[Three-dimensional analysis of the mandible with impacted mandibular second molar].

OBJECTIVE: To study the developmental and morphological characteristics of the mandible in patients with impacted mandibular second molar and to predict the possible trend of mandibular development via three-dimensional (3D) measurement and analysis. METHODS: A total of 88 cases of impacted group and 88 cases of control group were screened out. 3D measurements were performed by using Mimics software. A total of 23 landmark points and 17 measurements were determined. The measurements were analyzed by t-test. RESULTS: The mandible length, the space between the first molars, the space between mandibular angles, and the width between the first molars in the impacted group were lower than those in the control group (P<0.05). Moreover, the value of the submandibular angle was higher than that in the control group (P<0.05). CONCLUSIONS: The impacted mandible of patients with mandibular second molar showed lack of sagittal and width development, and the impacted mandibular second molar was a manifestation of its degeneration.

Three-dimensional measurement and analysis of mandibular characteristics in subjects with impacted mandibular second molars.

OBJECTIVE: To investigate the morphological characteristics of the mandible in subjects with impacted mandibular second molars by measuring and analysing the mandible in three dimensions. SETTING AND SAMPLE POPULATION: In this retrospective study, the data of a total of 52 609 subjects who underwent cone-beam computed tomography (CBCT) for diagnosis and treatment were reviewed. According to the inclusion and exclusion criteria, 183 subjects with impacted mandibular second molars and 176 age- and sex-matched controls were included. METHODS: A retrospective case-control study was designed. The 183 subjects were divided into two groups: group 1 (G1) comprised 120 patients with unilaterally impacted mandibular second molars, and group 2 (G2) comprised 63 patients with bilaterally impacted mandibular second molars. Group 3 (G3) contained 176 age- and sex-matched controls. The mandible was reconstructed with nineteen landmarks using Mimics software. Twelve linear lengths and 3 angles were measured. RESULTS: The bilateral germination gap, mandibular body width and gonion width in G1 were significantly lower than those in G3 (P < .05), while the gnathion angle and first molar width values in G1 were significantly higher than those in G3 (P < .05). The results in G2 were similar to those in G1, but the differences between G2 and G3 were greater than those between G1 and G3. There were no significant differences in the other measurements among the groups. CONCLUSION: The mandibles of the subjects with impacted second molars were constricted in terms of the sagittal length and transverse width.

Miniplacas como dispositivos de anclaje temporal (DAT) en la verticalización del segundo molar inferior impactado / Miniplates as temporary anchorage devices (TAD) for uprighting the impacted second mandibular molar

La impactación de los segundos molares inferiores permanentes es una patología con una incidencia del 0.03 or ciento a 0.04 por ciento del total de dientes retenidos, que en la mayoría de los casos debido a una posición impredecible del tercer molar, el resultado final es la exodoncia de ambas piezas dentarias.Dentro de los dispositivos de anclaje temporal, existen dos tipos, los minimplantes y las miniplacas. A través de este caso clínico se demuestra la eficiencia de las miniplacas en la verticalización de los segundos molares inferiores impactados sobre otras medidas terapéuticas debido a que su uso es un método predecible, rápido y seguro que no genera efectos secundarios indeseables. Además, estas miniplacas son colocadas a distancia de las piezas dentarias, por lo que no interfiere en los movimientos dentales.

Mandibular second molar impaction is a pathology with an incidence of 0.03% - 0.04% of the total of the impacted teeth due to animpredictible position of the third molar in most cases. As a consequence, where the final result is dental extraction of both teethThere are two types of temporary skeletal anchorage devices minimplants and miniplates. This case shows the miniplate efficiency in thesecond molar verticalization which is a predictible, fast and safe method without any side effects when compared with other treatments.In addition, miniplantes do not interfere with dental movements because they are placed far enough from the teeth.