Molar interarch relationship

molar interarch relationship

Both intraarch and interarch relationships were used to generate an ideal tooth Malocclusion, Angle Class III/therapy; Molar/pathology; Serial Extraction. Molar Relationship: According to Angle, the mesiobuccal cusp of the maxillary first molar Inter-arch problems (open bite/deep bite/cross bite). the interarch molar relationship. Contemporary edgewise extraction treatment. ( upper premolars or upper and lower premolars). almost always.

Size discrepancies in molars and first key to optimal occlusion

This may be influenced by many factors including space, facial biotype, inclination of the occlusal plane, anatomy and treatment strategies 1 - 2. In the vast majority of cases, the second molars receive little attention on the part of the orthodontist 3 - 4which can be verified by the lack of studies on this theme in the literature, particularly in terms of angulation. Historically, it was Andrews 5 who evaluated more than individuals with a natural and seemingly perfect occlusion, with regards to angle, inclination, prominence, width and length of each tooth crown.

Over recent years, this study has continually been revised, updated and applied to several ethnic groups, and has been used in order to create and evaluate an ideal orthodontic bracket prescription 6 - 9. Over the years, the original prescription proposed by Andrews has been changed, with the development of new prescriptions aimed at creating more natural, faster, safer and better cost benefit results 6 - 7.

However, in order to develop a prescription that can position the teeth closer to the normal natural, studies are needed on the position and angle that are deemed normal 3 - 4.

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Andrews 8in his different prescriptions, favored 5. Therefore, the aim of this study was to evaluate the angulation deemed satisfactory and normal in a population group with a normal occlusion, using plaster models and panoramic radiographs, evaluating the correlation between the two methods, ultimately permitting individualization of accessory bonding.

Malocclusion classes ©

Thus, the aim of this study was to assess the angle of the upper permanent second molars in 30 Brazilian schoolchildren with a normal occlusion, using panoramic radiographs and plaster models, as well as to evaluate the correlation between the measurements obtained by both methods.

Sample selection A retrospective study was performed using a convenient sample from the local institution. In order to obtain the sample, individuals residing in the municipality of Campinas SP had their patient records assessed with the aim of selecting those who adhered to the inclusion criteria of a normal occlusion: The final sample size used to perform this study was composed of 30 Brazilian individuals, 12 males and 18 females.

The average age in the sample was 14 years and 7 months, with a standard deviation of 1 year and 8 months, ranging between 11 years and 3 months and 17 years and 1 month.

Panoramic radiographs and measuring the angle of the upper second molars For each of the 30 individuals selected, one panoramic radiograph was taken for tracing.

A static occlusal analysis based on ideal interarch and intraarch relationships.

The individuals were placed with their occlusal plane parallel and the medial sagittal plane perpendicular, both in relation to the ground, with occlusion of the teeth prevented via a tongue depressor placed between the anterior teeth. The method previously described by Tavano et al. The tracings were performed using a light-box, in a low-light environment, aided by black paper shades to help visualize the anatomic structures.

A single trained researcher perfomed the traces. In order to obtain the highest confidence in the values observed, the angle of the upper right and left second molars was measured in panoramic radiographs at two moments, with a time interval of 30 days between measurements.

The following anatomical structures were traced: The following points were also highlighted: The demarcated reference lines were: After linear demarcation, the angles formed by the superior and inferior reference lines, as well as that formed by the long axis of the upper permanent second molars Figure 1 were measured with a protractor in each radiograph, and the values were recorded.

According to Angle, the mesiobuccal cusp of the maxillary first molar aligns with the buccal groove of the mandibular first molar.

molar interarch relationship

The maxillary canine occludes with the distal half of the mandibular canine and the mesial half of the mandibular first premolar. The teeth all fit on a line of occlusion which, in the upper arch, is a smooth curve through the central fossae of the posterior teeth and cingulum of the canines and incisors, and in the lower arch, is a smooth curve through the buccal cusps of the posterior teeth and incisal edges of the anterior teeth.

There is alignment of the teeth, normal overbite and overjet and coincident maxillary and mandibular midlines.

molar interarch relationship

The mesiobuccal cusp of the maxillary first permanent molar occludes with the mesiobuccal groove of the mandibular first permanent molar. The distal incline of the maxillary canine occludes with the mesial incline of the mandibular first premolar. The molar relationship shows the mesiobuccal groove of the mandibular first molar is DISTALLY posteriorly positioned when in occlusion with the mesiobuccal cusp of the maxillary first molar.

Size discrepancies in molars and first key to optimal occlusion

Usually the mesiobuccal cusp of maxillary first molar rests in between the first mandibular molar and second premolar. The molar relationships are like that of Class II and the maxillary anterior teeth are protruded. Teeth are proclaimed and a large overjet is present.