In this study, endodontic treatments of maxillary second premolars with unusual anatomical configuration were presented. Maxillary second premolars usually have one root with one or two root canals. The occurrence of variations in anatomical configuration is also common; therefore, it must be taken into account in clinical and radiographic evaluation during the endodontic treatment. These teeth may also require special shaping and filling techniques. This article reports and discusses the treatment recommendations for unusual occurrences of anatomical configurations in four different maxillary second premolars.

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In this study, we report an endodontic treatment of the maxillary second premolar with three root canals and distinct foramens. The possibility of three root canals in this tooth is quite small; however, it must be taken into account in clinical and radiographic evaluation during endodontic treatment. Many times, their presence is noticed only after canal treatment due to continuing post-operative discomfort.

ABSTRACT. The aim of this study was to evaluate the histogical and morphological aspects of the condyle in response to mandibular protrusion induced by composite resin occlusal planes. Thirty fiveweek-old male Wistar rats were selected and randomly divided in two groups. One group received a composite resin type of oclusal plane that induced mandibular protrusion, and the other was the control group, without treatment. Animals were euthanized after experimental time intervals of 7, 21 and 30 days. For histological analysis, thickness of the proliferative, serial and hypertrophic layers was measured, as well as each layer separately. The highest difference in cartilage thickness was observed at day 21, showing a significant increase of the proliferative layer. There were also other histomorphological changes related to occlusal plane interference. Condylar forward repositioning induced by composite occlusal planes influenced the endochondral ossification, increasing the proliferative layer.Keywords: articular cartilage, mandibular condyle, angle class II malocclusion.Avaliação histológica e morfológica da cartilagem condilar de ratos frente a estímulos de protrusão mandibular RESUMO. Este estudo teve como objetivo avaliar os aspectos histológicos e morfológicos do côndilo mandibular diante da protrusão induzida por um plano inclinado fixo de resina. Para tanto, trinta ratos Wistar machos com cinco semanas de vida foram divididos aleatoriamente em dois grupos. Um grupo experimental (E) recebeu o plano inclinado fixo de resina, que induziu a mandíbula à protrusão, e o outro consistiu no grupo controle (C), sem tratamento. Os animais foram eutanasiados após 7, 21 e 30 dias de experimento. Para análise histológica, foi realizada a mensuração da espessura condilar total, incluindo as camadas proliferativa, seriada e hipertrófica, assim como cada camada separadamente. A maior espessura da cartilagem foi observada em 21 dias no grupo E, com significante aumento da camada proliferativa. Também foram verificados níveis de histodiferenciação nos demais períodos, caracterizando interferência do plano inclinado. Concluiu-se que a indução do posicionamento condilar em avanço por meio do plano inclinado fixo interferiu no processo de ossificação endocondral, aumentando a atividade da camada proliferativa.Palavras-chave: cartilagem articular, côndilo mandibular, má-oclusão de angle classe II.

Posteriorly repositioning the mandible produced a series of histological and morphological responses in the condyle, suggesting condylar and mandibular adaptation in rats.