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ExperimentaL Oral Medicine
Published in Samuel Dreizen, Barnet M. Levy, Handbook of Experimental Stomatology, 2020
Samuel Dreizen, Barnet M. Levy
A model for the development of follicular cysts wherein epithelial-lined structures about the crowns of murine tooth germs form in heterotropic sites has been developed by Riviere and Sabet.70 Maxillary first molar tooth germs from 7-day-old mice of either sex were used as grafts and 2- to 4-month-old adult males as recipients. The grafts were placed in the fourth mammary fat pads that were surgically exposed and closed over with wound clips in the skin after graft emplacement. Donor mice were of the BBA/2J inbred strain, and recipients were either of the same strain (syngeneic transplant) or of the Balb/c inbred strain (allogeneic graft). Fat pads containing the transplanted tooth germs were removed 1, 2, and 3 weeks after grafting. They were processed histologically and read microscopically.
Clefts and craniofacial
Published in Tor Wo Chiu, Stone’s Plastic Surgery Facts, 2018
Class I – Normal occlusion. The mesiobuccal cusp of the permanent maxillary first molar occludes in the buccal groove of the permanent mandibular molar. Essentially each upper molar tooth should sit half a tooth in front of the corresponding lower tooth.
Anatomy and Embryology of the Mouth and Dentition
Published in John C Watkinson, Raymond W Clarke, Terry M Jones, Vinidh Paleri, Nicholas White, Tim Woolford, Head & Neck Surgery Plastic Surgery, 2018
Posterior to the premolars are three molars whose size decreases as one passes backwards. Each has a large rhomboid (upper jaw) or rectangular (lower jaw) occlusal surface with four or five cusps. The maxillary first molar has a cusp at each corner of its occlusal surface and the mesiopalatal cusp is connected to the distobuccal by an oblique ridge. A smaller cusplet or tubercle (cusplet of Carabelli) usually appears on the mesiopalatal cusp. The tooth has three widely separated roots, two buccal and one palatal. The smaller maxillary second molar has a reduced distopalatal cusp. Its three roots are less divergent and two of them may be fused. The maxillary third molar, the smallest, is very variable in form. It usually has three cusps (the distopalatal being absent) and commonly the three roots are fused.
Periapical status and technical quality in root canal filled teeth in a cross sectional study in Jönköping, Sweden
Published in Acta Odontologica Scandinavica, 2023
Zlatan Silnovic, Thomas Kvist, Fredrik Frisk
Somewhat surprisingly, we found that AP in root canal filled molars was evenly distributed between those with adequate and inadequate root canal filling quality, respectively. A possible explanation may be that it is difficult to correctly assess root canal filling quality in molars. By using computed cone beam tomography (CBCT) the estimation of root canal filling quality may be more adequate in multirooted teeth [26]. For example, Mashyakhy et al. [27] found in a CBCT investigation of 208 root canal filled teeth that 18% exhibited ‘missed canals’. In maxillary first molars the prevalence was as high as 40.6%. The overall prevalence of AP among teeth with missed canals was 90%. Thus, it is possible and even likely that a significant fraction of teeth, in particulars molars, judged to have an adequate root canal filling quality in our study would have been judged differently (i.e. poor quality and missed canals) if CBCT had been used instead of intra oral radiographs.
Morphological variations and prevalence of aberrant traits of primary molars
Published in Annals of Human Biology, 2021
P. Sujitha, R. Bhavyaa, M. S Muthu, M. Kirthiga
The parastyle is a paramolar cusp of Bolk that occurs on the mesiobuccal surface of upper molars (Turner et al. 1991). Although the literature pertaining to this trait is negligible, it is said to be predominant in deciduous molars (Kustaloglu 1962). In the present study, the results yielded a prevalence rate of 0.51% in primary maxillary second molars and 3.48% in primary maxillary first molars. Studies conducted among southwestern and northwestern Indians (Kustaloglu 1962) gave a prevalence of 5.2% and 4.7%, respectively, in primary maxillary second molars. The prevalence found in the present study was comparatively less in primary maxillary second molars. However, the prevalence of the parastyle was higher in primary maxillary first molars. The literature suggests primary maxillary first molars to be the “premolar section” of the primary dentition and to resemble certain features of premolars (Nelson and Ash 2012). The literature also suggests that this trait occurs more in premolars (Kustaloglu 1962), which can be the reason for its higher prevalence in primary maxillary first molars.
Occlusal load modelling significantly impacts the predicted tooth stress response during biting: a simulation study
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
Harnoor Saini, David C. Ackland, Lulu Gong, Oliver Röhrle
To this end, dental structures, including the first right mandibular molar enamel and dentin, the cortical and cancellous mandibular bone, and a section of the left and right mandibular fossa, were manually segmented from the CT scans using ITK-SNAP (version 2.4.0) (Yushkevich et al. 2006). Since dentin and cementum have similar mechanical properties (Shaw et al. 2004), these materials were combined into one structure. The thickness of the articular discs of the TMJ was defined from the width of the space between the mandibular condyles and the fossae. The periodontal ligament (PDL) geometry was based on the mandibular molar root geometry and defined as a uniform layer with an approximate thickness of 0.20 mm similar to other investigations (e.g. McGuinness et al. 1992; Toms and Eberhardt 2003). The maxillary first molar geometry was segmented from the micro-CT images. The rubber sample used in the biting simulations had dimensions 20x10x5mm (Röhrle et al. 2018).