ABSTRACT
Introduction: The general feature of occlusal curvature,when viewed from the front, consists of a buccal inclinationof the maxillary molars and a lingual inclination of themandibular molars. The fourth key of Andrews six keys ofocclusion is related to the curve of Wilson, describing theposterior inclination of the crowns of the lower posterior teethas a concave curve, setting the molars with a lingual torque.The aim of this study was to measure buccolingual inclinationof maxillary and mandibular first molars in untreated sampleof pre-orthodontic patients.Material and Methods: CBCT scans from 36 untreatedsubjects (26 females and 10 males; average age, 24.6 years) withminimal dental discrepancies, no prior history of orthodontictreatment, minimal dental wear, no posterior crossbite, nocrowns or significant restorations on any first molars, absenceof remaining primary dentition, were selected. The angleswere measured between long axis of each maxillary molar to avertical reference line that was perpendicular to the horizontalreference line and between each mandibular first molar to thesame reference line.Results: The average inclination of maxillary molar was+4.98º ± 4.26º. There was no significant difference betweenthe right and left mean values. The average inclinationof mandibular molar was -13.10º ± 6.10º. There was nosignificant difference between the right and left values.Conclusion: Maxillary and mandibular molars have a naturalcurvature of their inclinations where the maxillary molarshave a slight buccal inclination and mandibular molars have aslight lingual inclination
ABSTRACT
Background: The maxillary canines are of great importance both aesthetically and functionally. Ectopic eruption of maxillary canines cause various complications among which root resorption of adjacent incisors is most common. Objective: The objectives of this study were to investigate the prevalence, extent of resorption, and predisposing risk factors for incisor root resorption associated with impacted maxillary canines. Methods: Unilaterally and bilaterally impacted canines (n=53) from 42 patients (27 female, 15 male) who visited Department of Orthodontics for treatment were evaluated. CBCT scans were taken with NewTom GiANO NNT Scanner keeping in mind the risks associated with ectopic eruption of maxillary canines and were analyzed with 3D visualization software. Results: Among the studied impactions, 79.2% were impacted palatally and 11.3% buccally. The lateral incisors were the teeth most affected by resorption. 18 incisors were resorbed, which included 16 lateral incisors (30.2 per cent) and 2 central incisors (3.8 per cent). Among lateral incisors, the resorption was slight in 11 cases (20.8 per cent), moderate in 3 cases (5.6 per cent), and severe in 2 cases (3.8 per cent) while among central incisors, the resorption was only slight in 2 cases (3.8 per cent). A correlation was found between the proximity/contact of the impacted canine to the incisors and their resorption. Follicle size did not play a major role in incisor resorption. Conclusion: Canine impaction poses a higher risk for root resorption of adjacent incisors. Physical proximity (<0.5 mm) between impacted canine and adjacent roots of incisors is the most important predictor for root resorption. The width and the shape of the dental follicle of the impacted canines do not correlate with root resorption of maxillary incisors.
ABSTRACT
Background: The maxillary permanent canines play a key role in smile design. Any morphological defect or eruption anomaly, affecting the maxillary permanent canine has a negative impact on the smile and facial esthetics of the person. The purpose of this study was to examine whether a clinically significant association exists between maxillary transverse dimension and palatally displaced canines (PDC). Methods: Twenty-four subjects (8 males and 16 females) with PDC were matched to twenty-four subjects (8 males and 16 females) without PDC (control) for age, sex and posterior occlusion. Prior to any orthodontic treatment, a CBCT scan was taken on all the patients. On axial and coronal sections of CBCT images, the maxillary basal bone widths and interdental widths at the maxillary first premolars, second premolars and first molars were measured. Results: The maxillary basal bone widths and interdental widths at the maxillary first premolars, second premolars and first molars between the subjects with palatally displaced canines and the control group showed no statistically significant differences in their means, thus indicating that there was no statistically significant difference in maxillary transverse dimensions between the affected subjects and the control subjects. Conclusion: Skeletal and dental maxillary transverse width was not related to the occurrence of palatally displaced canine. Thus, affected patients exhibit adequacy of maxillary dental arch width