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The gastrointestinal tract
Published in Simon R. Knowles, Laurie Keefer, Antonina A. Mikocka-Walus, Psychogastroenterology for Adults, 2019
Christopher F.D. Li Wai Suen, Peter De Cruz
Digestion starts in the mouth (Figure 1.3). There, teeth break down large pieces of ingested food into smaller pieces. Various types of teeth are adapted to various functions. Incisors, located at the front of the mouth, with their sharp fine surface, are designed to cut food, while the pointy canine teeth are designed for tearing food. Molars and pre-molars are large teeth situated at the back of the mouth. By the action of chewing, the top and bottom molars and pre-molars rub their surfaces together, grinding the food into smaller particles.
Head and neck
Published in Tor Wo Chiu, Stone’s Plastic Surgery Facts, 2018
Complications include Damage to gums and teeth, which may lead to loosening; avoid using incisors over a long period. In children, piriform rim and circummandibular wiring are alternatives to arch bars and IMF screws. In edentulous patients, gunning splints can be used, held in place with wires passed around the mandible and through the maxillary sinus.Fracture deviation – there is a tendency to twist fragments towards the tongue.Occlusion should be checked once or twice a week, changing to elastics as necessary.Airway problems are unusual, but wire cutters should be kept by the patient, particularly just after surgery.Healing will take about 4–6 weeks, but this needs to be balanced against the negative effects on TMJ function; there is a trend to use IMF for shorter periods.
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
There are two incisors, a central and a lateral, in each half jaw or quadrant (Figures 41.11 and 41.12). Viewed from the front, the crowns are trapezoid, the maxillary incisors (particularly the central) being larger than the mandibular. They are surmounted by the biting or incisal edges. In side view their labial profiles are convex while their lingual surfaces are concavo-convex (the convexity near the cervical margin being due to a low ridge or cingulum, prominent only on upper incisors). The roots of incisors are single and rounded in maxillary teeth, but flattened mesiodistally in mandibular teeth. The upper lateral incisor may be congenitally absent or may have a reduced form (peg-shaped lateral incisor).
Sex-specific reference values for the crown heights of permanent anterior teeth and canines for assessing tooth wear
Published in Acta Odontologica Scandinavica, 2023
Paula Roca-Obis, Ona Rius-Bonet, Carla Zamora-Olave, Eva Willaert, Jordi Martinez-Gomis
On the day of measurement, age, gender, body height and details of whether the participant had any anterior tooth restorations were obtained by interview-based questionnaire at the Barcelona University School of Dentistry (Catalonia, Spain). Anterior tooth restorations were assessed by intraoral examination and incisal wear was assessed and scored according to an 8-point ordinal scale of the finer-grained quantification module [14]. Briefly, incisal tooth wear was graded on a tooth-by-tooth basis as grade 0 as no visible wear; grade 1a, 1 b or 1c as minimal wear, facets or noticeable flattening of incisal edges, within the enamel, grade 2, 3a, 3 b and 4 as wear with dentine exposure and loss of clinical crown height ≤1/3, 1/3-1/2, 1/2-2/3, >2/3, respectively. In the same session, one researcher (P R-O) measured the clinical crown height from incisal edge to the most apical curvature of the gingival margin, for each permanent anterior tooth and canine. Measurement was performed using the external edges of a digital calliper and recorded to the nearest 0.01 mm (Figure 1). We excluded restored anterior teeth for which the actual height could not be determined. Teeth scoring ≥ 2, indicating wear with dentine exposure, or teeth on which enamel wear could have reduced crown height were considered worn and excluded from the analysis. In this study, six tooth groups were considered, i.e. central incisors, lateral incisors and canines in the maxillary and mandibular arch.
KCTD1 and Scalp-Ear-Nipple (‘Finlay–Marks’) syndrome may be associated with myopia and Thin basement membrane nephropathy through an effect on the collagen IV α3 and α4 chains
Published in Ophthalmic Genetics, 2023
Dongmao Wang, Paul Trevillian, Stephen May, Peter Diakumis, Yanyan Wang, Deb Colville, Melanie Bahlo, Una Greferath, Erica Fletcher, Barbara Young, Heather G. Mack, Judy Savige
Scalp-Ear-Nipple (SEN, Finlay-Marks, OMIM 181,270) syndrome is a rare ectodermal dysplasia, with about 30 families reported worldwide, that is characterised by a scalp defect, abnormal ears and rudimentary breasts and nipples (3). Clinical features in Scalp-Ear-Nipple syndrome are highly penetrant and usually evident from birth. The posterior scalp defect heals in infancy with a scar. The external ears are small and dysplastic, and the superior helix is often everted. Hearing may be impaired. The breasts do not develop, and lactation is not possible. There may be partial webbing of some digits, dystrophic nails, sparse secondary hair, and reduced sweating. The upper central incisors are widely spaced. Ocular abnormalities have been described only occasionally and include myopia, coloboma, and cataracts (1,4). Renal abnormalities reported include cysts (5), pelviureteric reflux or duplication (2), and unilateral or bilateral hypoplasia or unilateral agenesis (1,6). Proteinuria and hypertension are common, and end-stage kidney failure occurs. However, many clinical reports are of children where the renal phenotype is not yet apparent.
Incidence of impacted teeth requiring fenestration, traction, and orthodontic treatment in Japan
Published in Orthodontic Waves, 2021
Haruhisa Nakano, Chie Tachiki, Takuma Sato, Michiko Tsuji, Mikiko Mano, Yusuke Minoura, Kiyofumi Ogawa, Yasuyo Nomura, Takemi Soya, Yutaka Koshio, Ken Miyazawa, Noriyoshi Shimizu, Keiji Moriyama
It is well known that maxillary incisors exhibit root resorption during the eruption of canines [49]. Schroder et al. [50] documented a meta-analysis of 953 studies and stated that root resorption of the maxillary incisors occurs due to contact with the canines during eruption. Ericson and Kurol [51] conducted a research study on 156 maxillary canines showing ectopic eruption in 107 individuals. In that study, 72 incisors showed resorption, of which 58 (38%) were lateral incisors, and 14 (9%) were central incisors. Furthermore, a strong correlation between the ectopic eruption of canines and root resorption of incisors was evident. In this study, root resorption of adjacent teeth showed a slightly lower tendency, with 174 (10.3%) out of 1,683 cases. In particular, the maxillary lateral and central incisors had the highest frequency of root resorption, and no significant difference was observed between the left and right teeth (Tables 5,6).