Analice Giovani Pereira

Influence of flexion angle of files on the decentralization of oval canals during instrumentation

The aim of this study was to evaluate the influence of the flexion angle of files on the decentralization of root canals during instrumentation. Fifteen lower incisors were instrumented with Protaper Universal files and radiographed in two directions (mesiodistal and buccolingual) before and after instrumentation with a #15 K-file in position for evaluating the flexion angle of files. The specimens were also scanned before and after instrumentation using micro-computed tomography to obtain the canal area and the distance from the center position of the file to the canal walls. Sections located 1.0 mm (end of the canal), 3.0 mm (apical third), 9.0 mm (middle third), and 15.0 mm (cervical third) from the apex were verified. After instrumentation, the flexion angles of files decreased by an average of 0.76º in the buccolingual direction and 1.92º in the mesiodistal direction (p < 0.001); the canal area increased by an average of 0.58, 0.37, 0.23 and 0.13 mm(2) from the cervical to the end of the root canal (p < 0.001). Non-instrumented areas were observed on the buccal and lingual walls, and effective action of files was determined on the mesial and distal walls. The sections from the end of the canal showed canal deviation toward the lingual wall, whereas the other sections showed deviation toward the buccal wall. The flexion angles of files influence the final shape of the root canal, resulting in file decentralization along the pathway of the canal.

Influence of core-finishing intervals on tensile strength of cast posts-and-cores luted with zinc phosphate cement

The core finishing of cast posts-and-cores after luting is routine in dental practice. However, the effects of the vibrations produced by the rotary cutting instruments over the luting cements are not well-documented. This study evaluated the influence of the time intervals that elapsed between the cementation and the core-finishing procedures on the tensile strength of cast posts-and-cores luted with zinc phosphate cement. Forty-eight bovine incisor roots were selected, endodontically treated, and divided into four groups (n = 12): GA, control (without finishing); GB, GC, and GD, subjected to finishing at 20 minutes, 60 minutes, and 24 hours after cementation, respectively. Root canals were molded, and the resin patterns were cast in copper-aluminum alloy. Cast posts-and-cores were luted with zinc phosphate cement, and the core-finishing procedures were applied according to the groups. The tensile tests were performed at a crosshead speed of 0.5 mm/min for all groups, 24 hours after the core-finishing procedures. The data were subjected to one-way analysis of variance (ANOVA) and Tukeys test (α = 0.05). No significant differences were observed in the tensile strengths between the control and experimental groups, regardless of the time interval that elapsed between the luting and finishing steps. Within the limitations of the present study, it was demonstrated that the core-finishing procedures and time intervals that elapsed after luting did not appear to affect the retention of cast posts-and-cores when zinc phosphate cement was used.

The dentin chemical degradation and saliva roles on Noncarious Cervical Lesions – literature review

This review elucidates the dental structure chemical degradation and saliva roles in the origin and progression of NCCLs. Dentin chemical degradation is a predominant factor that contributes to the origin and progression of noncarious cervical lesions, which includes the biocorrosive factors: chemical, biochemical, electrochemical and piezoelectric dentin effects. The biocorrosive process involves endogenous and exogenous agents. As regard to saliva roles, the flow rate, buffering capacity, pH and its protein composition are valid parameters to identify biocorrosive factors. Thus, the association of acids agents, altered salivary parameters and specifics proteases are important conditions to promote dental wear. It can be concluded that endogenous and exogenous acids agents, salivary parameters and specific oral biomarkers are important to support the diagnostic and management of dental wear and noncarious cervical lesions.

Abordagem multidisciplinar para reabilitação estética do sorriso com laminados cerâmicos minimamente invasivos

INTRODUCAO: A constante busca por um sorriso harmonico e estetico eleva o nivel de exigencia e de expectativa dos pacientes. Esse fato propicia o desenvolvimento de novos materiais e tecnicas na Odontologia, visando procedimentos mais conservadores e resultados cada vez mais previsiveis esteticamente. OBJETIVO: O objetivo deste trabalho e relatar tratamento multidisciplinar com a associacao de cirurgia periodontal e confeccao de laminados cerâmicos em CAD-CAM na harmonizacao do sorriso. APRESENTACAO DO CASO: Paciente M.C.B.M., genero feminino, 21 anos, apresentou-se insatisfeita com o sorriso. Relatou queixa do contorno gengival, tamanho e formato dos dentes, alem da presenca de manchas na superficie vestibular dos dentes anteriores superiores. DISCUSSAO: Inicialmente a paciente foi submetida a plastia gengival para aumento de coroa clinica. Posteriormente, executou-se o clareamento dental, moldagem para enceramento com silicone por adicao, confeccao de mock-up em resina bis-acrilica e preparo dos elementos 13,12,11,21,22,23. A paciente foi submetida ao escaneamento pelo sistema CAD/CAM Cerec – Sirona e enviado ao laboratorio protetico. Laminados cerâmicos foram fresados em blocos reforcados por dissilicato de litio. Os laminados foram cimentados utilizando cimento resinoso fotoativado. CONCLUSAO: Conclui-se que adequado planejamento integral e inter-relacao entre as areas da odontologia sao fundamentais para o exito nos procedimentos periodontais e restauradores.

Critical Instrumentation Area: Influence of Root Canal Anatomy on the Endodontic Preparation

The aim of this study was to evaluate the root canal anatomy of mandibular incisors before and after endodontic instrumentation, identifying regions inaccessible to the action of files (Critical instrumentation Area - CA) in a three-dimensional perspective. Thirty human mandibular central incisors were selected, assigned to two groups (n=15) and instrumented using ProTaper Universal rotary files. In the RX group, longitudinal digital radiographic images were obtained in the buccolingual (BL) and mesiodistal (MD) views. In the CT group, cross-sectional micro-computed tomography (µCT) images were obtained at 3, 9 and 15 mm from the apex. The canal area of the specimens was evaluated before and after instrumentation using digital images from each group. Data were analyzed using t-test, one-way ANOVA with subdivided parcels and Tukeys test (α=0.05). The canal area found in the MD radiographs was larger than in the BL radiographs, which was also confirmed in the transversal images (p<0.01). The CA was only detected in the MD radiographs and µCT scans. On the root canal configuration, a continuous reduction in the canal conicity was observed in BL radiographs, while in MD view there was a constriction at the cervical third and subsequent increase at the middle third (p<0.01). The conical shape of the root canal was observed only in the BL view. The canal enlargement in BL radiographs was not indicative of homogeneous instrumentation, since unprepared areas (CA) were also verified on the buccal and lingual walls in different images.