Intra-arch widths: a meta-analysis

Three-dimensional analysis of dental arch forms in Italian population

BACKGROUND

The aim of this study was the comparison of male and female upper and lower dental arch form in untreated Italian patients by 3D analysis, to find differences in shape, in transversal and longitudinal diameters between sexes, and to give a representative set of population's dental arch to clinicians in order to provide suitable orthodontic treatment.

METHODS

The sample consisted of 3D scans of dental casts deriving from 104 Italian untreated patients (Male = 35, Female = 69) in permanent dentition. An evaluation of the arch form was performed by angular and linear values on every patient using a 3D software (SolidWorks®). A Student's two-tailed t test was used to determine if the differences in measurements between the male and female groups were significant and the level of significance was set at P < 0.05.

RESULTS

Statistically significant differences in upper and lower transversal and longitudinal diameters were found. Male arch widths were significantly larger than those of females. Male intercanine, intermolar, and interpremolar diameters were significantly greater than females. Dental arch depth was significantly smaller in the female group. Anterior upper dental arch form was flatter, wider, and less sharp in the female group.

CONCLUSIONS

Basing on the anatomical arches differences found between sexes concerning Italian patients, it is suggested to have regard to each patient pre-treatment arch form, width, and depth during orthodontic treatment according to gender.

Class III malocclusion and bilateral cross-bite in an adult patient treated with miniscrew-assisted rapid palatal expander and aligners

This case report describes the use of a miniscrew-assisted rapid palatal expander and aligners to correct bilateral cross-bite and crowding in an adult patient with a Class III skeletal pattern. A digitally designed surgical guide was three-dimensionally printed and used to accurately insert four miniscrews into the palate; these were employed to anchor a novel miniscrew-assisted rapid palatal expander appliance without any dental anchorage. Cone-beam computed tomograms before and after miniscrew-assisted rapid palatal expander treatment demonstrated the orthopedic expansion of the maxilla without dental tipping. The patient was then fitted with aligners to correct crowding and malocclusion. This case report demonstrates the successful treatment of an adult patient with a narrow maxilla and bilateral cross-bite using a nonsurgical, conservative treatment.

A secondary analysis to determine variations of dental arch measurements with age and gender among Ugandans

BACKGROUND

Dental arch dimensions are useful in dental practice and in forensic odontology. Local data is essential because ethnic differences exist in dental arch dimensions. In the Ugandan population no studies had been done on dental arch dimensions. The objective of the current study was to determine the variations in dental arch dimensions with age and gender in a sample of dental casts from the Ugandan population.

METHOD

This was a secondary analysis of dental casts previously prepared using mandibular and maxillary arch impressions of 220 children (85 boys and 135 girls) aged 12-17 years recruited from schools in Kampala, Uganda. Dental arch dimensions for the maxilla and mandibular casts were taken using a digital vernier calliper. The data was analysed using the means based independent samples t test to obtain the descriptive statistics with regression analysis being used to obtain the regression coefficients and constants using STATA 12.

RESULTS

The overall maxillary dimensions were significantly smaller in females than males by 1.50 mm (95% CI -2.91 to -0.09, P = 0.04), controlling for age group. The overall dimensions of the mandible were also smaller in younger participants, though this was not statistically significant.

CONCLUSION

From this study we observed significant differences in arch dimensions between males and females that are of forensic value for this population. There is need for more study of the differences in arch dimensions with age using a larger and more age diverse study population.

Optimal parameters for final position of teeth in space closure in case of a missing upper lateral incisor

Background

The aim of this study was to provide clinical indications for the correct management of appliances in space closure treatment of patients with agenesis of the upper lateral incisors.

Methods

Virtual setup for space closure was performed in 30 patients with upper lateral incisor agenesis. Tip, torque and in-out values were measured and compared with those of previous authors.

Results

In the upper dentition, the tip values were comparable to those described by Andrews (Am J Orthod 62(3):296-309, 1972), except for at the first premolars, which require a greater tip, and the first molars, a lesser tip. The torque values showed no differences except for at the canines, where it was greater, and the in-out values were between those reported by Andrews and those by Watanabe et al. (The Shikwa Gakuho 96:209-222, 1996) (except for U3 and U4).

Conclusions

The following prescriptions are advisable: tip 5°, torque 8° and in-out 2.5 for U1; tip 9°, torque 3° and in-out 3.25 for U3; tip 10°, torque −8° and in-out 3.75 for U4; and tip 5°, torque −8° and in-out 4 for U5. Andrews' prescription is suitable for the lower jaw, except for at L6. It is also advisable to execute selective grinding (1.33 ± 0.5 mm) and extrusion (0.68 ± 0.23 mm) on the upper canine during treatment, and the first premolar requires some intrusion (0.56 ± 0.30 mm).