Relationship between Class III malocclusion and hyoid bone displacement during swallowing: a cine-magnetic resonance imaging study.

OBJECTIVE: The displacement of the hyoid bone (HB) is a critical biomechanical component of the swallowing function. The aim of this study was to evaluate the swallowing-induced vertical and horizontal displacements of the HB in subjects with 2 different magnitudes of skeletal Class III malocclusion, by means of real-time, balanced turbo-field-echo (B-TFE) cine-magnetic resonance imaging. METHODS: The study population comprised 19 patients with mild skeletal Class III malocclusion, 16 with severe skeletal Class III malocclusion, and 20 with a skeletal Class I relationship. Before the commencement of the study, all subjects underwent cephalometric analysis to identify the nature of skeletal malformations. B-TFE images were obtained for the 4 consecutive stages of deglutition as each patient swallowed 10 mL of water, and the vertical and horizontal displacements of the HB were measured at each stage. RESULTS: At all stages of swallowing, the vertical position of the HB in the severe Class III malocclusion group was significantly lower than those in the mild Class III and Class I malocclusion groups. Similarly, the horizontal displacement of the HB was found to be significantly associated with the severity of malocclusion, i.e., the degree of Class III malocclusion, while the amount of anterior displacement of the HB decreased with an increase in the severity of the Class III deformity. CONCLUSIONS: Our findings indicate the existence of a relationship between the magnitude of Class III malocclusion and HB displacement during swallowing.

Orthodontic treatment of a patient with unerupted maxillary central and lateral incisors and canine: a case report.

AIM: The aim of this case report was to describe the orthodontic and periodontal management of a patient with three impacted anterior teeth. METHODS: An 18-year-old female with Class I crowding on a Class I skeletal base presented with the chief complaint of an unaesthetic smile. Clinical examination revealed an impacted upper right permanent canine (13), lateral (12) and central incisor (11), a retained deciduous incisor and moderate crowding in the lower arch. The impacted teeth were surgically exposed (closed exposure) and aligned with fixed appliances. The 12 was extracted due to root resorption and 44 extracted to resolve the lower arch crowding. A fraenectomy and gingival recontouring were required. RESULTS: Orthodontic treatment resulted in improved overjet, overbite and an acceptable facial profile. The patient reported improved self esteem. CONCLUSIONS: While impacted anterior teeth are a clinical challenge, their surgical exposure, in combination with fixed appliances, is a conservative treatment plan which is not without complications.

Rectangular body ostectomy for the treatment of severe mandibular prognathism.

OBJECTIVE: The aim of this article was to present the surgical technique and the outcomes of rectangular body ostectomy in the treatment of severe mandibular prognathism. METHODS: Mandibular setback by bilateral rectangular body ostectomies combined with Le Fort I level maxillary advancement was performed. The deep bony concavity of paranasal area was grafted with bone blocks harvested from the ostectomized segments of the mandible. RESULTS: Satisfactory functional and aesthetic outcomes were obtained by rectangular body ostectomy combined with Le Fort I level maxillary advancement and an acceptable profile was provided for the patient. CONCLUSIONS: The mandibular rectangular ostectomy remains a safe and versatile procedure with predictable results in well-selected cases.

Orthodontic approach to dilacerated central incisor localized horizontally on the anterior nasal spine: a case report.

The purpose of this paper was to present a case of surgical exposure of a horizontally impacted permanent maxillary left central incisor followed by fixed orthodontic treatment to eruption in a 9-year-old boy with a 2-mm overjet and 2-mm overbite who had sustained a traumatic injury to his primary maxillary central incisors when he was 6-years-old. Panoramic, occlusal, and cepholometric radiographs showed the affected tooth's crown to be positioned horizontally, and a CT scan showed the impacted central incisor's crown to be located below the anterior nasal spine and its apex to be located parallel to the palatal plane. A treatment plan was devised that included surgically exposing the impacted teeth and applying extrusive forces in the direction of the occlusal plane to bring about eruption. After 22 months of treatment, the central incisor erupted into the oral cavity. The patient now possesses the confidence to smile and enhanced self-esteem.

Nasal cavity volume changes after rapid maxillary expansion in adolescents evaluated with 3-dimensional simulation and modeling programs.

INTRODUCTION: The purpose of this study was to evaluate the effects of rapid maxillary expansion on nasal cavity volume by using 3-dimensional simulation and modeling programs. METHODS: The study group consisted of 15 patients (9 boys, 6 girls; mean age, 13.86 years) with maxillary constriction. Computed tomography scans were obtained before treatment and 6 months after the end of expansion. All computed tomography data were transferred to a computer, and the nasal cavity and maxillary teeth were segmented by using the Mimics and Simplant Ortho software programs (both, Materialise, Leuven, Belgium). Paired samples t tests were used to compare pretreatment and posttreatment nasal cavity volumes and maxillary areas. Data analysis was performed by using the software program SPSS for Windows (version 15.00; SPSS, Chicago, Ill). RESULTS: Rapid maxillary expansion treatment induced significant increases in nasal cavity volume (P ≤ 0.001) and maxillary transverse dimensions (P ≤ 0.001). CONCLUSIONS: Both anterior-to-posterior and coronal-to-cranial expansions were observed after rapid maxillary expansion treatment, with the direction of expansion most likely affected by resistance from the cranial bones.

Effect of vitamin C on bone formation in the expanded inter-premaxillary suture. Early bone changes.

AIM: The aim of this experimental study was to histomorphometrically evaluate the effects of vitamin C administration on bone formation in response to expansion of the rat inter-premaxillary suture. MATERIALS AND METHODS: A total of 30 50- to 60-day old Wistar male rats were divided into three groups of equal number. The inter-premaxillary suture in each animal was expanded with a 0.49 N force applied to the upper incisors. At 24 h after appliance placement, control animals received saline solution (group I) and two groups were given a single dose of vitamin C using two different methods [locally into the suture (group II) and systemically via intramuscular injection (group III)]. The area of new bone (µm(2)), the perimeter around the new bone (µm), Feret's diameter (µm), and the percentage of new bone to non-ossified tissue (%) were measured and compared. Kruskal-Wallis and Tukey tests were used for statistical evaluation at the p<0.05 level. RESULTS: We observed significant differences among the groups in all histomorphometric parameters. New bone area, bone perimeter, Feret's diameter, and percentage of new bone dimensions were significantly higher in group III than the others (p<0.001). Histomorphometric measurements of bone architecture revealed that this improved in the group administered with vitamin C systemically, while local injection revealed significantly less bone growth than the control group. CONCLUSION: The systemic administration of vitamin C during the early stages of inter-premaxillary suture expansion may stimulate bone growth. However, local injection of this antioxidant into an orthopedically-expanded suture area has negative effects on bone formation.

Rigid external maxillary distraction and rhinoplasty for pyknodysostosis.

AIM: This article reports the treatment of an 33-year-old female patient with pyknodysostosis by rigid external distraction II midface distraction system. STUDY DESIGN: The patient with pyknodysostosis described in this report had severe midfacial hypoplasia. Correction of this by use of routine orthognathic surgery would require osteosynthesis and bone grafting. Risk of infection and/or nonunion after such a surgical procedure was considered too great, and therefore the possibility of treatment by distraction osteogenesis of the maxilla was evaluated. The rigid external distraction II midface distraction system was used to relocate the hypoplastic maxilla at anterior-inferior projection. CONCLUSIONS: Distraction osteogenesis should be considered as the primary reconstructive method for maxillofacial deformities in patients with sclerosing bone dysplasias, since this is the second reported case treated successfully with rigid external distraction.

Measurement accuracy of a computer-assisted three-dimensional analysis and a conventional two-dimensional method.

OBJECTIVE: To determine the differences between manual and cephalometric measurements on different sections of the human skull, which were obtained using computer-assisted three-dimensional (3D) analysis and conventional two-dimensional (2D) techniques. MATERIALS AND METHODS: Measurements were carried out on 13 dry human skulls, then 2D cephalograms and 3D computed tomographic (CT) images were obtained. Anatomic landmarks were determined and marked with clay before CT images were taken, and the same landmarks were marked with the help of metallic balls and pins for lateral and frontal cephalograms. Manual, lateral/frontal cephalometric, and computer-assisted 3D cephalometric measurements were compared statistically. One-way analysis of variance and Tukey Honestly Significant Difference tests were used to compare the results among the groups. RESULTS: All measurements were statistically insignificant between the computer-assisted 3D and manual measurements. On the other hand, the differences between the conventional 2D and the manual measurements were statistically significant. The greatest amount of magnification was found at the Nasion-Menton distance (14.6%), which was located at the farthest distance from the central x-ray beam in the lateral cephalogram (P < .01). For the same reason, the greatest enlargement (16.2%) was observed in the distance between the zygomaticomaxillary sutures on the conventional frontal cephalogram (P < .01). CONCLUSIONS: The computer-aided 3D cephalometric measurements were found to be more accurate than the conventional cephalometric measurements. The results revealed that 3D cephalometric measurements were consistent with the manual measurements. In addition, the magnification and distortion might limit the results of conventional cephalometric measurements.

Response of the expanded inter-premaxillary suture to intermittent compression. Early bone changes.

OBJECTIVE: To determine the response of the expanded premaxillary suture in the rat to an externally applied force. Specifically, to investigate early bone changes in the expanded suture to intermittent loading and unloading. METHODS: Twenty-four 50 to 60 day-old Wistar rats were assigned to three groups. The inter-premaxillary sutures in all animals were expanded with a 50 g force applied to the upper incisors. Group I served as the control, whereas in Groups II and III the incisors were subjected to intermittent loading and unloading after five days of expansion. The intermittent forces were produced by a cam (0.416 mm, 100 cycles per minute) applied to the disto-gingival margins of the upper incisors. The mechanical stimuli were applied daily over nine days for six seconds in Group II (30 grams force, 10 cycles/day) and 10 minutes in Group III (30 grams force, 1000 cycles/day). Bone regeneration in the suture was evaluated histomorphometrically. The area of new bone (microm2), the perimeter around the new bone (microm), Feret's diameter (microm) and the percentage of new bone to non-ossified tissue (%) were measured and compared. RESULTS: Statistically significant differences were found between the groups for all histomorphometric parameters. New bone area (p < 0.001), bone perimeter (p < 0.001), Feret's diameter (p < 0.001) and percentage of new bone (p < 0.001) were significantly larger in the experimental groups as compared with the Control group. The histomorphometric measurements confirmed that more new bone was deposited in the sutures subjected to intermittent loading and unloading. CONCLUSION: The application of cyclic loading and unloading to the orthopaedically expanded inter-premaxillary suture during the early retention phase stimulated the formation of new bone.

Onlay iliac bone grafting as an ancillary augmentation procedure for paranasal rejuvenation during bimaxillary surgery.

OBJECTIVE: The aim of this paper is to present the outcome of iliac bone block grafts used for paranasal augmentation during bimaxillary orthognathic surgery for the patient with deep concavity of canine fosse. STUDY DESIGN: Preoperative evaluation of the patient, done with 3-dimensional (3D) surgical simulation software, revealed deep bony concavity of paranasal area and insufficient soft tissue improvement when Le Fort I level maxillary advancement was accomplished. The deficient sites were grafted and better profile was achieved with 3D simulation. After the leveling phase, Le Fort I advancement and mandibular setback with sagital split osteotomies were performed. Bony deficiency of paranasal regions were corrected simultaneously with autogenous iliac block grafts to obtain maximum improvement in the profile. RESULTS: More satisfactory esthetic results were obtained with paranasal augmentation, and acceptable profile was provided for the patient. CONCLUSIONS: Bimaxillary orthognathic surgery combined with augmentation of paranasal area is an efficient method to obtain better aesthetic outcome for patients with severe concave profile. Paranasal augmentation with iliac bone block grafting is a novel technique to ensure favorable soft tissue support and esthetic appearance of the patient.

Cephalometric evaluation of patients treated by maxillary anterior segmental distraction: a preliminary report.

OBJECTIVE: The aim of this study was to evaluate the cephalometric results of distraction osteogenesis in patients with premaxillary deficiency. MATERIAL AND METHODS: In this study, an individual tooth-borne distraction device was used for advancement of the maxillary anterior segment. Unilateral or bilateral distraction was performed for 7 patients, according to the specific requirements of the individuals. Cephalometric radiographs were taken before treatment (T0), after distraction (T1), and after consolidation for 8 weeks (T2). RESULTS: Cephalometric analysis revealed that the premaxilla was moved forward and upward and the length of palatal plane increased. CONCLUSION: These alterations improved the soft tissue profile and solved the space deficiency of the maxilla by increasing the arch perimeter.

Multitomographic evaluation of the dental effects of two different rapid palatal expansion appliances.

Rapid palatal expansion (RPE) is widely used in the treatment of transverse maxillary deficiencies. Generally, there are two types of RPE appliances: banded and bonded expanders. The purpose of this prospective study was to compare the dental effects of banded and bonded appliances. The study consisted of 23 patients (13 females and 10 males) with a bilateral maxillary deficiency. Twelve patients (seven females and five males) with a mean age of 14.8 +/- 0.3 years were treated with banded RPE and 11 patients (six females and five males) with a mean age of 15.1 +/- 0.7 years with bonded RPE. Multitomographic radiographs were taken before (T0) and at the end (T1) of expansion while the patients were wearing an acrylic mandibular appliance in which ball bearings and bars were embedded. Statistical analyses of the measurements at T0 and T1 were undertaken with a paired t-test, and the difference between the groups assesed with a Student's t-test. In both groups, the angle between the radiographic image of the bar and the axial inclination of the upper first premolar and molar teeth was (5.34 and 2.73 degrees for the right premolars, 5.17 and 2.28 degrees for the left premolars, 11.83 and 3.73 degrees for the right molars, and 9.75 and 5.64 degrees for the left molars in the banded and bonded groups, respectively. The distance from the vestibular cortical plate to the palatal root of these teeth (1.17 and 1.23 mm for the right premolars, 2.46 and 1.09 mm for the left premolars, 2.75 and 0.64 mm for the right molars, 2.23 and 0.96 mm for the left molars in the banded and bonded groups, respectively) increased (both P < 0.01). These increases indicated buccal tipping of the teeth. Comparison of the two groups showed that tipping of the first molar and premolar teeth in the banded group was significantly more than in the bonded group (P < 0.01 and P < 0.001, respectively).

Forsus Nitinol Flat Spring and Jasper Jumper corrections of Class II division 1 malocclusions.

OBJECTIVE: To compare the effects of Forsus Nitinol Flat Spring (FNFS) and Jasper Jumper (JJ) in the correction of Class II division I malocclusions. MATERIALS AND METHODS: Our research was conducted on 48 adolescents, who had a normal or horizontal growth pattern and retrognathic mandible. The patients were divided into three equal groups randomly. First group was treated with FNFS, and the second group was treated with JJ appliances, whereas the third group was the control group. Lateral cephalograms and study models were obtained after the leveling phase and at time of the removal of the appliances. RESULTS: Cephalometric analysis revealed that both the appliances stimulated mandibular growth, increased the anterior face height because of the lower face, and elongated the posterior face height because of the growth of temporomandibular joint. Maxillary central incisors were extruded, retruded, and distally tipped. Contrarily, intrusion, protrusion, and labial tipping were observed in the mandibular central incisors. Distal movement and intrusion of the maxillary first molars and mesial movement and extrusion of the mandibular first molars were the other dental alterations. Overjet and overbite were decreased, and a Class I molar relationship and improvement in the profile were attained in both treatment groups. Cast model analysis showed expansion in the maxillary and mandibular dental arches. CONCLUSIONS: Both the appliances were effective in the treatment of Class II malocclusion and revealed nearly same alterations in the skeletal, dental, and soft tissue parameters.

Use of zygomatic anchors during rapid canine distalization: a preliminary case report.

Rapid canine distalization is a technique involving periodontal ligament distraction. The primary aim of this technique is to distalize the canines without anchorage loss and to shorten the duration of orthodontic treatment. After the rapid canine distalization, the healing process of the periodontal ligament is similar to rapid palatal expansion and requires a consolidation period. The long consolidation period of the technique conflicts with the second aim. Skeletal anchorage systems seem to compensate for this conflict because they can be also used for retraction of incisors during consolidation period. This case report presents the orthodontic treatment of a 16-year-old female, who had a bimaxillary retrusion and a dental Class II division I malocclusion. Upper first premolars were extracted and, while the canines were being distalized rapidly by periodontal ligament distraction, the incisors were retracted using a zygomatic anchorage system. The treatment of the patient was completed in five months without any anchorage loss.

Effects of nitric oxide in orthodontic tooth movement in rats.

The purpose of this study was to evaluate the role of nitric oxide (NO) in orthodontic tooth movement in rats. Nomega-nitro-L-arginine methyl ester (L-NAME) was used as NO synthase (NOS) inhibitor, and nitro-L-arginine (NLA) was used as NOS precursor. Fifty-four Sprague-Dawley rats were divided into 3 equal groups, and each group was divided into 3 subgroups. In the first 8 subgroups, 20 g of force was applied to the maxillary incisors with a spring. NLA was administered in the first 3 subgroups at 10(-4), 10(-5) and 10(-6) mol/L (20 microL/12 hours), respectively. L-NAME was administered in the next 3 subgroups with the same order, amount, and prescription. The last 3 subgroups were evaluated as control groups; in the seventh subgroup, 0.9% NaCl (saline solution) was injected (20 microL/12 hours). Only the force was administered in the eighth subgroup, and no chemical solution or orthodontic force was used in the last subgroup. The rats were killed on the fifth day of the experiment. Their premaxillae were dissected, and tissue sections were obtained from the coronal, middle, and apical thirds of the incisor roots. Multinuclear osteoclasts, Howship's lacunae, capillary vascularization, and orthodontic tooth movement were significantly increased in the NLA groups compared with the L-NAME and control groups.

Effects of PGI2 and TxA2 analogs and inhibitors in orthodontic tooth movement.

This study evaluates the effects of prostacyclin (PGI2) and thromboxane A2 (TxA2) in orthodontic tooth movement and osteoclastic activity in rats. The study sample consisted of 150 male Sprague-Dawley rats. The rats were randomly divided into five equal groups, and each group was again equally divided into three subgroups (SGs). Twenty grams of reciprocal force was applied to maxillary incisors of the rats with a spring bent from 0.35 mm stainless steel wire, except for the rats in the last SG. Iloprost (PGI2 analog), indomethacin (PGI2 inhibitor), U 46619 (TxA2 analog), and imidazole (TxA2 inhibitor) were dissolved in 0.9% NaCl (saline solution), and each material was prepared in three different concentrations (10(-4), 10(-5), and 10(-6) M/L). Iloprost was administered (20 microL/12 hours) in the first three SGs with the sequence of 10(-4), 10(-5), and 10(-6) M/L. Indomethacin, U 46619, and imidazole were administered in the next nine SGs with the same sequence and dose. In SG 13, 0.9% NaCl solution was administered (20 microL/ 12 hours) to the rats together with orthodontic force. Only orthodontic force was not used in SG 14, and neither any solution nor orthodontic force was used in the last SG. The rats were sacrificed on the fifth day of the experiment, premaxillae were dissected, and cross samples were taken. The results showed that PGI2 and TxA2 analogs increased the number of multinuclear osteoclasts, osteoclastic bone resorption, and rate of orthodontic tooth movement.

Multidisciplinary treatment of "twinned" permanent teeth: two case reports.

Twinned teeth usually appear in the anterior region of the dental arch. Besides orthodontic malocclusions, such as protrusion, crowding, or diastema, they also cause esthetic problems. Different treatment methods can be used according to the requirements of the situation. This article reports multidisciplinary treatment of 2 patients whose maxillary central teeth were twinned with supernumerary incisors. The twinned tooth was reshaped following endodontic treatment in 1 of the patients and orthodontic treatment was performed with edgewise mechanics. In the second case, however, it was determined that the twinned tooth had 2 separate roots. There was also another supernumerary lateral incisor in the dental arch that increased the severity of the crowding. The twinned tooth was hemisected and the other supernumerary tooth was extracted. The patient wore a removable appliance for initial tooth movements and treatment was finished with fixed appliances.

Comparison of some effects of acetylsalicylic acid and rofecoxib during orthodontic tooth movement.

The purpose of this study was to examine the effects of 2 different anti-inflammatory drugs on gingival crevicular fluid (GCF) volume and on prostaglandin E(2) (PGE(2)) levels of the GCF during orthodontic tooth movement. A total of 36 extraction patients, aged 17.6 +/- 2.5 years (mean +/- standard deviation), were divided into 3 groups. Acetylsalicylic acid (aspirin) and rofecoxib (Vioxx, Merck, Whitehouse Station, NJ) were used for pain control in the first and second groups; the third group was used as a control. Gingival crevicular fluid was sampled at the beginning of tooth movement and at 24, 48, and 168 hours. An automated enzyme immunoassay was used to measure PGE(2) in GCF. The intragroup differences were evaluated with the Wilcoxon test, and the differences between the groups were determined with the Mann-Whitney U test. Gingival crevicular fluid volumes of the groups did not change significantly during the experimental period. Depending on the variations of fibroblast activation, PGE(2) levels of all the groups increased at 24 and 48 hours and decreased at 168 hours. When the drugs were compared, it was found that the inhibition effect of aspirin on PGE(2) was more than that of rofecoxib. The results suggest that rofecoxib can be used during orthodontic treatment, but further study is recommended.