Quantitation of transverse maxillary dimensions using computed tomography: a methodological and reproducibility study

Craniomandibular transverse tomographic evaluation after anterior open bite orthodontic treatment with miniplates anchorage

BACKGROUND

Skeletal anterior open bite (SAOB) represents one of the most complex and challenging malocclusions in orthodontics. Orthodontic treatment supported by miniplates enable to reduce the need for orthognathic surgery. Transverse dimension may be affected by intrusion biomechanics. This study aims to assess transverse bone alterations in patients with SAOB who underwent orthodontic treatment with absolute anchorage using four miniplates.

METHODS

A total of 32 patients of both sexes, with an average age of 33.8 years, diagnosed with SAOB and treated orthodontically with four miniplates (one in each hemiarch), were selected for this study. Tomographic examinations were performed before (T1) and after (T2) orthodontic treatment. Linear measurements (width of the maxillary base, maxillary alveolar, maxillary root, maxillary dental cusp, mandibular alveolar) and angular measurements (maxillary intermolar angle) were assessed in these images. The Shapiro-Wilks normality tests were applied to verify data distribution, and the paired t-test was used to compare the initial and final measures obtained.

RESULTS

Among the evaluated parameters, the maxillary alveolar width, maxillary dental cusp width, mandibular alveolar cusp width, and intermolar angle showed statistically significant differences between T1 and T2 (p < 0.05). However, maxillary base and maxillary root widths showed no significant difference (p > 0.05).

CONCLUSIONS

Intrusion and distalization with miniplates in SAOB therapy may lead to significant expansive changes, due to molars cusps width and buccal inclination increase restricted at the alveolar level.

Three-Dimensional Cone-Beam Computed Tomography Evaluation of Changes in Naso-Maxillary Complex Associated with Rapid Palatal Expansion

The introduction of Cone-Beam Computed Tomography (CBCT) in orthodontics has added a new tool to diagnosis and treatment planning. The aim of this prospective clinical trial was to investigate the changes in the dimensions of the naso-maxillary complex in growing patients after RPE using CBCT. A total of 16 growing children (8 females, 6 males) with a mean age of 11, 12 ± 1 and 86 years underwent RPE as part of their comprehensive orthodontic treatment. CBCT scans were obtained before RPE (T1), immediately after RPE (T2) and 6 months after RPE (T3). The dimensions of the nasal width, nasal floor and the aperture of the midpalatal suture were calculated in different coronal slices of CBCT. Evaluation of the mean value variance per measurement at the three time intervals were performed using the paired Wilcoxon signed-rank test. Differences between the three time intervals were assessed by performing Multiple Pairwise Comparisons. A statistically significant increase in all measurements was seen immediately after RPE expansion (T2–T1) and six months after expansion (T3–T1). Between the end of expansion and 6 months in retention (T3–T2), a decrease was observed for all measurements. RPE can cause expansion of the nasal cavity in growing patients. The expansion of the midpalatal suture follows a triangular pattern of opening.

Three-dimensional dentoskeletal changes following minimally invasive surgically assisted rapid palatal expansion: a prospective study

Dentoskeletal changes in minimally invasive surgically assisted rapid palatal expansion (SARPE) were evaluated using cone beam computed tomography (CBCT). This was a prospective study of 30 patients who underwent minimally invasive SARPE performed under local anaesthesia plus sedation by the same surgeon, in an ambulatory setting. Pre- and postoperative CBCT images were obtained for each patient. A statistically significant increase in the linear transverse dimensions of the maxilla occurred systematically. In the canine region, a mean increase of 5.84 mm occurred at the apex level and 7.82 mm at the crown level. These dimensions were 4.83 mm and 7.68 mm, respectively, in the molar region. The cross-sectional area of the maxilla increased by a mean 12.9 mm² at the palate level and 23.3 mm² at the crown level. Dental inclination to the buccal aspect was detected (mean 6.1° at the canines and 8.4° at the first molars). The alveolar process tipped buccally 10° at the molar level. Nasal width increased a mean of 3.0 mm at the canine level. Through a three-dimensional analysis, this study found that minimally invasive SARPE was effective in the correction of transverse maxillary discrepancies> 5 mm in non-growing patients. Although dental inclination to the buccal aspect occurred, significant expansion of the maxilla at the skeletal and dentoalveolar levels was confirmed.

Maxillary transverse deficiency diagnosed by 3 methods and its relationship with molar angulation in patients with skeletal Class III malocclusion

INTRODUCTION

The objective of this study was to evaluate the relationship between maxillary transverse deficiency (MTD) diagnosed by 3 methods and molar angulation measured in 3-dimensions in patients with skeletal Class III malocclusion, which could give reference to the selection of diagnostic methods in MTD patients.

METHODS

Cone-beam computed tomography data of 65 patients with skeletal Class III malocclusion (mean age 17.35 ± 4.45 years) were selected and imported into MIMICS software. Transverse deficiencies were evaluated by 3 methods, and molar angulations were measured after reconstructing 3-dimensional planes. Two examiners performed repeated measurements to assess the intraexaminer and interexaminer reliability. Pearson correlation coefficient analyses and linear regressions were performed to determine the relationship between a transverse deficiency and molar angulations. One-way analysis of variance was used to compare the diagnostic results of 3 methods.

RESULTS

The novel molar angulation measurement method and 3 MTD diagnostic methods have the interexaminer and intraexaminer intraclass correlation coefficient values >0.6. The transverse deficiency diagnosed by 3 methods was significantly and positively correlated with the sum of molar angulation. There was a statistically significant difference for the transverse deficiencies diagnosed by the 3 methods. The transverse deficiency was significantly higher in Boston University's analysis than in Yonsei's analysis.

CONCLUSIONS

Clinicians ought to choose the diagnostic methods properly, considering the feature of the 3 methods and the individual difference of each patient.

A novel maxillary transverse deficiency diagnostic method based on ideal teeth position

BACKGROUND

This study proposed a novel maxillary transverse deficiency diagnostic method and evaluated the skeletal Class I and the mild skeletal Class III groups.

METHODS

Pre-treatment data from 30 mild skeletal Class III and 30 skeletal Class I patients were collected and uploaded to the Emeiqi Case Management System to design the ideal teeth positions. On these positions, the first bi-molars width was measured at the central fossa and center resistance, the maxillary first bi-premolars width was measured at the central fossa, and the mandibular first bi-premolars width was measured at the distal contact point by Mimics, then width differences of two groups were calculated respectively.

RESULTS

At ideal teeth positions, there was no statistically significant difference in the maxillomandibular width in the premolar area between the two groups, but there was in the molar area, and this difference was caused by the difference in mandible width between the two groups.

CONCLUSIONS

We proposed a new transverse diagnostic method and found that even the Class I group was not quite up to standard in the molar area on ideal teeth positions, and the Class III group had more severe maxillary transverse deficiency than the Class I group. Meanwhile, the maxillary transverse deficiency in the Class III group was mainly caused by the larger width of the mandible.

What are the intra-arch risk factors for palatally displaced maxillary canine? - Results of a case-control study

INTRODUCTION

This study aimed to identify the intra-arch risk factors for palatally displaced canine by comparing the maxillary transverse dimensions, palatal depth (PD), and arch length (AL) of the subjects with and without impacted canine using cone-beam computed tomography (CBCT).

METHODS

In this prospective case-control study, 79 CBCT images of gender- and skeletal feature-matched subjects (25 cases and 54 controls) were compared. Based on the CBCT images, maxillary transverse widths at four levels (molar basal, molar alveolar, premolar basal, and premolar alveolar), maxillary PD, and maxillary AL were measured. Group comparisons were assessed using analysis of variance (ANOVA), followed by post-hoc Scheffe's test, and risk factors were identified using univariate and multivariate logistic regression.

RESULTS

The impacted canine group showed significantly smaller molar alveolar width, premolar alveolar width, PD, and greater AL compared to the control group (P = 0.046, P < 0.001, P = 0.003, and P = 0.001, respectively). No significant difference was observed in the molar and premolar basal width measurements between the two groups. Multivariate analysis showed that impacted maxillary canine was influenced by premolar alveolar width (odds ratio (OR): 0.669), PD (OR: 0.532), and AL (OR: 1.739).

CONCLUSION

Intra-arch risk factors, such as reduced maxillary premolar transverse alveolar width, PD, and greater AL, are associated with palatally displaced canine.

Transverse Growth of the Maxillo-Mandibular Complex in Untreated Children: A Longitudinal Cone Beam Computed Tomography Study

The aim of this study is to evaluate the longitudinal transverse growth of the maxillo-mandibular complex in untreated children using the Cone Beam Computed Tomography (CBCT). Two sets of scans on 12 males (mean 8.75 years at T1 and 11.52 years at T2) and 18 females (mean 9.09 years at T1 and 10.80 years at T2) were analyzed using Dolphin 3D imaging. The transverse widths of various maxillary and mandibular skeletal landmarks and the dentoalveolar and dental landmarks at the level of first molars were measured. Overall, there were greater increases in the transverse dimension in the posterior than anterior portions of the maxilla and mandible. The increase in intergonial width of the mandible seems to be primarily due to the lengthening of the mandibular body. The dentoalveolar process at the first molar level increases at an equal rate corono-apically and is independent to the changes in molar inclination. When comparing maxillary dentoalveolar changes with that of the mandible, greater increases were noticed in the maxilla, which might be explained by the presence of sutural growth in the maxilla. Moreover, the first molars maintain their coordination with each other despite the differential increase in the maxillary and mandibular dentoalveolar processes.

Three-segment versus 2-segment surgically assisted rapid maxillary expansion

OBJECTIVE

To compare the 2 surgically assisted rapid maxillary expansion (SARME) techniques, the conventional 2-segment osteotomy between maxillary central incisors and the 3-segment osteotomy between maxillary lateral incisors and canines bilaterally. Authors hypothesized that the 3-piece would provide better bone expansion.

STUDY DESIGN

A pilot study was conducted; 19 patients were divided into 2 groups: conventional 2-segment osteotomy (10 patients) and 3-segment osteotomy (9 patients). Dental and skeletal measurements of the preoperative and postoperative cone beam computed tomography images were analyzed. Pre- and postoperative periodontal probing was performed, patients' cosmetic perception was evaluated in a colored visual analog scale (VAS), and surgical time was measured with a regular chronometer.

RESULTS

Three-segment SARME resulted in greater bone expansion (5.12 vs 6.20 mm; P = .016), less molar inclination (7.16 vs 3.57 degrees; P = .028), better patient cosmetic perception (3.13 vs 7.68 in a VAS; P = .000), and longer surgical time (43 vs 52 minutes; P = .026). Furthermore, the 2-segment group presented necrosis of 1 central incisor.

CONCLUSIONS

Results suggest that 3-piece SARME is more effective for bone expansion of the maxilla.

Buccolingual Inclination of Canine and First and Second Molar Teeth and the Curve of Wilson in Different Sagittal Skeletal Patterns of Adults Using Cone-Beam Computed Tomography

Objectives

This study aimed to assess the buccolingual inclination of canine and first and second molar teeth and the curve of Wilson in different sagittal skeletal patterns in untreated adults using cone-beam computed tomography (CBCT).

Materials and Methods

Sixty-six CBCT scans of adults (mean age: 28.74 ± 5.25 years) were evaluated in this cross-sectional study. The images were standardized using the Frankfurt horizontal plane and the interorbital line. The sagittal skeletal pattern was determined using the ANB angle and Wits appraisal. Inclination angles were measured by NNT Viewer and Mimics software. The curve of Wilson was measured by connecting the tips of mesiobuccal and mesiolingual cusps of maxillary first and second molars along the buccal groove and measuring the formed angle. Data were analyzed using ANOVA.

Results

The intraobserver agreement was 0.969. The mean inclination of maxillary first and second molars in class I and III patients was significantly higher than that in class II patients (P < 0.05). The mean inclination of mandibular first and second molars in class II patients was significantly higher than that in class I and III patients (P < 0.05). The difference in inclination of maxillary and mandibular canine teeth was not significant (P > 0.05). The mean curve of Wilson in second molars of class II patients was significantly higher than that in class I patients (P < 0.05).

Conclusion

In different sagittal skeletal patterns, a compensatory relationship exists between the opposing teeth, which, along with the standards of crowns, can be used to determine the appropriate position of teeth in dental arch.

Immediate dental and skeletal influence of distractor position on surgically assisted rapid palatal expansion with or without pterygomaxillary disjunction

The outcome of surgically assisted rapid palatal expansion (SARPE) can be affected by pterygomaxillary disjunction (PMD) and the distractor position. In this study, SARPE was performed, with or without PMD, in 20 fresh cadaver heads. Transverse expansion was conducted twice using a bone-borne distractor in the anterior and posterior positions, resulting in four groups (n=10). Cone beam computed tomography scans were completed before and after SARPE to evaluate maxillary changes. A comparative anterior decrease and posterior increase in midpalatal opening resulted from SARPE with PMD combined with a posteriorly placed distractor. Significant differences in the internal transverse changes were found between the two SARPE techniques combined with an anterior distractor at the level of the premolars and molars for alveolar ridge width (P=0.040, P=0.024), and at the level of the molars for the dental crown width (P=0.017) and corresponding tooth cusp width (P=0.018). In contrast, using a posteriorly placed distractor led to a significant difference for tooth cusp width only (P=0.050). No statistically significant differences were found between external transverse changes or between distractor positions. PMD is more important in achieving a more uniform and parallel transverse expansion pattern than the distractor position. However, a posterior distractor seems to intensify the effects of PMD.

Short-term treatment effects produced by rapid maxillary expansion evaluated with computed tomography: A systematic review with meta-analysis

OBJECTIVE

To identify the available evidence on the effects of rapid maxillary expansion (RME) with three-dimensional imaging and provide meta-analytic data from studies assessing the outcomes using computed tomography.

METHODS

Eleven electronic databases were searched, and prospective case series were selected. Two authors screened all titles and abstracts and assessed full texts of the remaining articles. Seventeen case series were included in the quantitative synthesis. Seven outcomes were investigated: nasal cavity width, maxillary basal bone width, alveolar buccal crest width, alveolar palatal crest width, inter-molar crown width, inter-molar root apex width, and buccopalatal molar inclination. The outcomes were investigated at two-time points: postexpansion (2-6 weeks) and post-retention (4-8 months). Mean differences and 95% confidence intervals were used to summarize and combine the data.

RESULTS

All the investigated outcomes showed significant differences postexpansion (maxillary basal bone width, +2.46 mm; nasal cavity width, +1.95 mm; alveolar buccal crest width, +3.90 mm; alveolar palatal crest width, +3.09 mm; intermolar crown width, +5.69 mm; inter-molar root apex width, +2.85 mm; and dental tipping, +3.75°) and post-retention (maxillary basal bone width, +2.21 mm; nasal cavity width, +1.55 mm; alveolar buccal crest width, +3.57 mm; alveolar palatal crest width, +3.32 mm; inter-molar crown width, +5.43 mm; inter-molar root apex width, +4.75 mm; and dental tipping, 2.22°) compared to pre-expansion.

CONCLUSIONS

After RME, skeletal expansion of the nasomaxillary complex was greater in most caudal structures. Maxillary basal bone showed 10% post-retention relapse. During retention period, uprighting of maxillary molars occurred.

Effect of orthodontic treatment on alveolar bone thickness in adults: a systematic review

Objectives:

This review aimed at evaluating changes in alveolar bone thickness after completion of orthodontic treatment.

Methods:

Only prospective clinical studies that reported bone thickness in adult patients undergoing non-surgical orthodontic treatment were considered eligible. MEDLINE, EMBASE and LILACS databases were searched for articles published up to July 2018.

Results:

A total of 12 studies met the selected criteria. Most of the studies showed that orthodontic treatment produces a reduction in bone thickness of incisors, mainly at the palatal side.

Conclusion:

On patients undergoing different orthodontic treatment techniques, there was a significant bone thickness reduction, mainly on the palatal side.

Clinical relevance:

These findings are relevant and have to be considered in diagnosis and planning of tooth movement, in order to prevent the occurrence of dehiscence and fenestration in alveolar bone.

Evaluation of the stability of maxillary expansion using cone-beam computed tomography after segmental Le Fort I osteotomy in adult patients with skeletal Class III malocclusion

Objective

The aim of this study is to quantitatively evaluate the stability of the skeletal and dental widths using cone-beam computed tomography (CBCT) after segmental Le Fort I osteotomy in adult patients with skeletal Class III malocclusion requiring maxillary expansion.

Methods

In total, 25 and 36 patients with skeletal Class III malocclusion underwent Le Fort I osteotomy (control group) and segmental Le Fort I osteotomy (experimental group), respectively. Coronal CBCT images were used to measure the dental and skeletal widths before (T1) and after (T2) surgery and at the end of treatment (T3). The correlation between the extent of surgery and the amount of relapse in the experimental group was also determined.

Results

In the control group, the dental width exhibited a significant decrease of 0.70 ± 1.28 mm between T3 and T2. In the experimental group, dental and skeletal expansion of 1.83 ± 1.66 and 2.55 ± 1.94 mm, respectively, was observed between T2 and T1. The mean changes in the dental and skeletal widths between T3 and T2 were -1.41 ± 1.98 and -0.67 ± 0.72 mm, respectively. There was a weak correlation between the amount of skeletal expansion during segmental Le Fort I osteotomy and the amount of postoperative skeletal relapse in the experimental group.

Conclusions

Maxillary expansion via segmental Le Fort I osteotomy showed good stability, with a skeletal relapse rate of 26.3% over approximately 12 months. Our results suggest that a greater amount of expansion requires greater efforts for the prevention of relapse.

The value of cone beam computed tomography imaging in surgically assisted rapid palatal expansion: a systematic review of the literature

This study aimed to evaluate the reliability of cone-beam computed tomography (CBCT) imaging of the maxillary structures and the postoperative dentoskeletal, nasal airway, periodontal, and facial soft tissue changes after surgically assisted rapid palatal expansion (SARPE). A systematic review of the literature on CBCT analysis of SARPE was performed. The PubMed, Embase, and Cochrane Library databases were searched. Nine articles were included, involving a total of 228 patients. The general trend was tooth-borne distraction with pterygomaxillary dysjunction. A systematic increase in all transverse dimensions at the dentoalveolar and dental levels, as well as a certain degree of tipping and extrusion of the anchorage teeth and tipping of the skeletal segments, was detected. Soft tissue findings reflected the underlying dentoalveolar changes. A decrease in the buccal alveolar bone thickness and alveolar crest level occurred. Results confirm that CBCT is an accurate and reliable method to assess anatomical changes after SARPE. Although this systematic review provides valuable preliminary information about the effects of SARPE, results should be interpreted with caution due to the low level of evidence of the publications, great heterogeneity among study groups regarding outcome variables and surgical-orthodontic protocols, and lack of long-term data.

Diagnostic methods for assessing maxillary skeletal and dental transverse deficiencies: A systematic review

Objective

To evaluate the accuracy and reliability of the diagnostic tools available for assessing maxillary transverse deficiencies.

Methods

An electronic search of three databases was performed from their date of establishment to April 2015, with manual searching of reference lists of relevant articles. Articles were considered for inclusion if they reported the accuracy or reliability of a diagnostic method or evaluation technique for maxillary transverse dimensions in mixed or permanent dentitions. Risk of bias was assessed in the included articles, using the Quality Assessment of Diagnostic Accuracy Studies tool-2.

Results

Nine articles were selected. The studies were heterogeneous, with moderate to low methodological quality, and all had a high risk of bias. Four suggested that the use of arch width prediction indices with dental cast measurements is unreliable for use in diagnosis. Frontal cephalograms derived from cone-beam computed tomography (CBCT) images were reportedly more reliable for assessing intermaxillary transverse discrepancies than posteroanterior cephalograms. Two studies proposed new three-dimensional transverse analyses with CBCT images that were reportedly reliable, but have not been validated for clinical sensitivity or specificity. No studies reported sensitivity, specificity, positive or negative predictive values or likelihood ratios, or ROC curves of the methods for the diagnosis of transverse deficiencies.

Conclusions

Current evidence does not enable solid conclusions to be drawn, owing to a lack of reliable high quality diagnostic studies evaluating maxillary transverse deficiencies. CBCT images are reportedly more reliable for diagnosis, but further validation is required to confirm CBCT's accuracy and diagnostic superiority.

Comparison of transverse analysis between posteroanterior cephalogram and cone-beam computed tomography

OBJECTIVES

To evaluate maxillary and mandibular alveolar and basal bone widths using cone-beam computed tomography (CBCT) and to verify the correlation between CBCT images and posteroanterior (PA) cephalograms.

MATERIALS AND METHODS

The CBCT scans and PA cephalograms were obtained from 20 men (age range  =  24.0-29.1 years; mean age  =  27.2 years; SD  =  2.8 years) and 20 women (age range  =  20.3-28.1 years; mean age  =  26.4 years; SD  =  3.2 years) with normal occlusion. On CBCT images, maxillary and mandibular bone widths were measured at three posterior sites and five bone levels. The differences between maxillary and mandibular bone widths were calculated and compared with conventional transverse width of PA cephalograms.

RESULTS

Statistically significant differences in maxillary and mandibular bone widths were detected at different levels and sites. Bone widths were significantly increased from the alveolar crest toward the basal bone in the maxillary molar and mandibular second premolar and molar areas. A statistically significant correlation was only found between CBCT images and PA cephalograms for maxillomandibular width at the first molar area.

CONCLUSION

The results of this study suggested that three-dimensional assessment of maxillomandibular width is mandatory for the transverse analysis.

Three-dimensional computed tomographic analysis of changes to the external features of the nose after surgically assisted rapid maxillary expansion and orthodontic treatment: a prospective longitudinal study

INTRODUCTION

The aim of this prospective, longitudinal study was to evaluate changes to the external shape and form of the nose after surgically assisted rapid maxillary expansion and orthodontic treatment. The changes were registered using a 3-dimensional computer tomography technique, based on superimposition on the anterior base of the skull.

METHODS

The subjects comprised 35 patients (mean age, 19.7 years; range, 16.1-43.9 years). Low-dose, helical computerized tomography images were taken at treatment start and after orthodontic treatment, about 18 months postsurgery. The 3-dimensional models were registered and superimposed on the anterior cranial base.

RESULTS

There were in general significant widening and overall anterior and inferior displacement of the nasal soft tissues. The changes varied in size and direction. No correlation was found between the initial and final widths of the nose, or between the initial and final widths of the nostrils.

CONCLUSIONS

After surgically assisted rapid maxillary expansion, the most obvious changes to the external features of the nose were at the most lateral alar bases. The difference in lateral displacement profoundly influenced the perception of a more rounded nose. Patients with narrow and constrained nostrils can benefit from these changes. The 3-dimensional superimposition applied in this study is a reliable method, circumventing projection and measurement errors.

Effects of orthopedic maxillary expansion on nasal cavity size in growing subjects: a low dose computer tomography clinical trial

OBJECTIVE

The aim of this retrospective clinical trial was to evaluate the effects of rapid maxillary expansion on skeletal nasal cavity size in growing subjects by use of low dose computer tomography.

METHODS

Eight Caucasian children (three male; five female) with a mean age of 9.7 years (SD±1.41) were the final sample of this research that underwent palatal expansion as a first phase of orthodontic treatment. The maxillary expander was banded to the upper first molars and was activated according a rapid maxillary expansion protocol. Low-dose computer tomography examinations of maxilla and of the low portion of nasal cavity were performed before inserting the maxillary expander (T0) and at the end of retention (T1), 7 months later. A low-dose computer tomography protocol was applied during the exams. Image processing was achieved in 3 steps: reslicing; dental and skeletal measurements; skeletal nasal volume computing. A set of reproducible skeletal and dental landmarks were located in the coronal passing through the first upper right molar furcation. Using the landmarks, a set of transverse linear measurements were identified to estimate maximum nasal width and nasal floor width. To compute the nasal volume the lower portion of the nasal cavity was set as region of interest. Nasal volume was calculated using a set of coronal slices. In each coronal slice, the cortical bone of the nasal cavity was identified and selected with a segmentation technique. Dependent t-tests were used to evaluate changes due to expansion. For all tests, a significance level of P<0.05 was used.

RESULTS

Rapid maxillary expansion produced significant increases of linear transverse skeletal measurements, these increments were bigger in the lower portion of the nasal cavities: nasal floor width (+3.15 mm; SD ± 0.99), maximum nasal width (+2.47 mm; SD ± 0.99). Rapid maxillary expansion produced significant increment of the total nasal volume (+1.27 cm(3) ± SD 0.65). The anterior volume increase was 0.58 cm(3) while the posterior one was 0.69 cm(3).

CONCLUSION

In growing subjects RME is able to significantly enlarge the dimension of nasal cavity. The increment is bigger in the lower part of the nose and equally distributed between the anterior e the posterior part of the nasal cavity.

Avaliação da inclinação dentária no tratamento compensatório do padrão II com tomografia computadorizada

OBJETIVO: avaliar as alterações nas inclinações dos dentes anteriores causadas pelo tratamento ortodôntico, utilizando-se aparelho Straight-Wire, prescrição II Capelozza, antes e após a fase de nivelamento com fios ortodônticos de aço de secção retangular. MÉTODOS: foram selecionados 17 indivíduos adultos de padrão facial II, má oclusão Classe II, indicados para tratamento ortodôntico compensatório. As inclinações dos dentes anteriores foram avaliadas em três tempos clínicos, após o uso dos fios ortodônticos de diâmetros 0,020" (T1); 0,019" x 0,025" (T2) e 0,021" x 0,025" (T3), através de exames de tomografia computadorizada. Empregou-se a análise de variância de Friedman, com nível de significância de 5%, na comparação entre os tempos. RESULTADOS: observou-se que o fios retangulares empregados não foram capazes de produzir uma mudança significativa na mediana da inclinação dentária, exceto por uma discreta alteração nos incisivos laterais inferiores (p<0,05). Por outro lado, constatou-se que a variação das inclinações observadas era menor no fio retangular 0,021" x 0,025", principalmente para os incisivos superiores (p<0,001). CONCLUSÃO: fios retangulares 0,021" x 0,025" produzem uma maior homogeneidade no grau de variação na inclinação dos incisivos superiores, embora sem mudança significativa na sua mediana.

M, Souza MMGD, Nojima MG. Efeitos transversais da expansão rápida da maxila em pacientes com má oclusão de Classe II: avaliação por Tomografia Computadorizada Cone-Beam

OBJETIVO: avaliar por meio de Tomografia Computadorizada Cone-Beam (TCCB) os efeitos transversais, imediatos e após o período de contenção, da expansão rápida da maxila (ERM) em pacientes com má oclusão de Classe II. MÉTODOS: dezessete crianças (idade inicial média de 10,36 anos) com má oclusão de Classe II e deficiência transversal esquelética da maxila foram submetidas ao protocolo de ERM com aparelho expansor de Haas. TCCBs foram realizadas antes dos procedimentos clínicos (T1), imediatamente após a estabilização do parafuso expansor (T2) e após completados 6 meses de contenção e removido o aparelho (T3). Com o software Dolphin, foram possíveis a manipulação das imagens e as mensurações. O teste t de Student pareado foi utilizado para identificar significância estatística (p<0,05) entre os intervalos T2 e T1, T3 e T2, e T3 e T1. RESULTADOS: imediatamente após a ERM, ocorreu aumento significativo da largura maxilar basal, alveolar e dentária de 1,95mm, 4,30mm e 6,89mm, respectivamente, e inclinação vestibular dos primeiros molares direito (7,31º) e esquerdo (6,46º). Ao final do período de contenção, o aumento transversal foi mantido e a inclinação dentoalveolar retornou ao valor inicial. CONCLUSÕES: a ERM foi efetiva no aumento da dimensão transversa da maxila, tanto esquelético quanto dentário, sem causar inclinação dos molares de ancoragem em pacientes com má oclusão de Classe II.

Effects of bonded rapid palatal expansion on the transverse dimensions of the maxilla: a cone-beam computed tomography study

INTRODUCTION

The purpose of this study was to examine the maxillary response on the transverse dimensions to rapid palatal expansion (RPE) by using cone-beam computed tomography (CBCT).

METHODS

Twenty-four children (average age, 9.9 years) who had RPE treatment with a bonded expander were included. Pretreatment orthodontic records (T1) and immediately after expansion (T2) CBCT images were taken for all patients. For each patient, the width of the nasal cavity at the level of the maxillary first permanent molar and second deciduous molar (or second permanent premolar), the width of the maxillary basal bone, and the width of the midpalatal suture at the level of the second deciduous molar (or the second permanent premolar), the first deciduous molar (or first permanent premolar), and the deciduous canine (or permanent canine) at T1 and T2 were measured. In addition, the amount of tipping for both the maxillary right and left first permanent molars was measured.

RESULTS

From T1 to T2, mean increases in nasal width, related to the mean jackscrew opening (8.19 mm), occurred at the levels of the first permanent molars of 33.23% (2.73 mm, P <0.05) and the second deciduous molars of 37.32% (3.06 mm, P <0.05). Significant increases in basal bone of the maxilla were found at all levels (P <0.05), with mean increases of 40.65% (3.33 mm), 44.08% (3.49 mm), 46.73% (3.83 mm), and 46.83% (3.62 mm) of the mean jackscrew opening at the levels of the first permanent molars, and the second deciduous molars, first deciduous molars, and deciduous canines, respectively. Significant openings in the midpalatal sutures was found at all levels (P <0.05), with mean increases of 52.82% (4.33 mm), 53.23% (4.36 mm), 54.35% (4.46 mm), and 52.77% (4.33 mm) of the jackscrew opening at the levels of the first permanent molars, and the second deciduous molars, first deciduous molars, and deciduous canines, respectively. The right first molar tipped buccally an average of 6.2 degrees (P <0.05), and the left first molar tipped buccally 5.6 degrees (P <0.05).

CONCLUSIONS

After RPE, significant increases in the transverse dimensions of the nasal cavity, the maxillary basal bone, and the midpalatal suture opening occurred, with the greatest increase in the midpalatal suture followed by basal bone and nasal cavity. The midpalatal suture opened in a parallel fashion. Moreover, significant buccal tipping occurred on both maxillary first molars.

Hyrax appliance opening and pattern of skeletal maxillary expansion after surgically assisted rapid palatal expansion: a computed tomography evaluation

OBJECTIVE

The objective of this study was to evaluate, using computed tomography, correlations between Hyrax appliance opening and post-SARPE skeletal changes.

STUDY DESIGN

Fifteen patients underwent SARPE according to a specific protocol and were followed. Linear and angular measurements of the anterior, intermediate, and posterior portions of the maxilla were evaluated. The correlation between maxillary expansion and appliance opening was investigated.

RESULTS

Significant overall expansion was observed. In the anterior and intermediate portions of the maxilla, the increase in maxillary width was greater than that observed in the posterior portion. The degree of appliance opening was significantly greater than that of the skeletal expansion. Also, no linear correlation between appliance opening and regional maxillary expansion was established.

CONCLUSION

The transverse expansion of the maxilla was less than uniform. The lack of linear correlation between appliance opening and skeletal expansion is attributable to multiple factors, including those related to the device, the surgical technique, and the craniofacial deformity itself.

Transverse effects after surgically assisted rapid maxillary expansion in the midpalatal suture using computed tomography

Surgically assisted rapid maxillary expansion is the treatment of choice for correcting maxillary transverse deficiency in adults. Traditionally, the appliance for expansion is tooth-borne and tissue-tooth-borne devices (Hyrax and Haas). Although a number clinical and radiographic studies have evaluated the surgically assisted rapid maxillary expansion, only limited information is available to study the transverse movement of the midpalatal suture with computed tomography. Forty adult patients of both sexes, ranging in age from 18 to 38 years, with bilateral transverse maxillary deficiency were operated on. Twenty patients had Hyrax expander, and 20 had Haas expander. Under general anesthesia, subtotal Le Fort I osteotomy was performed including pterygomaxillary dysjunction. The width of the midpalatal suture opening was measured at the anterior edge of the midpalatal suture and at the junction of the midpalatal suture and palatal bones, using computed tomography in axial acquisition, obtained in the preoperative period and immediately after the end of expansion. A digital caliper was used to measure Haas and Hyrax distance on the central jackscrew preoperatively and postoperatively. The proportion between the midpalatal suture expansion and the amount of expansion on the jackscrew was evaluated. The mean of midpalatal suture opening and screw opening for Haas group was 5.19 and 8.78 mm, and for the Hyrax group, 5.85 and 8.51 mm, respectively. Both groups showed parallel-shaped separation of the midpalatal opening with no significant difference in the anterior and posterior portion. Midpalatal/jackscrews opening proportion was greater in the Hyrax group (69,2%) than in the Haas group (60%).

R, Raymundo MV, Raymundo DV, Ferreira SN. Tomografia computadorizada de feixe cônico (Cone beam): entendendo este novo método de diagnóstico por imagem com promissora aplicabilidade na Ortodontia

OBJETIVO: este artigo visa informar e atualizar o profissional da área odontológica a respeito da tomografia computadorizada, incluindo informações concernentes à aquisição de imagens, dose de radiação e interpretação do exame tomográfico, com distinção entre a tomografia computadorizada tradicional e a tomografia computadorizada de feixe cônico. Adicionalmente, as possibilidades de aplicação deste método de diagnóstico por imagem na Ortodontia são discutidas. CONCLUSÕES: resultado de avanços tecnológicos, da redução da exposição à radiação e da ótima qualidade da imagem, as expectativas apontam para uma utilização mais abrangente da tomografia computadorizada de feixe cônico na Odontologia e na Ortodontia. Com a definição de novos conhecimentos gerados pela visão tridimensional do crânio e da face, o futuro reserva a renovação de conceitos e paradigmas, assim como a redefinição de metas e planos terapêuticos ortodônticos.

Using Computed Tomography to Evaluate Maxillary Changes After Surgically Assisted Rapid Palatal Expansion

Surgically assisted rapid palatal expansion (SARPE) is the procedure of choice for treating transverse maxillary deficiency in adult patients. The use of computed tomography (CT) as a method of evaluating the efficiency of this procedure has not been yet reported. Consequently, few landmarks for use in evaluating maxillary expansion have been defined. The goals of the present study were to define parameters to assess skeletal changes after SARPE and to use CT to evaluate those parameters. From June of 2004 to May of 2005, 15 patients underwent SARPE (a modified Le Fort I maxillary osteotomy without pterygomaxillary separation, together with a sagittal palatal osteotomy) according to a defined protocol. To determine the pattern of transversal expansion, linear and angular measurements of the anterior, intermediate, and posterior portions of the maxilla were evaluated in axial and coronal views. The cross-sectional area of the maxilla was calculated to obtain general information about maxillary expansion. The reliability of the method was confirmed. Significant overall expansion was observed. However, different patterns of expansion were seen in the three regions analyzed. In the anterior and intermediate portions of the maxilla, the increase in maxillary width was greater than that observed in the posterior portion. The transverse expansion of the maxilla achieved through SARPE without pterygoid plate separation was less than uniform. The accurate evaluation of the postoperative changes was heavily dependent upon images acquired through CT.

Evaluation of the effects of rapid maxillary expansion in growing children using computer tomography scanning: a pilot study

The principle of rapid maxillary expansion (RME) as a method to expand the transverse dimension of the palate and maxillary dental arch is by no means new, and previous studies have reported the effects of the method using a variety of radiographic methods. In the present study, the effect of a Hyrax splint appliance was studied in a group of nine growing children (six females, three males; mean age 8 years 1 month) undergoing orthodontic treatment. The changes were evaluated on pre- and post-treatment computer tomographic scans taken using a low-dosage protocol. The results demonstrated a clear appliance-induced effect in all patients, although the relative contribution of dental, alveolar, and skeletal changes varied from subject to subject. The average expansion, measured at the molar crowns, was 3.6 mm, whereas the actual sutural opening, the main aim of RME, was as low as 1.6 mm. The findings of this study raise doubts as to the efficiency of the Hyrax appliance and further comparative studies are recommended to evaluate other methods of maxillary expansion.