Effect of orthodontic therapy on the facial profile in long and short vertical facial patterns

Lip and incisor changes in patients with different ethnicities treated with extraction versus nonextraction: A cone-beam computed tomography study

BACKGROUND

This study used cone-beam computed tomography (CBCT) via voxel-based superimposition to evaluate lip and incisor changes after orthodontic treatment with four premolar extractions (Ext) versus nonextraction (Non-Ext) among African American (AA) and White (W) patients.

METHODS

A total of 240 CBCTs of 120 adolescent orthodontic patients with Class I skeletal/dental relationships were included. Patients were initially divided according to treatment, and then each group was subdivided according to patients' ethnicity (Ext/W = 30, Ext/AA = 30, Non-Ext/W = 30, and Non-Ext/AA = 30). CBCTs were imported into Invivo6 for voxel-based superimposition. Lip and incisor measurements were recorded. Independent t tests and two-way ANOVA were used for statistical assessment.

RESULTS

The Non-Ext/W group had a greater increase in all outcome variables compared with the Non-Ext/AA group, with a significant change in volume and position of upper (UL) and lower lips (LL), inclination of upper (U1) and lower incisors (L1), and position of U1. The Ext/AA group had a greater decrease in all measured outcomes compared with the Ext/W group, with significant change in inclination of U1 and L1, and position and volume of LL. W patients had more crowding than AA patients in both treatment approaches. Retraction ratios of 6.5:1 and 2.1:1 were recorded between the U1 and UL positions, and L1 and LL positions, respectively. There were no direct interaction effects between ethnicity and treatment, nor were there any significant effects of ethnicity after controlling for the covariates.

CONCLUSIONS

Ethnicity alone has no impact on incisor and lip position after treatment. However, ethnicity in the form of initial presentation of malocclusion can have a significant influence.

Incisors inclination in relation to lip parameters: a CBCT study

INTRODUCTION

With the introduction of Cone Beam Computed Tomography (CBCT) in dentistry, precise measurements are now attainable.

OBJECTIVE

This study seeks to explore the correlation between incisors inclination and various lip parameters utilizing CBCT technology. Moreover, it aims to assess whether specific incisors inclinations significantly influence lip thickness, length, and position.

MATERIAL AND METHODS

This was a retrospective observational study of available records of orthodontic patients (n=84) aged between 11 and 17.5 years old with pre- and post-treatment CBCT imaging. The 3D Slicer software was used to assess lip parameters and incisors inclinations while adhering to standard CBCT imaging methods. Statistical analysis was conducted to find associations between incisors inclination and lip parameters.

RESULTS

Within certain limits of incisor inclination, lip parameters showed minimal impact. Changes in upper incisor inclination within an average of 5° did not significantly correlate with upper lip parameters. Similarly, changes in lower incisor inclination within an average of 5.6° had no significant effect on lower lip parameters. However, inclination changes of tooth #21 within 5.4° significantly affected upper lip length within 0.35mm.

CONCLUSIONS

Lip parameters remained unaffected with specific ranges of incisor inclinations, except for a slight effect on upper lip length with changes in inclination of tooth #21. Clinicians can consider the specific ranges of incisors inclination during treatment planning, especially for patients concerned about lip appearance.

Hard and soft tissue shape variation and changes in Class II division 1 malocclusion during orthodontic treatment: a geometric morphometric analysis

BACKGROUND

This study aims to determine the hard and soft tissue shape variation and its changes in Class II division 1 malocclusion before and after orthodontic treatment using Geometric Morphometric Analysis.

METHODS

This retrospective study included 141 pre-treatment and near-end treatment lateral cephalometric radiographs of Class II division 1 malocclusion patients aged 16-40 years with a skeletal II pattern (ANB > 4o). 32 landmarks in Cartesian coordinates were created and identified using MorphoJ software to establish a shape analysis.

RESULTS

The vertical dimensions (hypodivergent to hyperdivergent facial profiles) showed the largest variation in the general shape of hard and soft tissue, followed by the anteroposterior dimensions (mild to severe skeletal II patterns). Variations of lip shape (long to short), lip protuberance (everted to inverted), and nasolabial angle (obtuse to acute) were present. Orthodontic treatment affected the shape of the hard and soft tissue significantly (p < 0.0001). T2 showed significant uprighting of upper incisors (17.5o) and lower incisors (3.7o), improved NLA (8o), an increase in upper lip thickness (1.5 mm), and a reduction in lower lip thickness (0.7 mm) (p < 0.05).

CONCLUSION

Vertical and anteroposterior shape variations were found. Orthodontic treatment had an impact on both hard and soft tissue shapes. Hence, understanding both the hard and soft tissue shape variations and the orthodontic treatment changes is crucial for an accurate diagnosis and treatment plan to achieve a successful outcome and excellent patient satisfaction.

3D analysis of maxillomandibular morphology in hyperdivergent and hypodivergent individuals: A cross-sectional study

INTRODUCTION

The aim of this cross-sectional study was to investigate maxillomandibular morphology in hyperdivergent and hypodivergent individuals, using 3D surface models generated by cone-beam computed tomography (CBCT).

METHODS

The sample consisted of 60 CBCTs (30 males, 30 females) patients aged 12-30 years, divided into two groups comprising hyperdivergent (≥35°) and hypodivergent (≤30°) individuals, according to the mandibular plane (MP) angle. Multiplanar reconstructions were used to mark the landmarks, and 3D surface models were created to evaluate structures of the maxillomandibular complex, including condyle, ramus, symphysis and palatal height. Intergroup comparisons were performed by independent t-test. Pearson's correlation test was used (P < .05) to evaluate the correlation of the MP angle with the angles and linear measurements of other structures.

RESULTS

Significant differences were found between the groups regarding condylar width, ramus height, condylar plus ramus height, mandibular length, gonial angle, palatal plane angle and palatal-mandibular angle. No differences (P > .05) were found for the condylar height, symphysis inclination angle or palatal height. Correlations (P < .05) were found between the MP angle and structures of the maxillomandibular complex.

CONCLUSIONS

Hyperdivergent (MP ≥ 35°) and hypodivergent (MP ≤ 30°) individuals present different skeletal morphology regarding condylar width, ramus height, condylar plus ramus height, mandibular length, gonial angle, palatal plane angle and palatal-mandibular angle. There is a significant correlation between MP angle and morphological structures such as condyle, ramus, symphysis, palatal plane angle and palatal-mandibular angle.

Influence of lip position on esthetics perception with respect to profile divergence using silhouette images

BACKGROUND

The aim of the study was to determine the facial divergence and lip position combinations that are most and least preferred, and to investigate whether age or gender has an impact on these preferences.

METHODS

The current investigation was carried out on a sample of 1077 individuals who were not experts in the field (253 men and 824 females). The research employed black silhouette photographs of profiles featuring different lip locations and profile divergences. The recruitment of participants was conducted in order to assess the attractiveness of the profiles, employing a Likert scale. The various positions of the lips and variations in facial profiles were thoroughly categorized. Results were analyzed using the Chi-square test.

RESULTS

The findings of the research demonstrated that aesthetic perceptions displayed diversity when considering different lip locations and profile divergences. It was shown that neutral lip positions were predominantly favored, accounting for approximately 40.2% of the total frequencies in the anterior diverging group. It is noteworthy to highlight the aesthetically pleasing features exhibited by those with the most prominent lip position, occurring at a frequency of 10.9% in straight-diverging group. In the posterior divergent group, the most protruded lip position, showed very attractive aesthetics with frequency (7.1%). Gender, age, region, and level of education had significant influence on aesthetic perception.

CONCLUSIONS

The variety of aesthetic preferences is influenced by the location of the lips and the divergence of the facial profile, resulting in different outcomes within the categories of anterior, straight, and posterior divergence. Clinicians are advised to customize the treatment regimen in order to correspond with the unique desires and preferences of the patient.

Analyzing the effects of tooth extraction on the lip in orthodontic treatment

INTRODUCTION

The aim of this study was to analyze changes occurring in the lip and facial soft-tissue profile after fixed orthodontic treatment, with or without tooth extraction, in patients with dental class II malocclusion.

MATERIALS AND METHODS

Measurements were made on cephalometric films of 75 individuals with dental class II malocclusion before and after fixed orthodontic treatment. The patients were divided into three groups: no extraction, extraction of upper two premolars, or extraction of four premolars. The parameters measured were: basic upper lip thickness (BULT), vermilion upper lip thickness (VULT), upper lip inclination (ULI), basic lower lip thickness (BLLT), vermilion lower lip thickness (VLLT), lower lip inclination (LLI), face axis angle (Ba-N/PtmGn), labiomental angle, facial convexity angle, and total face convexity angle. The results were analyzed statistically using the Wilcoxon, Kruskal-Wallis, and Mann-Whitney U tests.

RESULTS

It was found that the VULT value in the group with no extraction was lower than the four-extraction group (P = 0.001; P < 0.05). The VULT value in the upper-two extraction group was significantly lower than that in the four-extraction group, and the Ba-N/PtmGn in the no-extraction group was lower than that in the four-extraction group (P = 0.001; P < 0.05).

CONCLUSIONS

These findings suggest that tooth extraction in orthodontic treatment may affect the vermilion upper lip thickness and facial axis, but that this does not have any negative effects on the soft-tissue facial profile. Premolar tooth extraction can be performed by establishing an accurate diagnosis and treatment plan to avoid undesirable and negative effects on the facial soft-tissue profile.

Factors that affect lip changes following incisor retraction in Vietnamese adults with a convex facial profiles

OBJECTIVE:

This study aimed to evaluate the factors that influence lip change through the results of tooth anterior retraction by fixed orthodontic treatment in Vietnamese adult patients with a convex facial profile.

MATERIALS AND METHODS:

This prospective study included 32 Vietnamese adults who have convex facial profiles. Digital software measurements according to Arnett's analysis and the superimposition method were performed to evaluate the changes in dentoskeletal structures, and soft tissue variables included lip change. A multiple logistic regression model was applied with various explanatory variables to analyze the correlation.

RESULTS:

The study revealed a strong correlation of lip change at the site of the cervical point and incisal edge of the upper incisors, and the cervical position demonstrated a stronger correlation. The ratio between lip change and incisor retraction in patients is approximately 1:2.3 at the incisal edge and 1:1.3 at the cervical point.

CONCLUSION:

Lip change was associated with incisor retraction at the cervical and incisal edge, but it did not correlate with the rotation axis of the upper incisors.

Photographic Profile Analysis in Preschool Children of Thiruvananthapuram, Kerala

Aim

The purpose of the study is to establish baseline normative data regarding facial soft tissue profile measurements in preschool children of Thiruvananthapuram.

Materials and methods

The present study was a cross-sectional study conducted at the Department of Pedodontics, Government Dental College, Thiruvanthapuram. Two hundred fifty children of 3 to 5 years of age reporting at the outpatient department with complete primary dentition and flush terminal plane molar relation were the sampling unit. Children with mixed dentition, with the a presence of proximal caries and any oral habit and maxillofacial trauma/pathology/developmental defects, were not included in the study. The level of significance for the study was set as p < 0.05.

Results

Mean values of the study variable with standard deviation obtained with a narrow range of 95% the confidence interval indicated higher accuracy of the study.

Conclusion

The values obtained in the study can be used as a reference for an initial orthodontic evaluation of a child during the early mixed dentition period. The study will help in predicting the direction of growth of the dentofacial region, its effect on facial parameters, and, hence, the treatment plan can be modified accordingly. The study will serve as the reference study for further studies with molar plane relation other than FTP.

How to cite this article

Gautam B, Sreedharan S, et al. Photographic Profile Analysis in Preschool Children of Thiruvananthapuram, Kerala. Int J Clin Pediatr Dent 2019;12(2):111–115.

Improvement of facial profile by nonextraction orthodontic treatment with temporary skeletal anchorage devices and visual treatment objectives

A 15-year-old girl with a convex profile and a retrognathic chin was referred for improvement of her profile. Nonextraction orthodontic therapy with temporary skeletal anchorage devices was used to improve her facial balance in a total active treatment time of 26 months. Her occlusion and profile were significantly improved by the treatment. Posttreatment records after 12 months showed excellent results with good occlusion and facial harmony.

Long-term stability of soft tissue changes in anterior open bite adults treated with zygomatic miniplate-anchored maxillary posterior intrusion

OBJECTIVES

To evaluate soft tissue changes and their long-term stability in skeletal anterior open bite adults treated by maxillary posterior teeth intrusion using zygomatic miniplates and premolar extractions.

MATERIALS AND METHODS

Lateral cephalograms of 26 patients were taken at pretreatment (T1), posttreatment (T2), 1 year posttreatment (T3), and 4 years posttreatment (T4).

RESULTS

At the end of treatment, the soft tissue facial height and profile convexity were reduced. The lips increased in length and thickness, with backward movement of the upper lip and forward movement of the lower lip. The total relapse rate ranged from 20.2% to 31.1%. At 4 years posttreatment, 68.9% to 79.8% of the soft tissue treatment effects were stable. The changes in the first year posttreatment accounted for approximately 70% of the total relapse.

CONCLUSIONS

Soft tissue changes following maxillary posterior teeth intrusion with zygomatic miniplates and premolar extractions appear to be stable 4 years after treatment.

Comparison of the effect of labiolingual inclination and anteroposterior position of maxillary incisors on esthetic profile in three different facial patterns

Objective:

To test the null hypothesis that there is no effect of esthetic perception of smiling profile in three different facial types by a change in the maxillary incisor inclination and position.

Materials and Methods:

A smiling profile photograph with Class I skeletal and dental pattern, normal profile were taken in each of the three facial types dolichofacial, mesofacial, and brachyfacial. Based on the original digital image, 15 smiling profiles in each of the facial types were created using the FACAD software by altering the labiolingual inclination and anteroposterior position of the maxillary incisors. These photographs were rated on a visual analog scale by three panels of examiners consisting of orthodontists, dentists, and nonprofessionals with twenty members in each group. The responses were assessed by analysis of variance (ANOVA) test followed by post hoc Scheffe.

Results:

Significant differences (P < 0.001) were detected when ratings of each photograph in each of the individual facial type was compared. In dolichofacial and mesofacial pattern, the position of the maxillary incisor must be limited to 2 mm from the goal anterior limit line. In brachyfacial pattern, any movement of facial axis point of maxillary incisors away from GALL is worsens the facial esthetics. The result of the ANOVA showed differences among the three groups for certain facial profiles.

Conclusion:

The hypothesis was rejected. The esthetic perception of labiolingual inclination and anteroposterior of maxillary incisors differ in different facial types, and this may effect in formulating treatment plans for different facial types.

Effect of different incisor movements on the soft tissue profile measured in reference to a rough-surfaced palatal implant

INTRODUCTION

The aim of this study was to evaluate soft tissue profile changes after a wide range of incisor movements in the anterior and posterior directions in nongrowing patients. Identifying baseline values more prone to substantial soft tissue profile changes was of high interest.

METHODS

For this retrospective study, 47 pairs of lateral cephalograms of nongrowing white patients were superimposed. The cephalograms were taken with the same palatal implant in situ before and after treatment. To increase the accuracy of the measurements, the palatal implants were used as stable reference structures in close relation to the incisors.

RESULTS

Horizontal changes of the most anterior point of the maxillary incisor showed a significant correlation to horizontal changes of the upper and lower lips (P <0.001). For every millimeter of horizontal change of the most anterior point of the maxillary central incisor, a change of 0.59 mm at labrale superior can be expected. Also, the angulations of the upper and lower lips were significantly correlated to the most anterior point of the maxillary incisor. Lip retraction was less pronounced in patients with initially thicker lips than in those with thinner lips.

CONCLUSIONS

The major contributing factors for predicting the soft tissue profile change during orthodontic treatment are the amount of horizontal movement of the most anterior point of the maxillary incisor, the amount of bite opening, and the initial lip thickness. Although there are significant correlations between dental movements and soft tissue changes in larger samples, predictions for individuals may be inconsistent.

Dynamic smile evaluation in different skeletal patterns

Objective:

To evaluate dynamic smile in different skeletal patterns and to correlate vertical smile parameters with the underlying causative factors.

Materials and Methods:

A total of 150 participants ranging in age from 16–25 years were selected and divided into one of three groups—horizontal, average, and vertical skeletal pattern—using the following three cephalometric parameters: SN-MP, FMA, and Jarabak ratio. Videographic records of smile were obtained, and measurements were recorded and analyzed at rest, including upper lip length, and during smile, including maxillary incisal display, interlabial gap, intercommisural width, change in upper lip length, and smile arc. Differences among the three groups were subjected to two-way analysis of variance and post hoc and chi-square tests for smile arc. Correlations between vertical smile variables and vertical skeletal (N-ANS, N-Me) and dental cephalometric measurements (U1 to palatal plane) were also investigated.

Results:

Vertical parameters were significantly increased in the vertical pattern when compared with the horizontal pattern, ie, upper lip length (P &lt; .01), maxillary incisal display (P &lt; .001), interlabial gap (P &lt; .001), and change in upper lip length (P &lt; .001), whereas intercommisural width was significantly decreased in vertical pattern when compared with the horizontal pattern (P &lt; .001). Flat smile arc was seen more frequently in the horizontal pattern. Positive correlations were found between the N-Me, U1-PP, and change in upper lip length with vertical smile parameters.

Conclusions:

Different skeletal patterns exhibit their characteristic smile features. Upper lip length is not responsible for increased incisal display during smile. Increased incisal display during smile is more closely associated with upper lip elevation than vertical skeletal and dental factors.

Velocity of Canine Retraction in Angle Class I Treated with First Premolar Extraction: Effect of Facial Pattern

Recently, new methods have been applied to increase velocity of tooth movement. A standard mean of tooth movement velocity remains to be established, however. Moreover, to our knowledge, no studies have investigated the effect of factors affecting this velocity. The aim of the present study was to investigate the effect of facial pattern on the mean velocity of canine retraction in selected cases of orthodontic treatment carried out at this hospital. A total of 112 patients with Angle Class I crowding treated with extraction of the bilateral maxillary and mandibular first premolars and a conventional edgewise bracket were selected at random. The canine retraction period was defined as that between the end of leveling and the beginning of anterior retraction, and was obtained from medical records. Calipers were used to measure how far the canine cusps moved between pre- and post-surgically on superimposed cephalometric tracings. The velocity of canine retraction was significantly slower in the maxilla of male patients with a brachyofacial pattern (p<0.01). Canine retraction is the longest stage of orthodontic treatment. Here, movement was slowest in the maxilla of male patients with a brachyofacial pattern. This indicates that treatment may take longer than average in male patients with a brachyofacial pattern, and that this should be explained prior to commencing such work.

Distal movement of the mandibular dentition with temporary skeletal anchorage devices to correct a Class III malocclusion

This case report describes the treatment of an 18-year-old man with a skeletal Class III pattern and a full-step Class III malocclusion. The orthodontic treatment included distal movement of the mandibular dentition with temporary skeletal anchorage devices. The total active treatment time was 30 months. His occlusion and facial appearance were significantly improved by the orthodontic treatment. Posttreatment records 2 years later showed excellent results with good occlusion and facial balance.

Influence of treatment with and without extractions on the growth pattern of dolichofacial patients

OBJECTIVE: The objective of this retrospective study was to compare, by means of lateral cephalograms, the facial growth pattern changes due to the treatment with and without extractions of four first premolars in dolichofacial individuals. METHODS: Groups 1 and 2 were constituted of 23 dolichofacial patients each, with Class II malocclusion, division 1 and initial age average of 12.36 and 12.29 years, respectively. Patients from Group 1 were treated without extractions and Group 2 was treated with extraction of the four first premolars, given that both used occipital headgear. Groups were compatibilized according to age, treatment period, gender and malocclusion severity. The t test was applied for intergroups comparison. RESULTS: Most variables (SN.PP, SN.Ocl and FMA) did not present statistically significant difference between groups. CONCLUSION: Although the treatment with extractions tend to reduce the mandibular plane angle (SN.GoGn) and the facial axis (NS.Gn), the analyzed treatment protocols did not affect in a clinically relevant way the facial growth pattern.

Comparação das dimensões de tecido mole entre padrões faciais distintos

OBJETIVO: o presente estudo destinou-se a comparar a morfologia tegumentar de indivíduos segundo a tipologia facial. MÉTODOS: foram utilizadas 90 telerradiografias de pacientes de ambos os sexos, de 12 a 16 anos de idade, divididas em três grupos distintos, referentes a cada padrão morfológico: mesofacial, dolicofacial e braquifacial. Os grupos foram comparados no que se refere às medidas de espessura e altura do lábio superior e inferior, além da espessura do mento mole. Ainda, foi apurada a presença de correlações entre as variáveis de tecido mole avaliadas e medidas cefalométricas de natureza dentária e esquelética. RESULTADOS E CONCLUSÕES: os lábios superiores e inferiores, assim como o mento mole, não apresentaram diferenças em relação às suas espessuras em todos os grupos morfológicos. Porém, as alturas do lábio superior e inferior foram significativamente maiores para os dolicofaciais quando esses foram comparados aos demais grupos. Braquifaciais apresentaram menor altura do lábio superior quando comparados aos mesofaciais, embora ambos não tenham se diferenciado significativamente no que se refere à altura do lábio inferior. A análise das correlações estabelecidas entre as variáveis dos tecidos moles e duros indicou evidências de um desenvolvimento vertical dos lábios superior e inferior em acompanhamento ao desenvolvimento vertical do esqueleto. O posicionamento vertical do incisivo superior se correlacionou significativamente aos mesmos parâmetros labiais, o que garantiu um nível de exposição semelhante desse elemento dentário em todos os grupos.

Three-dimensional facial surface analysis of patients with skeletal malocclusion

Three-dimensional (3D) laser surface scanning analysis has taken hold in orthodontics, as well as craniomaxillofacial and plastic surgery as a new tool that can navigate away from the limitations of conventional two-dimensional methods. Various techniques for 3D reconstruction of the face have been used in diagnosis, treatment planning and simulation, and outcomes follow-up. The aim of the current prospective study was to present some technical aspects for the assessment of facial changes after orthodontic and orthognathic surgery treatment using 3D laser surface scanning. The technique proposed for facial surface shape analysis represented three-dimensionally the expected surgical changes, and the reduction of the postoperative swelling was verified. This study provides technical information from the data collection to the 3D virtual soft-tissue analysis that can be useful for diagnostic information, treatment planning, future comparisons of treatment stability or facial postoperative swelling, and soft-tissue profile assessment.

Profile changes of patients treated with and without premolar extractions

INTRODUCTION

In this study, we evaluated and compared treatment effects and long-term soft-tissue profile changes in patients treated with extraction of 4 first premolars and with a nonextraction protocol.

METHODS

Cephalometric records of 98 patients were evaluated. For half (n = 49) of the patients, treatment included the extraction of 4 first premolars; the other 49 patients had no premolar extractions. The groups were evaluated before treatment (T1), at the end of treatment (T2), and at least 4 years postretention (T3).

RESULTS

At T1, the extraction group had more protrusive lower lips than the nonextraction group, as measured by the Z-angle. At T2, the Z-angles had improved in both groups and were not significantly different. During treatment, upper lip vermilion and superior thicknesses increased, whereas lower lip vermilion thickness decreased in both groups. Except for lower lip inferior thickness, which increased significantly in the nonextraction group, no other soft-tissue differences were significant. Significant growth of the nose occurred during from T1 to T2 in both groups, and there was a tendency for the incisors in both groups to return to pretreatment values. The nose also continued to grow during that period.

CONCLUSIONS

Overall, the soft-tissue facial profile measurements for both extraction and nonextraction samples were similar at T3, and there were no clinically significant correlations between hard- and soft-tissue variables at T1, T2, and T3.

Stability of anterior open-bite extraction and nonextraction treatment in the permanent dentition

INTRODUCTION

Although stability of anterior open-bite extraction and nonextraction treatment has been investigated, results suggesting that extraction treatment is more stable have not been confronted. Therefore, the purpose of this cephalometric study was to compare the long-term stability of anterior open-bite extraction and nonextraction treatment in the permanent dentition.

METHODS

Group 1 consisted of 21 patients treated without extractions, and group 2 included 31 patients treated with extractions who had orthodontic treatment with fixed appliances. Cephalometric headplates were obtained at pretreatment, posttreatment, and postretention. The groups were compared at these 3 times and during the treatment and posttreatment periods with independent t tests. The number of patients with a clinically significant relapse of the open bite was compared between the groups with chi-square tests.

RESULTS

During treatment, the maxillary incisors had greater retraction amounts, and the mandibular incisors had greater retraction and lingual tipping, and less extrusion in the extraction group. In the posttreatment period, the extraction group demonstrated statistically greater stability of the overbite. However, there was no statistically significant difference in the percentages of patients with clinically significant relapse of the open bite between the groups.

CONCLUSION

Open-bite extraction treatment has greater stability of the overbite than open-bite nonextraction treatment.

Occlusal and cephalometric Class II Division 1 malocclusion severity in patients treated with and without extraction of 2 maxillary premolars

INTRODUCTION

The purpose of this study was to compare the initial occlusal and cephalometric severity of Class II Division 1 malocclusion patients treated with and without extraction of 2 maxillary premolars.

METHODS

Dental study models and cephalograms of 62 patients were selected. Those in group 1 (n = 42) were treated without extractions, and those in group 2 (n = 20) were treated with 2 maxillary premolar extractions. Grainger's treatment priority index (TPI) was used to assess the final and the initial occlusal status of each subject. Variables such as overjet and overbite were also evaluated. Independent t tests were used to compare the occlusal variables at the posttreatment stage, the occlusal and cephalometric variables at the pretreatment stage, and the improvement in TPI values between the groups.

RESULTS

Patients treated with 2 maxillary premolar extractions had greater initial occlusal TPI values, overjets, cephalometric apical base anteroposterior discrepancies, maxillary incisor protrusions, and anteroposterior molar discrepancies than those treated without extractions.

CONCLUSIONS

For patients with more severe anteroposterior discrepancies, an extraction plan provides more effective treatment with less need for patient compliance.

Buccolingual inclinations of posterior teeth in subjects with different facial patterns

This study compared the buccolingual inclination of the posterior teeth in subjects with a horizontal growth pattern (proportionally short lower anterior face height) with that of subjects with a vertical growth pattern (proportionally long lower anterior face height). Seventy subjects with permanent dentition were divided into 2 groups. Group I comprised 35 subjects (16 male, 19 female) with Class II Division 2 malocclusion with a horizontal growth pattern, and group II comprised 35 subjects (15 male, 20 female) with a vertical growth pattern. Buccolingual inclinations of the first molar and second premolar were indirectly assessed on photocopies of buccolingual sections of these teeth by measuring their occlusal surface (represented by an imaginary line connecting the lingual and buccal cusps) inclination. The groups were compared with t tests (P <.05). The maxillary posterior teeth of subjects with a vertical growth pattern had a significantly greater buccal inclination compared with those of subjects with a horizontal growth pattern. However, there were no statistically significant differences in the inclinations of the mandibular posterior teeth between the 2 groups.

Lateral facial soft-tissue prediction model: analysis using Fourier shape descriptors and traditional cephalometric methods

This study was designed to investigate the relationship between traditional skeletal cephalometric measurement and Fourier analysis of the lateral soft-tissue profile. A random sample of 121 untreated subjects of European descent, with wide ranges of malocclusions and underlying facial patterns, was selected in the Orthodontic Unit at the University of Melbourne. Lateral cephalograms were available for all subjects. Both traditional lateral cephalometric analysis and Fourier soft-tissue profile analysis were carried out. Multivariate statistical analysis among 11 hard-tissue cephalometric measurements and the first 50 Fourier harmonics was then performed. This analysis formed the basis for a subsequently proposed soft-tissue prediction model. From this model, 50 predicted x- and y-harmonics were generated for each subject in the total sample. Calculation of Pearson's correlation coefficients between the actual and predicted harmonics revealed strong relationships for many of the lower-order harmonics. To further test the model, the prediction-coefficients derived from all 121 subjects were then used to make predictions for the first 50 x- and y-harmonics for a subgroup of 10 independent test subjects. Once again, Pearson's correlations between the actual and predicted harmonics of the test model in the lower-order harmonics revealed strong associations. Superimposition of the actual and predicted soft-tissue outlines, however, revealed that much actual detail in the region between the nose and the chin was still lost using the predicted Fourier harmonics. This suggests that soft-tissue prediction based on this Fourier test model, while already useful in Forensic facial reconstruction, may not yet be appropriate for useful diagnosis and planning in clinical disciplines.