Microtensile Bond Strength of Self-Etch Adhesives on Dentin Treated with Chlorhexidine.

AIM: To evaluate the microtensile bond strength of self-etching adhesive systems in dentin treated with 2% chlorhexidine digluconate (CHX). MATERIALS AND METHODS: The occlusal surfaces of 20 human molars were removed and divided into eight groups: 1A, Clearfil SE adhesive (SE) with self-etching technique (TS); 1B, SE with TS and previous application of CHX; 2A, Scotchbond Universal (SBU) adhesive with TS; 2B, SBU adhesive with TS and previous application of CHX; 1C, SE with total-etching technique (TT); 1D, SE with TT and previous application of CHX; 2C, SBU with TT; 2D SBU with TT and previous application of CHX. Composite resin (5mm) was applied on the hybridized surface. Samples were subjected to microtensile test and evaluated on Scanning Electron Microscope (SEM) and with energy-dispersive X-ray (EDX). RESULTS: Low values of bond strength were observed in groups 1A (39,77±11,56) and 2A (40,84±12,49) comparing with 1B (22,86±5,18) and 2B (27,02±5,58). TS group presented adhesive type remover fracture while TT groups presented cohesive at the top of hybrid layer. EDX revealed the presence of CHX crystals for TS, which was not found in the TT. CONCLUSION: The previous application of chlorhexidine on dentin decreased the bond strength of adhesive systems on self-etching technique.

Evaluation of the Antimicrobial Effect on Enterococcus Faecalis of Bioceramic Cements with and without Silver Nanoparticles.

OBJECTIVE: To compare the antimicrobial effect of bioceramic endodontic cements with and without silver nanoparticles on Enterococcus faecalis. MATERIALS AND METHODS: Six groups were evaluated (n=8), and divided according to the materials: MTA Flow + AgNP ; MTA Flow Group; Bio C Repair + AgNP; Bio C Repair; PBS Cimmo + AgNP; PBS Cimmo. The groups were maintained for 72 h in the suspension of Enterococcus faecalis in Simulated Body Fluid (SBF). Samples of 100 µL were removed from the suspension at 0, 24, 48 and 72 h and seeded in triplicate in a Petri dish. Colony forming units (CFU) were counted using a colony counter. All procedures described were performed in a laminar flow chamber. Two-way ANOVA followed by Tukey's post hoc test and paired t-test were used for statistical analyses (α = 0.05). RESULTS: The addition of silver nanoparticles resulted in a statistically significant difference for MTA and CIMMO PBS cements (p⟨0.05), with the lowest bacterial growth being shown by the MTA group. For all groups, only the times of 48 and 72 h presented results without differences. CONCLUSION: The addition of silver nanoparticles to bioceramic cements was efficient to promote an acceleration of bacterial death.

Longevity of Resin Composite and Amalgam Posterior Restorations: A Systematic Review.

OBJECTIVES: The objective of this systematic review was to compare the longevity of direct amalgam and composite resin restorations, in posterior teeth, through clinical, prospective or retrospective studies, with at least 5 years of follow-up. MATERIALS AND METHODS: Studies published in the last 15 years (from 2006 to 2021) were collected using the PubMed and Medline databases. RESULTS: The search strategy associated with the established inclusion and exclusion criteria resulted in a total of 17 articles. Factors related to failures in the performance of restorations were analyzed together with the clinical performance results of each material over the years of study, according to the methodology of each article. CONCLUSIONS: Regardless of the restorative material, the successful results over more than 5 years are due much more to the correct application of the technique, the operator's skill/knowledge and factors related to the patient, such as the type of tooth, number of faces involved in the restoration and oral hygiene.

Influence of Flat Occlusal Splint on Stresses Induced on Implants for Different Fixed Prosthetic Systems.

OBJECTIVE: The flat occlusal plate has been recommended to reduce stress concentration in implant prosthesis treatments. The purpose was to investigate the influence of the occlusal splint on three-element implant-supported fixed prosthesis. MATERIALS AND METHODS: A three-dimensional virtual model was created consisting of a cortical and spongy bone block simulating the region from first premolar to the maxillary first molar using two HE or MT implants (4 x 11mm) with Ti and/or Y-TZP abutments. The second premolar was the pontic of the prosthesis. The three-element fixed prosthesis with a zirconia infrastructure and Y-TZP coating were cemented, in addition to using a flat occlusal splint made of acrylic resin in the region. Combined axial and oblique loads of 100N and 300N were applied. RESULTS: The tensile stresses on MT implant bone tissue produced values of 4-19% lower than those of HE implants. The lowest differences were observed for oblique loading with an occlusal splint, with a 4% (Ti-Y-TZP) and 9% (Ti-Ti) decrease. When the compressive stresses were evaluated, HE implants produced lower values than MT implants. CONCLUSION: A significant increase was observed in the oblique loading stresses in the absence of occlusal splints, regardless of the applied load.

Prevalence of oro-dental anomalies among schoolchildren in Sana'a city, Yemen.

Practitioners and policy-makers need information about the relative frequency of dental anomalies among children in their region. This study investigated the prevalence of different oral anomalies among schoolchildren in Sana'a city, Yemen. A sample of 1000 private and public schoolchildren aged 4-12 years were examined by the same examiner using disposable tongue blades. The total prevalence of oral anomalies was 15.1%, most commonly in boys (male:female ratio 3.2:1) aged 7-12 years. The most prevalent dental anomaly related to hard tissues was tooth hypoplasia (2.8%), followed by hypocalcification (2.6%), then microdontia (0.5%), macrodontia (0.4%), hypodontia (0.4%), supernumerary teeth (0.3%), tooth transposition (0.3%), dental fusion (0.2%) and gemination (0.2%). The most prevalent soft tissues anomaly was fissured tongue (4.0%), followed by ankyloglossia (1.8%), geographic tongue (0.9%), macroglossia (0.4%) and hairy tongue (0.3%). Appropriate measures need to be taken early to mitigate the negative impact and later costs of treatment of anomalies.

Microhardess and depth of cure of a spectrum of light-cure composite resins: a comparative study.

AIMS AND OBJECTIVES: To determine the proportion of composite resin materials that is capable of bulk or large incremental cure. MATERIALS AND METHODS: This study was carried out at the Dental Biomaterials and Biomechanics Laboratory, Dental School, University of Manchester, England. Six randomly selected composite resins and one experimental sample were employed for this study. The technique employed by Watts et al. was employed for the study. Knoop hardness number (KHN) was measured as a function of depth of the material at 0.2 mm intervals. One-Way ANOVA test and linear regression were used for statistical analysis. RESULTS: Clearfil Majesty Posterior has the highest value for microhardness and depth of cure while Els extra low shrinkage A3 has the lowest value for micro hardness and depth of cure. Estelite 0 and Clearfil Majesty Posterior (28.6%) have depths of cure greater than 3.0 mm and may, therefore, be capable of large incremental cure. Gradia Dentin and Els extra low shrinkage A3 (28.6%) have depths of cure lesser than 2.0 mm while Filtek Silorane (experimental material) has a depth of cure of 2.4 mm. NEUN and Els extra low shrinkage A2 have depths of cure of 2.3 and 2.5 mm respectively. CONCLUSIONS: It appears that Clearfil Majesty Posterior and Estelite 0 (28.6%) can effectively be cured in bulk or large increments. It is imperative to investigate the depth of cure of composite resin materials before using them in bulk or large increments.

Extensive review in the detection of the malignant transformation of pleomorphic adenoma.

BACKGROUND AND OBJECTIVES: There is an increasing likelihood of malignant change in pleomorphic adenoma (PA) with time. This extensive review aims to highlight the current areas of difficulty or controversy in the diagnosis of malignant transformation of pleomorphic adenoma - a subject of most interest and challenge to a pathologist. It is also the objective of this review to compare the clinical and pathological points-of-view on the diagnosis of malignant transformation of pleomorphic adenoma. METHODS: A literature search using MEDLINE, accessed through the National Library of Medicine PubMed interface, for articles relating to malignant transformation of pleomorphic salivary adenoma written in the English language. RESULTS: The updated literature indicates that carcinomas in pleomorphic adenoma may arise in an older age group than benign lesions and are usually larger and longer standing lesions. The use of molecular changes to study malignant transformation of pleomorphic adenoma, unfortunately, have no specific expression on the tumor suppressor genes to detect the malignant transformation of pleomorphic adenoma from pathological point view. CONCLUSION: The use of combined clinical evidence and pathological evidence are very important in the detection of the malignant transformation of pleomorphic adenoma. KEYWORDS: pleomorphic adenoma, malignant transformation of pleomorphic adenoma.