Mandibular morphology and pharyngeal airway space: A cephalometric study

Introduction

Mandibular retrognathism is considered to be the most important risk factor for upper airway obstruction.

Aim

This cross-sectional study intended to examine the relationship between craniofacial morphology and the pharyngeal airway space (PAS) in patients with mandibular retrognathism and mandibular prognathism, when compared to normal subjects. The study also analyzed the influence of mandibular morphology on pharyngeal length (PL).

Materials and Methods

The PAS was assessed in 92 females (age 15-30 years) further divided into three groups - Group 1- normal mandible (76°≤ SNB ≤82°; n = 31); Group 2-mandibular retrognathism (SNB <76°; n = 31); Group 3-Mandibular prognathism (SNB >82°; n = 30). All subjects were examined by lateral cephalometry with head position standardized using an inclinometer. Craniocervical angulation, uvula length, thickness and angulation were compared among different groups.

Results

The results showed no statistically significant difference in the pharyngeal airway between the three groups. Measurements of PL showed statistically significant higher values for retrognathic mandible group than normal and prognathic mandible group.

Conclusion

There is no significant difference between PAS between patients with mandibular retrognathism, normal mandible and mandibular prognathism. Mandibular retrognathism patients show a significantly higher uvula angulation than patients with mandibular prognathism. Craniocervical angulation showed maximum value in retrognathic mandible group followed by normal and prognathic mandible group respectively. Mean PL for retrognathic mandible patients was significantly higher than prognathic mandible patients.

Interdisciplinary treatment of a periodontally compromised adult patient with multiple missing posterior teeth

This article reports the comprehensive, interdisciplinary treatment of a 50-year-old periodontally compromised adult patient with multiple missing posterior teeth. After initial periodontal treatment, the maxillary first molars and right central incisor were intruded orthodontically. Miniscrews were used to intrude the maxillary first molars by 3 mm. The mandibular arch was restored with a tooth-supported overdenture. Root coverage of the maxillary right central incisor was performed using Alloderm (Biohorizons, Birmingham, Ala). At the end of the interdisciplinary therapy, the results were esthetically pleasing, with the patient's oral functions restored to the optimum. The emphasis of this report is to highlight the importance of integrating various specialties such as periodontics, orthodontics, endodontics, and restorative dentistry toward a common goal of improving the patient's oral health, function, and esthetics.

A comparative evaluation of the retention of metallic brackets bonded with resin-modified glass ionomer cement under different enamel preparations: A pilot study

Introduction:

For orthodontists, the ideal bonding material should be less moisture-sensitive and should release fluoride, thereby reducing unfavorable iatrogenic decalcification. Resin-Modified Glass Ionomer Cements (RMGICs), due to their ability to bond in the presence of saliva and blood can be a very good bonding agent for orthodontic attachments especially in the areas of mouth, which are difficult to access. Moreover, their fluoride releasing property makes them an ideal bonding agent for patients with poor oral hygiene. However, their immediate bond strength is said to be too low to immediately ligate the initial wire, which could increase the total number of appointments. The effect of sandblasting and the use of sodium hypochlorite (NaOCL) on the immediate bond failure of RMGIC clinically have not been reported in the literature until the date. This investigation intended to assess the effect of sandblasting (of the bracket base and enamel) and NaOCL on the rate of bond failure (with immediate ligation at 30 min) of Fuji Ortho LC and its comparison with that of conventional light cured composite resin over a period of 1 year.

Materials and Methods:

400 sample teeth were further divided into 4 groups of 100 each and bonded as follows: (1) Group 1: Normal metallic brackets bonded with Fuji Ortho LC. (2) Group 2: Sandblasted bracket base and enamel surface, brackets bonded with Fuji Ortho LC. (3) Group 3: Deproteinized enamel surface using sodium hypochlorite and brackets bonded with Fuji Ortho LC. (4) Group 4: Normal metallic bracket bonded with Transbond XT after etching enamel with 37% phosphoric acid. This group served as control group.

Results and Conclusion:

Results showed that sandblasting the bracket base and enamel, can significantly reduce the bond failure rate of RMGIC.

An evaluation of the Pi analysis in the assessment of anteroposterior jaw relationship

OBJECTIVE

This study has investigated two new cephalometric variables, the Pi angle and Pi linear in the evaluation of anteroposterior skeletal discrepancy.

DESIGN

Retrospective cross-sectional study.

SETTING

Manipal College of Dental Sciences, Manipal, India

SUBJECTS AND METHOD

A sample of 155 subjects (mean age 19·7 years) were subdivided into skeletal class I, II and III groups based upon ANB angle. Descriptive data were calculated for each variable and group. Receiver operating characteristics curves were used to examine sensitivity and specificity of the Pi angle in the discrimination between different skeletal groups. Correlation coefficients were obtained for each of the parameters to compare their relationship with other parameters in the class I group. Coefficient of determination, regression coefficient, regression equation and standard error of estimate were also calculated from the parameters showing significant correlation with the Pi angle.

RESULTS

Mean values for the Pi angle in skeletal class I, II and III subjects were 3·40 (±2·04), 8·94 (±3·16) and -3·57 (±1·61) degrees, respectively. For the Pi linear they were 3·40 (±2·20), 8·90 (±3·56) and -3·30 (±2·30) mm for class I, II and III subjects, respectively. Receiver operating characteristic curves showed that a Pi angle greater than 5 degrees had 89% sensitivity and 82% specificity for discriminating a skeletal class II group from class I. A Pi angle of less than 1·3 degrees had 100% sensitivity and 84% specificity in discriminating skeletal class III groups from class I. The overall accuracy for discriminating class II groups from class I was 85% and for class III from class I, 90%. Thus, a cut-off point between class I and II groups could be considered a Pi angle of approximately 5 degrees and between class I and class III, approximately 1·3 degrees. There were no statistically significant correlations found between Pi angle and ANB (0·07), Beta angle (-0·04) and WITS analysis (0·19). The highest level of correlation was obtained for the Pi angle and Pi linear (0·96).

CONCLUSION

The anglar and linear components of the Pi analysis are a suitable method for assessing anteroposterior jaw discrepancy in daily clinical practice.

Osteogenesis imperfecta and pneumatization of bone-- a hidden reality

Osteogenesis imperfecta is a bone disorder in which three factors that influence bone strength (quality, mass, and geometry of osseous tissue) are affected. Pneumatization refers to the development of air-filled cavities inside the bone. Knowledge about these air-filled cavities provides valuable information for understanding the diagnosis and spread of various pathologic entities like hemangiomas, giant cell tumors, eosinophilic granulomas, and even metastatic tumor deposits. This paper presents a case in which radiologic, clinical, biochemical, and karyotypic evaluations lead to a diagnosis of osteogenesis imperfecta.

Correction of bilateral impacted mandibular canines with a lip bumper for anchorage reinforcement

Multiple treatment options are available to patients with impacted manibular canines in addition to a retained deciduous canine. This article describes the treatment of a prepubertal girl, aged 10 years 6 months, with a skeletal Class I, dental Class II Division 1 malocclusion, retrognathic mandible, deep overbite, proclined maxillary incisors, midline diastema, and bilateral mandibular canine impaction. The orthodontic treatment plan included extraction of the deciduous canine and forced eruption of the impacted canines. A modified lip bumper appliance was used both for forced eruption and to reinforce anchorage. Through the collaborative efforts of an orthodontist and an oral surgeon, an excellent esthetic and functional outcome was achieved.

Perception of smile esthetics among Indian dental professionals and laypersons

INTRODUCTION

Patients' perceptions and expectations regarding their appearance play a significant role in treatment planning. The purpose of this study was to compare the perceptions of orthodontists, general dentists, and laypersons regarding smile esthetics after symmetrical and asymmetrical alterations in anterior teeth and their supporting tissues.

MATERIALS AND METHODS

Alterations were made in the crown length, crown width, midline diastema, and gingiva-to-lip relationship of the maxillary anterior teeth in the close-up photograph of a woman's smile. The attractiveness of the smile in the original image and in each of the modified images were assessed by orthodontists (n=40), dentists (n=40), and laypersons (n=40) and scored using a visual analog scale (VAS). The mean VAS scores were calculated for each photograph. ANOVA was used for comparisons between photographs and between groups. To determine threshold levels at which each group discriminated between esthetic and less esthetic dental features were determined by one-way ANOVA (F-test) followed by Newman-Keul's range test.

RESULTS

Orthodontists were found to be more critical when evaluating smile images compared to general dentists and laypersons. Symmetrical or asymmetrical alterations in the mesio-distal width of the lateral incisor of up to 2 mm was not perceived as unesthetic by general dentists and laypersons.

CONCLUSION

Laypersons are more accepting of minor variations in anterior tooth size and alignment than orthodontists.

Investigation of the transmigrated canine in an orthodontic patient population

OBJECTIVE

To investigate the prevalence, demographic and clinical characteristics of transmigrated canines in a south Indian orthodontic patient population.

DESIGN

Retrospective observational study.

SETTING

Manipal University, Manipal, India.

SUBJECTS AND METHODS

Panoramic radiographs of 3500 patients were examined and data collected regarding the number and side of transmigrated canines, sex and age of patients, any other associated pathologies and subsequent treatment. Transmigrated canines were classified according to Mupparapu's classification.

RESULTS

The prevalence of transmigrated canines in this population was found to be 0.46% of which, seven were males (age: 17-51 years) and nine were females (age: 17-35 years). All transmigrated canines were unilateral and impacted. Eleven canines migrated from the left to the right side, and five migrated from the right to the left. Of the 16 patients, 13 had retained primary canines and 3 had exfoliated primary canines. Eight canines exhibited a type 1 transmigratory pattern, type 2, type 4 and type 5 transmigratory patterns were exhibited by two canines each. One of the canines was classified as type 3. Three canines were associated with dentigerous cyst formation. Four cases were treated by orthodontic traction, while one was removed surgically. Others were observed periodically.

CONCLUSIONS

Diagnosis of transmigration at earlier stages is important to prevent more complex occlusal problems.

Unusual intraosseous transmigration of impacted tooth

Transmigration of an impacted tooth through the symphyseal suture is a rare and special developmental anomaly of unknown etiology that is unique to the mandibular canine. Maxillary canine transmigration is even rarer. Transmigrated canines are particularly significant due to the aesthetic and functional importance. A maxillary lateral incisor crossing the mid-palatal suture has never been reported in the literature. The aim of this report is to present the first case of simultaneous transmigration of a lateral incisor and canine in the maxilla. The paper also reports four unusual cases of unilateral canine transmigration in the maxilla and mandible and successful eruption of one of the transmigrated mandibular canines following orthodontic traction. Etiology of transmigration and its clinical considerations are also discussed.

Management of multiple impacted teeth

An impacted or missing permanent tooth can add significant complications to an otherwise straightforward case. When multiple impacted teeth are present, the case complexity increases further. Developing a treatment sequence, determining appropriate anchorage, and planning and executing sound biomechanics can be a challenge. The following case report illustrates a patient with three retained primary teeth and three impacted permanent canines. After careful treatment planning and extraction of multiple primary teeth;, followed by attempted guided eruption of impacted teeth, the patient finished with a significantly improved functional and aesthetic result.

Success rate of microimplants in a university orthodontic clinic

Introduction. The purpose of this study was to examine the success rate and find factors affecting the clinical success of microimplants used as orthodontic anchorage. Methods. Seventy-three consecutive patients (25 male, 48 female; mean age, 22.45 years) with a total of 139 screw implants of 2 types were examined. Success rate was determined according to 18 clinical variables. Results. The overall success rate was 87.8%. The clinical variables of microimplant factors (type), patient factors (sex, skeletal and dental relationships, overbite, jaw involved, side involved and site involved), and treatment factors (type of insertion, time of loading, purpose of microimplant insertion, mode of loading, type of anchorage used, direction of forces applied) did not show any statistical difference in success rates. Mandibular angle, vertical position of implant placement, oral hygiene status, and inflammation showed significant difference in success rates. Conclusions. Proper case selection and following the recommended protocol are extremely essential to minimise failures.

Influence of first premolar extraction on mandibular third molar angulation

OBJECTIVE

To compare the angular changes in the developing mandibular third molars in both first premolar extraction and nonextraction cases and to determine whether premolar extraction results in a more mesial movement of the mandibular buccal segment and causes favorable rotational changes in the mandibular third molar tilt, which can enhance later eruption of the third molars.

MATERIALS AND METHODS

Pretreatment (T1) and posttreatment (T2) panoramic radiographs were taken of 25 subjects who had been treated by the extraction of all the first premolars and 25 subjects who had been treated with nonextraction. The horizontal reference plane was used to measure and compare the changes in the angles of the developing mandibular third molars.

RESULTS

The mean uprighting of the mandibular third molars seen in the extraction group was 8.2 +/- 5.4 degrees on the left side and 6.3 +/- 6.5 degrees on the right side following treatment (T2 - T1). For the nonextraction group the mean difference was 1.3 +/- 4.3 degrees on the left side and 1.7 +/- 5.4 degrees on the right side. There was a statistically significant difference between the groups (P = .012 on the right side and P < .001 on the left side).

CONCLUSIONS

Premolar extractions had a positive influence on the developing third molar angulations. Nonextraction therapy did not have any adverse effects.

Maxillary protraction with and without maxillary expansion: a finite element analysis of sutural stresses

INTRODUCTION

In this finite element study, we compared the stress patterns along the various craniofacial sutures with maxillary protraction with and without expansion.

METHODS

Two 3-dimensional analytic models were developed, 1 simulating maxillary protraction and the other simulating maxillary protraction with expansion. The model consisted of 108799 10 node solid 92 elements (tetrahedron), 193633 nodes, and 580899 degrees of freedom.

RESULTS

The overall stresses after maxillary protraction with maxillary expansion were significantly higher than with a facemask alone. The magnitude of stress on the craniofacial sutures with maxillary protraction alone was in the range of a few millinewtons per square millimeter, whereas, with maxillary protraction with maxillary expansion, the stresses ranged from a few newtons per square millimeter to a few hundred newtons per square millimeter. The pattern of stress distribution also differed with the 2 treatment modalities as did the sutures experiencing maximum and minimum stresses.

CONCLUSIONS

The osteogenic potential of such low stresses after maxillary protraction can be questioned. High stresses generated in various craniofacial sutures after maxillary protraction with expansion are responsible for disrupting the circummaxillary sutural system and presumably facilitating the orthopedic effect of the facemask.

Skeletal response to maxillary protraction with and without maxillary expansion: a finite element study

INTRODUCTION

The purpose of this finite element study was to evaluate biomechanically 2 treatment modalities-maxillary protraction alone and in combination with maxillary expansion-by comparing the displacement of various craniofacial structures.

METHODS

Two 3-dimensional analytical models were developed from sequential computed tomography scan images taken at 2.5-mm intervals of a dry young skull. AutoCAD software (2004 version, Autodesk, San Rafael, Calif) and ANSYS software (version 10, Belcan Engineering Group, Cincinnati, Ohio) were used. The model consisted of 108,799 solid 10 node 92 elements, 193,633 nodes, and 580,899 degrees of freedom. In the first model, maxillary protraction forces were simulated by applying 1 kg of anterior force 30 degrees downward to the palatal plane. In the second model, a 4-mm midpalatal suture opening and maxillary protraction were simulated.

RESULTS

Forward displacement of the nasomaxillary complex with upward and forward rotation was observed with maxillary protraction alone. No rotational tendency was noted when protraction was carried out with 4 mm of transverse expansion. A tendency for anterior maxillary constriction after maxillary protraction was evident. The amounts of displacement in the frontal, vertical, and lateral directions with midpalatal suture opening were greater compared with no opening of the midpalatal suture. The forward and downward displacements of the nasomaxillary complex with maxillary protraction and maxillary expansion more closely approximated the natural growth direction of the maxilla.

CONCLUSIONS

Displacements of craniofacial structures were more favorable for the treatment of skeletal Class III maxillary retrognathia when maxillary protraction was used with maxillary expansion. Hence, biomechanically, maxillary protraction combined with maxillary expansion appears to be a superior treatment modality for the treatment of maxillary retrognathia than maxillary protraction alone.

Idiopathic failure of eruption of multiple permanent teeth: report of 2 adults with a highlight on molecular biology

Multiple unerupted teeth with no obvious etiology is a rare dental anomaly. Various local and systemic factors have been implicated in the failure of eruption of multiple permanent teeth. But the localization of the genetic defect in the phenotype of failure of eruption is largely unknown at present. Our aims in this article were to consolidate and organize the available information regarding the molecular biology of tooth eruption and to corroborate the current evidence with the report of 2 adult cases of failure of eruption of multiple permanent teeth without a known cause.