Prediction of mandibular growth rotation

Avaliação cefalométrica dos efeitos do aparelho de protração mandibular (APM) associado à aparatologia fixa em relação às estruturas esqueléticas em pacientes portadores de má oclusão Classe II, 1ª divisão

OBJETIVO: este estudo objetivou avaliar as respostas cefalométricas esqueléticas provocadas pelo Aparelho de Protração Mandibular, em jovens brasileiros portadores de má oclusão Classe II, 1ª divisão, associado à Ortodontia corretiva fixa. MÉTODOS: a amostra consistiu de 56 telerradiografias em norma lateral de 28 pacientes, sendo 16 do sexo feminino e 12 do masculino. A idade inicial média foi de 13,06 anos e o período médio da terapia com o APM foi de 14,43 meses. As telerradiografias laterais foram obtidas antes e após o tratamento, tendo sido comparadas por dois examinadores calibrados para identificar as alterações esqueléticas do APM, utilizando-se 16 grandezas cefalométricas lineares e angulares. Algumas variáveis independentes (idade do paciente, sexo, padrão facial, modelo de APM, tempo total de uso do aparelho, arco usado durante a terapia com APM e técnica ortodôntica utilizada) foram consideradas e associadas às referidas grandezas, no intuito de demonstrar a influência dessas variáveis sobre as grandezas As respostas ao tratamento foram analisadas e comparadas pelos testes Wilcoxon Signed Ranks e Mann-Whitney para um nível de significância de 5%. RESULTADOS: os resultados mostraram uma restrição no deslocamento anterior da maxila, um aumento na protrusão mandibular, uma melhora no relacionamento anteroposterior das bases ósseas e estabilidade do plano mandibular em relação à base do crânio. Observou-se, ainda, influência das variáveis idade, padrão facial e tipo de APM utilizado. CONCLUSÕES: o APM consistiu numa alternativa eficaz no tratamento da má oclusão de Classe II, 1ª divisão, propiciando alterações do componente esquelético com resultados clínicos satisfatórios.

Cross-sectional human mandibular morphology as assessed in vivo by cone-beam computed tomography in patients with different vertical facial dimensions

INTRODUCTION

The goal of this study was to look at mandibular cortical bone in live patients using cone-beam computed tomography (CBCT) to determine differences in cortical plate thicknesses and mandibular cross-sectional height and width in patients with different vertical facial dimensions.

METHODS

A total of 111 scanned patients were used. Of these subjects, 43 were included in the average vertical facial dimension group (average face), 34 in the high vertical facial group (long face), and 34 in the low vertical facial group (square short face). Cross-sectional slices of the mandible were developed with the cone-beam scans to evaluate the cortical bone between the dentition at 13 locations. Each section was then measured at 8 sites, which included 1 height and 2 width measures of the cross-sectional area and 5 cortical plate thicknesses. An analysis of variance (ANOVA) with a posthoc Bonferroni statistical analysis was used with a significance level of P  ≤0.0167.

RESULTS

The long-face group had slightly more narrow cortical bone than the other 2 facial groups at a few selected sites of the mandible. The height of the cross-sectional area of the mandible in the long-face group was shorter posteriorly than in the other 2 groups and became greater toward the symphysis.

CONCLUSIONS

Mandibular height and width differed more than cortical bone thickness among the 3 types of subjects with different vertical facial dimensions, but statistically significant differences were evident is some sites for cortical bone thickness.

Estudo comparativo das proporções faciais entre jovens melanodermas e leucodermas dos 8 aos 10 anos de idade

OBJETIVO: avaliar as proporções faciais, em jovens melanodermas e leucodermas do sexo feminino, dos 8 aos 10 anos de idade, e verificar as possíveis diferenças existentes entre os grupos. MÉTODOS : os autores examinaram, de forma transversal, 70 telerradiografias realizadas em norma lateral, igualmente divididas entre os dois grupos, sendo 22 aos 8 anos, 18 aos 9 anos e 30 aos 10 anos. Todas as pacientes apresentavam perfil facial harmonioso e oclusão normal, e ausência de tratamento ortodôntico prévio. Avaliaram-se as proporções AFAI/AFAT (ENA-Me/N-Me), AFPT/AFAT (S-Go/N-Me), AFPI/AFPT (Ar-Go/S-Go) e AFPI/AFAI (Ar-Go/ENA-Me). Os dados foram analisados por meio da estatística descritiva, teste t de Student para a comparação entre os grupos raciais, análise de variância com teste de Bonferroni para comparação entre as idades e coeficiente de correlação de Pearson para a verificação do grau de associação entre as proporções faciais. Em todos os testes estatísticos utilizou-se o nível de 5% de significância. RESULTADOS: não existiram diferenças estatisticamente significativas entre os grupos e entre as idades dentro dos grupos, independentemente da variável analisada. CONCLUSÃO: não ocorreram diferenças estatisticamente significativas nas proporções faciais entre jovens leucodermas e melanodermas brasileiras. As proporções faciais mantiveram-se constantes dos 8 aos 10 anos de idade, independentemente do grupo racial.

Association between overbite and craniofacial growth pattern

The purpose of the present study was to assess the association between overbite and craniofacial growth pattern. The sample comprised eighty-six cephalograms obtained during the orthodontic pretreatment phase and analyzed using the Radiocef program to identify the craniofacial landmarks and perform orthodontic measurements. The variables utilized were overbite, the Jarabak percentage and the Vert index, as well as classifications resulting from the interpretation of these measurements. In all the statistical tests, a significance level of 5% was considered. Measurement reliability was checked by calculating method error. Weighted Kappa analysis showed that agreement between the facial types defined by the Vert index and the direction of growth trend established by the Jarabak percentage was not satisfactory. Owing to this lack of equivalency, a potential association between overbite and craniofacial growth pattern was evaluated using the chi-square test, considering the two methods separately. No relationship of dependence between overbite and craniofacial growth pattern was revealed by the results obtained. Therefore, it can be concluded that the classification of facial growth pattern will not be the same when considering the Jarabak and the Ricketts anayses, and that increased overbite cannot be associated with a braquifacial growth pattern, nor can openbite be associated with a dolichofacial growth pattern.

Evaluation of extraction and non-extraction treatment effects by two different superimposition methods

The aim of this study was to determine whether different evaluation methods may be the cause of the varied outcomes of research that have evaluated the effects of extraction and non-extraction therapy on jaw rotation. This retrospective study consisted of the pre- (T1) and post- (T2) treatment lateral cephalograms of 70 skeletal Class I subjects with an optimal vertical mandibular plane angle, who had undergone fixed orthodontic treatment. Thirty-five of the subjects (20 females and 15 males, mean age: 14.7 years) were treated with four first premolar extractions and 35 (22 females and 13 males, mean age: 15 years) without extractions. T1 and T2 radiographs were superimposed using Björk's structural method and Steiner's method of sella-nasion line registered at sella. A Wilcoxon test was used to evaluate the changes between T1 and T2 and the Mann-Whitney U-test to determine differences between the extraction and non-extraction and Björk and Steiner groups. No significant difference was found between the methods of Steiner and Björk according to the spatial changes of the cephalometric points in the extraction and non-extraction groups. The maxilla showed forward rotation in the extraction group and backward rotation in the non-extraction group with both superimposition methods, but the differences were not significant in either inter- or intraclass comparisons. The mandible showed forward rotation in the extraction group with both superimposition methods but, in the non-extraction group, forward rotation was recorded with Björk's method and backward rotation with Steiner's method. These findings were not significant in either inter- or intraclass evaluations. No significant difference was found between the groups or methods.

Correlations between dentoskeletal variables and deep bite in Class II Division 1 individuals

This study aimed to evaluate the cephalometric pattern of Class II Division 1 individuals with deep bite, and to determine possible correlations between dentoskeletal variables and deep bite. Comparisons were also made between genders and cases that were to be treated both with and without premolar extraction. A total of 70 lateral cephalograms were used, from both male (n = 35) and female (n = 35) individuals with an average age of 11.6 years, who simultaneously presented with ANB ≥ 5º and overbite ≥ 4 mm. Statistical analysis involved parametric (t-test) and non-parametric (Mann-Whitney) tests for independent samples, as well as the Spearman correlation test (p ≤ 0.05). The values of Go-Me, Ar-Pog, PM-1 and PM-CMI were higher in males (p < 0.05). However, no significant differences were found among the averages of the cephalometric measurements when the sample was divided by treatment with and without extraction. Deep bite was positively correlated to the PM-1 and SNA measurements, and negatively correlated to the Go-Me, Ar-Pog, SNB and SNGoMe measurements. The main factors associated with the determination of deep bite in Angle's Class II Division 1 cases were: greater lower anterior dentoalveolar growth and/or lower incisor extrusion, horizontal growth pattern, maxillary protrusion and mandibular retrusion.

Effectiveness of the passive lingual arch for E space maintenance in subjects with anterior or posterior rotation of the mandible: a retrospective study

OBJECTIVE

The aim of this study was to determine whether or not lingual arches in subjects with anterior or posterior mandible rotation can produce different effects in the prevention of first permanent molar mesial migration.

SUBJECTS AND METHODS

Forty-two patients with a mean age of 9 ± 0.8 years were selected from the Department of Orthodontics, University of Catania, Italy. These subjects were treated with a passive mandibular fixed lingual arch. The sample was divided into 3 groups according to the gonial angle in order to establish the pattern of mandible growth: mandibular posterior rotation (MPR), mandibular growth in straight-downward direction (MSD) and mandibular anterior rotation (MAR). Lateral cephalograms and study models of the patients before and after treatment were examined to determine any positional changes of the mandibular first molars and incisors.

RESULTS

Statistically significant differences between the MPR group and the other 2 (MSD and MAR) were found as regards mandibular first molar and incisor positional changes. No significant differences were found between the MSD and MAR groups.

CONCLUSION

The results indicate that the effect of lingual arch is influenced by mandibular growth patterns. In patients with MPR, the lingual arch preserves arch length but the mesial migration of first permanent molars is not completely blocked.

Changes in vertical dentofacial morphology after adeno-/tonsillectomy during deciduous and mixed dentitions mouth breathing children--1 year follow-up study

OBJECTIVE

The aim of this 1 year follow-up study was to investigate, in mouth breathing children, the impact of respiration normalization on vertical dentofacial growth during two stages of dental development after adeno-/tonsillectomy.

METHOD

Linear and angular cephalometric measurements, as well as tracing superimposition of serial lateral cephalograms of 39 patients in the treatment group were compared with those of 31 untreated mouth breathing controls. Cephalometric records in the treatment group comprised registrations made at baseline before surgery (T(0)), and then at approximately 1 year post-operatively (T(1)). Corresponding registrations were available for the control group, with a baseline cephalometric radiograph taken approximately 1 year before the second one (T(0) and T(1), respectively). Treatment and untreated groups were divided into deciduous and mixed dentition groups to aid the identification of an optimum timing for normalizing the respiration after T&A, under a vertical dentofacial perspective.

RESULTS

After 1 year of follow up, no statistically significant difference on vertical dentofacial growth was observed in deciduous or mixed dentitions treatment groups compared to the same occlusal developmental stage of untreated control groups.

CONCLUSION

The results indicate that regarding the vertical dentofacial growth pattern normalization of the mode of respiration after T&A in young children (deciduous dentition) is not more effective than in older children (mixed dentition).

Long-term dentoskeletal changes with the Bionator, Herbst, Twin Block, and MARA functional appliances

OBJECTIVE

To determine if the long-term dentoskeletal changes in patients treated with tooth-borne functional appliances were comparable to each other and to matched controls.

MATERIALS AND METHODS

The experimental sample consisted of 80 consecutively treated patients who were equally divided into Bionator, Herbst, Twin Block, and mandibular anterior repositioning appliance (MARA) groups. The control group comprised 21 children with untreated skeletal Class II malocclusions. Lateral cephalograms were taken for the treated group at T1 (initial records), T2 (completion of functional therapy), and T3 (completion of fixed appliance therapy). A repeated measure analysis of variance (ANOVA) was used to assess the differences between and within groups. If ANOVA results were significant, Tukey-Kramer tests were used to determine where the significant differences occurred.

RESULTS

(1) Temporary restriction of maxillary growth was found in the MARA group (T2-T1). (2) SNB increased more with the Twin Block and Herbst groups when compared with the Bionator and MARA groups. (3) The occlusal plane significantly changed in the Herbst and Twin Block groups. (4) The Twin Block group expressed better control of the vertical dimension. (5) The overbite, overjet, and Wits appraisal decreased significantly with all of the appliances. (6) The Twin Block group had significant flaring of the lower incisors at the end of treatment. (7) Over the long-term, there were no significant soft tissue changes among treated and untreated subjects.

CONCLUSIONS

No significant dentoskeletal differences were observed long-term, among the various treatment groups and matched controls.

Soft tissue images from cephalograms compared with those from a 3D surface acquisition system

OBJECTIVE

To assess whether 2D cephalometrics is comparable with 3D imaging devices and whether 3D technology could replace traditional 2D image capture in posttreatment evaluation.

MATERIALS AND METHODS

The study is a prospective evaluation of superimposition techniques obtained from a cohort of 40 patients who underwent orthognathic surgery in a private practice environment. Surgical records were obtained from lateral cephalometric radiographs taken by a Kodak 8000C machine, and the 3D images were obtained from the 3dMD stereo photogrammetric camera capture system. Pre- and postlateral cephalometric records were superimposed on the cranial base (SN line) while pre- and post-3D surgical records were superimposed on the regional best-fit method. A mathematical algorithm, or best-fit calculation, was carried out on the selected surfaces. Each set of superimposed records was analyzed, and five soft tissue landmarks were plotted. The differences between the five surface points were analyzed for each set of records.

RESULTS

The final sample consisted of 34 subjects with full records. A total of 680 surface landmarks were plotted and analyzed. The mean differences of the soft tissue landmarks were analyzed for each pair of data sets and were found to range between 1.06 and 8.07 mm and 1.26 and 7.34 mm for lateral cephalometric and 3D readings, respectively. Paired t-tests were carried out using the SPSS 15.0 software, and they showed that the results were not statistically significant between the superimposition techniques on the image capture systems (P > .05).

CONCLUSIONS

The types of superimposition techniques used in the imaging modalities studied were comparable with one another.

Dental implant systems

Among various dental materials and their successful applications, a dental implant is a good example of the integrated system of science and technology involved in multiple disciplines including surface chemistry and physics, biomechanics, from macro-scale to nano-scale manufacturing technologies and surface engineering. As many other dental materials and devices, there are crucial requirements taken upon on dental implants systems, since surface of dental implants is directly in contact with vital hard/soft tissue and is subjected to chemical as well as mechanical bio-environments. Such requirements should, at least, include biological compatibility, mechanical compatibility, and morphological compatibility to surrounding vital tissues. In this review, based on carefully selected about 500 published articles, these requirements plus MRI compatibility are firstly reviewed, followed by surface texturing methods in details. Normally dental implants are placed to lost tooth/teeth location(s) in adult patients whose skeleton and bony growth have already completed. However, there are some controversial issues for placing dental implants in growing patients. This point has been, in most of dental articles, overlooked. This review, therefore, throws a deliberate sight on this point. Concluding this review, we are proposing a novel implant system that integrates materials science and up-dated surface technology to improve dental implant systems exhibiting bio- and mechano-functionalities.

Post-treatment evaluation of a magnetic activator device in Class II high-angle malocclusions

SUMMARY

The purpose of this study was to evaluate changes in dentofacial growth before, during, and after use of a magnetic activator device (MAD) II in high-angle Class II division 1 patients. Lateral cephalometric and hand-wrist radiographs of 10 patients (six girls and four boys) with an average chronological age of 10 years 5 months were obtained at the beginning of the observation period (T1, 9.5 months), beginning of MAD II application (T2), at the end of the treatment (T3), and approximately 4 years after the end of treatment (T4). Thirteen linear, 1 ratio, and 10 angular measurements were evaluated. Paired t-tests were used for statistical evaluation of differences that occurred between the time points. The increase in gonial angle, GnGoAr angle, S-N, Co-Gn, Go-Ar, ANS-Me, S-Go, and N-Me distances and the decrease of overjet, U1-NA distance, and ANB angle were statistically significant during the treatment. At T4, there was a decrease in gonial angle and U1-NA distance, which was significant. The changes as a result of treatment were stable at T4.

Mandibular growth, remodeling, and maturation during infancy and early childhood

OBJECTIVE

To describe the growth, maturation, and remodeling changes of the mandible during infancy and early childhood.

MATERIALS AND METHODS

Seven Bolton-Brush Growth Study longitudinal cephalograms (N = 336) of each of 24 females and 24 males, taken between birth and 5 years of age, as well as early adulthood, were traced and digitized. Five measurements and nine landmarks were used to characterize mandibular growth, remodeling, and degree of adult maturity.

RESULTS

Overall, mandibular length showed the greatest growth changes, followed by ramus height and corpus length. Corpus length was the most mature of the three linear measures; ramus height was less mature than overall mandibular length. The greatest growth rates occurred between 0.4-1 year; yearly velocities decelerated thereafter. The ramus remodeled superiorly only slightly more than it remodeled posteriorly. Male mandibles were significantly (P < or = .05) larger, displayed greater growth rates, and were significantly less mature than female mandibles. There were no significant differences in mandibular growth or maturation between Class I and Class II patients.

CONCLUSIONS

The mandible displays decelerating rates of growth and a maturity gradient during infancy and early childhood, with males showing more growth and being more mature than females.

Duration of the pubertal peak in skeletal Class I and Class III subjects

OBJECTIVE

To estimate and compare the duration of the pubertal growth peak in Class I and Class III subjects.

MATERIALS AND METHODS

The data examined consisted of pretreatment lateral cephalometric records of 218 skeletal Class I or Class III subjects (93 female and 125 male subjects) of white ancestry. The duration of the pubertal peak was calculated from the average chronological age intervals between stages CS3 and CS4 of the cervical vertebral maturation in Class I vs Class III groups (t-test).

RESULTS

In skeletal Class I subjects, the pubertal peak had a mean duration of 11 months, whereas in Class III subjects it lasted 16 months. The average difference (5 months) was statistically significant (P < .001).

CONCLUSIONS

The growth interval corresponding to the pubertal growth spurt (CS3-CS4) was longer in Class III subjects than in subjects with normal skeletal relationships; the larger increases in mandibular length during the pubertal peak reported in the literature for Class III subjects may be related to the longer duration of the pubertal peak.

Cervical vertebrae maturation method: poor reproducibility

INTRODUCTION

The cervical vertebrae maturation (CVM) method has been advocated as a predictor of peak mandibular growth. This method relies on the clinician's ability to determine the stage of maturation of the vertebrae. Careful examination of reports of this technique shows methodologic flaws that can lead to inflated levels of reproducibility. The purpose of this study was to evaluate the reproducibility of CVM stage determination by using a more stringent methodology.

METHODS

Ten practicing orthodontists, trained in the CVM method, evaluated 30 individual and 30 pairs of cephalometric radiographs in 2 sessions to determine the CVM stage. Interobserver and intraobserver reliability was determined by using the Kendall coefficient of concordance and the weighted kappa statistic.

RESULTS

All degrees of interobserver and intraobserver agreement were moderate (Kendall's W, 0.4-0.8). Interobserver agreement levels for CVM staging of the 10 orthodontists at both times were below 50%. Agreement improved marginally with the use of 2 longitudinal radiographs. Intraobserver agreement was only slightly better; on average, clinicians agreed with their own staging only 62% of the time.

CONCLUSIONS

Based on these results, we cannot recommend the CVM method as a strict clinical guideline for the timing of orthodontic treatment.

Mandibular rotation and remodeling changes during early childhood

OBJECTIVE

To describe the mandibular rotation and remodeling of younger children.

MATERIALS AND METHODS

The sample included 43 males and 43 females who participated in the Bolton-Brush Growth Study at Case Western Reserve University in Ohio. They were chosen on the basis of having Class I (n = 45) or Class II (n = 41) molar relationships and longitudinal lateral cephalograms at three developmental stages of the dentition: late primary (T1: 5.7 +/- 0.5 y), early mixed (T2: 8.4 +/- 0.6 y), and full permanent dentition (T3: 15.4 +/- 0.5 y). Each subject's cephalograms were traced and four landmarks were digitized. Cranial base and mandibular superimpositions were performed with the use of natural reference structures.

RESULTS

Yearly rates of true rotation, apparent rotation, and angular remodeling showed significant (P < .05) changes throughout. True rotation was moderately correlated with angular remodeling and apparent rotation. Although no significant sex differences in annual rates of rotation were noted, subjects with Class I molar relationships showed significantly more angular remodeling from T2-T3 than did subjects with Class II molar relationships. Rates of true forward rotation were significantly greater with T1-T2 than with T2-T3 (1.3 and 0.7 degrees/y, respectively).

CONCLUSION

Although significant amounts of true mandibular rotation and angular remodeling occur during childhood and adolescence, true rotation is greatest during the transition from late primary to early mixed dentition.

The aponeurotic tension model of craniofacial growth in man

Craniofacial growth is a scientific crossroad for the fundamental mechanisms of musculoskeletal physiology. Better understanding of growth and development will provide new insights into repair, regeneration and adaptation to applied loads. Traditional craniofacial growth concepts are insufficient to explain the dynamics of airway/vocal tract development, cranial rotation, basicranial flexion and the role of the cranial base in expression of facial proportions. A testable hypothesis is needed to explore the physiological pressure propelling midface growth and the role of neural factors in expression of musculoskeletal adaptation after the cessation of anterior cranial base growth. A novel model for craniofacial growth is proposed for: 1. brain growth and craniofacial adaptation up to the age of 20; 2. explaining growth force vectors; 3. defining the role of muscle plasticity as a conduit for craniofacial growth forces; and 4. describing the effect of cranial rotation in the expression of facial form.Growth of the viscerocranium is believed to be influenced by the superficial musculoaponeurotic systems (SMAS) of the head through residual tension in the occipitofrontalis muscle as a result of cephalad brain growth and cranial rotation. The coordinated effects of the regional SMAS develop a craniofacial musculoaponeurotic system (CFMAS), which is believed to affect maxillary and mandibular development.

Development of occlusal traits and dental arch space from adolescence to adulthood: a 25-year follow-up study of 245 untreated subjects

INTRODUCTION

The purpose of this study was to examine longitudinally the development of specific occlusal traits and space conditions in an Icelandic sample.

METHODS

The sample comprised 245 adolescents examined clinically in the late mixed or permanent dentition and again 25 years later. All subjects were orthodontically untreated, and all had the full complement of teeth at both examinations.

RESULTS

A significant increase in the prevalence of mandibular anterior crowding and mesial molar relationships and a decrease in the prevalence of excessive overjet and maxillary anterior spacing were seen. The persistence of malocclusion traits ranged from 17.9% to 53.4% for maxillary anterior spacing and crowding, mandibular spacing, overjet, overbite, and distal molar occlusion, whereas anterior mandibular crowding and molar crossbite were still found in 72.7% and 75.0%, respectively, at the second examination. Normal occlusal traits and space conditions at adolescence stayed mostly unchanged, with the exception of 11.2% of the subjects, who developed mandibular anterior crowding between the first and second examinations.

CONCLUSIONS

Deterioration of normal occlusal traits and space relationships was uncommon in this study, whereas self-correction of malocclusion traits and space anomalies was relatively frequent.

Jarabak 's cephalometric analysis of Brazilian black patients

The treatment of skeletal disharmonies presents better results when performed during the growth period. The physical changes that occur in every individual express growth, which is ruled by genetic, general and environmental factors. In order to identify such disharmonies and hence concentrate the clinical actions during treatment and influence facial growth, cephalometrics appears as a useful a diagnostic tool for identifying facial growth patterns or growth direction. Jarabak's cephalometric analysis is used to assess facial growth pattern of subjects with normal occlusion or malocclusions. The purpose of this study was to obtain mean values for cephalometric measurements from Jarabak's cephalometric analyses of black Brazilian subjects resident in the city of Piracicaba, São Paulo state, Brazil and vicinities, who presented Class I molar relationship with normal overjet and overbite, mild or no tooth crowding or spacing, and no history of orthodontic treatment. A sample of 37 stone plaster casts and 37 lateral teleradiographs from both male and female individuals aged 10 to 14 years was evaluated. Data were analyzed statistically by Student's t-test at 5% significance level. There was no significant differences between genders. The cephalometric measurements obtained in this study were similar to the Jarabak's standards, except for S-N mean value in females (66.50 mm +/- 3.16), which was significantly lower than the standard.

Cephalometric changes produced by locally applied anabolic steroid in Wistar rats

BACKGROUND AND OBJECTIVE

There is a strong relationship between neuromuscular activity and facial skeletal morphogenesis. The systemic use of anabolic steroid accelerates craniofacial growth and induces high functional activity of rats' masticatory muscles. The present study examines the effect of an anabolic steroid locally applied in the masseter muscle of growing rats with the purpose of verifying possible craniofacial changes with minimum drug side effects, using cephalometric analysis.

MATERIALS AND METHODS

Forty-three 3-week-old Wistar rats were evaluated and divided into two groups: (1) NAN group (local bilateral masseter injection of nandrolone decanoate - 0.05 microg/3 microl/bi-weekly) and (2) CON group (local bilateral masseter injection of sterile oil - 3 microl). Tukey and Wilcoxon tests were used.

RESULTS

In NAN group the cephalometric measures showed horizontalized facial growth (reduce of FMA angle -p<0.01), increase of posterior facial height, decrease of anterior facial height, reduction of gonial angle (p<0.05), increase of mandibular height (p<0.01). There was no variation in the length of the mandible, in the skull and animals' weight gain, thus demonstrating that no important systemic effect occurred.

CONCLUSION

The local injection of nandrolone in the masseter muscle of rats was capable to alter the growth direction and the morphology of the craniofacial complex in Wistar rats.

Cephalometric superimpositions

OBJECTIVE

To test the hypothesis that there is no difference between the information produced by superimposition of serial lateral headfilms on anatomical structures and that produced by superimposition on metallic implants according to the protocols of Björk.

MATERIALS AND METHODS

Serial cephalograms of 10 untreated subjects who had tantalum implants placed in the maxilla and mandible during childhood were analyzed. Headfilms taken at six consecutive stages of cervical vertebral maturation (CS1-CS6) for six female and four male subjects were used. Tracings were superimposed according to the methods of superimpositions advocated by the American Board of Orthodontics (ABO). In addition, superimpositions along the inferior border of the mandible were performed. Finally, superimpositions of serial tracings on stable intraosseous implants were made to determine the actual growth and remodeling patterns of the maxilla and mandible.

RESULTS

The ABO maxillary superimposition method underestimates the vertical displacement and overestimates the forward movement of maxillary landmarks. Superimposing on the internal cortical outline of the symphysis and the inferior alveolar nerve canals generally approximates the mandibular superimposition on implants, although the lower anterior border of the symphysis may be a preferable area of superimposition. Superimposition on the lower border of the mandible does not reflect accurately the actual pattern of growth and remodeling of the mandible.

CONCLUSIONS

When analyzing serial headfilms, erroneous information concerning patterns of bone growth and remodeling can be obtained if convenient, but biologically incorrect superimposition protocols are used. In addition, tooth movements measured can be distorted significantly depending on the method of superimposition.

Three-dimensional analysis of facial morphology surface changes in untreated children from 12 to 14 years of age

INTRODUCTION

The developing face is of interest to orthodontists, especially if orthodontic treatment can influence the outcome of facial growth. New 3-dimensional (3D) modalities have enabled clinicians to better understand the facial changes in a developing child.

METHODS

Fifty-nine children with normal body mass indexes were evaluated with a previously validated 3D laser imaging device over a 2-year period. Surface changes were evaluated on normal and average faces. These changes were seen as mean surface changes and color maps.

RESULTS

The results suggest that the surface areas of change in average faces were generally downward and forward with respect to the nose and soft-tissue nasion. The lips also translated in a downward direction as the nose grew, and there was a general increase in the vertical dimension. Some subjects were in the "great changes" category, boys significantly more so than girls.

CONCLUSIONS

The following conclusions can be made from this 3D study of changes of facial morphology in children: (1) surface changes are greater in boys than in girls; (2) differences in the timing of surface changes in boys and girls are clinically significant, with boys exhibiting more changes later; (3) positive surface changes occur in the nose, brows, lips, and vertical dimensions of the face; (4) the eyes deepen, and the cheeks become flatter; and (5) 3D imaging is a useful tool in analyzing changes to the face over time.

"Effective" TMJ and chin position changes in Class II treatment

OBJECTIVE

To evaluate the "effective" temporomandibular joint (TMJ) changes (the sum of condylar modeling, glenoid fossa modeling, and condylar position changes within the fossa), and their influence on chin position in patients with a Class II division 1 malocclusion treated orthodontically with a multibracket appliance and Class II elastics (Tip-Edge) and orthopedically with a fixed functional appliance (Herbst).

MATERIALS AND METHODS

Two groups of successfully treated subjects were evaluated: Tip-Edge (n = 24) and Herbst (n = 40). The Bolton Standards served as a control group. Lateral head films obtained before treatment and after an observation period of 2.6 years (Herbst also after 0.6-year period) were analyzed.

RESULTS

In comparison with the Herbst and control groups, the Tip-Edge group exhibited less favorable sagittal "effective" TMJ growth and chin position changes necessary for skeletal Class II correction.

CONCLUSIONS

Orthodontic therapy with a multibracket appliance and Class II elastics seems not to have any favorable sagittal orthopedic effect on the mandible, while bite jumping with the Herbst appliance has a favorable sagittal orthopedic effect on a short-time basis.

Mandibular Growth Changes and Cervical Vertebral Maturation

Objective: To evaluate mandibular dimensional changes and regional remodeling occurring during five intervals of circumpubertal growth.

Materials and Methods: This investigation evaluated a unique sample of subjects in whom tantalum implants were placed into the craniofacial complex during childhood. The sample was obtained from the Mathews and Ware implant study originally conducted at the University of California San Francisco in the 1970s, with longitudinal cephalometric records of 20 subjects (13 female, 7 male) available for evaluation. Cephalograms at six consecutive stages of cervical vertebral maturation (CS1 through CS6) were analyzed.

Results: Peak mandibular growth was noted during the interval from CS3 to CS4. Forward rotation of the mandible was due to greater mandibular growth posteriorly than anteriorly. Progressive closure of the condylar-ramus-occlusal (CRO) angle resulted in a forward and upward orientation of the ramus relative to the corpus of the mandible due to increased vertical growth of the condyle.

Conclusions: A peak in mandibular growth at puberty was substantiated. Mandibular remodeling and condylar rotation continue to occur after the growth spurt.

[Etiological aspects of anterior open bite]

INTRODUCTION

Open bite is a multifactorial phenomenon and no single factor can account for open-bite. Etiology plays an important role in diagnosis. Heredity, unfavorable growth patterns, incorrect jaw postoure, are the characteristics of skeletal open bite.

DIGIT SUCKING

Depending on where the thumb is placed, a number of different types of dental problems can develop. Malocclusions of the late mixed or permanent dentitions, caused by thumb sucking are not self corrected and orthodontic treatment is necessary for their correction.

LYMPHATIC TISSUE

In order to produce oral respiration, the mandible is postured inferiorly with the tongue protruded and resting against the oral floor. This postural alteration induces dental and skeletal modifications similar to those caused by thumb sucking. This may cause excessive eruption of the posterior teeth, leading to an increase in the vertical dimension of the face and result in development of anterior open bite.

TONGUE THRUST

Tongue habits cause an anterior open bite or they develop secondarily to thumb sucking. In skeletal open bite the tongue habit acts as a secondary factor which helps to maintain or exacerbate the condition. Many orthodontists have had a discouraging experience of completing dental treatment, with what appeared to be good results, only to discover that the case had relapsed because the patient had a tongue thrust swallowing pattern.

CONCLUSION

Dentoalveolar or habitual open bite is caused by habits, which influence the growth and development of dentoalveolar processes and contribute to occlusal disharmonies. Prior to eruption of adult dentition, open bite related to oral habits is usually not a concern as when the habits stop, because the erupting dentition tends to improve spontaneously. Treatment is usually not necessary until permanent teeth erupt (approximately 6 years old).