Quantitative skeletal evaluation based on cervical vertebral maturation: a longitudinal study of adolescents with normal occlusion

The Implications of Artificial Intelligence in Pedodontics: A Scoping Review of Evidence-Based Literature

BACKGROUND

Artificial intelligence (AI) has emerged as a revolutionary technology with several applications across different dental fields, including pedodontics. This systematic review has the objective to catalog and explore the various uses of artificial intelligence in pediatric dentistry.

METHODS

A thorough exploration of scientific databases was carried out to identify studies addressing the usage of AI in pediatric dentistry until December 2023 in the Embase, Scopus, PubMed, and Web of Science databases by two researchers, S.L.R. and A.L.G.

RESULTS

From a pool of 1301 articles, only 64 met the predefined criteria and were considered for inclusion in this review. From the data retrieved, it was possible to provide a narrative discussion of the potential implications of AI in the specialized area of pediatric dentistry. The use of AI algorithms and machine learning techniques has shown promising results in several applications of daily dental pediatric practice, including the following: (1) assisting the diagnostic and recognizing processes of early signs of dental pathologies, (2) enhancing orthodontic diagnosis by automating cephalometric tracing and estimating growth and development, (3) assisting and educating children to develop appropriate behavior for dental hygiene.

CONCLUSION

AI holds significant potential in transforming clinical practice, improving patient outcomes, and elevating the standards of care in pediatric patients. Future directions may involve developing cloud-based platforms for data integration and sharing, leveraging large datasets for improved predictive results, and expanding AI applications for the pediatric population.

Three-dimensional dentoskeletal effects of the Angelalign A6 clear aligners in a skeletal Class II growing patient: A case report

This case report illustrates the successful nonsurgical and nonextraction treatment of a 12-year-old boy with skeletal Class II deep bite malocclusion undergoing two-phase clear aligner treatment. During A6 mandibular advancement phase, Class II buccal segment relationship was corrected by differential forward growth of the mandible, unplanned distalization of maxillary posterior teeth, and unplanned mesialization of mandibular posterior teeth. The maxillary sagittal curve of occlusion was deepened, the mandibular curve of Spee was not fully levelled, and the maxillary arch experienced downward-backward rotation resulting in premature contact on anterior and posterior open bite. Buccal crown tipping of maxillary posterior teeth was observed after arch expansion. The forward growth of the mandible improved the skeletal relationship, and the advancement of the chin position and sagittal movements of the incisors altered the nose-lip-chin relationship, resulting in an improved profile of the patient. During refinement phase, the posterior open bite was corrected. The mandibular plane angle did not increase throughout the treatment. The patient was satisfied with the aesthetic and functional outcome.

Ontogenetic patterns in human frontal sinus shape: A longitudinal study using elliptical Fourier analysis

Frontal sinus morphology is highly variable across individuals, but little is known regarding how or at what age that variation is reached. Existing ontogenetic studies are conflicting and often cross-sectional in nature, limiting understanding of individualistic growth. Studies investigating sinus growth with longitudinal series often focus on lateral cephalograms and consequently do not capture the sinus morphological features that are most relevant to clinical and medicolegal settings (e.g., arcade/scalloping, width-to-height dimensions, asymmetry). Longitudinal analysis of sinus morphology from frontal radiographs is important to understand when sinus morphology stabilizes. The purpose of this study was to investigate at what age the frontal sinus attains its final shape, and whether sex-based differences in ontogeny are evident, using a longitudinal sample of posterior-anterior (PA) frontal radiographs from the AAOF Legacy Collection. Frontal sinus outlines were manually traced in 935 radiographs from 111 individuals (55F/56M) spanning 8-29 years of age. Outlines were subjected to elliptical Fourier analysis (EFA) and underwent principal components analysis (PCA). PC1 (51.02% of variation) appears to represent the relative height and breadth of the sinus, PC2 (11.73%) and PC3 (10.03%) captures the degree of relative complexity in the outlines. Individual PC scores were plotted against age-in-months with individual Loess growth curves. Overall, younger individuals typically display relatively shorter, flatter sinuses, increasing in vertical complexity with age. Mixed-effect models on PC1 indicate significant effects for the repeated measure of years (p < 0.001). Within individuals, Euclidean distances of PCs between each sinus outline and their oldest-age outline (i.e., final morphology) were calculated and plotted against age-in-months with Loess growth curves. The results indicate that final frontal sinus morphology is mostly attained by 20 yoa regardless of sex. There is sexual dimorphism in ontogenetic trajectories: females attain frontal sinus shape earlier than males. Specifically, Loess growth curves of the Euclidean distances to final sinus shape indicate that female shape shows decreased development at 14-16 yoa, with males approaching stabilization at 18-20 yoa. These trends were supported by paired t-tests on PC1 between each year and the oldest age, whereby significant differences end for females starting at 15 and 18 yoa for males. The timing of shape-stabilization in the current study closely aligns with previous studies on linear and size dimensions, indicating a close relationship between the ontogeny of frontal sinus shape and size. This research has several implications in diverse fields. Documenting ontogenetic patterns in modern humans could lead to more accurate interpretations of frontal sinus variation in hominin lineages. Understanding the age at which frontal sinus shape and size stabilizes in pediatric populations has important clinical implications, with future studies needed to investigate if/how sinus development directly relates to sinonasal disease susceptibility (e.g., sinusitis), surgical complications, and/or expected trauma patterns. For forensic practitioners utilizing frontal sinus comparisons for decedent identifications, it is important to know at what age these features stabilize to understand how much change may be expected between antemortem and postmortem radiographs.

Development of a multi-stage model for intelligent and quantitative appraising of skeletal maturity using cervical vertebras cone-beam CT images of Chinese girls

PURPOSE

Nowadays, the integration of Artificial intelligence algorithms and quantified radiographic imaging-based diagnostic procedures is hailing amplified deliberation particularly in assessment of skeletal maturity. So we intend to formulate a logistic regression model for intelligent and quantitative estimation of Fishman skeletal maturation index (SMI) based on the parameters attained from the cervical vertebrae CBCT images of Chinese girls.

METHODS

From 709 hand wrist radiographs and CBCT images, 447 samples were randomly selected (called as G1) to build a logistic regression model. The reliability and reproducibility were assessed by the intraclass correlation coefficient (ICC) and weighted Cohen's kappa, followed by Spearman's rank correlation coefficient to identify the parameters significantly associated with the SMI. Two hundred and sixty-two other subjects (named G2) were recruited for external examination of the models by direct visual comparison and the receiver operating characteristic (ROC) curve. In cases of confusion and mispredictions, the model was modified to improve the consistency.

RESULTS

Five significant parameters (Chronological age, C3 height (H3)[Formula: see text], C4 upper width (UW4), C4 lower width (LW4), and the ratio of posterior height to lower width of C4 ([Formula: see text]) were administered into logistic regression model. Despite total agreement percentage which was 84% (total AUC = 0.92), unsatisfactory performance was noticed for the 6th and 8th stages which were confused with their neighboring stages. After adjustments of the models, the total agreement percentage and AUC were upgraded to 88% and 0.96, respectively.

CONCLUSION

Consistency and fitness evaluation of our models demonstrated adequate prediction percentage and reliability for automated classification of skeletal maturation. The presented constructed logistic regression model has the potential to serve as a maturity evaluation index in clinical craniofacial orthopedics in Chinese girls. The proposed model in this study showed promising strength for being expended in the event of other clinical multi-stage conditions.

Can IGF-1 serve as a reliable skeletal maturity indicator? A meta-analysis

BACKGROUND

Many clinical studies have evaluated the role of biochemical mediators like insulin-like growth factor 1 (IGF-1) in assessment of skeletal maturity. But still the reliability of IGF‑1 as an indicator of skeletal maturity remains controversial.

OBJECTIVE

To assess the correlation between IGF‑1 and different radiographic skeletal maturity indicators.

SEARCH METHODS

Seven electronic databases (PubMed, Scopus, EMBASE, Medline, Cochrane CENTRAL, Web of Science and SciELO) were searched until January 2020 without any restriction based on language or date of publication.

SELECTION CRITERIA

The study design included cross-sectional and longitudinal studies comparing IGF‑1 and other skeletal maturity indicators (SMIs).

DATA COLLECTION AND ANALYSIS

Data extraction was done by two reviewers independently; 15 studies were eligible to be included in the quantitative synthesis.

RESULTS

There was significant positive correlation between IGF‑1 and different SMIs until puberty which was 0.95 (confidence interval [CI] = 0.89, 1.02) for males and 0.87 (CI = 0.77, 0.97) for females. A negative correlation between IGF‑1 and different SMIs was found after puberty which was -0.86 (CI = -0.97, -0.75) for males and -0.89 (CI = -0.98, -0.81) for females. The type of SMI compared and type of IGF‑1 sample used accounted for the high heterogeneity found across the studies. Chronological age and number of months passed after puberty showed moderate negative correlation with mean IGF‑1 levels which were -0.57 (CI = -0.67, -0.47) and -0.54 (CI = -0.66, -0.42). Annual increments in mandibular length showed significant positive correlation of 0.69 (CI = 0.48, 0.90).

CONCLUSIONS

IGF‑1 would serve as a promising alternative to conventional radiographic skeletal maturity indicators and in predicting the amount of residual mandibular growth.

Intelligent quantitative assessment of skeletal maturation based on multi-stage model: a retrospective cone-beam CT study of cervical vertebrae

OBJECTIVE

To develop new logistic regression estimative models of the cervical vertebral maturation index (CVMI) based on cone-beam CT (CBCT)-derived parameters for intelligent evaluating skeletal maturation.

METHODS

From 231 CBCT volumes (age range 7-17, mean age 11.09 years), 154 were randomly selected to produce 2D sagittal projections of the second to fourth cervical vertebrae (C2-C4). From 19 quantitative parameters, significant predictors were deduced to formulate logistic models. Using the CVMI and significant predictors of 77 other subjects, performance of the models was externally examined by direct comparison and the area under the receiver operating characteristic curve (AUC). Models were modified if required, to improve their accuracy.

RESULTS

Chronological age, C3 height ([Formula: see text], and ratio of posterior height to lower width of C4 [Formula: see text] were entered as significant predictors. Accuracy of the models was acceptable (total AUC = 0.91) except for 4th and 5th stage (AUC of 0.82 and 0.83, respectively), which were mis-predicted inversely. Adjusted models were generated by bivariate logistic regression analysis and adding significant parameters ([Formula: see text] and [Formula: see text], with odds ratios of 3.308 and 3.38, respectively) from 58 subjects in 4th and 5th stages of CVMI in the model establishment group. The total AUC increased to 0.94, along with an increase in the accuracy of the latter optimized models to 77.9 and 87%, respectively.

CONCLUSION

The new intelligent models reliably estimated skeletal maturation and can be utilized in the clinical field or machine learning-based skeletal maturation assessment.

Evaluation of the Artificial Neural Network and Naive Bayes Models Trained with Vertebra Ratios for Growth and Development Determination

Objective

This study aimed to evaluate the success rates of the artificial neural network models (NNMs) and naive Bayes models (NBMs) trained with various cervical vertebra ratios in cephalometric radiographs for determining growth and development.

Methods

Our retrospective study was performed on 360 individuals between the ages of 8 and 17 years, whose cephalometric radiographs were taken. According to the evaluation of cephalometric radiographs, growth and development periods were divided into 6 vertebral stages. Each stage was considered as a group, each group had 30 girls and 30 boys. Twenty-eight cervical vertebral ratios were obtained by using 10 horizontal and 13 vertical measurements. These 28 vertebral ratios were combined in 4 different combinations, leading to 4 different datasets. Each dataset was split into 2 parts as training and testing. To prevent the overfitting, a 5-cross fold validation technique was also used in the training phase. The experiments were conducted on 2 different train/test ratios as 80%-20% and 70%-30% for both NNMs and NBMs.

Results

The highest determination success rate was obtained in NNM 3 (0.95) and the lowest in NBM 4 (0.50). The determination success of NBM 1 and NBM 3 was almost similar (0.60). The success of NNM 2 did not differ much from that of NNM 1 (0.94). The determination success of stage 5 was relatively lower than the others in NNM 1 and NNM 2 (0.83).

Conclusion

The NNMs were more successful than the NBMs in our developed models. It is important to determine the effective ratio and/or measurements that will be useful for differentiation.

Cervical vertebral maturation (CVM) stage as a supplementary indicator for the assessment of peak height velocity (PHV) in adolescent idiopathic scoliosis (AIS)

BACKGROUND

Radiographic methods in evaluating the skeletal maturity include Risser sign and Tanner-Whitehouse score. They are either inappropriate or too complex for a busy clinic setting. The cervical vertebral maturation (CVM) stage is commonly used in orthodontics but has been less acknowledged in studies of spinal growth. The purpose of this study was to evaluate whether the CVM stage could be used as an alternative to Risser sign in determining peak height velocity (PHV).

METHODS

This was a two-stage study. Inclusion criteria for stage I study were adolescent female idiopathic scoliosis (AIS) patients, aged between 9-16 years old, who had undergone full spine imaging with clear visibility of the cervical spine. Patients in the stage II study had follow-up through CVM stage 2-4. The correlation between CVM and Risser was analyzed. The spinal growth parameters were measured at each follow-up, and the growth velocity of parameters (PaGVs) was calculated. The PaGVs at CVM stage 2-4 were further compared.

RESULTS

A total of 170 AIS patients were included for stage I study (mean age 12.7 years). The CVM stages were found to correlate strongly with the Risser sign (r=0.85, P<0.01). For those patients with Risser stage 0 with closed TC, 71% were CVM stage 3. Fifty-one patients were included for stage II study. The stature growth velocity averaged 5.4 cm/year in CVM stage 2 patients and 6.3 cm/year in CVM stage 3 patients, which was significantly greater growth than that in CVM stage 4 patients (3.3 cm/year, both P<0.01); similarly, the growth velocity of arm span, trunk height, and spinal lengths were also significantly higher in CVM stage 3 patients compared to CVM stage 2 and 4 patients.

CONCLUSIONS

The CVM stage could provide an alternative option for the assessment of skeletal maturity of subjects with idiopathic scoliosis. CVM stage 3 may be a new sign of PHV.

Usage and comparison of artificial intelligence algorithms for determination of growth and development by cervical vertebrae stages in orthodontics

Background

Growth and development can be determined by cervical vertebrae stages that were defined on the cephalometric radiograph. Artificial intelligence has the ability to perform a variety of activities, such as prediction-classification in many areas of life, by using different algorithms, In this study, we aimed to determine cervical vertebrae stages (CVS) for growth and development periods by the frequently used seven artificial intelligence classifiers, and to compare the performance of these algorithms with each other.

Methods

Cephalometric radiographs, that were obtained from 300 individuals aged between 8 and 17 years were included in our study. Nineteen reference points were defined on second, third, and 4th cervical vertebrae, and 20 different linear measurements were taken. Seven algorithms of artificial intelligence that are frequently used in the field of classification were selected and compared. These algorithms are k-nearest neighbors (k-NN), Naive Bayes (NB), decision tree (Tree), artificial neural networks (ANN), support vector machine (SVM), random forest (RF), and logistic regression (Log.Regr.) algorithms.

Results

According to confusion matrices decision tree, CSV1 (97.1%)–CSV2 (90.5%), SVM: CVS3 (73.2%)–CVS4 (58.5%), and kNN: CVS 5 (60.9%)–CVS 6 (78.7%) were the algorithms with the highest accuracy in determining cervical vertebrae stages. The ANN algorithm was observed to have the second-highest accuracy values (93%, 89.7%, 68.8%, 55.6%, and 78%, respectively) in determining all stages except CVS5 (47.4% third highest accuracy value). According to the average rank of the algorithms in predicting the CSV classes, ANN was the most stable algorithm with its 2.17 average rank.

Conclusion

In our experimental study, kNN and Log.Regr. algorithms had the lowest accuracy values. SVM-RF-Tree and NB algorithms had varying accuracy values. ANN could be the preferred method for determining CVS.

Dental and skeletal maturation in female adolescents with temporomandibular joint osteoarthritis

Occurrence of temporomandibular disorders (TMDs) and temporomandibular joint (TMJ) osteoarthritis (OA) during adolescence may have interactions with mandibular and dental development. The aim of the present study was to investigate relationships between occurrence of TMD and TMJ OA and extents of dental and skeletal development in juvenile female patients. In total, 95 female adolescents (age range, 11-15 years) were selected. Among them, 15 subjects (control) had no signs of TMD, 39 TMD patients did not have OA (TMDnoOA), 17 TMD patients were at initial stage of TMJ OA (TMJOA), and 27 patients showed progressive stage of TMJ OA (TMJOA). Dental age was estimated by Demirjian's stages used in a previous study with Korean adolescents. Craniofacial parameters and cervical vertebrae maturation (CVM) stages, representing skeletal maturity levels, were measured using lateral cephalograms. The estimated dental age was significantly lower than chronological age in all groups, but CVM differences were not statistically significant. Dental age was the lowest, and differences between the chronological age and estimated dental age were the highest among initial stage of TMJOAs followed by progressive stage of TMJOAs, TMDnoOAs and control and were not associated with CVM stages. Cephalometric parameters revealed significant clockwise rotation of the mandible among the TMJOAs compared with controls and TMDnoOAs and were not associated with CVM stages as well. The juvenile female patients with TMD, particularly TMJ OA, showed retarded dental development, mandibular backward positioning and hyperdivergent facial profiles. The TMJ OA may be associated with retarded dental development but not with skeletal maturations.

Cervical Vertebral Body's Volume as a New Parameter for Predicting the Skeletal Maturation Stages

This study aimed to determine the correlation between the volumetric parameters derived from the images of the second, third, and fourth cervical vertebrae by using cone beam computed tomography with skeletal maturation stages and to propose a new formula for predicting skeletal maturation by using regression analysis. We obtained the estimation of skeletal maturation levels from hand-wrist radiographs and volume parameters derived from the second, third, and fourth cervical vertebrae bodies from 102 Japanese patients (54 women and 48 men, 5–18 years of age). We performed Pearson's correlation coefficient analysis and simple regression analysis. All volume parameters derived from the second, third, and fourth cervical vertebrae exhibited statistically significant correlations (P < 0.05). The simple regression model with the greatest R-square indicated the fourth-cervical-vertebra volume as an independent variable with a variance inflation factor less than ten. The explanation power was 81.76%. Volumetric parameters of cervical vertebrae using cone beam computed tomography are useful in regression models. The derived regression model has the potential for clinical application as it enables a simple and quantitative analysis to evaluate skeletal maturation level.

Application of statistical shape analysis for the estimation of bone and forensic age using the shapes of the 2nd, 3rd, and 4th cervical vertebrae in a young Japanese population

OBJECTIVE

From computed tomographic images, the dentocentral synchondrosis can be identified in the second cervical vertebra. This can demarcate the border between the odontoid process and the body of the 2nd cervical vertebra and serve as a good model for the prediction of bone and forensic age. Nevertheless, until now, there has been no application of the 2nd cervical vertebra based on the dentocentral synchondrosis.

METHODS

In this study, statistical shape analysis was used to build bone and forensic age estimation regression models. Following the principles of statistical shape analysis and principal components analysis, we used cone-beam computed tomography (CBCT) to evaluate a Japanese population (35 males and 45 females, from 5 to 19 years old).

RESULTS

The narrowest prediction intervals among the multivariate regression models were 19.63 for bone age and 2.99 for forensic age. There was no significant difference between form space and shape space in the bone and forensic age estimation models. However, for gender comparison, the bone and forensic age estimation models for males had the higher explanatory power.

CONCLUSION

This study derived an improved objective and quantitative method for bone and forensic age estimation based on only the 2nd, 3rd and 4th cervical vertebral shapes.

Evaluating the agreement of skeletal age assessment based on hand-wrist and cervical vertebrae radiography

INTRODUCTION

The aim of this study was to examine the agreement of skeletal age assessment based on hand-wrist radiographs with cephalogram-based cervical vertebrae evaluation. To circumvent bias and loss of information from staging, a quantitative approach was applied to determine morphologic changes.

METHODS

We analyzed 730 sets of radiographs (cephalogram and hand-wrist) of untreated subjects (352 boys, 378 girls; age range, 6-18 years) from a growth study, each sex as a separate sample. Skeletal age was determined on the hand-wrist radiographs according to the method of Greulich and Pyle. Morphometric changes of the vertebral bodies C2 through C4 were measured (concavity, anterior height, and angle) and tested for correlations with the method of Greulich and Pyle. All correlating variables were included in a multiple linear regression to generate a calculated skeletal age. To establish the agreement between the method of Greulich and Pyle and calculated skeletal age, Bland-Altman plots were made, limits of agreement were identified, and cross-tables (before and after peak height velocity) were computed. Similarly, the agreement between the method of Greulich and Pyle and each subject's chronologic age was estimated for comparison.

RESULTS

Concavity of C2, C3, and C4; anterior height of C3 and C4; and the angle of C3 correlated with skeletal age highly significantly (P <0.0001) in both sexes, and calculated skeletal age was established based on a linear regression. The agreement between the method of Greulich and Pyle and calculated skeletal age was modest (limits of agreement: boys, ±3.5 years; girls, ±3.3 years) and substantially weaker than the agreement between the method of Greulich and Pyle and chronologic age (limits of agreement: boys, +2.1 to -1.7 years; girls, +2.2 to -1.2 years). Similarly, calculated skeletal age resulted in considerably more false predictions of peak height velocity (boys, 18.9%; girls, 12.9%) than did chronologic age (boys, 7.1%; girls, 7.4%).

CONCLUSIONS

Morphometric assessment of age-dependent changes in the cervical spine offers no advantage over chronologic age, in either assessing skeletal age or predicting the pubertal growth spurt.

Correlation between three-dimensional morphological changes of the hyoid bone with other skeletal maturation methods in adolescents

OBJECTIVE

The study compares growth changes of hyoid bone in cone-beam computed tomography (CBCT) with conventional skeletal maturation methods to examine their potential implications in the development of a three-dimensional method.

STUDY DESIGN

Subjects (n = 62, 11-17 years of age) were exposed to CBCT at a six-month interval (T1/T2/T3). Ten-hyoid distances were compared with age, hand wrist skeletal maturation index (SMI), and cervical vertebral maturation stage (CS).

RESULTS

The length of greater cornua (GC) was most frequently, moderate to highly correlated with age (right: 0.57/0.53/0.58; left: 0.45/0.50/0.48), SMI (right: 0.52/0.40/0.45; left: 0.42 at T3), and CS (right: 0.52 at T1), followed by the length of the hyoid bone with age (right: 0.50/0.49/0.47; left: 0.44/0.47 at T1/T2), SMI (right: 0.45/0.41 at T1/T2), and CS (right: 0.48 at T1). The width of body of the hyoid (HB) width was correlated with age (0.43/0.44/0.44). The GC-HB gap was correlated with age (right: -0.41 at T3) and SMI (right: -0.42 at T1).

CONCLUSION

Peripubertal hyoid maturation did not yield sufficient diagnostic information for considerations in the development of a 3D-skeletal maturation method.

Interrelationship and limitations of conventional radiographic assessments of skeletal maturation

Assessments of skeletal maturation (ASM) are used by clinicians to optimize treatments for each patient. This study examines the interrelationship between and limitations of hand-wrist and cervical vertebrae maturation methods in adolescent patients. Radiographs (hand-wrist and lateral cephalometric) were obtained from patients (n=62, 11 to 17 years of age) at two-time periods (T1/T2) with time intervals of 9.75 to 16.50 months. Radiographs were scored using cervical vertebral maturation staging (CS) and Fishman's skeletal maturation indices (SMI). Functional data analysis was used to visually assess maturational changes of the cervical vertebrae. Both SMI and CS increased over the period of observation. Age was moderately correlated with SMI (0.707/0.651 at T1/T2) and mildly correlated with CS (0.431/0.314 at T1/T2). There was some evidence of gender variability in SMI. The correlations between SMI and CS were 0.513 and 0.372 at T1 and T2, respectively. Functional data analysis illustrated the difficulty in differentiating contiguous cervical stages. Discrepancies exist between both scoring methods. Further studies are needed to overcome the difficulties encountered with CS. Clinicians are advised to use ASM methods with caution in adolescent patients given the aforementioned discrepancies. Separate references for boys and girls are not required.

[Indications for radiography in orthodontics and dentofacial orthopedics]

The risks associated with the use of ionizing radiation are a constant concern not only for practitioners but also for legislators who have included this ethical rule in the Code of public safety. It proposes reduction of risks by insisting that all X-Rays be taken only when they accord with one of the fundamental principles of X-Ray protection: they must be justified by clear diagnostic need. In direct application of this principle the French government in 2006 published a guide for the management of radiological and dental and stomatological examinations. However, this document dealt only slightly with orthodontics, a field in which the flourishing and burgeoning of radiological techniques made it urgent that regulations for use of X-Rays in orthodontics be brought up to date on an ongoing and permanent basis. The objective of this article is, accordingly, after presentation of a systematic and critical analysis of the lit erature, to propose up-to-date recommendations for proper taking of orthodontic X-Ray films.

[Cervical vertebrae: Mandibular growth dynamism indicators?]

A study of mandibular growth maturation was performed on a population of 103 patients during orthodontic treatment (69 girls and 34 boys) from 11 to 16 years, having initially a Class II skeletal discrepancy. The relationship between wrist maturation indices and the cervical vertebrae maturation was studied by Lamparski classification. Significant correlations were found between Björk stages, MP3=, MP3 cap and MP3 U and respectively Lamparski stages as CVS 2, CVS 3-4 and CVS 5-6. This retrospective longitudinal study identified three mandibular variables at three different maturation stages according to Björk classification and to the six stages of Lamparski classification. The relationships between these different maturation stages and a quantitative mandibular response permit to estimate optimal time for our orthodontic therapy. The results indicate a significant increase in mandibular length between CVS 4 and CVS 5, suggesting the persistence of a condylar response to a stimulation therapy after CVS3 or CVS 4 stages (MP3 cap). Mandibular growth seems to continue after MP3 U stage or CVS 5 stage.

Accuracy and repeatability of computer aided cervical vertebra landmarking in cephalogram

The accuracy and repeatability of computer aided cervical vertebra landmarking (CACVL) were investigated in cephalogram. 120 adolescents (60 boys, 60 girls) aged from 9.1 to 17.2 years old were randomly selected. Twenty-seven landmarks from the second to fifth cervical vertebrae on the lateral cephalogram were identified. In this study, the system of CACVL was developed and used to identify and calculate the landmarks by fast marching method and parabolic curve fitting. The accuracy and repeatability in CACVL group were compared with those in two manual landmarking groups [orthodontic experts (OE) group and orthodontic novices (ON) group]. The results showed that, as for the accuracy, there was no significant difference between CACVL group and OE group no matter in x-axis or y-axis (P>0.05), but there was significant difference between CACVL group and ON group, as well as OE group and ON group in both axes (P<0.05). As for the repeatability, CACVL group was more reliable than OE group and ON group in both axes. It is concluded that CACVL has the same or higher accuracy, better repeatability and less workload than manual landmarking methods. It's reliable for cervical parameters identification on the lateral cephalogram and cervical vertebral maturation prediction in orthodontic practice and research.