Tridimensional Changes in Mandibular Arch after Rapid Maxillary Expansion Therapy: A Clinical Study

Aim: The upper jaw transverse deficit is certainly one of the most common clinical issues in the orthodontic field. It can be due to skeletal or dental factors, and its etiology may be both genetic and environmental. Rapid maxillary expanders (RMEs) are certainly the most effective appliance for upper transverse deficiency correction. The aim of this study was to evaluate the changes that occurred in the mandibular arch during treatment with RMEs in growing subjects by analyzing tridimensional lower digital casts. Materials and Methods: The study group (SG) consisted of 20 subjects (10 M, 10 F; mean age 9.4 ± 2.8 years old) randomly selected at the Department of Orthodontics at the University of Rome, "Tor Vergata". The inclusion criteria were negative posterior transverse interarch discrepancy ≥ 4 mm, mixed dentition phase with first permanent molars erupted, and prepubertal skeletal maturation stage (CS1-2), evaluated on a lateral radiograph through the Cervical Vertebral Maturation method. The SG was compared to an untreated control group (CG) of 20 subjects (10 M, 10 F, mean age 8.7 ± 2.3 years old) enrolled with the same inclusion criteria. The SG was treated by using RMEs. Dental casts of the lower arch were taken at two different times (T0-T1 = 6 months). All the dental casts were scanned with an OrthoXscan (Dentaurum 6mmbh E Co., Ispringen, Germany) and twenty points on the mandibular arch were digitized using Viewbox software. A Student t-test was used to compare the means of the quantitative variables associated with the effect of the device over time T0 and T1. Results: The results show a statistically significant increase (p < 0.05) in the intercanine and the intermolar diameters between the times T0 and T1 when compared to the CG. Conclusions: Rapid maxillary orthopedic expansion may achieve an increase in mandibular intercanine and intermolar diameter.

3D evaluation of maxillary morphology in Marfan growing subjects: a controlled clinical study

Background

Marfan syndrome is a rare autosomal dominant inherited disease of the connective tissue associated with various craniofacial abnormalities. Aim of the present study was to assess the variability of palatal shape in a sample of 31 Marfan patients compared to a control group of no syndromic subjects, in two stages of dentition, by using 3D geometric morphometric analysis.

Methods

Thirty one growing subjects with Marfan syndrome were selected and divided into two subgroups: MG1 with mixed dentition (10 M, 6F, mean age 7+/− 0.7 years), MG2 with permanent dentition (8 M, 7F, mean age 13+/− 0,5 years). Each subgroup was compared to a control group (CG1 mixed dentition, 9 M, 7F, mean age 7.6+/− 0.5 years; CG2 permanent dentition, 9 M, 6F, mean age 12.8+/− 0.7 years) matched on age, sex distribution, stage of dentition and skeletal maturation. Then the two subgroups were compared one to each other. For each patient maxillary dental casts were taken, scanned and digitized. 3D geometric morphometric methods were applied. Procrustes analysis was used and principal component analysis was performed to reveal the main patterns of palatal shape variation.

Results

Both Marfan subgroups showed important reductions in the transversal plane associated with a deep palatal vault when compared to the control groups (MG1 vs CG1 P = 0,003; MG2 vs CG2 P = 0,07). Moreover a statistically significant difference between the palatal shape of MG1 and MG2 was found (P = 0.017) showing a significant worsening of palatal depth and constriction from mixed to permanent dentition in Marfan subjects.

Conclusion

Marfan subjects showed a specific palatal morphology with maxillary constriction and deeper palatal vault when compared to a control group of healthy subjects. The constriction and the depth of the palatal vault in Marfan patients worsen from mixed dentition to permanent dentition more then in no syndromic subjects.