Panoramic radiographs: a tool for investigating skeletal pattern

Comparison of the accuracy of bracket axial positioning with and without radiographic support and according to practitioner experience: A three-dimensional study

INTRODUCTION

Accurate bracket positioning remains challenging. To avoid angulation errors, some recommend examining the panoramic radiograph during bonding. However, it can cause distortions. Cone-beam computed tomography (CBCT) provides a more precise panoramic reconstruction but with higher radiation doses. The main objective of this study is to compare the accuracy of axial positioning between direct bonding without radiography, with conventional panoramic radiograph, and with panoramic reconstruction from CBCT. The secondary objectives are to evaluate positioning accuracy of each tooth and to assess the influence of practitioner level of experience.

METHODS

Thirty practitioners, divided into two groups based on their experience performed direct bonding on a model thrice: without radiography, then with the conventional panoramic radiograph, then with the panoramic reconstruction from CBCT. Models were scanned, and angulation errors were measured using OrthoAnalyzer. Values were compared using the Friedman's test followed by the Bonferroni correction for multiple comparisons (P-value = 0.05).

RESULTS

For the low level of experience group, angulation errors were significantly greater than the accepted limit without radiographic reference, and significantly lower with CBCT reconstruction. For the high level of experience group, angulation errors were significantly lower than the accepted limit for the three bonding methods. For every tooth, using the panoramic reconstruction from CBCT as a reference, was the most accurate method, regardless of the level of experience. More experienced practitioners made fewer errors for the three methods.

CONCLUSIONS

Panoramic reconstruction from CBCT is the most accurate method to limit angulation errors during direct bonding. Conventional panoramic radiography remains a reliable tool if used with caution. Bonding without any radiographic reference should be avoided especially for less experienced practitioners.

Accuracy of Gonial Angle Measurements Using Panoramic Imaging versus Lateral Cephalograms in Adults with Different Mandibular Divergence Patterns

Introduction

Gonial angle is an important craniofacial parameter providing information about symmetry and vertical dimensions of the facial skeleton. It can be measured on panoramic radiographs and lateral cephalograms. Reliable assessment of the gonial angle is challenged by the superimpositions associated with lateral cephalograms. The aim of the current study was to assess the precision of panoramic imaging in measuring the gonial angles compared to lateral cephalograms in adult patients with different mandibular divergence patterns.

Methods

Panoramic radiographs and lateral cephalograms of 448 adults (18-30 years old) were utilized in the study. The gonial angle was determined on the lateral cephalograms using an online AI-driven assessment tool (WebCephTM) and compared to the panoramic measurements among the different gender, malocclusion, and mandibular divergence groups.

Results

Statistically significant differences were recorded between measurements taken on lateral cephalograms or panoramic radiographs (p=0.022). In addition, statistically significant differences were reported in gonial angle measurements on panoramic radiographs among the different mandibular divergence groups (p=0.004) for FMA (p=0.002) for Sn-GoMe.

Conclusion

While cephalometry is considered the gold standard tool for reliable gonial angle assessment, panoramic radiographs were more accurate in detecting the differences between the divergence groups in the current study.

Exploring Age and Gender Identification Through Mandibular Parameters Using Orthopantomography: An Observational Study

Aim This study aims to examine five mandibular parameters: coronoid ramus height, condylar ramus height, projective ramus height, minimum ramus breadth, and gonial angle, using orthopantomography (OPG). Introduction The mandible, a crucial part of the human skull, demonstrates sexual dimorphism, which makes it an important tool for determining sex in forensic and anthropological investigations. Its form and structure are relatively resistant to significant changes after death. Among all skeletal components, the mandible stands out as a primary indicator of sexual differences. In forensic investigations, establishing the age and sex of an individual is considered a crucial initial step. This process can be particularly challenging in scenarios involving mass casualties, natural calamities, or extensively fragmented remains. Due to its responsiveness to growth patterns, the mandible is adept at accurately determining both age and sex. Materials and methods This study employed a sample size of 500 individuals, split equally between males and females, with 250 participants each. The age bracket chosen for this cohort ranged from 20 to 30 years, considering that bone growth characteristics within this range can assist in sex determination. The height of the mandibular ramus was assessed using Planmeca software, and subsequent data analysis was conducted using SPSS. Results When estimating age, the condylar ramus height exhibited the smallest standard error (0.010), whereas the maximum standard error for the gonial angle was 0.028. Positive t values were observed for the gonial angle (1.182), minimum ramus breadth (0.114), and coronoid ramus height (0.733). In terms of determining sex, the gonial angle, coronoid ramus height, and projective ramus height demonstrated positive coefficient functions, specifically 0.676, 0.090, and 0.286, respectively. Conversely, both the minimum ramus breadth and the condylar ramus height displayed negative values of -0.385 and -0.126, respectively. Conclusion Among the parameters evaluated, condylar ramus height emerges as the most suitable choice for estimating age, while gonial angle, coronoid ramus height, and projective ramus height are preferable for determining sex.

Mandibular second premolar distoangulation: a longitudinal follow-up from the mixed to the permanent dentition

OBJECTIVE

The aim of this study was to assess the frequency of mandibular second premolar (MnP2) distoangulation among orthodontic patients and the angular changes after a longitudinal follow-up.

METHODS

The sample was collected from the orthodontic records of 865 patients. The distoangulation group was composed of 42 patients (mean age 9.29 ± 1.24 years, 16 male, 26 female) with distoangulation of MnP2. The control group was composed of 32 patients (mean age 9.38 ± 1.10 years, 15 male, and 17 female) without distoangulation of MnP2. Panoramic radiographs taken in the mixed (T1) and the early permanent dentition (T2) were analyzed in both groups. Longitudinal angular changes (distal angle θ and premolar-molar angle γ), degree of root formation, second premolar depth, and prevalence of associated dental anomalies were analyzed. Intergroup comparison was performed with Mann-Whitney, t-tests, and chi-square tests (P < 0.05).

RESULTS

The prevalence of MnP2 distoangulation in the mixed dentition was 4.85%. The distoangulation group showed a smaller initial distal angle (59.34o ± 8.41) when compared to control group (79.88o ± 7.60). The spontaneous eruption of the MnP2 with distoangulation was observed in 76.57% of the sample. MnP2 distoangulation was significantly associated with agenesis of its antimere, small maxillary lateral incisors, and deciduous molar infraocclusion.

LIMITATIONS

Severe cases of MnP2 distoangulation were absent in this study.

CONCLUSIONS

The frequency of MnP2 distoangulation among orthodontic patients was 4.85%. Mild to moderate distoangulated Mnp2 spontaneously uprighted from the mixed to the permanent dentition. Small lateral incisors, second premolar agenesis, and infraocclusion of deciduous molar were frequently found in cases with MnP2 distoangulation.

Effect of orthodontic extraction of mandibular premolars on third molar angulation after treatment with fixed appliances : A cross-sectional study

PURPOSE

Orthodontic treatment involving premolar extractions might improve the angulation of lower third molars, which are the teeth most often impacted. This study analyzes the impact of first/second lower premolar extraction during orthodontic therapy on the angulation of mandibular third molars.

METHODS

A total of 120 patients treated non-extraction (n = 40), with extraction of first (n = 40), or second lower premolars (n = 40) were included. The mesiodistal angulation of lower third molars relative to the adjacent tooth and their developmental stage were evaluated from posttreatment orthopantomograms. Between-group differences were statistically evaluated at a significance level of 0.05.

RESULTS

The orthopantomograms of 120 patients (51% female) with a median age of 15.2 years at the time of debonding were evaluated after a mean treatment duration time of 2.9 years. No difference (P > 0.05) was seen between the average angulation of the lower third molars of the right (mean = 24.4°, standard deviation [SD] 13.6°) and the left side (mean = 23.6°, SD 14.1°). No differences in the angulation of the lower third molar were found between the non-extraction and extraction groups for the right (P = 0.44) or the left side (P = 0.22). Likewise, no differences were found when comparing the first and second premolars for the right (P = 0.26) or the left side (P = 0.10). Premolar extraction was associated with an advanced root development stage of the right third molar (odds ratio 7.1; 95% confidence interval 1.1-48.1; P = 0.04), with no differences between extraction of the first or second premolar (P = 0.10).

CONCLUSION

Orthodontic treatment involving premolars extractions might be associated with a small acceleration in root development, but not with the angulation, of lower third molars.

Intra- and Interrater Agreement of Face Esthetic Analysis in 3D Face Images

The use of three-dimensional (3D) facial scans for facial analysis is increasing in maxillofacial treatment. The aim of this study was to investigate the consistency of two-dimensional (2D) and 3D facial analyses performed by multiple raters. Six men and four women (25-36-year-old) participated in this study. The 2D images of the smiling and resting faces in the frontal and sagittal planes were obtained. The 3D facial and intraoral scans were merged to generate virtual 3D faces. Ten clinicians performed facial analyses by investigating 14 indices of 2D and 3D faces. Intra- and interrater agreements of the results of 2D and 3D facial analyses within and among the participants were evaluated. The intrarater agreement between the 2D and 3D facial analyses varied according to the indices. The highest and lowest agreements were found for the dental crowding index (0.94) and smile line curvature index (0.56) in the frontal plane, and Angle's classification (canine) index (0.98) and occlusal plane angle index (0.55) in the profile plane. In the frontal plane, the interrater agreements were generally higher for the 3D images than for the 2D images, while in the profile plane, the interrater agreements were high in the Angle's classification (canine) index however low in the other indices. Several occlusion-related indices were missing in the 2D images because the posterior teeth were not observed. Esthetic analysis results between 2D and 3D face images can differ according to the evaluation indices. The use of 3D faces is recommended over 2D images to increase the reliability of facial analyses, as it can fully assess both esthetic and occlusion-related indices.

Digital Radiographic Study of Gonial angle in Forensic Odontology in a Tertiary Care Centre: A Descriptive Cross-sectional Study

Introduction:

Gonial angle measurements serve as an important parameter of the craniofacial complex and are usually studied on lateral cephalograms, but recently panoramic radiographs have also been used. The aim of this study is to measure the gonial angle using orthopantomogram and lateral cephalogram based on age, gender, ethnicity, and skeletal malocclusion in a tertiary care hospital.

Methods:

This is a descriptive cross-sectional study comprising 350 selected radiographs of apparently healthy individuals collected for a period of one year, from the Department of Oral Radiology of a tertiary care centre of Nepal. Gonial angle measurements were recorded from digital panoramic radiograph (both right and left side) and lateral cephalogram. Data was collected in terms of age, gender, ethnicity, and skeletal malocclusion and then statistically analysed using the Statistical Package for the Social Sciences version 20.

Results:

The mean gonial angle for panoramic right, left and lateral cephalogram was 122.490±7.570, 123.620±7.060, and 124.150±6.910, respectively. There was a decrease in the mean values of the gonial angle observed as age advances seen in all the radiographs. The gonial angle measured in Class III malocclusion was higher in all the radiographs, followed by Class II and Class I. Gonial angles obtained in females were higher than the males in all the radiographs. Finally, the Aryan population showed a higher gonial angle compared to the Mongolian population in all the radiographs.

Conclusions:

Panoramic radiograph (left side), could be considered as a reliable tool to measure the gonial angle.

Effects of Angle class II correction with the Forsus fatigue resistant device on mandibular third molars : A retrospective study

PURPOSE

The goal was to evaluate the effects of Angle class II malocclusion treatment using the Forsus fatigue resistant device (FRD, 3M, St. Paul, MN, USA) on the position and angulation of mandibular third molars and retromolar space.

PATIENTS AND METHODS

In all, 58 class II patients (mean age 13.6 ± 1.8 years) treated with the FRD (FRD group) were compared with 51 class I patients (mean age 13.5 ± 1.6 years) who underwent orthodontic treatment (control group). A total of 109 mandibular third molars in the FRD group and 91 in the control group were evaluated. Changes in the retromolar space, angulation of the second (ɣ) and third molars (β), and the angle between these teeth (α) were assessed with panoramic radiographs taken at the beginning and the end of the treatment. Data were statistically analyzed.

RESULTS

At the end of the treatment, there were significant increases in ɣ and β in the FRD group and ɣ in the control group (p < 0.05). The decrease in α in the FRD group and increase in the control group were not significant (p > 0.05); however, this change led to a small significant change between the groups (p < 0.05). The retromolar space significantly increased in the FRD group compared to the control group (p < 0.05). No significant correlation was found between retromolar space and third molar uprighting in any of the groups (p > 0.05).

CONCLUSION

Class II correction with FRD led to mesialization of the lower arch which provided an increase in the retromolar space. Little improvement in the uprighting of the third molars occurred.

An Interdisciplinary Management of Severe Facial Asymmetry Due to Hemifacial Microsomia

This case report outlines the importance of an interdisciplinary approach and a patient centric outcome for the treatment of facial asymmetry resulting from hemifacial microsomia. Different treatment modalities are available to treat asymmetries. However, the best treatment outcome can be achieved only when the treatment plan is individualized for every patient. This report portrays an adult patient with hemifacial microsomia, who had facial asymmetry from the level of supraorbital region with a Class II skeletal base. Orthodontic treatment, along with surgical management, was required to transform the patient into a symmetrical profile, which is esthetically pleasing. A sound knowledge of the various technologies and resources that are available to us and making the best use of it to bring out a drastic change in the patient's life. Combined effort of the orthodontists and oral surgeons are required to manage patient's with hemifacial microsomia that has caused the severe facial asymmetry. Moreover, special attention has to be given to a patient-centric outcome.

TMD symptoms and vertical mandibular symmetry in young adult orthodontic patients in North Sumatra, Indonesia: a cross-sectional study

Background: Temporomandibular joint disorder (TMD) includes symptoms of pain and dysfunction in the muscles of mastication and the temporomandibular joint. Differences in vertical condylar height, observed in the assessment of mandibular asymmetry, is a structural alteration that represents a risk factor for TMD. The study aimed to evaluate the association between TMD symptoms and vertical mandibular symmetry in young adult orthodontic patients in North Sumatra, Indonesia.  Methods: The cross-sectional study included 18-25-year-old (mean ± SD, 21.9 ± 2.0 years) old orthodontic patients admitted to the Dental Hospital of Universitas Sumatera Utara, Medan, between June 2016 and March 2017. Vertical mandibular asymmetry was assessed from all 106 subjects using Kjellberg's technique from pre-treatment panoramic radiographs. The TMD symptoms were assessed by structural interviews using modified questionnaires based on Temporomandibular Disorder Diagnostic Index and Fonseca's Anamnestic Index. Results: Of the 106 subjects, 26 (24.5% of the total) with vertical mandibular symmetry and 39 (36.8%) with vertical mandibular asymmetry were positive for TMD symptoms. By contrast, 17 patients (16.0% of the total) with vertical condylar symmetry and 24 patients (22.6%) with vertical mandibular asymmetry were regarded negative for TMD symptoms. There was no significant difference (p=0.520) in TMD symptoms based on vertical mandibular symmetry. Conclusion: The results from this studied Sumatran population indicate that there are common TMD symptoms in young adult orthodontic patients, but there is no significant association between vertical mandibular asymmetry and TMD symptoms. Further study on the development of TMD, mandibular asymmetry and treatment planning for growing patients is suggested, using longitudinal and transitional approaches.

TMD symptoms and vertical mandibular symmetry in young adult orthodontic patients in North Sumatra, Indonesia: a cross-sectional study

Background: Temporomandibular joint disorder (TMD) includes symptoms of pain and dysfunction in the muscles of mastication and the temporomandibular joint. Differences in vertical condylar height, observed in the assessment of mandibular asymmetry, is a structural alteration that represents a risk factor for TMD. The study aimed to evaluate the association between TMD symptoms and vertical mandibular symmetry in young adult orthodontic patients in North Sumatra, Indonesia.  Methods: The cross-sectional study included 18-25-year-old (mean ± SD, 21.9 ± 2.0 years) old orthodontic patients admitted to the Dental Hospital of Universitas Sumatera Utara, Medan, between June 2016 and March 2017. Vertical mandibular asymmetry was assessed from all 106 subjects using Kjellberg's technique from pre-treatment panoramic radiographs. The TMD symptoms were assessed by structural interviews using modified questionnaires based on Temporomandibular Disorder Diagnostic Index and Fonseca's Anamnestic Index. Results: Of the 106 subjects, 26 (24.5% of the total) with vertical mandibular symmetry and 39 (36.8%) with vertical mandibular asymmetry were positive for TMD symptoms. By contrast, 17 patients (16.0% of the total) with vertical condylar symmetry and 24 patients (22.6%) with vertical mandibular asymmetry were regarded negative for TMD symptoms. There was no significant difference (p=0.520) in TMD symptoms based on vertical mandibular symmetry. Conclusion: The results from this studied Sumatran population indicate that there are common TMD symptoms in young adult orthodontic patients, but there is no significant association between vertical mandibular asymmetry and TMD symptoms. Further study on the development of TMD, mandibular asymmetry and treatment planning for growing patients is suggested, using longitudinal and transitional approaches.

Comparison of Orthopantomogram and Lateral Cephalogram for Mandibular Measurements

Aim:

The aim of the present study is to clarify the possible application of orthopantomogram (OPG) for evaluating craniofacial specifications such as angular and linear measurements of the mandible by comparing with lateral cephalogram.

Materials and Methods:

OPG and lateral cephalogram were taken from 100 patients of age group 16–35 years from Chettinad Dental College and Research Institute. Linear measurements (body length and ramus height) and angular measurement (gonial angle) were assessed both in lateral cephalogram and OPG. Independent t-test was performed for comparison of OPG and lateral cephalogram using SPSS with a probability level of P < 0.05 considered to be statistically significant.

Results:

The results of the present study show that there is no statistically significant difference in ramus height and gonial angle when compared between OPG and lateral cephalogram while statistically significant difference exists for body length between OPG and lateral cephalogram.

Conclusion:

It may be concluded that panoramic radiography can be used to determine the gonial angle and ramus height as accurately as a lateral cephalogram. However, clinicians should be vigilant when predicting horizontal measurement from OPGs.

Influence of orthodontic premolar extraction therapy on the eruption of the third molars: A systematic review of the literature

BACKGROUND

Through a systematic literature review, the authors assess the effect of premolar extractions on third-molar (M3) eruption considering eruption rate, retromolar space, and molar angulation.

TYPES OF STUDIES REVIEWED

The authors performed a systematic search using MEDLINE and Web of Science databases up through April 2017 to identify quality studies available comparing M3 eruption between a group with premolar extraction and a group without premolar extraction.

RESULTS

Twelve comparative retrospective cohort studies met all the inclusion criteria. The authors found in 5 studies comparing the rate of M3 eruption that there were significantly higher results in the group with extractions. They found in 5 studies comparing the evolution of the retromolar space significantly higher results in the group with extractions. Lastly, concerning the uprighting of the M3 during treatment, the authors found only 2 studies showing significant differences between the 2 groups, each time in favor of the group with extractions.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The dental literature on premolar extraction related to the eruption of the M3 is composed of average-quality retrospective studies. Premolar extraction significantly improves the chances of M3 eruption, but the level of evidence of comparative retrospective cohort studies is low. Clinicians must continue to rely on their judgment regarding premolar extraction on a case-by-case basis until the evidence is stronger. Retrospective studies with standardized protocols and more detailed methodologies are required to obtain higher levels of evidence.

Comparative analysis of the gonial angle on lateral cephalometric radiographs and panoramic radiographs

We measured the gonial angle (GA) on panoramic radiography (PR) and analyzed the correlation between the GA on PR and lateral cephalometric radiography (LCR). In total, 49 PR films and LCR films from dentate young adults were evaluated. Orthodontists plotted four points (articulare, menton, posterior gonion, and lower gonion) on the PR and carefully traced them. Using a protractor, two radiologists measured the GA on LCR images. A simultaneous experimental study of two dry skulls was performed to compare the GA on LCR and PR. The GA was slightly smaller on the PR of the dry mandible than on the LCR and tended to decrease continuously with magnitude toward the Frankfort horizontal plane. The mean GA was 115.1 ± 5.2° on PR and 122.2 ± 6.4° on the LCR. The values were highly correlated (Pearson product-moment correlation coefficient, 0.801). The GA on PR was nonsignificantly smaller than that measured on LCR. The difference may be due to head position, the inclination angle of the mandibular body, and/or the direction of the incident X-ray beam.

An evaluation of panoramic radiograph to assess mandibular asymmetry as compared to posteroanterior cephalogram

Aim and Objectives

To assess the reliability of orthopantomograms (OPGs) in detecting facial asymmetry.

Materials and Methods

The OPGs and posteroanterior cephalograms for 10 patients with facial asymmetry were obtained from the outpatient department of the dental college. These radiographs were traced and analyzed. Six measurements (four linear and two angular measurements) were made on both sides. Asymmetry was defined by subtracting the right and the left side measurements. The differences from OPG were compared to those obtained from posteroanterior cephalograms. The kappa statistics and intra-class correlation coefficient (ICC) were used to calculate the differences.

Results

The ICC was calculated between OPGs and posteroanterior cephalograms difference measurements. The class interval for all measurements was noted between 0.61 and 0.84. The ICC was 0.7861, which shows strong correlation between the values (P < 0.0005) by probability 10−5, within 95%, coefficient correlation lies between 0.61 and 0.84. Kappa test gives a value of 0.64, which shows strong agreement between the measurements.

Conclusion

Individually, the measurements from OPGs may not be reliable but the obtained difference between the values of the OPGs and the posteroanterior cephalograms are comparable in nature and show strong correlation and can be used to detect facial asymmetry.

Comparison of gonial angle determination from cephalograms and orthopantomogram

Introduction:

Gonial angle is an important parameter of the craniofacial complex giving an indication about the vertical parameters and symmetry of the facial skeleton. Both orthopantomogram (OPG) and lateral cephalograms can be used for the measurement of gonial angle. Because of the superimpositions seen on lateral cephalograms, reliable measurement of the gonial angle becomes difficult. The aim of the present study is to check the possible application and reliability of OPG for gonial angle determination by clarifying whether there is any significant difference between the determination of gonial angle from OPG and cephalogram.

Materials and Methods:

Gonial angle measurements were made on lateral cephalograms and orthopantomograms of 98 patients - 44 males (mean age 25.9 years) and 54 females (mean age 21.3 years), and compared using Statistical Package for Social Sciences.

Results:

One-way analysis of variance demonstrated no significant differences between the values of gonial angles determined by lateral cephalogram and panoramic radiography. Pearson correlation showed a high correlation between cephalometric and OPG gonial angle value.

Conclusion:

Panoramic radiography can be used to determine the gonial angle as accurately as a lateral cephalogram. For determination of the gonial angle, an OPG may be a better choice than a lateral cephalogram as there are no interferences due to superimposed images of anatomical structures as in a lateral cephalogram. Thus, the present study substantiates the possibility of enhancing the clinical versatility of the panoramic radiograph, which is an indispensable tool for dental diagnosis.

Influence of treatment including second molars on final and postretention molar angulation

OBJECTIVE

Evaluate axial mesiodistal inclinations of the mandibular molars in orthodontically treated cases, analyzing whether inclusion of second mandibular molars in treatment mechanics has any influence on final and postretention molars angulations.

METHODS

The sample comprised 150 panoramic radiographs of 50 patients. Patients were treated with extraction of four first premolars and divided into 2 groups: Group 1 comprised 25 subjects without inclusion of mandibular second molars during orthodontic treatment, whereas Group 2 comprised 25 subjects with inclusion of mandibular second molars. Panoramic radiographs at three observation times were evaluated: pretreatment, posttreatment and postretention. The statistical analysis included one-way analysis of variance (ANOVA) for intragroup evaluation and independent t-tests for intergroup comparisons.

RESULTS

Intragroup analysis demonstrated significant uprighting of mandibular first and second molars during treatment in Group 2, which remained stable during the postretention stage. Intergroup comparison demonstrated that Group 2 presented first and second molars significantly more uprighted in relation to Group 1 in both post-treatment and postretention stages.

CONCLUSIONS

It was concluded that inclusion of mandibular second molars in the orthodontic mechanics is relevant not only to correct the angulation of these teeth, but also to aid mandibular first molars uprighting.

Agreement between panoramic and lateral cephalometric radiographs for measuring the gonial angle

Background

The gonial angle is one of the most important measurements required for orthodontic treatment and orthognathic surgery. It is difficult to determine the accurate measurement of each gonial angle on cephalometric radiographs because of superimposition of the left and right angles.

Objectives

The aim of the present study was to determine the right and left gonial angles on panoramic radiographs and to compare them with an evaluated cephalometric sample.

Patients and Methods

A total of 80 panoramic and 80 cephalometric radiographs were obtained from 6 to 12-year-old children and the gonial angle was determined by the tangent of the inferior border of the mandible and the most distal aspect of the ascending ramus and the condyleon both panoramic and cephalometric radiographs. We used Pearson’s correlation coefficient and paired t-test for comparison.

Results

The mean gonial angle was 127.07 ± 6.10 and 127.5 ± 6.67 degrees on panoramic and cephalometric radiographs, respectively. There was no statistically significant difference between the measured gonial angles on panoramic and cephalometric radiographs and also no difference between the right and left (both Ps = 0.18)

Conclusion

The value of the gonial angle measured on panoramic radiography was the same as that measured on the routinely used cephalometric radiography.

Effect of premolar extraction on mandibular third molar impaction in young adults

OBJECTIVE

To test the null hypothesis that orthodontic therapy with or without premolar extraction does not result in any difference in third molar impaction.

MATERIALS AND METHODS

Two groups were formed: 22 patients in one group with first premolar extractions and 22 patients in the other group without extractions. All patients were nongrowing subjects who had normal gonial angles and were skeletal Class I at the beginning of treatment. The available space for third molars, inclination of second and third molars, and angle between the second and third molars were evaluated. Also, the correlation of measured parameters and type of orthodontic therapy with the eruption of third molars was evaluated.

RESULTS

Of the third molars, 81.8% were impacted in the nonextraction group and 63.6% were impacted in the extraction group. Impaction of mandibular third molars was significantly correlated to the pretreatment and posttreatment inclination of third molars and the angle between the second and third molars. In the extraction therapy group, the retromolar distance increased significantly with a mean of 1.30 ± 1.25 mm.

CONCLUSIONS

When the inclination of the third molar is inconvenient, the tooth may remain impacted even if there is enough retromolar space.

Extraction of maxillary first molars improves second and third molar inclinations in Class II Division 1 malocclusion

INTRODUCTION

The aim of this study was to assess the changes in inclination of the maxillary second (M2) and third (M3) molars after orthodontic treatment of Class II Division 1 malocclusion with extraction of maxillary first molars.

METHODS

Two groups of subjects were studied. The experimental group consisted of 37 subjects, 18 boys and 19 girls (mean age, 13.2 ± 1.62 years). The inclusion criteria were white origin, Class II Division 1 malocclusion, overjet ≥4 mm, no missing teeth or agenesis, and maxillary M3 present. All patients were treated with extraction of the maxillary first molars and the Begg technique. Standardized lateral cephalometric radiographs were taken at the start of active treatment (T1) and at least 3.7 years posttreatment (T2). The control group was drawn from the archives of the Nittedal Growth Material (Oslo University, Oslo, Norway) and included 54 untreated Class I and Class II subjects,18 boys and 36 girls (mean age, 13.4 ± 1.99 years) followed up for a minimum of 3.6 years. M2 and M3 inclinations relative to the palatal plane (PP) and functional occlusal plane (FOP) were measured and compared between groups and time periods.

RESULTS

M2 to PP inclination improved significantly in both the control group (M2-PP at T1, 17.7° ± 5.81°, and at T2, 11.9° ± 4.61°) and the experimental group (M2-PP at T1, 26.7° ± 5.75°, and at T2, 6.9° ± 6.76°). There were also significant increases of the mesial inclination of M3 in the control group (M3-PP at T1, 30.1° ± 8.54°, and at T2, 19.6° ± 9.01°) and extraction group (M3-PP at T1, 32.2° ± 7.90°, and at T2, 12.8° ± 7.36°). By using the FOP as the reference system, no significant change in the inclination of M2 was observed in the control group, whereas, in the extraction group, although more distally inclined at T1, M2 ended up mesially inclined at T2 (M2-FOP at T1, 14.2° ± 4.62°, and at T2, -6.2° ± 6.10°; P <0.0001). M3 inclinations were similar between the groups at T1 (M3-FOP control, 17.3° ± 9.35°; M3-FOP experimental, 19.6° ± 7.37°), and these improved significantly in both groups. However, M3 uprighting was almost 4 times greater in the extraction group (M3-FOP from T2-T1, 5.6° vs 19.9°). The greatest distal inclination of M3 at T2 in the extraction group was 9.4°, a value attained by only 43% of the control group.

CONCLUSIONS

Extraction of the maxillary first molars in Class II Division 1 patients results in significant uprighting of M2 and M3 and facilitates the normal eruption of M3.

Reliability of panoramic radiographs for the assessment of mandibular elongation after distraction osteogenesis procedures

To determine whether panoramic radiographs could be used for evaluation of changes in the vertical and horizontal dimensions following internal curvilinear mandibular distraction osteogenesis.

STUDY DESIGN

A retrospective cohort study included 25 patients who underwent bilateral mandibular distraction surgery. Three panoramic radiographs and lateral cephalograms from each patient were available: before distraction, immediately upon termination of the distraction process, and at the end of the follow-up period. The radiographs were traced by plotting Condylion, Gonion, and Menton. The linear distances between Condylion and Gonion and between Gonion and Menton were measured on each side, and the correlation was calculated.

RESULTS

No significant differences were found between the values of the linear measurements determined by lateral cephalograms and panoramic radiographs (p ≥ 0.079), excluding one measurement. The correlation test for these radiographs showed very high, positive and statistically significant correlations, for both sides of the internal mandibular distraction (r > 0.77, p ≤ 0.0001), apart from three measurements.

CONCLUSION

Panoramic radiographs, with mandibular length (Co-Go and Go-Me) measurements, can be used as an alternative to lateral cephalograms, i.e. as a reliable tool for assessing vertical and horizontal dimensional changes resulting from internal mandibular distraction achieved by a curvilinear distractor.

Incremental growth of the maxillary tuberosity from 6 to 20 years-A cross-sectional study

OBJECTIVES

Although the maxillary tuberosity (MT) is a major growth site of the maxilla, its time-related growth was not fully investigated. The objectives of the study were to evaluate the MT growth from 6 to 20 years of age defining the peak growth age and to assess time-related indicators.

DESIGN

Panoramic radiographs from 189 patients were divided in a cross-sectional study into six age groups. A special panoramic analysis was developed including 18 parameters and 3 time-related indicators, i.e., chronological age, crown/root development stages of the maxillary second (M(2)) and third (M(3)) molars and eruption stages.

RESULTS

From 6 to 20 years, the MT vertical growth was 5.17-fold greater than the horizontal. The horizontal growth covered 36% of the maxillary growth but was inadequate to secure space for third molar eruption despite a 51% increase in MT area. MT peak growth was between 8 and 9 years and 10-11 year. During these 14 years, the maxillary length increased by pneumatisation of the maxillary sinus (86%), growth of the MT (36%) and decrease of the anterior maxillary region (-22%). Of the 18 examined parameters, 83% showed dependency to the combination chronological age with M(2), M(3) crown/root development stage and 72% to the combination chronological age with M(2), M(3) eruption stage.

CONCLUSION

MT growth peak occurs with initiation of root development of M(2) and shortly before M(2) eruption (8-9 years to 10-11 years). Dental time-related indicators adjunct with the chronological age provide an effectual system to define MT growth potential.

Mesiodistal angulations of the mandibular canines, premolars and molars with or without the presence of third molars

SUMMARY

The purpose of the present research was to compare the normal average values of mesiodistal axial angulation, with the mesiodistal axial angulation of canines, premolars and mandibular molars in individuals with and without the presence of the mandibular third molars. Panoramic radiographs of 19 male and 21 female Caucasians, with a mean age of 22.35 years, who had not undergone orthodontic treatment were studied. The subjects were divided into two groups: group I, 20 radiographs of subjects without, and group II, 20 radiographs of subjects with mandibular third molars. The mean values of the groups were compared using a Student's t-test. The results show that, in both groups, the mandibular premolars and molars had enhanced angulation in the mesial direction, when compared with a control group of 42 Caucasians ranging in age from 12 to 17 years with a 'normal' occlusion (P < 0.05), while the mesiodistal axial angulation of the mandibular canines was similar to the control group (P < 0.05). The two groups, when compared, exhibited similar angular values for the canines, premolars and mandibular molars (P < 0.05), indicating no influence of the third molars.

Panorametry: suggestion of a method for mandibular measurements on panoramic radiographs

Background

Orthopantomography (panoramic radiography) has been used for the study of measurements involving particularly the prediction of the eruption of impacted lower third molars and analyses of measurements of the ramus and head of mandible. The discrepancies involved with the projection of this radiographic image has stimulated the search for further ways to use it, particularly in orthodontic treatments and oral and maxillofacial surgeries. The author proposes a graphimetric method for the mandible, based on panoramic radiography. The results are expressed in linear and angular measurements, aiming at bilateral comparisons as well as the determination of the proportion of skeletal and dental structures, individually and among themselves as a whole. The method has been named Panorametry, and allows measurement of the mandible (Mandibular Panorametry) or the posterior mandibular teeth (Dental Panorametry). When combining mandible and maxilla, it should be referred to as Total Panorametry. It may also be used, in the future, with Cone Beam computed tomography (CT) images, and in this case it may be mentioned as CT Panorametry.

Linear Mandibular Measurements: Comparison between Orthopantomograms and Lateral Cephalograms

Objective:

To investigate the reliability of length measurements of the mandible by comparing orthopantomograms (OPTs) with lateral cephalograms.

Design:

Observational study.

Setting:

OPTs and lateral cephalograms were taken of 20 human dry skulls. Four orthodontists and four maxillofacial surgeons located landmarks on all radiographs using a computer program for cephalometric measurements. Intraobserver and interobserver variability in locating landmarks was assessed, as well as positioning of the skulls prior to radiography between the x-ray assistants. Magnification differences between the left and right side of the mandible on the OPT were determined for five skulls. Kappa statistics were used to calculate the intraclass correlation coefficient for intraobserver and interobserver differences. An F test was used to assess differences between methods and between type of observer.

Results:

No significant differences were found in the magnification factor of the left and right side of the mandible. Compared with a lateral cephalogram, the OPT had comparable reliability in measuring mandibular distances condylion-gonion, gonion-menton, and condylion-menton. No significant differences were observed between the x-ray assistants in taking the OPTs and lateral cephalograms or in repositioning the skulls. Significant differences were found between orthodontists and maxillofacial surgeons for landmark measurements.

Conclusion:

An OPT is as reliable as a lateral cephalogram for linear measurements of the mandible (condylion-gonion, gonion-menton, and condylion-menton).

Panoramic evaluation of mesiodistal axial inclinations of maxillary anterior teeth in orthodontically treated subjects

INTRODUCTION

The objectives of this study were to evaluate, through panoramic radiographs, the mesiodistal axial inclinations of the maxillary anterior teeth at the beginning and end of nonextraction orthodontic treatment, and to compare the results with the mesiodistal axial inclinations of a control sample with normal (acceptable) occlusions.

METHODS

The experimental sample consisted of 40 white patients (20 male, 20 female; mean age, 14 years) with Class I maloccusions who were treated orthodontically with a standard edgewise (not preadjusted) technique without extractions. The mean treatment period was 1.6 years. The control sample comprised 42 white subjects (14 male, 28 female; age range, 12-17 years) with untreated normal (acceptable) occlusions. Panoramic radiographs were taken of the patients at the beginning (T1) and end (T2) of treatment. The mean values of the mesiodistal axial inclination at T1 were compared with the mean values at T2, and both were compared with the mesiodistal axial inclinations of the control sample.

RESULTS

The mesiodistal axial inclinations of the maxillary anterior teeth of the experimental group at T1 were different from those of the control group for 50% of the evaluated teeth. In contrast, the inclinations at T2 were consistent with the normal anatomical configuration of the controls.

CONCLUSIONS

The panoramic radiograph is an effective tool for evaluating the mesiodistal axial inclinations of maxillary anterior teeth.