Flavio Uribe

Skeletal and dental asymmetries in Class II subdivision malocclusions using cone-beam computed tomography

INTRODUCTION The objective of this study was to compare the degrees of skeletal and dental asymmetry between subjects with Class II subdivision malocclusions and subjects with normal occlusions by using cone-beam computed tomography. METHODS Thirty subjects with Angle Class II subdivision malocclusions (mean age, 13.99 years) and 30 subjects with normal occlusions (mean age, 14.32 years) were assessed with 3-dimensional cone-beam computed tomography scans. Independent t tests were used to compare orthogonal, linear, and angular measurements between sides and between groups. RESULTS Total mandibular length and ramus height were shorter on the Class II side. Pogonion, menton, and the mandibular dental midline were deviated toward the Class II side. Gonion and the anterior condyle landmark were positioned more posteriorly on the Class II side. The mandibular dental landmarks were located more latero-postero-superiorly, and the maxillary dental landmarks more latero-antero-superiorly on the Class II side. There was loss of maxillary arch length, and the mandibular molar was closer to the ramus on the Class II side. CONCLUSIONS The etiology of Class II subdivision malocclusions is primarily due to an asymmetric mandible that is shorter and positioned posteriorly on the Class II side. A mesially positioned maxillary molar and a distally positioned mandibular molar on the Class II side are also minor contributing factors.

Three-dimensional cone-beam computed tomography-based virtual treatment planning and fabrication of a surgical splint for asymmetric patients: surgery first approach.

Virtual 3-dimensional planning in orthognathic surgery allows for a detailed visualization and analysis of skeletal and dental deformities, especially in patients with asymmetries. This approach also eliminates conventional stone model surgery through computer-aided fabrication of surgical stents. This article presents a new approach with 3-dimensional cone-beam computed tomography-based treatment planning for the surgical correction of facial asymmetry in conjunction with the surgery first approach. Good esthetic and occlusal outcomes were obtained for 2 patients after orthognathic surgery and orthodontic treatment with a short total treatment time.

Alveolar ridge width and height changes after orthodontic space opening in patients congenitally missing maxillary lateral incisors

The purpose of this study was to evaluate the dimensional changes of the alveolar ridge in patients with congenitally missing maxillary lateral incisors. The width and height of the alveolar ridge were compared before and after opening space for an endosseous dental implant between the central incisor and canine. Pre- and post-treatment dental stone models of 31 patients (8 males, 23 females; mean age 15.1 ± 7.9 years pre-treatment, 17.6 ± 8 years post-treatment) with unilaterally or bilaterally, congenitally missing maxillary lateral incisors were used in this study. Pre- and post-treatment measurements included: the space between the maxillary central incisor and canine, the depth of the labial concavity, and the width and height of the lateral incisor alveolar ridge. Two different techniques were used to measure the ridge width. Students paired samples t-test was used to test for significance. The alveolar ridge underwent statistically significant width loss (Method 1: 4-8 per cent, Method 2: 13-15 per cent) during the course of orthodontic treatment. A 6-12 per cent loss in ridge height was also noted. The depth of the labial concavity between the maxillary central incisor and canine nearly doubled. There was a significant decrease in the width and height of the alveolar ridge in patients congenitally missing a maxillary lateral incisor who received orthodontic treatment to create space for an endosseous dental implant.

Effect of cyclical forces on the periodontal ligament and alveolar bone remodeling during orthodontic tooth movement

OBJECTIVE To investigate the effect of externally applied cyclical (vibratory) forces on the rate of tooth movement, the structural integrity of the periodontal ligament, and alveolar bone remodeling. METHODS Twenty-six female Sprague-Dawley rats (7 weeks old) were divided into four groups: CTRL (unloaded), VBO (molars receiving a vibratory stimulus only), TMO (molars receiving an orthodontic spring only), and TMO+VB (molars receiving an orthodontic spring and the additional vibratory stimulus). In TMO and TMO+VB groups, the rat first molars were moved mesially for 2 weeks using Nickel-Titanium coil spring delivering 25 g of force. In VBO and TMO+VB groups, cyclical forces at 0.4 N and 30 Hz were applied occlusally twice a week for 10 minutes. Microfocus X-ray computed tomography analysis and tooth movement measurements were performed on the dissected rat maxillae. Tartrate-resistant acid phosphatase staining and collagen fiber assessment were performed on histological sections. RESULTS Cyclical forces significantly inhibited the amount of tooth movement. Histological analysis showed marked disorganization of the collagen fibril structure of the periodontal ligament during tooth movement. Tooth movement caused a significant increase in osteoclast parameters on the compression side of alveolar bone and a significant decrease in bone volume fraction in the molar region compared to controls. CONCLUSIONS Tooth movement was significantly inhibited by application of cyclical forces.

Effect of corticision and different force magnitudes on orthodontic tooth movement in a rat model

INTRODUCTION The aims of this study were to evaluate the effect of 2 distinct magnitudes of applied force with and without corticision (flapless corticotomy) on the rate of tooth movement and to examine the alveolar response in a rat model. METHODS A total of 44 male rats (6 weeks old) were equally divided into 4 experimental groups based on force level and surgical intervention: light force, light force with corticision, heavy force, and heavy force with corticision. The forces were delivered from the maxillary left first molar to the maxillary incisors using prefabricated 10-g (light force) or 100-g (heavy force) nickel-titanium springs. The corticision procedure was performed at appliance placement and repeated 1 week later on the mesiopalatal aspect of the maxillary left first molars, with the right sides serving as the untreated controls. Microcomputed tomography was used to evaluate tooth movement between the maxillary first and second molars, and the alveolar response in the region of the maxillary first molar on day 14. Osteoclasts and odontoclasts were quantified, and the expression of receptor activator of nuclear factor kappa ß ligand was examined. RESULTS Intragroup comparisons of bone volume fraction (BVF) and tissue density were found to be significantly less on the loaded sides, with the exception of BVF in the light force group. Intergroup comparisons evaluating magnitude of tooth movement, BVF, apparent density, and tissue density showed no significant differences. Histomorphometric analysis indicated that BVF was decreased in the light force group. No significant differences in the total numbers of osteoclasts and odontoclasts and the expression of receptor activator of nuclear factor kappa ß ligand were found between the groups. CONCLUSIONS No differences in tooth movement or alveolar response were observed with microcomputed tomography based on force level or corticision procedure. A flapless surgical insult in the mesiopalatal aspect of the first molar with a single-site corticision was unable to induce clinical or histologic changes after 2 weeks of orthodontic tooth movement regardless of the force magnitude. Histologic analysis of the furcation area showed that light force significantly decreased BVF.

Mini-implants vs fixed functional appliances for treatment of young adult Class II female patients

OBJECTIVE To compare the treatment effects of maxillary anterior teeth retraction with mini-implant anchorage in young adults with Class II division 1 malocclusion undergoing extraction of the maxillary first premolars with similar patients treated by a fixed functional appliance. MATERIALS AND METHODS Thirty-four young adult female patients (mean age 16.5 ± 3.2 years, overjet ≥ 6 mm) with a Class II division 1 malocclusion were divided into two groups: group 1 (G1), in which overjet correction was obtained with a fixed functional appliance (FFA), and group 2 (G2), in which upper first premolars were extracted, followed by space closure with MIs as anchor units. Dentoskeletal and soft tissue changes were analyzed on lateral cephalograms taken before (T1) and after (T2) correction of the overjet. RESULTS Both methods were useful in improving the overjet and interincisal relationships. Extrusion and mesial movement of the lower molar, together with lower incisor proclination, were noted in G1. G2 showed distalization and intrusion of the upper molar. The nasio-labial angle became more obtuse in G2, while lower lip protrusion was seen for G1. CONCLUSIONS The two treatment protocols provided adequate dental compensation for the Class II malocclusion, but did not correct the skeletal discrepancy. There were significant differences in the dental and soft tissue treatment effects between the two treatment protocols.

Orthodontic tooth movement causes decreased promoter expression of collagen type 1, bone sialoprotein and alpha-smooth muscle actin in the periodontal ligament.

OBJECTIVE To evaluate the effects of orthodontic tooth movement on the promoter expression of collagen type 1 (3.6Col1), bone sialoprotein (BSP) and alpha-smooth muscle actin (αSMA) in the periodontal ligament (PDL) using transgenic mice containing transgenes of these promoters fused to green fluorescent proteins (GFP). MATERIALS AND METHODS The maxillary first molars of 10-12 week-old transgenic mice were loaded with 10-12 g of force for 12, 48 h, or 7 days. Mice were transgenic for one of the following GFP-tagged bone markers of osteoblast lineage cells: 3.6-kb fragment of the rat collagen type 1 promoter (3.6Col1), BSP or α-smooth muscle actin (αSMA). Loaded molars under compression and tension were compared with contra-lateral unloaded controls. RESULTS On the compression side of the PDL, orthodontic tooth movement caused a significant decrease in GFP expression of all the promoters at each time point. On the tension side, there was a significant increase in BSP-GFP expression, 12 h following loading compared to the contralateral unloaded controls. CONCLUSIONS An in vivo tooth movement model using transgenic mice with promoter-GFP constructs provides an efficient and effective way of investigating the cellular events underlying orthodontic tooth movement. PDL cells may undergo decreased differentiation in response to the compressive force.

The relationship of facial anatomic landmarks with midlines of the face and mouth

STATEMENT OF PROBLEM The importance of the midline is well known to dentists. Currently, there are no verifiable guidelines that direct the choice of specific anatomic landmarks to determine the midline of the face or midline of the mouth. PURPOSE The purpose of this study was to determine the hierarchy of facial anatomic landmarks closest to the midline of the face as well as midline of the mouth. MATERIAL AND METHODS Three commonly used anatomic landmarks, nasion, tip of the nose, and tip of the philtrum, were marked clinically on 249 subjects (age range: 21-45 years). Frontal full-face digital images of the subjects in smile were then made under standardized conditions. A total of 107 subjects met the inclusion criteria. Upon applying exclusion criteria, images of 87 subjects were used for midline analysis using a novel concept called the Esthetic Frame. Deviations from the midlines of the face and mouth were measured for the 3 clinical landmarks; the existing dental midline was considered as the fourth landmark. The entire process of midline analysis was done by a single observer and repeated twice. Reliability analysis and 1-sample t tests were conducted at alpha values of .001 and .05, respectively. RESULTS The results indicated that each of the 4 landmarks deviated uniquely and significantly (P<.001) from the midlines of the face as well as the mouth. CONCLUSIONS Within the limitations of the study, the hierarchy of anatomic landmarks closest to the midline of the face in smile was as follows: the midline of the oral commissures, natural dental midline, tip of philtrum, nasion, and tip of the nose. The hierarchy of anatomic landmarks closest to the midline of the oral commissures was: natural dental midline, tip of philtrum, tip of the nose, and nasion. These relationships were the same for both genders and all ethnicities classified.

Mechanism of Class II correction in prepubertal and postpubertal patients with Twin Force Bite Corrector.

OBJECTIVE To compare the dentoskeletal effects and treatment efficiency of the Twin Force Bite Corrector (TFBC) appliance in Class II correction of patients treated before or after the pubertal growth spurt. MATERIALS AND METHODS Forty-one normodivergent Class II patients treated with the TFBC appliance were divided into two groups based on their cervical vertebral maturation stage (CVMS). Group 1 (G1) consisted of 23 patients (mean age 12.44 ± 1.59 years) where treatment was initiated before the pubertal growth spurt (CVMS I and II), while group 2 (G2) consisted of 18 patients (mean age 13.76 ± 1.44 years) where treatment was started after the pubertal growth spurt (CVMS III to V). Dentoskeletal measurements were made on lateral cephalograms taken before (T1) and after orthodontic treatment (T2). RESULTS During treatment, G1 had significantly greater skeletal correction than G2, with more dentoalveolar effects being observed in G2 than G1. However, on comparing both groups at the end of treatment (T2) when growth is complete, no differences in the parameters measured were observed. Overall, treatment time was significantly longer for G1 (3.67 ± 1.45 years) compared to G2 (2.75 ± 1.07 years). CONCLUSIONS There is no difference in overall dentoskeletal effects obtained at the end of treatment by the TFBC appliance in normodivergent prepubertal vs postpubertal patients. However, treatment efficiency based on treatment timing is significantly greater for the postpubertal group.

Oculofaciocardiodental Syndrome: A Rare Case and Review of the Literature

Oculofaciocardiodental syndrome is a rare genetic disorder affecting ocular, facial, dental, and cardiac systems. The clinical diagnosis of oculofaciocardiodental syndrome can be challenging due to a wide variety of symptoms. Oculofaciocardiodental syndrome is found only in females due to its X-linked inheritance pattern and embryonic lethality for males. Radiculomegaly of canines is the most consistent finding in these patients. In this report we present a female patient with characteristic facial features, as well as a comprehensive overview of oculofaciocardiodental syndrome. Diagnosis of oculofaciocardiodental syndrome in this patient was verified by genetic analysis, during which we found a novel mutation in BCOR.