Noncarious cervical lesions: Response from a 25-year clinical follow-up study.

STATEMENT OF PROBLEM: The etiology and diagnosis of noncarious cervical lesions (NCCLs) remain poorly understood. PURPOSE: The purpose of this clinical study was to examine NCCL progression in an existing group of participants, establish the incidence of new NCCLs in a 25-year follow-up study, and relate them to possible risk factors, including occlusal factors. MATERIAL AND METHODS: Thirty-three participants who had completed a questionnaire about their habits, diet, and personal information were evaluated in this observational retrospective study. Impressions were made, and casts from 3 time periods (Phase I in 1996, Phase II in 1999, and Phase III in 2021) were scanned to obtain digital casts. The casts were then evaluated in a 3-dimensional analysis software program (Geomagic Control; 3D Systems) to establish digital comparisons between NCCLs and occlusal wear. Furthermore, data from an occlusal analysis device (T-Scan; Tekscan) collected in Phase I was used to analyze occlusal interferences relating to the progression of NCCLs. The statistical analysis applied nonparametric tests, followed by the assessment of the association between NCCLs and risk factors, including occlusal wear, through binary logistic regression (α=.05). RESULTS: At the end of Phase III, 7 new individuals with NCCLs were detected compared with Phase II. The median percentage progression of NCCLs per participant was 0.0% in Phase I, 7.1% in Phase II, and 35.7% in Phase III (P<.005). Occlusal wear in Phase I was associated with 5.02 times the occurrence of NCCLs in Phase III; occlusal wear in Phase II was associated with 4.73 times the occurrence of NCCLs in Phase III; and occlusal wear in Phase III was associated with 1.94 times the occurrence of NCCLs in Phase III (P<.001). Occlusal interference in border movements of the mandible was associated with a 3.55 times greater chance of presenting NCCLs in Phase III (P<.001). Additionally, statistically significant risk factors for the presence of NCCLs in Phase III were an acidic diet (P=.043) and alcohol consumption (P=.021). CONCLUSIONS: The 25-year data showed an association between NCCLs and specific risk factors, including occlusal wear and occlusal interferences.

Filling Materials Efficacy on Preventing Biofilm Formation Inside Screw Access Channels of Implant Abutments.

The choice of the material used to fill screw access channels in implant-supported prostheses depends, in most cases, on operator's preference, without considering the susceptibility of biofilm colonization. Therefore, the aim of this study was to determine and compare the total amount of biofilm formed on different materials used to fill screw access channels in implant abutments. For this propose, titanium implant analogs were attached on abutments and divided into 5 groups: positive control (no filling material); negative control (closed with resin); and filled with cotton, gutta-percha, or polytetrafluoroethylene (PTFE). The analogs with attached abutments were then immersed in a brain heart infusion medium containing Candida albicans (strain 10231 from American Type Culture Collection [ATCC]) and incubated aerobically at 37°C with gentle agitation. After 15 days, materials were removed, and total viable biofilm on each material was quantified by methyl tetrazolium reduction assay at 490 nm. All experiments were performed in triplicate. Data were processed by IBM SPSS Statistic software using 1-way analysis of variance and Bonferroni post hoc tests to analyze differences between groups, with an overall significance level of P < .001. A significant difference was observed between cotton and gutta-percha (P < .017) and between cotton and PTFE (P < .025). However, there was no statistical difference between gutta-percha and PTFE (P > .050). Thus, this in vitro experiment showed that gutta-percha and PTFE presented lower biofilm formation compared with cotton when used to fill screw access channels. These results can provide a basis for future clinical studies that can be a guide to decreasing the occurrence of gaps and bacterial growth inside the implant/abutment attachment site. In addition, controlled in vivo studies are necessary to confirm the clinical viability of findings of this study.

Torque removal evaluation of prosthetic screws after tightening and loosening cycles: an in vitro study.

OBJECTIVES: The aim of this study was to evaluate the variation in removal torque of implant prosthetic abutment screws after successive tightening and loosening cycles, in addition to evaluating the influence of the hexagon at the abutment base on screw removal torque. MATERIAL AND METHODS: Twenty hexagonal abutments were tightened to 20 regular external hex implants with a titanium alloy screw, with an insertion torque of 32 N cm, measured with a digital torque gauge. The implant/abutment/screw assemblies were divided into two groups: (1) abutments without hexagon at the base and (2) abutments with a hexagon at the base. Each assembly received a provisional restoration and was submitted to mechanical loading cycles. After this, the screws were removed and the removal torque was measured. This sequence was repeated 10 times, then the screw was replaced by a new one, and another cycle was performed. Linear regression analysis was performed. RESULTS: Removal torque values tended to decrease as the number of insertion/removal cycles increased, for both groups. Comparisons of the slopes and the intercepts between groups showed no statistical difference. There was no significant difference between the mean values of last five cycles and the 11th cycle. Within the limitations of this in vitro study, it was concluded that (1) repeated insertion/removal cycles promoted gradual reduction in removal torque of screws, (2) replacing the screw with a new one after 10 cycles did not increase resistance to loosening, and (3) removal of the hexagon from the abutment base had no effect on the removal torque of the screws.

Cerâmicas Feldspáticas em Dentes Posteriores pela Técnica CAD/CAM: uma Revisão de Literatura / Feldspatich Ceramics in Posterioes Teeth by CAD/CAM Technique: a Literature Review

O objetivo do presente estudo foi avaliar a indicação do uso das cerâmicas feldspáticas em dentes posteriores, pela técnica CAD/CAM (Computer-aided design [CAD] e computer-aided manufacturing [CAM]) chairside, em uma unidade de alta demanda, por meio de uma revisão de literatura. Uma pesquisa avançada foi realizada a partir da base de dados do PubMed, compreendendo os últimos 15 anos e utilizando os seguintes termos MeSH para pesquisa: "dental crowns", "CAD/CAM system", "porcelain" e "review". Dos 47 artigos levantados inicialmente, 30 foram selecionados para compor a amostra final. A partir do presente estudo foi possível concluir que o uso das cerâmicas feldspáticas desenvolvidas pela técnica CAD/CAM é seguro em dentes posteriores, desde que respeitada a técnica. Esta técnica constitui-se em excelente opção para tratamento odontológico em instituições de alta demanda restauradora que possuem altos níveis de exigência e prontidão, promovendo celeridade, evitando o uso de restaurações provisórias, reduzindo também a quantidade de urgências em próteses.

The present study aims to evaluate the indication of the use of feldspathic ceramics in posterior teeth, by the CAD/CAM technique (Computer-aided design [CAD] and computer-aided manufacturing [CAM]), in a public institution, through a literature review. An advanced search was carried out in the PubMed database, covering the last 15 years and using the following MeSH search terms: "dental crowns", "CAD/CAM system", "porcelain" and "review". Thirty out of the 47 articles initially surveyed were selected to compose the final sample. From the present study, it was possible to conclude that the use of feldspathic ceramics developed by the CAD/CAM technique is safe in posterior teeth, whether the technique is respected. This technique is an excellent option for dental treatment in institutions of high restorative demand that have high levels of demand and readiness, promoting celerity, avoiding the use of temporary restorations, also reducing the number of urgencies in prosthesis.

Osseointegrated implants placed at supracrestal level may harbour higher counts of A. gerencseriae and S. constellatus - a randomized, controlled pilot study.

PURPOSE: This study aimed at evaluating the bacterial colonization in dental implants inserted in the crestal or supracrestal position and correlated it to radiographic bone measurements. METHODS: Thirty-five implants with regular platform in nine patients (mean age 62.4±11.2 years) were inserted either at the bone crest level (control group) or at a suprecrestal level (test group). Radiographic examination was performed at baseline (implant installation) and after 6 months. Clinical and microbiological data were collected after 6 months. Digital radiography was used to assess bone remodeling (marginal bone loss and optical alveolar density). Bacterial profile was analyzed by checkerboard DNA-DNA hybridization, including a panel of 40 bacterial species. RESULTS: After 6 months, there were significantly higher counts of Actinomyces gerencseriae (p=0.009) and Streptococcus constellatus (p=0.05) in the test group. No significant differences between test and control groups were observed for marginal bone loss (p=0.725) and optical alveolar density (p=0.975). Probing depth was similar in both groups. CONCLUSION: Significantly higher counts of A. gerencseriae and S. constellatus were found in implants placed at the supracrestal level compared to the ones placed at the bone level. No relation was found between the installation level of dental implants and peri-implant bone remodeling.