SNA Angle Research Articles

Treatment and posttreatment effects of a facial mask combined with a bite-block appliance in Class III malocclusion

In this cephalometric investigation, we analyzed the treatment and posttreatment effects of an orthopedic protocol for Class III malocclusion consisting of a facial mask combined with a removable bite-block appliance. The treated sample consisted of 22 Class III patients treated with the facial mask and bite-block protocol before the pubertal growth spurt (mean age, 8.9 +/- 1.5 years). Treated subjects were evaluated after facial mask and bite-block therapy and at a posttreatment observation in absence of retention. The treated group was compared with a matched control group of 12 untreated Class III subjects. All treated and control subjects were postpubertal at the final observation. Significant differences between the treated and control groups were assessed with the Mann-Whitney U test (P <0.05). Both angular and linear sagittal measurements of the maxilla showed significant improvements during active treatment. Significant improvements of SNA angle, ANB angle, overjet, and molar relationship remained stable during the posttreatment period. No significant effect was found in the mandibular skeletal measures. No significant protraction of the maxillary incisors or retraction of the mandibular incisors was observed. A bite-block appliance in the mandibular arch with a facial mask enabled effective control of mandibular rotation with progressive closure of the gonial angle. This added to the favorable maxillary outcomes of the treatment protocol.

Effectiveness of maxillo-mandibular advancement in obstructive sleep apnea patients with and without skeletal anomalies

This study evaluates the effectiveness of maxillo-mandibular advancement (MMA) in patients with obstructive sleep apnea syndrome (OSAS), even those without skeletal anomalies, indicating the possibility of extending this procedure to more patients. Two groups with different skeletal patterns were studied pre- and post-surgery. Group 1 (11 patients) had severe or moderate OSAS and maxillo-mandibular hypoplasia and/or mandibular deformities (SNA angle 78 degrees or less or SNA angle>78 degrees but with SNB<65 degrees and severe skeletal class II malocclusion). Group 2 (11 patients) had severe or moderate OSAS without maxillo-mandibular hypoplasia or deformity (SNA angle>80 degrees , dental class I occlusion). Analysis comprised: apnea hypopnea index (AHI), posterior airway space (PAS), SNA and SNB angles, Epworth sleepiness scale (ESS), body mass index (BMI), and a subjective standardized questionnaire about aesthetic appearance. All patients had increased PAS width and complete remission of objective and subjective OSAS symptoms evaluated by AHI and ESS. Results in both groups are comparable. Data were analysed using t-test; p<0.005 was statistically significant. All patients were satisfied with the functional and aesthetic results. MMA is effective in patients with severe or moderate OSAS, even in those without skeletal and/or occlusal anomalies and can be considered in more patients.

Treatment of maxillary deficiency by miniscrew implants – a case report

This case report illustrates the treatment of a 12-year-old boy with maxillary deficiency using miniscrew implants. The patient rejected the use of extraoral appliances and future surgical correction; therefore the patient was treated using Class III elastics connected from two mandibular miniscrew implants to an upper removable appliance. The miniscrews were inserted between the permanent canines and first premolars under local anaesthesia. The treatment lasted for 8 months after which favourable correction of the malocclusion was observed. The SNA and ANB angles increased by 3 degrees and the IMPA increased by 4 degrees . This case demonstrates that miniscrews can be a suitable alternative method to extraoral appliances and possibly surgery in mild Class III cases.

Five-Year Follow-Up of Maxillary Distraction Osteogenesis on the Dentofacial Structures of Children With Cleft Lip and Palate

To determine the long-term outcomes of maxillary distraction osteogenesis (DO) on skeletal and dental structures of growing children with cleft lip and palate. Severe maxillary deficiencies were treated with a rigid external distractor device followed by a consolidation period. Preoperative and postoperative orthodontic treatment lasted a mean of 14 months and 16 months, respectively. The landmarks on standard lateral cephalometric x-rays were digitized and angular and linear measurements were compared by Student's t test to assess the changes before distraction, after distraction, after consolidation, at 1-year follow-up, and at 2-year follow-up. Long-term follow-up (5 years) was interpreted according to mean values because of the small sample size. During DO, the maxilla was horizontally advanced and moved downward as indicated by the significant changes at the SNA and ANB angles (13 degrees) and at maxillary points A, ANS, and PNS. The increase at the divergence between the maxilla and mandible (ANS-PNS/Me-Go) was found to be significant. The mandible (B, Pg, Me) also moved downward (2-4 mm) and backward (Gn) significantly because of mandibular autorotation. The overjet increased (mean increase, 13.7 mm) and the overbite decreased significantly. The advancement of the upper incisors (13.3 mm) and upper molars (12.3 mm) was slightly more than the skeletal points. In a long-term follow-up (5 years), the ANB angle and horizontal overjet continued to decrease but both values remained positive, indicating a Class I relationship. This cephalometric study of young adolescents with cleft lips and palates found great improvement in dentofacial structure after maxillary DO and stability in maxillary skeletal advancement. During a 5-year follow-up, the achieved dentoskeletal treatment outcome was partly diminished. The extreme need for maxillary advancement or facial correction because of psychosocial stress and providing an easier approach for finalizing osteotomy are the major 2 indications for DO treatment.

唇顎裂症例に対する早期顎裂部骨移植の臨床的評価

AIM: The purpose of this study was to evaluate the effectiveness of early alveolar bone grafting in patients younger than 8 years.MATERIALS AND METHODS: The treated group comprised 15 patients (mean age, 13.2 years; range, 11.4-16.3 years) with cleft lip and alveolus (13 unilateral and 2 bilateral clefts) who underwent alveolar bone grafting at Kitasato University Hospital between July 1999 and January 2004. The mean age at the time of surgery was 6.8 years (range, 5.3 to 7.11) and the mean follow-up period after grafting was 6.6 years (range, 4.8 to 9.1) . We evaluated maxillary growth, bone bridge formation, alveolar bone height and overjet in the cleft area, molar overjet on the cleft side, dental arch width, and basal arch width. The control group comprised 13 patients (mean age, 13.4 years; range, 12.4-14.2) with unilateral cleft lip and alveolus who underwent alveolar bone grafting. The mean age at the time of surgery was 9.2 years (range, 8.0 to 11.4). The Mann-Whitney U-test was used to examine the statistical significance of differences between the two groups in upper jaw growth, dental arch width, and basal arch width.RESULTS: Maxillary growth was not significantly restricted in any of the patients in the treated group, with a mean SNA angle of 82.4° and 81.6° and a mean ANB angle of 7.3° and 6.1° before and after grafting, respectively. After surgery, the mean dental arch width was 44.8 mm, and the mean basal arch width was 48.8 mm. Bone bridge formation in the cleft area was observed in all patients in the treated group, and the alveolar bone height was similar to that on the non-cleft side. A proper overjet was achieved in 14 of the 15 patients by orthodentic treatment after grafting. In the control group, the mean SNA angle was 80.8°, the mean dental arch width was 44.0 mm, and the mean basal arch width was 48.8 mm after bone grafting. There was no significant difference in SNA angle, dental arch width, and basal arch width between the treated and control groups.CONCLUSION: The results suggest that early alveolar bone grafting followed by orthodontic treatment at least does not affect the maxillary growth of patients with cleft lip and alveolus who are younger than 8 years.

Does Pregnancy or Use of Contraceptives Influence Adult Facial Changes?

Aim of this study was to test the hypothesis that documented differences between males and females in adult facial changes are caused by pregnancy or the use of contraceptives. Cephalograms were obtained of 96 females and 38 males (mean age 21.8 years and 22.4 years respectively), T1. The second cephalogram was taken 10.3 and 10.6 years later (T2). The subjects had not undergone orthodontic treatment or surgery during the observation period. Information on the number of births and use of oral contraceptives was available for each female, and they were divided into groups according to use (CP) or non-use (NCP) of contraceptive pills, and number of children born. The linear hard tissue changes were relatively small, none exceeding 2 mm. The S-N line increased in all groups - more in females than in males, with the greatest change in the women with three children group. The parameter Cd-Prgn increased more in males than in females. The angles SNA and SNB increased in the males and decreased in the females. The other angles decreased in males, while the changes were more variable in the females. The soft tissue changes varied greatly. Few of the differences between males and females were statistical significant. Few of the differences between adult males and females in facial changes are caused by pregnancies or the use of oral contraceptives.

Genetic influence and heritability in mandibular prognathism of Korean families

Results: The average age of the probands was 22.1. The average SNA, SNB and ANB angles of the probands were 81.2� , 84.1�and -2.9� , respec- tively. A total of 2729 (male 1,354, female 1,375) family members were examined, and the affected ratio of the families was 3.5 % with no significant difference between genders. 45% of families had at least one member with a Class III malocclusion other than the proband. The a ffected ratio of the first-degree relatives (10.9%) was significantly higher than those of the second-degree (3.3%) and third-degree (1.9%) relative s. The affected ratio of the total relatives from the male probands (4.2%) was significantly higher than that of the female probands (2.8%). Heritabilit y (h2 , Falconer' method) was estimated to be 29.8% (0.298±0.059) in first-degree relatives. Conclusion: These results showed the significant influence of mandibular prognathism with relatively low heritability in first-degree relat ives in Korean families of probands, who had undergone orthognathic surgery to correct a skeletal Class III malocclusion.

Craniofacial characteristics of patients with heart disease

Children with congenital heart disease commonly experience delayed growth. Studies comparing growth and development of these children generally found that they have decreased height and weight, but with no information on craniofacial growth. The aim of this study was to evaluate the craniofacial characteristics of patients with heart disease. We used lateral head cephalograms of 131 patients, aged 8 to 12, attending the Department of Pediatrics of the Hospital of the State University of Rio de Janeiro in Brazil on a routine basis. The study group comprised 50 boys and 38 girls with congenital heart disease. The control group included 20 boys and 23 girls with no heart disease. The skeletal, dental, growth, esthetic, and vertical patterns were analyzed with several cephalometric measurements. The chi-square test was applied to verify a possible association between sex and heart disease, and the Student t test was used to verify differences between the groups of patients with and without heart disease. Heart disease is not sex-related (chi-square = 0.267). But some measurements had sex differences in the groups with and without heart diseases. The Student t test showed significant differences between the groups in the SNA angle measurement in male patients (P = 0.032), and in ANB angle (P = 0.002) and the relationship of the lower lip to the Steiner line (P = 0.034) in the girls. Skeletal patterns were characterized by maxillary protrusion in the boys with heart disease and by increased ANB angles in the girls without heart disease. The esthetic pattern showed a more pronounced lower lip in the girls without heart disease. However, from a clinical point of view, these were slight and irrelevant alterations. The results suggest that patients suffering from heart disease have similar craniofacial characteristics to those without this condition.

Skeletal characteristics and treatment outcome of five patients with Robin sequence.

To examine the variation in the precise skeletal characteristics and the treatment outcomes of five Japanese Robin sequence cases. The birth histories and orthodontic records of five Japanese Robin sequence patients were collected and analyzed. All cases had a retrognathic appearance with small SNA and SNB angles. They had significantly steep mandibular planes with lingual tipped incisors in both arches. The gonial angles in two cases were within the Japanese norm, whereas the remaining three showed significantly enlarged angles. Moreover, all cases showed a significantly shorter ramus length, but the mandibular body was short in only two cases. All had moderate or severe crowding in both arches, and therefore extraction of lateral dentition or lateral incisors was performed in conjunction with orthodontic treatment. An edgewise multibracket appliance was placed, and labial tipping of the lower incisors was performed in all cases. All obtained normal functional occlusion after active treatment, but the retrognathic appearance remained in most cases. The present cases with Robin sequence showed variation in the gonial angle and mandibular body length, although all commonly exhibited smaller SNA and SNB angles with significantly steep mandibular planes. Significant labial tipping of the lower incisors was required during the active treatment, and all cases finally obtained functional occlusion, indicating the relatively good prognosis on the occlusion of this sequence.

Craniofacial morphology in patients with hypophosphataemic vitamin‐D‐resistant rickets: a cephalometric study

Hypophosphataemic vitamin-D-resistant rickets (HVDRR) is a hereditary disease mainly transmitted as an X-linked dominant trait and characterized by certain general clinical signs (Filho HM, de Castro LC, Damiani D. Arq Bras Endocrinol Metab. 2006;50:802). In literature, only one study had been published in 1965 on the cephalometric findings in patients with HVDRR (Marks SC, Lindahl RL, Bawden JW. J Dent Child. 1965;32:259). This is the first detailed study on craniofacial characteristics of patients with HVDRR in the dental literature. The aim of this study was to determine the effect of HVDRR on the parameters of the craniofacial skeleton of young Jordanian patients using cephalometric analysis. Lateral cephalometric radiographs were made for 22 Jordanian children (aged 2-16 years) diagnosed with HVDRR. The cephalometeric parameters of HVDRR group were compared with those of normal control group matched for gender and chronological age using paired t-test. The HVDRR group had a significant increase in the SNBa angle (P < 0.01); as well as reduced anterior cranial base length (P = 0.01), reduced maxillary length, corpus mandibular length and mandibular height (P = 0.01, 0.04 and 0.008 respectively). The cranial base and gonial angles were significantly increased in diseased individual, but the SNA and ANB angles were significantly reduced (P = 0.018 and 0.000 respectively). The angulation of the lower incisor to mandibular plane was also significantly reduced in the diseased group compared with Jordanian norm (P = 0.004). Patients with HVDRR have deficiency in the anterior cranial base length, ramus height and cranial base angle. Patients with HVDRR also have class III skeletal relationship.

On the Interaction between Incisor Crown-Root Morphology and Third-Order Angulation

To evaluate the significance of crown-root angles (CRAs) by testing the null hypothesis that there are no significant differences in deviations of third-order angles to axial inclination values between Angle Class II division 2 incisors and a neutral occlusion control sample. The study group comprised n(total) = 130 whites with either Angle Class II division 2 (n(1) = 62; group A) or neutral (n(2) = 68; control group B) occlusal relationships. Upper central incisor inclination (U1) was assessed with reference to the cephalometric lines NA and palatal plane (U1NA/deg, U1PP/deg). Craniofacial sagittal and vertical relations were classified using angles SNA, SNB, ANB, and NSL-PP. Third-order angles were derived from corresponding dental cast pairs using an incisor inclination gauge. Welch's two-sample t-tests (alpha-level: .05) were used to test the null hypothesis. Single linear regression was applied to determine third-order angle values as a function of axial inclination values (U1NA, U1PP) or sagittal craniofacial structures (ANB angle), separately for group A and B. The discrepancy between axial inclination (U1NA, U1PP) and third-order angles is significantly different (P < .001) between groups A and B. Regression analysis revealed a simply moderate correlation between third-order measurements and axial inclinations or sagittal craniofacial structures. The hypothesis is rejected. The results of this study warn against the use of identical third-order angles irrespective of diminished CRAs typical for Angle Class II division 2 subjects. Routine CRA assessment may be considered in orthodontic treatment planning of Angle Class II division 2 cases.

Geometric Influence of the Sagittal and Vertical Apical Base Relationship on the ANB Angle

The objective of this study consisted in determining the variability of the ANB angle in relation to the position of the A- and B-points in the sagittal vertical plane. Using a theoretical model, we varied the position of the cephalometric points A and B in the sagittal vertical plane while its sagittal relationship was kept constant (Wits value = 0 mm). For this purpose, seven lines were erected perpendicular to the occlusal plane on a lateral cephalogram. The position of points A and B were determined on each of the vertical lines by calculating one anterior and one posterior angle in each case. In this way, the positions of all A- and B-points were clearly defined in the sagittal vertical plane. The characteristic of the ANB angle in the sagittal vertical plane was graphically represented by determining both points A and B using two angles instead of one. This revealed that the ANB angle for the same sagittal base relationship was characterized by major variations depending on the position of the A- and B-points in relation to the anterior cranial base. The larger the SNA and SNB angles were, the larger the corresponding ANB angle. At the same time, the absolute value of ANB increased with the length of the vertical distance between the points A and B. The ANB angle is strongly influenced by geometric factors. Accurate diagnosis of the sagittal base relationship should thus take the individual character of the ANB angle into account.

Variation in dentofacial morphology and occlusion in juvenile idiopathic arthritis subjects: a case-control study

Juvenile idiopathic arthritis (JIA) can severely disturb facial growth and affect occlusal development. In this case-control study, facial, functional, and occlusal characteristics of 100 JIA patients (35 males and 65 females; age range: 1.7-19.4 years) comprising all subtypes classified according to the revised classification criteria of the International League of Associations for Rheumatology (ILAR) were studied. They were compared with a mixed orthodontic control group (n=32; 12 males and 20 females) and with a Class II division 1 malocclusion group (n=19; eight males and 11 females). The JIA patients and controls were evaluated using clinical assessment, dental pantomograms, lateral cephalograms (LCGs), and dental casts. Compared with the age- and gender-matched mixed orthodontic controls, JIA patients showed a significantly greater prevalence of anterior open bites (AOBs; P<0.05; Wilcoxon matched pairs test). Cephalometrically, a larger mandibular plane (P<0.05) and SNA (P<0.001) angles and a smaller interincisal angle (P<0.001) were found. In comparison with the Class II division 1 controls, JIA patients showed a larger SNA (P<0.001; Wilcoxon matched pairs test) and SNB (P<0.05) angles and smaller lower anterior face heights (LAFHs; P<0.05). No differences were found for the mandibular plane, the gonial and the interincisal angles, or total face height. From this case-control study, it can be concluded that although JIA patients share occlusal characteristics with non-JIA patients with a Class II division 1 malocclusion, they are different with regard to the prevalence of condylar lesions and AOBs, as well as SNA and SNB angles and LAFH.

X-ray craniometric and x-ray cephalometric determination of angular parameters in German shepherd dogs

Analyses of the viscerocranial parameters in dogs has been avoided due to inconsistencies in defining the reference points for linear and angular measurements. In our study we classified the elements which refer to the balance of skeletal structures and teeth in relation to other osseous elements. By X-ray-photoimaging spatial relations within the osseous system of the head of German Shepherd dogs angular parameters (gonial angle Go, the angles Iv, SNA, SNB, ANB and NSBa) were constructed. Sagittal positions or inclinations of the upper and lower incisors were determined by angles C and D and their relationship was determined by the interincisal angle E. The position of the upper and lower eyeteeth in relation to the basic plane of the maxilla and mandible was determined by the numerical values of angles F and G. The opportunity to define the type of growth, and the changes between the face and the skull base, was provided by constructing the following angles of the polygon, as well as by the exact determination of their individual and total values: <SarGo, <NSAr, <ArGoIv, <GoIvMe.

Age-dependant cephalometric standards as determined by multilevel modeling

The purpose of this study was to evaluate the feasibility of constructing age-dependant cephalometric standards for white subjects by using 3 data sets. The data sets were the samples from the Fels Longitudinal Study (United States), the Michigan Growth Study (United States), and the Nijmegen Growth Study (The Netherlands). The 3 mixed-longitudinal samples provided data for 218 girls and 231 boys between 9 and 14 years of age and were compared based on 4 cephalometric angles: SNA, SNB, ANB, and SN/GoMe. Curve-fitting and statistical comparisons were performed with multilevel modeling procedures. All 4 angles showed linear changes over time. SNA and SNB increased, whereas ANB and SN/GoMe decreased. Based on paired-sample comparisons, the samples displayed statistically significant (P <0.05) differences for 50% of the growth velocities and 8% to 17% of the intercepts (size of the angle at 11 years). The SNA and SNB angles showed small and inconsistent differences across the samples. The ANB angle for the Fels boys decreased less than in the other 2 samples. The Nijmegen and Fels girls had the greatest and the least decreases, respectively, in the SN/GoMe angle. Most sample differences decreased over time. Based on the growth differences identified, we concluded that sagittal and vertical jaw relationships have different patterns of growth in different samples of white subjects; indiscriminate pooling of data, to create age-dependant cephalometric standards for white subjects is not recommended.

Soft and hard tissue changes after bimaxillary surgery in Turkish female Class III patients

Treatment of severe Class III malocclusion frequently requires a combination of orthodontics and orthognathic surgical procedures. The aims of this retrospective study were to assess the results of bimaxillary surgery on Turkish female subjects presenting with Class III malocclusions and to evaluate the correlation between soft and hard tissue changes. The sample consisted of 44 Turkish female Class III patients (mean age was 28.3+/-3.7 years) treated with bilateral sagittal split osteotomy and Le Fort I advancement with maxillary impaction. Lateral cephalograms were taken immediately before and 2.6+/-0.7 years after bimaxillary surgery. Paired t-test, Pearson correlation test and linear regression analysis procedures were used to assess the degree of correlation in terms of soft to hard tissue changes between the two cephalograms. All subjects presented with a presurgical concave profile. Maxillary advancement and impaction combined with mandibular setback surgery corrected the facial concavity and the improvement of horizontal and vertical positions. The lengths of the upper and lower lips and the horizontal position of the soft tissue pogonion were improved. The decrease in facial convexity angle was correlated with the increases in SNA angle and N-A distance. The significant increase in labiomental fold depth was significantly correlated with the significant decreases in N-ANS and ANS-Gn distances. The protrusion of the upper lip was correlated with the increases in SNA angle and N-A distance and also with the decrease in SNB angle. The retrusion of the lower lip was correlated with the decrease in N-B distance. The decrease in Sn to A distance was correlated with the increases in SNA, ANB and NAPg angles and N-A distance and also with the decrease in ANS-Gn distance. The increase in Pg' to Pg distance was correlated with the increases in SNA, ANB, NAPg angles and N-A distance. The increase in Si to B distance was correlated with the increases in SNA angle and N-A distance and also with the decreases in N-ANS and ANS-Gn distances. The decrease in Ls to U1 distance was correlated with the increases in SNA and ANB angles and with the increase in N-A distance and with the decreases in N-B and N-Pg distances. The decrease in Li to L1 distance was correlated with the increase in N-A distance. The elongation of the upper lip was correlated with the decrease in ANS-Gn distance. The increase in nasolabial angle was correlated with the decrease in ANS-Gn distance. Maxillary and mandibular soft and hard tissue movements showed significant correlations in horizontal and vertical directions 2.6+/-0.7 years after bimaxillary surgery.

Incisor Inclination – Risk Factor for Palatally-impacted Canines

The purpose of this study was to evaluate the torque of upper incisors and the maxillary size in sagittal direction in patients with impacted canines. Panoramic radiographs, cephalograms and pretreatment study models were evaluated in 199 patients (12.7 +/- 3.6 years) with impacted canines. The prevalence of malocclusions, inclination of the canine to the occlusal plane, incisors' inclination and maxillary size were determined. 45% of the patients showed symptoms of Class II, Division 2 malocclusion: at 18.5 degrees, the inclination of upper incisors (angle U1/NA) was lower and at 81.3 degrees the SNA angle higher than in patients with neutral conditions. There is no guidance for the erupting canine through the labial root torque of the upper incisors like in patients with missing lateral incisors. Patients with symptoms of Class II, Division 2 malocclusion should be regarded as a risk group for canine impaction.

A method for defining targets in contemporary incisor inclination correction

Different craniofacial properties require individual targets in incisor inclination. These requirements are mostly scheduled on the basis of cephalometric diagnosis, but, however, performed using straightwire appliances, which refer to third-order angles and not to cephalometric data. The objective of this study was to analyze the relationship between incisor third-order angles, incisor inclination, and skeletal craniofacial findings in untreated ideal occlusion subjects with natural dentoalveolar compensation of skeletal variation, in order to link the field of cephalometric assessment of incisor inclination with that of contemporary orthodontic incisor inclination correction. This study utilized lateral cephalograms and corresponding dental casts of 69 untreated Caucasians (21 males and 48 females between 12 and 35 years of age) with neutral (Angle Class I) molar and canine relationships and an incisor relationship that was sagittaly and vertically considered as ideal by three orthodontists (i.e. well supported by the antagonistic teeth and without the need for either deep or open bite correction). Upper (U1) and lower (L1) axial incisor inclinations were assessed with reference to the cephalometric lines NA and NL, and NB and ML, respectively. Sagittal and vertical skeletal relationships were classified using SNA (SNB) and NSL-ML (NSL-NL) angles. Third-order angles (U1TA and L1TA) were derived from direct dental cast measurements using an incisor inclination-recording appliance. The relationships between cephalometric and third-order measurements evaluated by calculating Pearson product-moment correlation coefficients (a = 0.05) showed strong correlations between cephalometric axial inclination data (U1NA/deg, L1NB/deg, U1NA/mm, L1NB/mm, U1NL, and L1ML) and sagittal-skeletal data, but no significant relationship between skeletal-vertical findings and incisor inclination. The mean U1TA was 4.9 (standard deviation [SD] 5.85) and the mean L1TA -3.0 (SD 6.9) degrees. Regression analyses were used for axial inclination (ANB angle designated as the independent variable) and for third-order data (U1NA, L1NB, U1NL, and L1ML designated as independent variables). Based on the correlations found in this study, a novel method for defining targets in upper and lower incisor third-order correction according to natural standards is presented. As a consequence, third-order movements can be adapted to cephalometric diagnosis with enhanced accuracy.

Alterações dentoesqueléticas e do perfil facial em pacientes tratados ortodonticamente com extração de quatro primeiros pré-molares

OBJETIVO E METODOLOGIA: o presente estudo prospectivo objetivou analisar cefalometricamente as alterações dentoesqueléticas e do perfil tegumentar após o tratamento ortodôntico de casos com extrações dos quatro primeiros pré-molares. A amostra consistiu de 30 jovens de ambos os gêneros, com idade média inicial de 12 anos e 4 meses, portadores de má oclusão Classe II, 1ª divisão de Angle. As principais referências do trabalho concentram-se nas grandezas cefalométricas dos incisivos superiores e inferiores em relação às coordenadas vertical e horizontal, bem como às alterações dos lábios e ângulo nasolabial pré e pós-tratamento. RESULTADOS: os resultados demonstraram que houve retração média dos incisivos superiores de 3,4mm e dos inferiores de 1,8mm. O ponto A sofreu discreta alteração devido à retração dos incisivos superiores, discriminada pela diminuição média do ângulo SNA (1,7 graus). Houve melhora na relação maxilomandibular, demonstrada pela diminuição das grandezas Wits e ANB. Não houve diferenças estaticamente significantes para as grandezas cefalométricas SN.GoGn e SN.GoMe, embora a altura facial ântero-inferior tenha aumentado, em decorrência do crescimento craniofacial normal. Observou-se que para cada 1mm de retração dos incisivos superiores, o ângulo nasolabial aumentou significativamente 2,8 graus, muito embora tenha ocorrido grande variabilidade individual. CONCLUSÃO: conclui-se que o tratamento com extrações de primeiros pré-molares sobre o perfil facial não se relaciona obrigatoriamente com o "achatamento" do mesmo, sendo também dependente da quantidade de apinhamento no pré-tratamento. As alterações foram decorrentes do crescimento e desenvolvimento facial, da quantidade de retração e da efetiva ancoragem durante a retração dos incisivos superiores e inferiores.

Prediction of oral discomfort and dysfunction in lingual orthodontics: A preliminary report

The purpose of this prospective study was to examine the influence of malocclusion on the amount of discomfort of patients who were treated with Incognito lingual brackets (T.O.P. Service, Ormco, Amersfoort, the Netherlands; ibraces in North and South America, Lingualcare, Dallas, Tex). Twenty-one female patients (mean age, 24.8 years; SD 10.7) participated in the investigation and completed a standardized questionnaire before and the day after placement of the appliance. One experienced orthodontist, blinded to the results of the questionnaires, evaluated their initial cephalograms and casts with respect to the parameters SNA, SNB, and ANB angles; overjet; overbite; maxillary and mandibular anterior contact-point displacement; crossbite; open bite; and missing teeth. Malocclusion measured on the casts had no significant impact on the amount of discomfort or dysfunction reported by the patients. The SNA (r = -0.619, P = .003) and SNB (r = -0.615, P = .003) angles, however, correlated significantly with the restriction of tongue space; patients with an SNB angle that was smaller than 1 SD from the norm were significantly more prone to experience severe restriction of tongue space (P = .003). The SNA and SNB angles are predictors for the level of tongue-space restriction after placement of lingual brackets: the smaller the angles, the more prone the patients are to experience discomfort.