Abstract: Odontometric measurements of anterior tooth crown sizes in a Chinese sample of 85 Class I occlusions were similar to those published in the white population except for larger upper lateral incisors and smaller upper central incisors in Chinese. Sex differences in tooth sizes were seen only in the maxillary and mandibular canines while differences between antimeres were not significant. The Bolton ratios of our Chinese sample revealed a Bolton ratio of 77.89 +/- 1.62 for the combined mesio-distal widths of the six mandibular anterior teeth as compared to the combined mesio-distal widths of the six maxillary anterior teeth. Surprisingly, the Bolton ratio in our sample compared favourably with those originally published by Bolton although the interfacial angles, overbite and overjet relationships were statistically different.

Abstract: Twenty-one patients who had undergone orthodontic treatment in combination with mandibular advancement surgery to treat Class II malocclusion and deep overbite were followed up. Median vertical relapse at the bony chin (after a mean followup of 16 months) was found to be 2.9 mm (44%). Sagittal advancement was found to have good stability; most of the patients exhibited some additional anterior movement of the chin during the follow-up period. At the same time, the entire mandible rotated counterclockwise and the gonial angle increased. Individual response to treatment varied greatly; two patients exhibited major horizontal relapse. Controlling the position of the mandibular proximal segment seemed to be the most important factor in posttreatment stability of this sample.

Abstract: Class II, division 2 malocclusion is a clinical entity which presents considerable difficulty in the provision of a stable treatment result. This article sets out the problems encountered, reviews ...

Abstract: A retrospective cephalometric study was carried out to compare the vertical dental changes between patients treated with the Andresen (30), Harvold (19), or Begg (30) appliances, and an untreated control group (24). It was found that all three appliances successfully reduced the overbite although the reduction tended to be more stable with the functional appliances. Overbite was reduced by a combination of factors which varied according to the appliance used, but included lower incisor intrusion or restraint, molar eruption, vertical growth of the face and lower incisor proclination in the functional groups. Relapse appeared to be primarily due to continued lower incisor eruption, retroclination of these teeth, and forward rotation of the mandible with continued growth.

Abstract: A case of congenital aglossia was orthodontically treated and long-term retention was observed from the age of 15 to 27. The patient had congenital absence of three lower incisors, abnormally small mandible (micrognathia), severe overbite and a telescopic bite in the premolar region accompanied by an extremely narrow lower arch. Orthodontic treatment was begun when the patient was 15 years and 6 months old. The active treatment period was 2 years and 9 months. At the present time, nine years have passed since the end of the active treatment, and intercuspation between the upper and lower arches is still good. It is suggested that the maintenance of the lower arch width is essential for long-term retention in cases of congenital aglossia.

Abstract: Surgical mandibular advancement can be used to correct an anteroposterior and/or vertical malocclusion. The procedure of choice is often the bilateral sagittal split osteotomy (BSSO). By varying the amount of presurgical overbite correction, the rotational movement of the distal segment of the osteotomy can be controlled. Consequently, the malocclusion and the resultant vertical and anteroposterior facial form changes are predictably planned to produce both the desired occlusion as well as the optimal esthetic facial result. Opening rotation of the distal segment elongates the lower face height by varying amounts depending on the nature of the rotation. The amount and type of rotation can be determined and quantified by the technique presented in this paper, which is based on a geometric theorem used to determine the kinematic center of rotation of an object. This technique can shorten treatment time and produce more predictable results. The specific applications are: 1) treatment planning for individual patients, 2) uniform analyses of treatments and grouping of treatment types, and 3) development of more accurate computerized treatment planning programs.

Abstract: The author devised a method of measuring soft tissue in order to determine the patient's soft tissue profile (STP) in cases of mandibular prognathism.The purpose was to find a procedure for applying preoperative orthodontic treatment and a means of determining the mode of operation. Charts of STP standard deviation among normally occluded male and female patients were made. The relations among Groups A, B, C, D and E were investigated by measuring soft tissue according to Sanborn's classification modified by Tsuji, et al.From these studies we concluded that both the hard and soft tissues of each group were closely related. This information guided us as to the manner in which the surgical procedure would be approached.Each of the above 5 groups were eventually classified into 3 types prior to preoperative orthodontic treatment.Type1Group A and E are characterized by forward protrusion of the chin and the upper and lower lips.They require labial tipping of the incisors of the mandibule, and occasionally lingual movement of the maxillary incisors in preoperative orthodontic treatment.Type 2Group D is typically characterized by severe mandibular prognathism, and requires labial tipping movement of the upper and lower incisors in preoperative orthodontic treatment. In cases where the operation is done only on the mandibule, consideration of tooth axis inprovement is required so that the width of posterior displacement dose not exceed 15.0mm.Type 3Group B and C are characterized by slight forward mandibular protrusion. The profile has pseudomandibular prognathism because of retrogression of the upper lip, and lower facial height. In preoperative orthodontic treatment, the overbite is shortened in order to decrease lower facial height. Postoperatively, the chin should be posteriorly receded and rotated upward. Furthermore, displacement shonld be minimized.

Abstract: A longitudinal roentgen cephalometric investigation of vertical craniofacial and dentoalveolar changes during 20 years of adulthood, was performed in 15 men and 15 women. Two lateral cephalograms taken at the average ages 25 and 45 years, were available of each subject. Skeletal and dental changes were described by 13 linear and four angular cephalometric measurements. The analysis of the linear variables showed that total anterior face height increased by 1.60 mm on average. Approximately one-fifth of this increase occurred in the upper and four-fifths in the lower face. In the dentoalveolar region, significant increments of all dimensions except overjet and overbite were found, indicating an eruptive movement of the teeth and a vertical development of their investing tissues. The analysis of the angular measurements showed that posterior rotation of the mandible and uprighting of the upper incisors had occurred during the period of investigation.