Evaluation of maxillary arch morphology in children with unilaterally impacted incisors via three-dimensional analysis of digital dental casts: a controlled study.

OBJECTIVE: The purpose of this work was to analyze variations in maxillary arch dimensions in subjects presenting unilaterally impacted maxillary permanent central incisors compared with a control group of subjects without eruption anomalies. METHODS: A group of 23 Caucasian children [8 females and 15 males, mean age 9.7 years, standard deviation (SD) 1.6 years] displaying unilaterally impacted maxillary permanent central incisors (impacted incisor group: IIG) were compared with a control group (CG) of 23 subjects (9 females; 14 males, mean age 8.8 years, SD 1.9 years) presenting no eruption disorders. Pretreatment dental casts were taken from each subject and the upper arch was scanned using a three-dimensional scanner. Linear measurements were taken on each digital model to analyze maxillary arch dimensions. Significant between-group differences were tested with the Student's t test (p < 0.05). RESULTS: The transverse and sagittal upper-arch measurements were significantly smaller in the IIG than in the CG. In particular, the anterior arch was 1.35 mm shorter in the IIG, while intercanine width was decreased by 2.51 mm on the impacted side. CONCLUSION: Children revealing unilaterally impacted maxillary central incisors demonstrated a significantly constricted maxillary transverse width and shorter arch on the impacted side compared with subjects with no eruption disorders.

Palatal surface and volume in mouth-breathing subjects evaluated with three-dimensional analysis of digital dental casts-a controlled study.

OBJECTIVE: To compare the anatomical characteristics of the maxillary arch, identified as palatal surface area and volume, between mouth-breathing and nose-breathing subjects using a three-dimensional (3D) analysis of digital dental casts. METHODS: Twenty-one Caucasian subjects (14 females and 7 males) with a mean age of 8.5 years [standard deviation (SD) 1.6 years] were selected according to the following criteria: mouth-breathing pattern due to allergic rhinitis, early mixed dentition, skeletal Class I relationship, and pre-pubertal stage of cervical vertebral maturation. This study group (SG) was compared with a control group (CG) of 17 nose-breathing subjects (9 females and 8 males, mean age: 8.5 years; SD: 1.7 years). For each subject, initial dental casts were taken and the upper arch was scanned using a 3D laser scanner. On each digital model, 3D measurements were performed to analyse maxillary arch morphology. Between-group differences were tested with the independent sample Student's t-test (P < 0.05). RESULTS: In mouth-breathing subjects, changes in physiological function of the upper respiratory tract resulted in skeletal adaptations of the maxillary arch. In the SG, both palatal surface area and volume were significantly smaller when compared with values of the CG. In particular, the palatal surface area and palatal volume were, respectively, 13.5 and 27.1 per cent smaller in the SG when compared to the CG. CONCLUSIONS: Subjects with prolonged mouth breathing showed a significant reduction of the palatal surface area and volume leading to a different development of the palatal morphology when compared with subjects with normal breathing pattern.

Evaluation of maxillary arch dimensions and palatal morphology in mouth-breathing children by using digital dental casts.

OBJECTIVE: The aim of the present study was to analyze the variations of maxillary arch size and of palatal morphology in subjects with prolonged mouth-breathing due to allergic rhinitis when compared with a control group with normal breathing pattern by using a three-dimensional analysis on digital casts. METHODS: 26 Caucasian children (19 females and 7 males) with a mean age of 8.5 years (SD 1.6 years) were selected according to the following criteria: mouth-breathing pattern due to allergic rhinitis, early mixed dentition, skeletal Class I relationship and prepubertal stage of cervical vertebral maturation. The study group was compared with a control group of 17 nasal breathing subjects (9 females; 8 males, mean age 8.5 years SD 1.7 years). For each subject an initial dental cast was taken and the upper arch was scanned by using a tridimensional scanner. On each digital model linear measurements were performed to analyze maxillary arch dimensions and palatal morphology. Significant between-group differences were tested with the Student t-test (p<0.05). RESULTS: the transverse dimension of the upper arch was significantly smaller in subjects of the study group thus confirming the influence of oral breathing on skeletal development with a significant constriction of the whole palate. The study group showed a higher and sharper palatal vault at the level of second deciduous molars and of first permanent molars. CONCLUSIONS: Children with mouth-breathing pattern showed a significant constriction of the maxillary arch and an increased palatal height when compared with subjects with normal breathing pattern.

Dentoskeletal effects of the fast-back molar distalizer followed by fixed appliances.

INTRODUCTION: The purpose of this study was to analyze the skeletal and dentoalveolar changes induced by the Fast-Back appliance followed by fixed appliances when compared with untreated Class II controls. MATERIALS AND METHODS: The treated and untreated samples consisted of 27 subjects each (16 girls and 11 boys in the Fast-Back Group, FBG; 15 girls and 12 boys in the control Group, CG) with mean ages at the start of treatment of 13 years 3 months in the FBG and 13 years 2 months in the CG. Subjects of the FBG were treated during either the pubertal or postpubertal periods. Lateral cephalograms were analyzed at 2 observation periods: before distalization (T1) and after comprehensive orthodontic treatment appliance (T2). The T1-T2 changes in the FBG were contrasted with those in the CG by means of Mann-Whitney U test (p<0.05). RESULTS: Treatment induced an average correction of molar relationship of 2.4mm. The significant correction of the overjet (2.1mm) was associated with a significant amount of lower incisor proclination (3.8 degrees). A significant extrusion of lower molars (1.8mm) was recorded in the FBG. The FBG showed also a significant increase in total mandibular length (Co-Gn, 2.6mm), a counterclockwise rotation of the palatal plane (1.4 degrees), an increase in anterior facial height (N-Me, 2.7 mm), and in mandibular ramus height (Co-Go, 2.6mm). CONCLUSIONS: The Fast-Back is an effective appliance for Class II correction during the pubertal or postpubertal periods.