In a period of up to 5 years, the resin cuspal coverage of endodontic treated teeth had a success rate of 96%, while the tooth survival rate was 100%. The type of support material on the opposing arch may influence the longevity of the restoration of endodontically treated teeth.

Objective. The aim of this study was to perform a systematic review of prevalence studies to determine the rate of malignant transformation of oral leukoplakia and assess the influence of demographic factors (age, gender, and geographic region) on the overall transformation rate. Study Design. A search was conducted for publications until July 2019 in 4 electronic databases and peer-reviewed journals. A manual search was performed on the bibliographies of the collected articles, and the authors were contacted for additional information. This study was previously registered with the trial number CRD42019126909 and study quality assessed through established methods. The results were expressed by means of proportions or odds ratios with a 95% confidence interval. Metaregression was undertaken to evaluate possible sources of heterogeneity, and funnel plot visual analysis was performed to assess publication bias.Results. The 34 observational epidemiologic studies included reported data on 26,209 patients with oral leukoplakia from 18 different countries. Meta-analysis of 32 studies (23,489 patients) presented an estimated overall mean proportion of malignant transformation rate of 9.70% (7.80À11.70) (I 2 = 98.66%; t 2 < 0.001; x 2 = 23.18; degrees of freedom [df] = 31). When comparing genders, the odds ratio favored males with 0.622 (0.468À0.826) (I 2 = 29.77%; t 2 = 0.089; x 2 = 22.78; df = 16). Conclusions. Within the limitations of the included studies in this systematic review, the results suggest that the malignant transformation rate was dependent on demographic factors and follow-up time. Future studies should include the development of guidelines to standardize the methodology for long-term follow-up assessment, thus reducing the risk of bias. (Oral Surg Oral Med Oral Pathol Oral Radiol 2020;000:1À12) Statement of Clinical RelevanceMost oral cancers develop from pre-existing lesions, oral leukoplakia being the most prevalent and well known. The early detection and treatment of leukoplakia have been debated, and one of the greatest challenges is identifying lesions that will undergo malignant transformation.

Objectives To evaluate the performance of two types of zirconia frameworks. Material and Methods From 2014 to 2016, in a prospective clinical trial, 150 patients were rehabilitated with 83 and 110 implant‐supported, screw‐retained, full‐arch ceramic‐veneered zirconia (PVZ) rehabilitations and monolithic zirconia with porcelain veneering limited to buccal (MZ) rehabilitations, respectively. Patients were consecutively enlisted according to pre‐defined inclusion criteria and evaluated on 4 months intervals. A Kaplan–Meier estimator was adopted, and the log‐rank test and Wilcoxon test used to test differences in survival and successful function in the two different groups. Results The average follow‐up time (±SD) and implant success rate was 608.80 ± 172.52 days with 99.53% implant success for the PVZ group and 552.63 ± 197.57 days with 99.83% success for the MZ group. According to the Kaplan–Meier estimator, the mean cumulative survival rate at the 2‐year follow‐up for framework fracture, major chipping, minor chipping, or any of the former combined to occur was 0.99, 0.95, 0.93 and 0.85 for the PVZ group (n = 18) and 0.99, 0.95, 0.95 and 0.89 for the MZ group (n = 15). No significant differences were found between the two groups. Conclusions Results suggest zirconia as a suitable material for frameworks in full‐arch implant‐supported rehabilitations. Both groups presented a low incidence of technical complications. When comparing the two different designs, the MZ group presented a lower technical complication rate, thus presenting itself as a viable alternative for full‐arch implant‐supported rehabilitations. Further clinical studies with longer follow‐ups (5 years) should be performed to evaluate the long‐term stability of such rehabilitations.

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3577 Background: While chemoradiation (CRT) is a curative treatment for SCCAC, many patients (pts) present primary resistance. As a rare tumor, the predictors of response in this setting remain unknown. Methods: Prospective cohort study aimed to evaluate predictive biomarkers (Ki-67, PD-L1, Human papillomavirus (HPV), HIV status and mutations in tumoral DNA) associated with complete response (CR) following standard CRT for localized SCCAC. Eligible pts had T2-4/N0-3/M0 disease and were candidates to standard CRT. CR at 6 months (m) measured by RECIST 1.1 was the primary endpoint. DNA mutations were analyzed by next-generation (NGS) TruSight Tumor26 panel. HPV positivity was tested by PapilloCheck Test. KI-67 and PD-L1 were evaluated by immunohistochemistry. Results: 78 pts were recruited from Jan/2011 to Dec/2015. 75 were evaluable for response. Median age 57 years; 49 (65%) were stage III, and 9 (12%) were HIV+. At 6m 47 (62.7%) had CR, 18 (24%) partial response (PR) and 10 (13.3%) disease progression. HPV was evaluated in 67 and found in 47 (70.1%), the majority HPV16. PD-L1 was tested in 61, 10 (16.4%) had > 1% positive expression. Ki-67 was performed in 65, a median was 50% (1-90%) per patient. Clinical stage, HIV status, median KI-67, HPV and PD-L1 positivity, and treatment interruption were tested as predictive factors of CR in 6m by logistic regression. On multivariable analyses, ECII patients were 4.7 more likely to achieve CR than ECIII (OR 4.70 CI95%1.36-16.30; p = 0.015). HIV was borderline significant (OR 2.53 CI95% 0.9-7.1; p = 0.079). Analyzing the patients with PR and CR HIV+ was significantly associated with poor response. Patients HIV- were 5.7 more likely to achieve CR or PR (OR 5.72 CI95%2.5-13.0; p < 0.001). 25 patients had tumor samples proper for NGS, 17 had at least one pathogenic mutation. The most common mutated genes were PIK3CA and MET in 6. There was no differences in CR rates according to MET (50% vs 47.3%, p = 1) or PIK3CA (33.3% vs 47.3%, p = 0.6) mutation status. TP53 codon 72 polymorphism was present in 72% (n = 18) and was not associated with CR (44% VS 57%, p = 0.6). Conclusions: Our study suggests that HIV+ pts are less responsive to CRT.

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