'Study of the maxillary yaw on cone beam computed tomography: A preliminary report and comparison between two different dento-skeletal malocclusions'.

OBJECTIVES: To assess the skeletal and dental maxillary transverse compensation (yaw) on the cone beam computed tomography (CBCT) three-dimensional reconstructed image of the skull in two groups of patients, both clinically affected by a class III malocclusion with deviation of the lower midline. MATERIALS AND METHODS: An observational retrospective study was designed to analyse differences in two groups of patients, the first one was composed by patients affected by horizontal condylar hyperplasia, the second one by patients affected by dento-skeletal asymmetric class III malocclusion. Each group was composed by 15 patients. Transverse analysis was performed by measuring five landmarks (three bilateral and two uneven) with respect to a mid-sagittal plane; sagittal analysis was performed by measuring the sagittal distance on the mid-sagittal plane between bilateral points. Means were compared through inferential analysis. RESULTS: In the condylar hyperplasia group, all differences between the two sides were not statistically significant, nor for canines' difference (P = .0817), for molars (P = .1105) or for jugular points (.05871). In the class III group, the differences between the two sides were statistically significant for molars (P = .0019) and jugular points (P = .0031) but not for canines (P = .1158). Comparing the two groups, significant differences were found only for incisors' midline deviation (P = .0343) and canine (P = .0177). CONCLUSION: The study of the yaw on CBCT should be integrated into three-dimensional cephalometry and could help in differentiating the various malocclusion patterns.

Impacted maxillary canines and root resorption of adjacent teeth: A retrospective observational study.

BACKGROUND: The prevalence of impacted maxillary canine is reported to be between 1% and 3%. The lack of monitoring and the delay in the treatment of the impacted canine can cause different complications such as: displacement of adjacent teeth, loss of vitality of neighbouring teeth, shortening of the dental arch, follicular cysts, canine ankylosis, recurrent infections, recurrent pain, internal resorption of the canine and the adjacent teeth, external resorption of the canine and the adjacent teeth, combination of these factors. An appropriate diagnosis, accurate predictive analysis and early intervention are likely to prevent such undesirable effects. The objective is to evaluate, by means of a retrospective observational study, the possibility of carrying out a predictive analysis of root resorption adjacent to the impacted canines by means of orthopantomographs, so as to limit the prescription of additional 3D radiography. MATERIAL AND METHODS: 120 subjects with unilateral or bilateral maxillary impacted canine were examined and 50 patients with 69 impacted maxillary canine (22 male, 28 female; mean age: 11.7 years) satisfied the inclusion criteria of the study. These patients were subjected to a basic clinical and radiographic investigation (orthopantomographs and computerized tomography). All panoramic films were viewed under standardized conditions for the evaluation of two main variables: maxillary canine angulations (a, b, g angles) and the overlapping between the impacted teeth and the lateral incisor (Analysis of Lindauer). Binary logistic regression was used to estimate the likelihood of resorbed lateral incisors depending on sector location and angle measurements. RESULTS: Results indicated that b angle has the greatest influence on the prediction of root resorption (predictive value of b angle = 76%). If ß angle <18° and Lindauer = I, the probability of resorption is 0.06. CONCLUSIONS: Evaluation of b angle and superimposition lateral incisor/impacted canine analysed on orthopantomographs could be one of the evaluation criteria for prescribing second level examination (CT and CTCB) and for detecting root resorption of impacted maxillary canine adjacent teeth.

Ramus marginalis mandibulae nervus facialis palsy in hemifacial microsomia.

AIM: The paralysis of the ramus marginalis mandibulae nervus facialis may occur in Hemifacial Microsomia (HM); the combination of both HM and palsy contributes to an elongation of the mandibular body. This study explores a possible correlation between neurological deficit, muscular atony, and structural deficiency. STUDY DESIGN: Of 58 patients with HM who had come to the University of Rome (Sapienza) Pre-surgical Orthodontics Unit, 4 patients were afflicted with Hemifacial Microsomia and ramus marginalis mandibulae nervus palsy; these patients underwent physical, neurological, opthamologic and systemic examinations. The results were then analysed in order to determine a possible correlation between neuro-muscular and structural deficit. METHODS: Electroneurographic and electromyographic examinations were performed to estimate facial nerve and muscles involvement. RESULTS: Neuroelectrographic exam showed a damage of the nervous motor fibres of the facial nerve ipsilateral to HM, with an associated damage of the muscular function, while neuro-muscular functions on the healthy side were normal. CONCLUSIONS: The peripheral nervous and muscular deficits affect the function of facial soft tissues and the growth of mandibular body with an asymmetry characterised by a hypodevelopment of the ramus (due to the HM) and by an elongation of the mandibular body (due to ramus marginalis mandibulae nerve palsy), so that the chin deviation is contralateral to HM. In these forms, a neurological examination is necessary to assess the neurological damage on the HM side. Neuromuscular deficiency can also contribute to a relapse tendency after a surgical-orthodontic treatment.