ABSTRACT
Objective@# To explore the design and manufacture of anatomical healing abutment for mandibular first molar implant in order to provide more choices for clinical healing abutment@*Methods@# The buccal lingual diameter and mesial distal diameter of the tooth neck, as well as the slope data of the four axial surfaces of the natural isolated teeth, were obtained by scanning the isolated mandibular first molar with a shining scanner. After statistical analysis of the data, the anatomical healing abutment of the mandibular first molar was designed and constructed using computer aided design/computer aided manufacturing (CAD/CAM).@*Results@#The mean buccal and lingual diameters of the mesial and distal diameters of the isolated mandibular first molars were (8.54 ± 0.78) mm and (7.87 ± 0.86) mm, and the tooth neck slopes of each axial surface of the isolated mandibular first molars were 17.53 °(buccal), 14.41 °(lingal), 13.40 °(mesial) and 13.43 °(distal), respectively. Three anatomical healing abutments with different peripheral diameters and heights of 5 mm were obtained according to a certain proportion of reduction of the natural teeth of the mandibular first molars@*Conclusion@#The anatomical healing abutment of the mandibular first molar can be quickly obtained by Shining scanning and CAD/CAM technology.
ABSTRACT
Gingival recession is one of the most usual esthetic concerns associated with the periodontal tissues. Classification of such condition is important to diagnose, determine the prognosis, and frame the treatment plan. Various classifications have been put forward since decades to classify gingival recession. Miller's classification is the widely used classification among all classifications, but certain drawbacks have been noted in this classification. Therefore, an effort is made to review most commonly used classification systems for gingival recession, and their drawbacks further come up with a proposal of new classification system for gingival recession.
ABSTRACT
PURPOSE: The objectives of the current study are to assess the accuracy of X-Ray Micro Computed Tomography (microCT) in measuring enamel thickness and to evaluate enamel thickness in maxillary incisors of Koreans. MATERIAL AND METHODS: Five maxillary incisors were embedded in resin block. These teeth were longitudinally sectioned labiolingually through the medial axis. After polishing, the teeth were scanned using a microCT (X-EYE SYSTEM; DRGEM, Seoul, Korea). On a scanning electron microscope (S-4300; Hitachi, Tokyo, Japan) (x20) and a microCT, nearly identical planes were reconstructed. In each tooth, the thickness of labial enamel was measured 1, 3 and 5 mm above the cementoenamel junction (CEJ). Thus, the accuracy of the microCT was evaluated. In addition, using 26 maxillary central incisors and 11 maxillary lateral incisors, in the medial axis and 2 mm remote areas mesially and distally from the medial axis, the thickness of labial enamel was measured 1, 3 and 5 mm above the CEJ along the long axis of the teeth RESULTS: Measurements from nearly identical planes in physical and microCT sections differed by 3.81%. An independent t-test was performed and this showed that there were no significant differences in the measurements between the two methods. Mean values of labial enamel thickness in maxillary central incisors 1, 3 and 5 mm above the CEJ were 0.32 +/- 0.01, 0.50 +/- 0.02 and 0.70 +/- 0.02 mm, respectively. Mean values of labial enamel thickness in maxillary lateral incisors 1, 3 and 5 mm above the CEJ were 0.30 +/- 0.01, 0.55 +/- 0.03 and 0.80 +/- 0.02 mm, respectively. CONCLUSION: In measuring enamel thickness, microCT is one of useful way of measurement. So according to the results of this research, when restoring a porcelain laminate veneer on maxillary incisors in Koreans, careful consideration is needed in the amount of enamel reduction.
Subject(s)
Axis, Cervical Vertebra , Dental Enamel , Dental Porcelain , Electrons , Incisor , Microscopy, Electron, Scanning , Tokyo , Tooth , Tooth Cervix , X-Ray MicrotomographyABSTRACT
Este estudo longitudinal investigou o efeito da ausência de junção amelocementária (JAC) na variação de pH extrarradicular durante clareamento interno. Dividiram-se 30 incisivos humanos extraídos em dois grupos experimentais (n = 12) e um grupo controle (n = 6). Nos espécimes do grupo experimental I, as junções amelocementárias foram mantidas intactas; no grupo experimental II, as mesmas foram completamente removidas por desgaste com ponta diamantada antes da inserção intracoronária de peróxido de hidrogênio a 30% (Magistral Pharma). No grupo controle, as câmaras pulpares foram repletas de soro fisiológico. Em cada intervalo experimental de 0, 24, 72, 96, 156, 192 e 270 horas, mensurava-se o pH extrarradicular por meio da sonda de um peagômetro (Micronal®) inserida na água destilada em que os espécimes eram imersos e, imediatamente, o agente clareador era renovado. A análise de variância a dois critérios revelou para o grupo II (JAC ausente) os menores valores de pH (4,3 ± 0,16), estatisticamente diferentes do grupo controle (7,1 ± 0,20) nos intervalos de 156, 192 e 270 horas, e do grupo I (5,9 ± 0,14) no período de 270 horas (p menor ou igual a 0,05). Concluiu-se que a ausência de união entre cemento e esmalte intensificou a redução de pH no meio extrarradicular somente após 270 horas de clareamento interno.
This longitudinal study investigated the effect of cementoenamel junction (CEJ) absence on the extraradicular pH variation during intracoronal bleaching. Thirty extracted human incisors were divided into two experimental groups (n = 12) and a control (n = 6). In specimens of group I the cementoenamel junctions were kept original whereas in group II they were completely removed through cut using a diamond bur prior the intracoronal insertion of 30% hydrogen peroxide (Magistral Pharma). For the control group the pulp chambers were flled with saline. In the experimental intervals of 0, 24, 72, 96, 156, 192 and 270 hours the extraradicular pH was measured by means of a pH meter (Micronal®) probe inserted in the distilled water in which the specimens were immersed, and soon afterwards the bleaching agent was renewed. The two-way analysis of variance revealed the lowest pH levels for group II (4.3 ± 0.16) which were statistically different from that of control group (7.1 ± 0.20), at the intervals of 156, 192 and 270 hours, and from that of group I (5.9 ± 0.14) at 270 hours (p less than or equal to 0.05). It was concluded that the absence of cementoenamel junction intensified the extraradicular decrease of pH only after 270 hours of intracoronal bleaching.