Standard and low-dose cone beam computer tomography protocol for orthognatodontic diagnosis: a comparative evaluation.

Considering the diagnostic capability offered by cone-beam computed tomography (CBCT), nowadays orthodontists often use this exam for treatment planning, especially in cases of impacted teeth, maxillary ipoplasia, orthognathic surgery etc. The aim of this study was to compare the radiation doses related to a conventional CBCT setting and that of a low dose protocol, usable in orthodontic practice. The absorbed organ doses were measured using an anthropomorphic phantom loaded with thermo-luminescent dosimeters related to sensitive organs (brain, bone marrow, salivary glands, thyroid, esophagus, oral mucosa, extrathoracic airways, lymph nodes). The device used was a MyRay Hyperion X9-11x5. The standard setting of the apparatus was 90 Kv, 36 mAs, CTDI/Vol 4.09 mGy, instead the low dose one was 90 Kv, 27 mAs, CTDI/Vol 2.89 mGy. Equivalent and effective doses have been calculated; the measurement of the effective doses was based on the ICRP recommendations. For the assessment of image quality, five readers, independent and experienced orthodontists, were asked to state if the images were sufficient enough to perform an orthodontic diagnosis. The lowest organ dose (5.01 microSv) was received by the esophagus during low dose CBCT acquisition. The highest mean organ dose instead (1227.67 microSv) was received by the salivary glands during conventional setting CBCT acquisition. Image quality has been considered sufficient for orthodontic diagnostic needs for both CBCT protocols. CBCT low dose setting should be preferred over the standard one in orthodontic practice, because it provides a significant lower radiation dose to the patients ensuring a good image quality. However, further studies are necessary to evaluate the opportunity of CBCT exams in orthodontic treatment planning.

3D facial soft tissue changes after rapid maxillary expansion on primary teeth: A randomized clinical trial.

OBJECTIVES: The aim of the present randomized controlled trial (RCT) was therefore the tridimensional evaluation of soft tissue changes after rapid maxillary expansion in growing patients. SETTING AND SAMPLE POPULATION: Treated group comprised 17 patients (10 males and 7 females) with a mean age of 9.8 ± 1.2 years, and control group comprised 17 patients (13 males and 4 females) with a mean age of 9.1 ± 2.1 years. MATERIAL & METHODS: All patients of the treated group underwent maxillary expansion with Haas-type expander while patients of the control group underwent no treatment. 3D facial scans were acquired at T1, at the beginning of treatment or observation period, and at T2, 18 months apart. The mean interval between the timepoints was 18.2 ± 0.4 months. RESULTS: The main differences between groups were reported in the nasal area. Nasal width (Alr-All) significantly increased in the treated group compared with the control. The increase in intereye and mouth width in the study group did not show differences with the control group. No significant differences were reported for lips' protrusion, angular measurements and facial heights between groups. The total nose volume difference was significantly higher in the treated group compared with control, and this result was related mainly to the significant increase in the nasal dorsum volume. CONCLUSION: Maxillary expansion produced significant increase in the nasal base and nasal volumes, but its clinical relevance is still questionable.

Cephalometric changes after headgear anchored to the deciduous second molars in the early mixed dentition.

AIM: The present study aimed to evaluate the cephalometric effects of a headgear anchored to the deciduous second molars in the early mixed dentition. MATERIALS AND METHODS: Study design: The study followed a retrospective longitudinal design and enrolled 31 consecutive patients (17 females and 14 males) treated with high pull (HP) headgear anchored to the deciduous second molars, average age 8y 5m± 5m at pre-treatment time (T0) and 9y 8m± 6m at post-treatment time (T1). All the patients wore the headgear for approximately 8-10 hours at night, with a force of 250 g per side. The active phase of treatment ended once patients obtained a distal step on permanent molars of at least 2 mm. Lateral cephalograms at T0 and T1 were taken; 10 angular measurements were chosen as variables of the study. The paired sample t-test was employed to assess the significance of the differences of each variable between T0 and T1. RESULTS AND CONCLUSION: In this group of Class II patients, HP headgear anchored to the deciduous second molars in the early mixed dentition produced: significant reduction of SNA angle, significant increase of SN/NL angle with no significant change in SN/ML angle, significant labial flaring of upper incisors. As clinically evaluated, the correction of the Class II occlusal relationship and the anterior crowding of maxillary arch were also accomplished.

Effects of rapid vs slow maxillary expansion on nasal cavity dimensions in growing subjects: a methodological and reproducibility study.

AIM: To evaluate the methodological feasibility of a RCT comparing skeletal changes of nasal cavity size obtained with RME and SME, assessed via CBCT. MATERIALS AND METHODS: Twenty Caucasian children with a mean age of 10.4 years were recruited and allocated to receive RME (10 subjects, mean age 10.4 years) or SME (10 subjects, mean age 10.5 years). INCLUSION CRITERIA: constricted maxillary arch, upper and lower first molars erupted, unilateral or bilateral posterior crossbite. EXCLUSION CRITERIA: age above 15 years, history of previous orthodontic treatment, periodontal disease, systemic disease affecting craniofacial growth, or craniofacial congenital syndrome. CBCT examinations were performed before treatment (T0) and 7 months after expander removal (T1). Changes of nasal width (NW), palatal width (PW) and total nasal volume (TNV) were assessed; palatal and nasal expansion was also calculated as a percentage of the increase of intermolar width IMW (PW% and NW%). RESULTS: The correlation between the first and the second readings ranged from 0.991 to 0.995 for linear measurements and was of 0.915 for volumetric measurements. The method error, as described by the value of ?, was in general less than 0.3 mm for linear measurements and 0.372 cm³ for volumetric measurements. All linear transverse skeletal and dental measurements and the nasal volume increased with both RME and SME protocols. CONCLUSION: The reported methodology can be reasonably used to investigate the transverse dimension of nasal cavity. The PW% and NW% parameters more accurately described the efficacy of the two expansion protocols as compared to their corresponding absolute measurement (PW and NW).

Evaluation of masseter muscle in different vertical skeletal patterns in growing patients.

AIM: The present study aimed to evaluate the relationship between masseter size, maxillary intermolar width and craniofacial vertical skeletal pattern. STUDY DESIGN: The study followed a prospective longitudinal design and enrolled 61 subjects (30 males and 31 females), 9-14 years of age (mean age 11.5) at 2-3 CVM stage. The participants were divided into three groups based on their vertical skeletal pattern which was estimated using the Frankfurt-mandibular plane angle: low-angle group (L-A), normal-angle group (N-A), high-angle group (H-A). An additional gender-based distinction was made. Maxillary intermolar width was measured on the maxillary cast of each patient by means of an electronic caliper; masseter volume was estimated by using magnetic resonance (MR) and masseter thickness was measured by means of ultrasonography (US). The US registrations were performed during the relaxation state (RS) and the maximum voluntary contraction (MVC) of the muscle. The indipendent samples T- test was used for sex comparisons; the analysis of variance test (ANOVA) was used to evaluate the differences between the three groups in males and females, and the Pearson r correlation coefficient was employed to assess the correlation between maxillary intermolar width and masseter volume. RESULTS AND CONCLUSION: Maxillary intermolar width, masseter volume and thickness showed significant gender differences; all the tested variables decreased significantly according to the facial vertical pattern, with greater values in females, especially in low- and normal-angle subjects; maxillary intermolar width and masseter volume showed significant correlations, higher in females.

Multimodal airway evaluation in growing patients after rapid maxillary expansion.

AIM: The objective of this study was to evaluate the airway volume of growing patients combining a morphological approach using cone beam computed tomography associated with functional data obtained by polysomnography examination after rapid maxillary expansion treatment. STUDY DESIGN: 22 Caucasian patients (mean age 8.3±0.9 years) undergoing rapid maxillary expansion with Haas type expander banded on second deciduous upper molars were enrolled for this prospective study. Cone beam computed tomography scans and polysomnography exams were collected before placing the appliance (T0) and after 12 months (T1). METHODS: Image processing with airway volume computing and analyses of oxygen saturation and apnoea/hypopnoea index were performed. RESULTS: Airway volume, oxygen saturation and apnea/hypopnea index underwent significant increase over time. However, no significant correlation was seen between their increases. CONCLUSION: The rapid maxillary expansion treatment induced significant increases in the total airway volume and respiratory performance. Functional respiratory parameters should be included in studies evaluating the RME treatment effects on the respiratory performance.

Comparison of cephalometric changes in Class II growing patients with increased vertical dimension after high-pull and cervical headgear treatment.

AIM: The aim of the present study was to evaluate the cephalometric changes in growing Class II patients with increased vertical dimension treated with cervical or high-pull headgear, by using an untreated control group with similar skeletal characteristics. MATERIALS: From the initial sample, 56 patients satisfied the inclusion and exclusion criteria; 20 patients were treated with cervical headgear (CHG), 15 with high-pull headgear (HHG), and 21 were not treated (CG). Cephalograms were available for each subject at baseline (T1) and after treatment/observation time (T2) for the three groups. A total of 17 measurements were taken on the lateral head films. Group comparison among CHG, HHG and CG was done using ANOVA test. CONCLUSION: In Class II high-angle growing patients, cervical headgear seems to be preferred in the correction of maxillary protrusion, molar relationship and increased anterior facial height. Extrusion of the upper molar may favour forward repositioning of the mandible and clockwise rotation in Class II patients with increased vertical dimension.

No Compliance Correction of Class II Malocclusion in Growing Patients Whit HERBST Appliance: A Case Report.

BACKGROUND: Class II malocclusion is the most common sagittal skeletal discrepancy, with a prevalent skeletal pattern of mandibular retrusion. The correction of mandibular retrusion with functional removable appliance needs a good patient's compliance; for this reason, some clinicians prefer to use no compliance apparatus. OBJECTIVE: Objective of the present therapy note is to demonstrate that the use of no compliance apparatus can provide a good correction of skeletal class II malocclusion. METHODS: In the present study, authors report a therapy note referred to a 10 years old patient, woman, affected by Class II, with mandibular retrusion and deep bite, treated in 2013 at the Dep. of Orthodontics of Messina University. An orthodontic treatment has been planned with the aim of stimulating mandibular growth; an Herbst appliance with a cantilever design, bonded on first maxillary and mandibular molars, has been used. After eleven months of functional therapy a bilateral molar class I have been obtained. RESULTS: In the therapy note proposed, authors obtained a resolution of mandibular retrusion, a correction of overjet, overbite and dental crowding in both arches, and a bilateral molar and canine class I has been achieved. CONCLUSION: Herbst appliance seems to be efficient in the correction of II Class Malocclusion, independently from patient's cooperation; moreover , early correction of Class II malocclusion with functional appliances produces several clinical advantages.