without prosthetic stomatitis and those who need repairing or changing their prostheses, recorded significantly higher OHIP-14sp total scores. CONCLUSIONS: The use of conventional complete dentures brings negative impacts in the OHRQoL of elderly patients, mainly in case of lower prostheses that required reparation or substitution, with a removable total denture as antagonist. The prosthetic stomatitis in this study was always associated to other severe illness, which may have influenced the self-perceived discomfort with the prostheses, as those patients were daily medicated with painkillers.

Changes in the teaching of prosthodontics adopted in the last academic course of the degree in dentistry in Spain during the first period of the COVID-19 pandemic.

OBJECTIVES: To investigate the impact of the COVID-19 pandemic in the teaching of prosthodontics, on the 5th course of the Bachelor's degree in Dentistry in Spain. METHODS: In June 2021, a two-section survey was submitted to the coordinators of prosthodontics of the 23 Spanish faculties of Dentistry. The first section was focused on the theoretical lessons, seminars, and clinical discussion sessions. The second part relied on the clinical teaching and the implemented preventive measures. RESULTS: The response rate was 100%. By the end of the 2020-21 course, both the theoretical and practical teaching were replaced by online activities, returning to face-to face in 2021-22. While most participants preferred in-person seminars and clinical discussion sessions, concerning the theory, comparable percentages of professors chose either face-to-face or blended learning (BL). The students' satisfaction with BL is high, but they seem more attentive in-person. At the beginning of the pandemic, the most common emergency in prosthodontics was debonding. Overall, a low concern about cross-infection was noticed. The barrier measures were the mainly adopted for prevention. CONCLUSIONS: Although the BL is appreciated in prosthodontics for theoretical lessons, face-to-face teaching appears to be the best option for seminars and clinical case discussions. The students are satisfied with BL. CLINICAL SIGNIFICANCE: In the face of the COVID-19 pandemic, the Spanish faculties of Dentistry responded quickly to continuing offering quality education through an accelerated digitization process that has created a new paradigm. Detailed analyses of these changes may help establish plans to respond systematically to unforeseen emergencies.

'Thermo-mechanical behavior of alternative material combinations for full-arch implant-supported hybrid prostheses with short cantilevers'.

OBJECTIVES: To compare the fracture resistance (FR) of three combinations of materials for full-arch maxillary implant-supported hybrid prostheses (HPs) with short cantilevers (≤ 10 mm). METHODS: Maxillary HPs were fabricated and classified as follows (n = 5 each): Group-1 (CC-A, control): acrylic-resin-veneered Co-Cr frameworks; Group-2 (CF-A): acrylic-resin-veneered carbon-fiber mesostructures; and Group-3 (CF-R): composite-resin-veneered carbon-fiber frames. Specimens were thermal-cycled (5,000 cycles; 5 °C-55 °C; dwell time: 30 s). Vertical loads were applied until failure, first at the 10-mm-long cantilever (LC), and, afterwards, at the anterior region (AR), using a universal testing machine (crosshead speed: 0.05 mm/s). The fracture pattern was assessed by stereomicroscope and SEM. The one-way ANOVA, the Bonferroni, and the independent samples t tests, were run (α= 0.05). RESULTS: At LC, CF-A, and CC-A samples exhibited the highest FR values (p< 0.001), showing no differences to each other. At AR, CC-A specimens recorded the highest FR, followed by CF-A samples (p< 0.001). CF-R HPs displayed the lowest FR at both locations (p< 0.001). The only group with differences between the tested sites was the CC-A, the AR being more resistant (p< 0.001). Most CC-A and CF-A HPs failed cohesively. CF-R prostheses mainly failed adhesively. CONCLUSIONS: Maxillary HPs with short cantilevers (≤ 10 mm) made of Co-Cr or carbon-fiber veneered with acrylic resin demonstrated an adequate mechanical resistance (> 900 N). CLINICAL SIGNIFICANCE: For maxillary HPs with cantilevers up to 10 mm, acrylic-veneered carbon- fiber mesostructures may be recommended, whereas coating carbon-fiber frames with composite resin seems not suitable.

Cardiovascular effect of dental anesthesia with articaine (40 mg with epinefrine 0,5 mg % and 40 mg with epinefrine 1 mg%) versus mepivacaine (30 mg and 20 mg with epinefrine 1 mg%) in medically compromised cardiac patients: a cross-over, randomized, single blinded study.

OBJECTIVES: The aim of the present study is to compare cardiovascular safety profiles of two dental anesthetics: articaine versus two standard mepivacaine solutions used during etiological periodontal treatment in cardiovascular patients. STUDY DESIGN: Using a cross-over study design, ten cardiovascular patients were randomly assigned to dental treatment with 1.8 mL of a local anesthetic injected on each quadrant of the mouth: Articaine (40 mg with Epinephrine 0.5 mg % and 40 mg with Epinephrine 1mg %) or Mepivacaine (30 mg and 20 mg with Epinephrine 1mg %). A computer programme enabled continuous longitudinal data collection: O2 saturation, blood pressure (BP) and heart rate (HR). RESULTS: No severe clinical side effects were observed. During the treatment period, we observed statistically significant differences as regards HR between injections with and without adrenalin (p< 0.039) and as regards systolic (p< 0.046) and diastolic (p < 0.046) blood pressure during the stabilization period. In both cases, the parameters under study increase. Age, gender, jaw treated, treatment duration and the rest of cardiovascular variables did not affect the results. None of the patients underwent ischemic alterations or any other complication derived from the treatment or the anesthesia. CONCLUSIONS: According to the results of our study, dental anesthetics with standard concentrations of Epinephrine seem to alter HR and BP. Although no cardiac ischemic alterations or any other cardiovascular complications have been observed, we must be cautious with the administration of anesthetics containing vasoconstrictors in patients with cardiovascular diseases.

'Role of the modulating factors on the self-perceived OHRQoL of fully dentate subjects and wearers of screw-retained and cement-retained implant-supported FPDs: A cross-sectional study'.

OBJECTIVES: This research aimed to compare the oral health-related quality of life (OHRQoL) between fully dentate subjects and edentulous patients wearing implant-supported fixed partial dentures (i-FPDs). The clinical conditions of both types of restorations were evaluated. METHODS: Participants were assigned to: Group-1 (SR, n = 50): screw-retained i-FPD wearers; Group-2 (CR, n = 50): cement-retained i-FPD wearers; and Group-3 (ND, n = 50): dentate subjects with a healthy natural dentition (controls). Patients answered the OHIP-14sp and QoLIP-10 questionnaires. Data related to sociodemographics, prosthesis features, peri­implant status, complications, and subjective evaluations, were compiled. Potential modulators of the OHRQoL and the i-FPDs' clinical conditions were assessed using non-parametric tests (α= 0.05). RESULTS: ND individuals were the least satisfied (OHIP-14sp; p< 0.001). Both prosthodontic groups reported similar levels of wellbeing, excluding the speaking difficulties, which were lower for SR wearers as shown by both scales (p = 0.001). The most discontented patients (OHIP-14sp) were: women (p = 0.022), under 65 years (p = 0.03), without partner (p< 0.001) and having a crown (p = 0.033). The level of education/schooling also affected the OHIP-14sp scores (p< 0.001). Implant mobility and peri­implantitis were more frequent among CR wearers (p-values= 0.008 and 0.05, respectively). CONCLUSIONS: The OHRQoL of both prosthodontic groups was comparably higher than that of the dentate subjects, who were the most nonconformist. The self-perceived satisfaction was mainly modulated by sociodemographic factors. CLINICAL SIGNIFICANCE: Overall, the retention system did not impact the OHRQoL, prosthetic problems, and subjective evaluations of i-FPD wearers. However, the cementation may increase the risk of peri­implant diseases.

Fracture resistance of cantilevered full-arch implant-supported hybrid prostheses with carbon fiber frameworks after thermal cycling.

OBJECTIVES: This in vitro study aimed to find the best combination of mesostructure and veneering materials for full-arch implant-supported hybrid prostheses (HPs) in terms of the fracture resistance (FR) of their cantilevers. METHODS: Three groups (n = 5 each) of maxillary HPs were fabricated: Group-1 (CC-A, control): Co-Cr frameworks coated with acrylic resin; Group-2 (CF-A): carbon fiber veneered with acrylic resin; and Group-3 (CF-R): carbon fiber coated with composite resin. All specimens were submitted to 5,000 thermal cycles (5 °C - 55 °C, dwell time: 30 s), and subjected to a single cantilever bending test in a universal testing machine (crosshead speed: 0.5 mm/min) until failure. The fracture pattern was assessed using stereo microscope and SEM. The one-way ANOVA and Bonferroni tests were run (α= 0.05). RESULTS: The FR yielded significant differences among the three groups (p< 0.001). CC-A samples reached the highest FR values (p ≤ 0.001), whereas both CF-A and CF-R HPs exhibited the comparably (p = 0.107) lowest FR. CC-A specimens failed cohesively (100%): mostly without chipping (80%). CF-A mesostructures were always broken at the connections of the distal implants. CF-R prostheses often failed adhesively (80%). CONCLUSIONS: The HPs made of Co-Cr veneered with acrylic demonstrated the best mechanical behavior, being the only group whose 13-mm long cantilevers exceeded the clinically acceptable FR of 900 N. The HPs constructed with carbon fiber frameworks showed, additionally, more unfavorable fracture patterns. CLINICAL SIGNIFICANCE: For HPs with cantilevers up to 13 mm, Co-Cr mesostructures coated with acrylic may represent the optimum combination of materials.

Differences in self-perceived OHRQoL between fully dentate subjects and edentulous patients depending on their prosthesis type, socio-demographic profile, and clinical features.

OBJECTIVES: This observational cross-sectional study aimed to evaluate and compare the oral health-related quality of life (OHRQoL) and clinical performance between dentate subjects and edentulous patients restored with conventional dentures or implant overdentures. METHODS: 85 edentulous patients were grouped as follows: Group-1 (CD): conventional denture wearers (n = 42), and Group-2 (IO): implant-retained overdenture wearers (n = 43). For the OHRQoL comparisons, a control group of subjects with a healthy natural dentition (Group-3, ND; n = 50) was included. Participants completed three validated questionnaires (OHIP-14sp, OHIP-20sp, and QoLIP-10). Socio-demographic data, prosthesis-related factors, clinical condition of the mouth, and patient subjective evaluations, were gathered. Descriptive and non-parametric probes were run (α = 0.05). RESULTS: The ND group was the most unsatisfied (OHIP-14sp; p ≤ 0.001). The OHIP-20sp attributed significantly worse Psychological disability (p = 0.029) and Handicap (p = 0.027) to CD wearers when compared to IO wearers. The CD group showed the significantly highest need for relining (p = 0.041), and the lowest retention (p = 0.011). The OHIP-14sp disclosed a significantly worse OHRQoL for those volunteers who had a job (p = 0.003), a basic education instead of a secondary one (p = 0.022), and no partner (p = 0.006). CONCLUSIONS: The overall OHRQoL was comparable for both prosthodontic groups, being modulated by socio-demographic and prosthesis-related features. Nonetheless, CD wearers presented prosthetic complications more frequently. CLINICAL SIGNIFICANCE: While dentate subjects were the most critical about their oral condition and its repercussion in their life, implant overdenture wearers tended to observe a better OHRQoL and clinical performance compared to conventional denture wearers.

Influence of CAD/CAM scanning method and tooth-preparation design on the vertical misfit of zirconia crown copings.

PURPOSE: To evaluate the influence of scanning method, finish line type and occlusal convergence angle of the teeth preparations on the vertical misfit of zirconia crown copings. METHODS: 20 standardized stainless-steel master dies were machined simulating full-crown preparations. The total convergence angle was 15 degrees or 20 degrees (n=10 each). Two of the finish line types: a chamfer (CH) and a shoulder (SH) were prepared around the contour of each abutment. Over these dies, 20 structures were made by CAD/CAM (Cercon, Dentsply). An optical laser digitized the wax patterns of 10 single-unit copings (WS), and 10 abutments were direct-scanned to design the cores by computer (DS). Zirconia milled caps were luted onto the models under constant seating pressure. Vertical discrepancy was assessed by SEM. Misfit data were analyzed using ANOVA and Student-Newman-Keuls (SNK) test for multiple comparisons at alpha = 0.05. RESULTS: Vertical gap measurements of WS copings were significantly higher than those of DS frames (P < 0.0001). SH exhibited statistically higher discrepancies than CH when combined with a 15-degree occlusal convergence angle regardless of the scanning method (P < 0.05). The taper angle of the preparation (15 degrees vs. 20 degrees) had no effect on the marginal adaptation of chamfered samples.

Impact of the retention system of implant fixed dental restorations on the peri-implant health, state of the prosthesis, and patients' oral health-related quality of life.

OBJECTIVES: To investigate the impact of the retention system (screwed or cemented) of implant fixed dental prostheses (i-FDPs) on the peri-implant health, prosthesis' state, patient self-evaluation of functionality and aesthetics, and oral health-related quality of life (OHRQoL). METHODS: 35 participants were classified into two groups according to the retention system of their metal-ceramic i-FDPs. For the analysis of peri-implant health and prosthetic complications, the implant units were individually assessed. Group 1 (SPD; n = 22): implant units for screwed i-FDPs; and Group 2 (CPD; n = 36): implant units for cemented i-FDPs. Data related to socio-demographics, design and installation of the superstructures, peri-implant condition, prosthetic complications, functionality, and aesthetics, were gathered. Patients answered the Oral Health Impact Profile (OHIP-14sp) questionnaire. Descriptive and parametric probes were run to evaluate the impact scores considering the study variables (α = 0.05). RESULTS: The plaque index, gingival index, functionality, aesthetics, and global evaluation made by the patient recorded significantly better results for the SPD group. The most affected OHIP-14sp domain was 'Physical pain', followed by 'Psychological discomfort', and 'Functional limitation'. The subscales: 'Functional limitation', 'Physical disability', and 'Social disability', attributed significantly worst OHRQoL to CPD users. CONCLUSION: A major presence of peri-implant disease, together with a worse functionality, aesthetics, and patient satisfaction were recorded in cemented i-FDPs with respect to the screwed ones. CLINICAL SIGNIFICANCE: The retention system of i-FDPs can impact the peri-implant health, the subjective functional and aesthetic evaluation of the restoration, and the patients' OHRQoL; the screw retention providing superior results than the cementation.

In vitro Comparative Study of Fibroblastic Behaviour on Polymethacrylate (PMMA) and Lithium Disilicate Polymer Surfaces.

Polymethyl methacrylate (PMMA) and lithium disilicate are widely used materials in the dental field. PMMA is mainly used for the manufacture of removable prostheses; however, with the incorporation of CAD-CAM technology, new applications have been introduced for this material, including as a provisional implant attachment. Lithium disilicate is considered the gold standard for definitive attachment material. On the other hand, PMMA has begun to be used in clinics as a provisional attachment until the placement of a definitive one occurs. Although there are clinical studies regarding its use, there are few studies on cell reorganization around this type of material. This is why we carried out an in vitro comparative study using discs of both materials in which human gingival fibroblasts (HGFs) were cultured. After processing them, we analyzed various cellular parameters (cell count, cytoskeleton length, core size and coverage area). We analyzed the surface of the discs together with their composition. The results obtained were mostly not statistically significant, which shows that the qualities of PMMA make it a suitable material as an implant attachment.

Influence of bone quality on the mechanical interaction between implant and bone: A finite element analysis.

OBJECTIVES: To evaluate the influence of bone type in terms of bone density and cortical bone thickness, on the stresses induced by two implants under compressive and oblique loads. METHODS: A numerical simulation technique based on the finite element method was applied. Two implant types (M-12 and Astra Tech) were introduced in a model matrix whose geometry was extracted from a real CBCT radiograph of the posterior mandibular region. The Young's module and Poisson's coefficient of the bone qualities described by Misch were calculated. Loads with amplitude of 400 N were exerted in two directions: compressive and 15° oblique to 5 mm above the uppermost part of the implant. RESULTS: The von Misses variant was analysed. Both implant types presented greater tension in the ​​cortical bone area than in the ​​trabecular bone region under compressive loading. For the oblique load condition, the stresses obtained in the cortical zone were significantly higher than those registered as a consequence of compressive loads in both implant types. CONCLUSIONS: Regardless of bone type, the M-12 implants presented lower tensions in the cortical bone than did the Astra implants. The tensions recorded for D3 and D4 bone types in the trabecular zone surrounding the M-12 implants were greater than those recorded for the Astra implants. CLINICAL SIGNIFICANCE: For both compressive and oblique loads, good mechanical behaviour was observed. The decrease in bone quality determines a worse stress distribution, and the cortical bone is overloaded. An efficient distribution of the forces may increase the implants' longevity.

All-ceramic inlay-retained fixed dental prostheses for replacing posterior missing teeth: A systematic review.

PURPOSE: To evaluate the current status of all-ceramic inlay-retained fixed dental prostheses (CIR-FDPs) for the replacement of posterior teeth. STUDY SELECTION: Screening of titles and abstracts, full-text analysis for inclusion eligibility, quality assessment, data extraction and evaluation of the scientific evidence were performed independently by two reviewers. The electronic databases MEDLINE/PubMed, EMBASE, Cochrane Central Register of Controlled Trials, and Compludoc were searched with no restriction to publication date or language. The quality of the studies was evaluated through: the original 'QDP' ('Questionnaire for selecting articles on Dental Prostheses') (for research papers); the 'Guidelines for managing overviews' of the Evidence-Based Medicine Working Group (for reviews); the Cochrane risk of bias tool; and the GRADE scale for grading scientific evidence. RESULTS: This review started with 4942 articles, which were narrowed down to 23 according to the selection criteria. The data was not statistically treated because of the heterogeneity of the studies. Zirconia-based CIR-FDPs may be recommended for restoring posterior single missing teeth, although the prosthesis/tooth bonded interface has yet to be improved. The addition of lateral wings to the classical inlay preparation seems promising. The weakest parts of CIR-FDPs are the connectors and retainers, while caries and endodontic problems are the most common biological complications. The fabrication of CIR-FDPs with monolithic zirconia may eliminate chipping problems. CONCLUSIONS: A three-unit CIR-FDP is a viable treatment option for replacing a posterior missing tooth. Appropriate case selection, abutment preparation and luting procedures may be decisive for clinical success.

Fracture load of metal-ceramic, monolithic, and bi-layered zirconia-based posterior fixed dental prostheses after thermo-mechanical cycling.

OBJECTIVES: This study aims to evaluate the fracture load of differently fabricated 3-unit posterior fixed dental prostheses (FDPs) with an intermediate pontic. METHODS: Fifty sets of two stainless-steel abutments were randomly assigned to five groups (n = 10 each) depending on the material and technique used for manufacturing the FDPs: (1) Metal-ceramic (MC, control); (2) Lava Zirconia (LZ, bi-layered); (3) Lava Plus (LM, monolithic); (4) VITA In-Ceram YZ (YZ, bi-layered); and (5) IPS e-max ZirCAD (ZZ, bi-layered). After being luted to the dies, all FDPs were submitted to thermo-mechanical cycling (120,000 masticatory cycles, 50 N; plus 774 thermal cycles of 5 °C/55 °C, dwell time: 30 s). Samples were then subjected to a three-point bending test until fracture in a universal testing machine (cross-head speed: 1 mm/min). Fracture load of the veneering ceramic (VF) and total fracture load (TF) were recorded. Microstructure and failure patterns were assessed. Data was analysed using one-way ANOVA and Tukey HSD post-hoc tests (α = 0.05). RESULTS: MC restorations recorded higher VF and TF values than did zirconia FDPs (p = 0.0001), which showed no between-group differences. Within the bi-layered groups, TF was significantly higher than VF. LM pieces registered lower average grain size than did LZ specimens (p = 0.001). Overall, the connector was the weakest part. CONCLUSIONS: All of the groups tested could withstand clinical chewing forces in terms of average fracture load. Zirconia-based samples performed similarly to each other, but showed lower mean fracture load values than did metal-ceramic ones. CLINICAL SIGNIFICANCE: Monolithic zirconia may be recommendable for solving the chipping problem.

Combination of straight and tilted implants for supporting screw-retained dental prostheses in atrophic posterior maxillae: A 2-year prospective study.

OBJECTIVES: To evaluate the two-year survival rate (SR) and marginal bone loss (MBL) of fixed dental prostheses (FDPs) supported by straight (S) and tilted (T) implants under the influence of diverse study variables. METHODS: A prospective investigation comprising 21 patients provided with a total of 27 maxillary screw-retained restorations fixed to 70 dental implants was developed. Two groups of implants were considered depending on their inclination with respect to the occlusal plane: Group 1 (S, n=37): straight/axial implants and Group 2 (T, n=33): tilted/angled fixations. Each FDP was supported by a combination of S and T implants. SR and MBL were assessed at the time of loading and two years after surgery. Patient-, surgical- and/or rehabilitation-related information was gathered. Data were statistically analysed at the α=0.05 significance level. RESULTS: After 24 months, a 100% SR was achieved and the MBL of S and T implants were statistically similar. T implants located in the molar region showed lower MBL than did those replacing premolars (p=0.031). CONCLUSIONS: Upright and angled fixations inserted at posterior maxillary areas resulted in comparable survival rates and peri-implant MBL after two years. The marginal bone resorption around tilted implants depended on their location. CLINICAL SIGNIFICANCE: Screw-retained restorations fixed to straight and tilted implants seem to be a safe treatment option in posterior atrophic maxillae.

Validation of the "Quality of Life related to function, aesthetics, socialization, and thoughts about health-behavioural habits (QoLFAST-10)" scale for wearers of implant-supported fixed partial dentures.

OBJECTIVES: To validate the 'Quality of Life related to function, aesthetics, socialization, and thoughts about health-behavioural habits (QoLFAST-10)' questionnaire for assessing the whole concept of oral health-related quality of life (OHRQoL) of implant-supported fixed partial denture (FPD) wearers. METHODS: 107 patients were assigned to: Group 1 (HP; n=37): fixed-detachable hybrid prostheses (control); Group 2 (C-PD, n=35): cemented partial dentures; and Group 3 (S-PD, n=35): screwed partial dentures. Patients answered the QoLFAST-10 and the Oral Health Impact Profile (OHIP-14sp) scales. Information on global oral satisfaction, socio-demographic, prosthetic, and clinical data was gathered. The psychometric capacity of the QoLFAST-10 was investigated. The correlations between both indices were explored by the Spearman's rank test. The effect of the study variables on the OHRQoL was evaluated by descriptive and non-parametric probes (α=0.05). RESULTS: The QoLFAST-10 was reliable and valid for implant-supported FPD wearers, who attained comparable results regardless of the connection system being cement or screws. Both fixed partial groups demonstrated significantly better social, functional, and total satisfaction than did HP wearers with this index. All groups revealed similar aesthetic-related well-being and consciousness about the importance of health-behavioural habits. Several study variables modulated the QoLFAST-10 scores. CONCLUSIONS: Hybrid prostheses represent the least predictable treatment option, while cemented and screwed FPDs supplied equal OHRQoL as estimated by the QoLFAST-10 scale. CLINICAL SIGNIFICANCE: The selection of cemented or screwed FPDs should mainly rely on clinical factors, since no differences in patient satisfaction may be expected between both types of implant rehabilitations.

'Pre-prosthetic use of poly(lactic-co-glycolic acid) membranes treated with oxygen plasma and TiO2 nanocomposite particles for guided bone regeneration processes'.

OBJECTIVES: Guided bone regeneration (GBR) processes are frequently necessary to achieve appropriate substrates before the restoration of edentulous areas. This study aimed to evaluate the bone regeneration reliability of a new poly-lactic-co-glycolic acid (PLGA) membrane after treatment with oxygen plasma (PO2) and titanium dioxide (TiO2) composite nanoparticles. METHODS: Circumferential bone defects (diameter: 10mm; depth: 3mm) were created on the parietal bones of eight experimentation rabbits and were randomly covered with control membranes (Group 1: PLGA) or experimental membranes (Group 2: PLGA/PO2/TiO2). The animals were euthanized two months afterwards, and a morphologic study was then performed under microscope using ROI (region of interest) colour analysis. Percentage of new bone formation, length of mineralised bone formed in the grown defects, concentration of osteoclasts, and intensity of osteosynthetic activity were assessed. Comparisons among the groups and with the original bone tissue were made using the Kruskal-Wallis test. The level of significance was set in advance at a=0.05. RESULTS: The experimental group recorded higher values for new bone formation, mineralised bone length, and osteoclast concentration; this group also registered the highest osteosynthetic activity. Bone layers in advanced formation stages and low proportions of immature tissue were observed in the study group. CONCLUSIONS: The functionalised membranes showed the best efficacy for bone regeneration. CLINICAL SIGNIFICANCE: The addition of TiO2 nanoparticles onto PLGA/PO2 membranes for GBR processes may be a promising technique to restore bone dimensions and anatomic contours as a prerequisite to well-supported and natural-appearing prosthetic rehabilitations.

Validation of a new, specific, complete, and short OHRQoL scale (QoLFAST-10) for wearers of implant overdentures and fixed-detachable hybrid prostheses.

OBJECTIVES: To validate a new index for assessing the whole concept of oral health-related quality of life (OHRQoL) of implant-prosthesis wearers. METHODS: 113 patients who were not requesting dental treatment were assigned to: Group 1 (CD; n=38): complete denture users (control); Group 2 (IO; n=38): implant overdenture wearers; and Group 3 (HP; n=37): hybrid implant prosthesis users. Patients answered the newly-designed 'Quality of Life related to Function, Aesthetics, Socialization, and Thoughts about health-behavioural habits' (QoLFAST-10) and the Oral Health Impact Profile (OHIP-20sp) questionnaires. Information on global oral satisfaction, socio-demographic, clinical, and prosthetic-related data were gathered. The QoLFAST-10 was investigated for reliability and validity. The Spearman's test determined the correlations between both indices' scores. Descriptive and non-parametric probes were run to assess the influence of the study variables on the OHRQoL (α=0.05). RESULTS: The QoLFAST-10 confirmed its psychometric capacity. HP wearers reported significantly better global and functional satisfaction than did IO wearers. The latter revealed significantly less consciousness about the importance of health-behavioural habits than did CD and HP groups. The level of education, complaints about the mouth, and the global oral satisfaction measures significantly modulated the QoLFAST-10 scores. CONCLUSIONS: Implant overdentures supplied lower functional and global satisfaction than did hybrid prostheses, and represent the least predictable option concerning the maintenance of the restoration. CLINICAL SIGNIFICANCE: The QoLFAST-10 may help in estimating the impact of implant restorations on patients' well-being. In this regard, hybrid prostheses seem to be the implant treatment of choice when compared with overdentures.