FMA Angle Research Articles

The effectiveness of pendulum, K-loop, and distal jet distalization techniques in growing children and its effects on anchor unit: A comparative study

A common strategy to correct Class II malocclusions using a nonextraction protocol in children is to move the maxillary molars distally using molar distalization appliances, which usually derive their anchorage from maxillary premolars, causing mesialization of premolars and protrusion of incisors. To evaluate the skeletal, dental and soft tissue changes produced by three different distalizing appliances, namely, pendulum, K-loop, and distal jet appliances. Sixty-six children of mean age 14.13 years requiring molar distalization were divided into three groups: Group I (pendulum appliance), Group II (K-loop), and Group III (distal jet). Lateral cephalometric films were taken before and after 5 months of molar distalization and following cephalometric parameters were used to assess the effects of maxillary molar distalization, namely, anteroposterior skeletal (SNA/SNB/ANB), vertical skeletal (face height ratio/Frankfort-mandibular plane [FMA]/angle formed between Maxillary plane & Mandibular plane (MM)), interdental (overjet/overbite), maxillary dentoalveolar, and soft tissue parameters. There was no significant age difference between the three groups. In overall treatment changes among the three groups, the Anteroposterior skeletal changes were not statistically significant, vertically FMA angle increased by 1.79° ± 2.25° and overbite reduced by 2.38 ± 1.83 mm. The maxillary first molars were distalized by an average of 4.70 ± 3.01 mm (Upper 6 [U6] to pterygoid vertical [PTV]). The maxillary central incisor labial tipping increased to an average of 1.61 ± 2.73 mm and cant of upper lip increased by 3.40° ± 5.88° are statistically significant (P < 0.05). All three distalization techniques in growing children produced significant effects on anchor unit. There was an increase in FMA angle, significant bite opening, proclination of the maxillary incisors and increase in the cant of the upper lip.

Assessment of position of mandibular canal in relation to mandibular plane in different growth patterns

ObjectivesTo evaluate the position and curvature of mandibular canal in relation to mandibular plane in horizontal (HG), average (AG) and vertical (VG) growth patterns. Methods100 lateral cephalograms were screened & analysed from amongst patient's records available in the institution. The growth pattern was assessed by FMA angle, Y-Axis, SN-Go-Gn angle and Jaraback's ratio, on the basis of these values, a sample was selected of 20 lateral cephalographs each in horizontal, average and vertical growth pattern. Rickett's Xi point was identified and mandibular canal was traced on each lateral cephalogram using Xi point which denotes the origin of mandibular canal. Distance between, Gonial point to Xi point, Mental foramen to mandibular plane (MF–M), Mandibular foramen to pterygoid vertical (Xi–PTV) and from deepest point on mandibular canal to mandibular plane (Mc–M) were measured to evaluate the position and curvature of mandibular canal in different growth patterns. ResultsIt was observed that, the distance from gonial point to mandibular foramen, mental foramen to mandibular border, mandibular foramen to pterygoid vertical was increased in horizontal growth pattern i.e., 22.05 mm ± 1.82, 15.12 mm ± 1.06, 57.20 mm ± 1.23, whereas it was reduced in vertical growth pattern i.e., 14.90 mm ± 1.55, 8.84 mm ± 1.41, 47.95 mm ± 2.25 respectively. Depth of curvature of mandibular canal was increased in horizontal growth pattern, 22.25 mm ± 4.89; while it was reduced in vertical growth pattern i.e., 16.32 mm ± 1.18. ConclusionsThe findings of this study showed that the position and curvature of the mandibular canal reflect the outer morphology and growth pattern of the mandible.

骨格性下顎前突症例における下顎枝分割位置の違いが術後成績に与える影響

The osteotomy line in sagittal split ramus osteotomy (SSRO) has a wide variation among surgeons. Recently, short lingual osteotomy (SL), in which the lingual split is limited up to the area near the mandibular foramen, is performed in many facilities. The reason for this is that SL can reduce the amount of interference between the proximal and distal segments, and shorten the operation time compared with Obwegeser osteotomy (Ob). However, since medial pterygoid muscles (MPM) are included in the proximal segments, SL is prone to induce backward rotation and distal positioning of the mandibular ramus due to the interference between MPM and distal segments when mandibular setback is performed.The purpose of this study was to compare the postoperative outcome of SL and Ob for mandibular prognathism. Twenty-two skeletal Class III cases without lateral deviation treated by SSRO in Meikai University Hospital, were examined. Among the 22 cases, 15 and 7 cases underwent SL and Ob, respectively. The postoperative changes of the proximal and distal segments were evaluated in lateral and postero-anterior cephalograms taken immediately before the surgery (T1), immediately after the surgery (T2), and one year after the surgery (T3). At T1, there was no significant difference in SNB, FMA, or gonial angle between the SL and Ob groups. No significant difference in the amount of mandibular setback was found between the two groups. Comparing values at T1 and T2, the proximal segments tended to rotate backward in the SL group, but there was no significant difference in the anterio-posterior position of proximal segments between the two groups. Comparing values at T2 and T3, counter-clockwise rotation of proximal segments was seen in the SL group but not in the Ob group. It is likely that this rotation of proximal segments in the SL group was caused by the muscular strength of MPM attached mainly to the proximal segments. Moreover, a significant negative correlation in the amount of rotation of proximal segments was detected between T1-T2 and T2-T3 in the Ob group, but not in the SL group.These findings indicate that special attention to the rotation in SL cases is important since a wider variation in the rotation of proximal segments may occur compared with the Obwegeser method.

Relationship of curve of Spee & dentofacial morphology in North Indian population – An in vitro study

ObjectiveThe purpose of the study was to evaluate the relationship of curve of Spee with dentofacial morphology using multiple linear regression analysis and to determine sexual dimorphism in North Indian population. MethodTwo hundred subjects were selected and divided into two groups of 100 males and 100 females. Lateral Cephalogram and models of all the subjects were taken. After tracing the cephalograms various dentofacial & dental parameters were measured: Dentofacial parameters were SNA angle, SNB angle, ANB angle, APDI angle, ODI angle, FMA angle, Ar-Go-Me, Go-Me, Ar-Go, G-Sn-Pog', Cm-Sn-Ls, U to E-line, and L to E line. Dental parameters were Curve of Spee, Intercanine width, Intermolar width, Arch length and Dental arch form. Data thus obtained were subjected to statistical analysis. ResultsThe results suggested that the curve of Spee is more influenced by the dental morphology as compared to the dentofacial morphology, but it is not affected by sexual dimorphism. ConclusionThere is a significant correlation between mandibular curve of Spee and certain dental and dentofacial parameters.

Upper Incisor Position and Bony Support in Untreated Patients as Seen on CBCT

To test the null hypothesis that there are no correlations between the morphology of the upper jaw, the position of the upper incisors, and facial type. From a sample of 191 patients, the FMA angle was used to select 20 short face type, 20 norm face type, and 20 long face type patients, aged 12 to 40 years. Using cone-beam computed tomography (CBCT), tomography was carried out on sagittal sections corresponding to the four upper incisors. Some parameters defining the dentoskeletal relationships, the alveolar thickness, the alveolar height, and the dental movement were measured. The measurements were processed using analysis of variance and Tukey's test. At the upper central incisors, short face type patients presented a greater alveolar bone thickness than long face type patients. In short face type and norm face type subjects the root apex of the upper incisors was farther away from the lingual cortex than in the long face type patients. At the central incisors the alveolar thickness was greater and the lingual cortex was higher with respect to the lateral incisors in all three facial types. At the upper incisors, facial type is statistically significantly correlated with both alveolar bone thickness and distance between the root apex and lingual cortex.

Cephalometric changes produced by locally applied anabolic steroid in Wistar rats

Background and objective There is a strong relationship between neuromuscular activity and facial skeletal morphogenesis. The systemic use of anabolic steroid accelerates craniofacial growth and induces high functional activity of rats’ masticatory muscles. The present study examines the effect of an anabolic steroid locally applied in the masseter muscle of growing rats with the purpose of verifying possible craniofacial changes with minimum drug side effects, using cephalometric analysis. Materials and methods Forty-three 3-week-old Wistar rats were evaluated and divided into two groups: (1) NAN group (local bilateral masseter injection of nandrolone decanoate – 0.05 μg/3 μl/bi-weekly) and (2) CON group (local bilateral masseter injection of sterile oil – 3 μl). Tukey and Wilcoxon tests were used. Results In NAN group the cephalometric measures showed horizontalized facial growth (reduce of FMA angle – p < 0.01), increase of posterior facial height, decrease of anterior facial height, reduction of gonial angle ( p < 0.05), increase of mandibular height ( p < 0.01). There was no variation in the length of the mandible, in the skull and animals’ weight gain, thus demonstrating that no important systemic effect occurred. Conclusion The local injection of nandrolone in the masseter muscle of rats was capable to alter the growth direction and the morphology of the craniofacial complex in Wistar rats.

Supraclusion, traitement orthodontique par plaque de surélévation antérieure et dimension verticale (2èmepartie)

If incisor overbite in the matter of orthodontic treatment entails difficulties with the appliances due to excessive overbite of the incisors, involving an anterior bite raiser to enable the unlocking of the occlusion and the bonding of the brackets on the anterior mandibular teeth poses the problem of the vertical behavior of the masticatory apparatus during treatment. A profile teleradiograph was therefore taken at the beginning of treatment and again once the occlusion had been lifted due to the presence of the bite raiser and within a period of three months. The sample was separated in two groups according to the value of FMA; a first group was composed of 44 cases exhibiting an FMA angle inferior to 25 degrees therefore similar to the cases analyzed by Dake and Sinclair in 1989, called "reference group" and a group of cases exhibiting an FMA angle superior to 25 degrees. The aim of this study is indeed to confront, as regards vertical behavior, the therapeutic approach of the authors with the one studied by Dake and Sinclair dealing with cases treated with Ricketts and Tweed technique (Schudy modified). Following Dake and Sinclair's approach, the authors managed to find out in cases with FMA inferior to 25 degrees that the vertical alterations in the study group were not different from those in the reference group. This means that in spite of the presence of an anterior bite raiser the mandibular plane angle had only increased by 1.8 degree, compared to 1.8 degree for the Ricketts group and 1.1 degree for the Tweed/Schudy group. As for the study sample with an FMA angle superior to 25 degrees, the vertical alterations in the study group show an increase of the angle of the mandibular plane equal to 1.2 degree, here again the increase is similar to the one observed in the reference group. It can thus be concluded that the use of an anterior bite raiser in conjunction with the Tip-Edge technique is not only advisable but strongly recommended both to unlock the occlusion but also to enable bracket bonding at the very beginning of treatment.