Different Types Of Malocclusion Research Articles

Evaluation of cranio-cervical muscle activity in adolescents with different malocclusions: a pilot surface emg study

Aims: This study aimed to investigate potential differences in cranio-cervical muscular activation among adolescents with different types of malocclusion. Methods: This study involved thirty-two adolescents aged 10-15 years, categorized into three groups based on Angle. Angle Class I/control group (n=10), Angle Class II (n=12), and Angle Class III (n=10). Surface electromyography (EMG) was utilized to evaluate the activation levels of the Masseter, Temporalis Anterior, Cervical Erector Spinae, Sternocleidomastoid, and Upper Trapezius muscles. Measurements were obtained during mandibular rest, maximum clenching, and chewing tasks. Results: The surface EMG activity of the Upper Trapezius muscle exhibited significant elevation in participants with Class III malocclusions relative to the other groups (p<0.05). While cranio-cervical muscle activities tended to be higher in the groups of Angle Class II and Class III in comparison to the Angle Class I, these differences did not achieve statistical significance, with the exception of the Upper Trapezius muscle (p>0.05). Conclusion: These findings indicate a link between malocclusion types and modified muscle activation patterns in the cranio-cervical region, specifically involving the Upper Trapezius muscle. Insights into cranio-cervical muscle activity can enhance the comprehensive evaluation of malocclusion effects and provide valuable guidance for orthodontic and rehabilitation interventions.

A CBCT Study Comparing the Outcomes of Volumetric Bone Mass and Mini-Implant Success with Different Types of Malocclusions

Objective: The present study aimed to determine the favorable site for orthodontic mini-implant insertion in both the maxilla andmandible in terms of cortical and trabecular bone thickness and density in different types of skeletal malocclusion using cone-beamcomputed tomography (CBCT).
 Methods: In this study, seventy-five CBCT examinations that were requested for different purposes were used, twenty-five in eachmalocclusion group (class I, class II and class III), class I (ANB: 2°-4°), class II (ANB > 4°), and class III (ANB < 2°) groups. RadiAntDicom Viewer was utilized, measurements were done at different sites in the jaws using standardized orientations, and the threemalocclusion groups were compared for cortical bone thickness and density as well as the density of trabecular bone, using the Kruskal-Wallis and Mann-Whitney test for non-parametric data and one-way ANOVA for parametric data.
 Results: The highest cortical bone thickness was between 1st and 2nd molars at a 6 mm distance from the alveolar crest ranging from1.03 mm to 1.2 mm in maxilla and 2.13 mm to 2.26 mm in the mandible. The difference between groups was only noticed betweencanine and 1st premolar which showed less buccal cortical bone thickness in class II cases with 1.07 mm. Cortical bone density wasnot significantly different between the three groups with maximum density between canine and 1st premolar with a density of 997.9 to1078 HU in the maxilla and the mandible 1245.4 to 1329.3 HU. The trabecular bone density was also highest between canine and 1stpremolar of both jaws, in maxilla 422.13 to 564.15 HU and mandible 509.81 to 799.04 HU. The difference between the groups wasonly in the anterior location between canine and 1st premolars which was less in class III cases with 509.81 HU.
 Conclusions: Skeletal relations can have an impact on the thickness of the cortical bone, although all skeletal classes have the samepattern in the maxilla, in the mandible between the canine and the 1st premolar, variations in bone thickness and trabecular densitymay be seen in various skeletal malocclusions. So, it is important to properly consider the placement of mini-implants with the skeletalrelation to achieve the maximum primary stability. Further researches are recommended, with long term follow up, on stability of mini-implants and its correlation with bone thickness and density.

Evaluation of Bolton's Ratio in Normal Occlusion and Different Types of Malocclusion in Iranian Population

Background: The Bolton analysis is commonly used by orthodontists. The Bolton ratios of different populations are significantly different from the standard values of Bolton. This study sought to examine the Bolton's anterior and overall ratios in various malocclusion types in Mashhad, Iran, in contrast to the Bolton’s standards. Methods: This descriptive-analytical study was conducted on 240 study models of patients (121 males and 119 females) in four groups (n= 60 cases) of normal occlusion, Class I, Class II, and Class III. The mesiodistal dimensions of the teeth were measured twice using a digital caliper. The anterior and overall ratios of Bolton were calculated. Statistical analysis was conducted utilizing SPSS 18.0. Results: The mesiodistal width of the maxillary lateral incisors in normal occlusion cases was greater than that in Class I, Class II, and Class III malocclusions (P<0.05). Conversely, the mesiodistal width of the maxillary first and second premolars was the greatest in Class II and the smallest in Class III malocclusion (P<0.05). Correlation was not observed between dental ratios (anterior and overall) and gender or malocclusion groups (P>0.05). Furthermore, the anterior ratio was significantly higher than the Bolton's standard in Class I and III malocclusion groups (P<0.05). The normal occlusion group's overall ratio was significantly lower than the Bolton's original ratio (P<0.05). Conclusion: Implementing the Bolton analysis in the population of Mashhad, Iran should be approached with caution.

The association between body posture and malocclusion - a literature review

Effective body posture entails the correct alignment of body parts in relation to each other and is crucial for preserving balance, stability, and the efficient operation of muscles and joints. The major types of posture abnormalities such as lordosis, kyphosis and scoliosis can lead to alterations in various areas of the body, such as stomatognatic system. The potential correlation between malocclusion and body posture remains a subject of controversy. The aim of this review is to investigate and evaluate the association between posture defects and malocclusion on the basis of literature. This literature review has analyzed 18 studies. Inclusion criteria: clinical researches published after 2010, regarding children and adults. PubMed and Google Scholar has been searched to identify the papers. In 18 analyzed studies, 2133 patients were enrolled (including 979 children aged 4-18). A positive correlation between scoliosis and different types of malocclusion has been proven by six papers. There are also other noteworthy dependencies, such as overjet and pelvic torsion, kyphosis and sagittal position of mandible, skeletal Class III and torticollis, cross bite and scapula plane. Adolescent Idiopathic Scoliosis significantly affects the stomatognathic system, leading to issues like crossbite, crowding, increased overjet, overbite, partial open bite, and midline deviation. Orthopedists should collaborate with orthodontists for comprehensive treatment, particularly during developmental stages.

Factors Influencing the Decision Process within Seeking Orthodontic Care among the Saudi Population: A Cross-sectional Survey

Aims & Background Orthodontic treatment is the first choice for the treatment of many different types of malocclusions, and patients’ decision processes while seeking orthodontic treatment are multifactorial. The aim of the present study is to assess these factors influencing the decision process regarding the public and orthodontic treatment for themselves or for their children, as well as the factors influencing the selection of an orthodontist versus a general dentist in Saudi Arabia. Materials and Methods A survey-based questionnaire was distributed through social media accounts that included questions about demographic data, reasons for seeking orthodontic care, barriers to care, and sources of information that may influence the decisions regarding the choice of orthodontic treatment for the participants and their children. Results The final sample included 320 responses from eligible participants (181 men & 139 women with a mean age of 39.98). ‘Family dentist recommendation’ was the most important reason for participants to seek out orthodontic treatment for themselves or a child while finding a caregiver who can handle complications and the availability of appointments were the most important barriers in seeking orthodontic treatment. Participants also assumed an orthodontist would be more reliable in finishing the treatment in the expected duration, yet they expected that treatment with a general dentist would be less costly and more convenient. Conclusion A referral from the family dentist has the most impactful influence on seeking orthodontic care. People are keen to have their treatment done by an orthodontist, but the major barrier in seeking orthodontic care is finding a suitable candidate. Parents prioritize orthodontic treatment for their children more than for themselves.

Gender Dimorphism of Skeletal Measurements and Dental Angle Classification in Orthodontic Patients.

The present study aimed to evaluate gender dimorphism of the skeletal and dental angles and measurements among different types of malocclusions in the Population of Jizan, Kingdom of Saudi Arabia (KSA). Cephalometric data were retrieved from the archived records of 272 dental patients, comprising 134 males and 138 females. Skeletal and dental malocclusions in both the sub-groups were digitally studied. The measurement reliability was assessed using the intra-class correlation coefficient (ICC). Non-parametric Mann-Whitney U tests were performed to evaluate the difference in skeletal and dental parameters between genders. The Chi-square test was done to determine the difference in malocclusion patterns amongst the gender. Statistical significance was noted in dental malocclusion (p-value = 0.003) and facial height, with females having a steeper mandible plan than males. The Sella-nasion-Nasion-Vertical line angles were reported high in females with no statistical significance. Linear cephalometric values were measured higher in males than females, whereas angular values and facial height parameters were lower in females than male. Within the limitation of this study, it could be concluded that there is a prominent difference measured in facial profiles of males and females with higher facial height in males. Clinical significance and limitations: These clinical outcomes will help orthodontists to analyze the accurate base angles and points to draft proper treatment plans considering the variation in the profile of males and females.

Major deleterious oral habits: a brief systematic review

Introduction: The deleterious habits in children, in the deciduous dentition phase, seem to be present in more than half of the child population, reaching rates greater than 90%, depending on the population studied, and dentofacial alterations may already be present in half of these individuals. Early identification is essential so that malocclusions, which are more difficult to treat, do not set in. Objective: It was to carry out a brief systematic review to highlight deleterious oral habits, as well as to point out their main predictors and treatments. Methods: The systematic review rules of the PRISMA Platform were followed. The research was carried out from April to June 2023 in Scopus, PubMed, Science Direct, Scielo, and Google Scholar databases. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: A total of 87 articles were found. A total of 32 articles were evaluated in full and 16 were included and developed in this systematic review study. Considering the Cochrane tool for risk of bias, the overall assessment resulted in 6 studies with a high risk of bias and 43 studies that did not meet GRADE. Since pediatric follow-up is more frequent than consultations with the pediatric dentist, the early identification of deleterious habits by physicians is of fundamental importance in referring these patients to dental treatment that diagnoses and removes these habits, before difficult-to-resolve malocclusions get settled. Preventive measures should also be taken, guiding parents so that deleterious oral habits do not take hold, such as a minimum period of six months of breastfeeding, finger sucking should be replaced by an orthodontic pacifier, the bottle should have an orthodontic spout, removing the habit of pacifier and bottle until the age of three. There is an association between deleterious habits and different types of malocclusions in different planes of space, with atypical swallowing being a habit that must be diagnosed early.

An Evaluation of the Ramus Mandibular Asymmetry on the Panoramic Radiography

This study is intended to focus on the evaluation of posterior vertical mandibular asymmetry by calculating the mandibular asymmetry index on the panoramic radiography in different types of malocclusions, considering the sexual dimorphism in children and adolescent patients and performing a comparative analysis between these groups. In this context, a cross-sectional study was conducted for a group of 214 patients (134 females and 80 males with a mean age of 9.5 ± 2 years). The asymmetry index was calculated for each patient according to the Habets method. The results were analyzed by using the independent Student t-test, ANOVA and Mann–Whitney U-test at the 95% confidence level (p < 0.05). The results of the analyses showed a statistically significant difference between males and females at the level of the condylar index (p = 0.023) and a significant difference in the unilateral posterior crossbite in the Mann–Whitney U test (p = 0.01). No statistically significant differences were found between males and females in the index of the mandibular ramus and condyle-plus-ramus. The highest value of the asymmetry index was recorded at the level of the condyle. We found higher values of asymmetry in Angle Class I malocclusions in all groups and in Class II/1 in the group of females.

Maxillary and Mandibular Interarch Width Among Different Malocclusions

Objective: To determine the association of maxillary and mandibular interarch width among different malocclusions. Material and Methods: This cross-sectional study was done at the Department of Orthodontics of the Dr. Ishrat Ul Ibad Khan Institute of Oral Health Sciences, Dow University of Health Sciences, Karachi, during a period of one year from January 2017 to December 2017. Individuals with a Class I canine and molar relationship with minor crowding, normal growth and development, and mal-aligned upper and lower dental arches. Class II molar and canine relationship on at least one side, Class II division 1 or 2 groups, bilateral Class III molar relationship in centric occlusion, Class III permanent canine relationship with excessive negative overjet, good facial symmetry, and participants had to have all their permanent teeth present except for their third molars were included. Readings were obtained by measuring the interarch width using a vernier gauge caliper. The calibration of the vernier caliper was checked daily using the standard technique. The intercanine arch width was measured from the cusp tip of one canine to the contralateral canine. Intermolar width was assessed as the distance between the central fossae of the left and right first molars. The readings were taken by a single examiner, and the measurement was repeated three times with an interval of two minutes between each measurement to reduce the possibility of errors. To assess the reliability of the measurements, the intra-examiner reliability was determined using the intraclass correlation coefficient (ICC). The collected data was analyzed using statistical software, SPSS version 26. Results: The study examined the maxillary and mandibular interarch widths of participants with different types of malocclusions. Class I had the highest maxillary intercanine width, and Class III had the highest maxillary intermolar width. Class III had the highest mandibular intercanine and intermolar width. Class II Division 2 had the lowest intercanine and intermolar width in both arches. Significant differences were observed in the mean intermolar width in the mandibular arch between Class II Division 2 and Class III malocclusions and in the maxillary intercanine width between Class I and Class II Division 2 malocclusions. No significant difference was found in other width measurements among the different types of malocclusions. Conclusion: It has been concluded that patients with Class III malocclusion had narrower upper width measurements compared to the normal occlusion sample. Keywords: Maxillary, mandibular, interarch width, malocclusion

Alveolar bone defects around mandibular anterior teeth in Class I, II, and III malocclusions: a retrospective CBCT evaluation

Background: The aim of this study was to quantitatively and qualitatively evaluate alveolar defects of mandibular anterior alveolar bone in three different types of malocclusion with cone-beam computed tomography (CBCT) by an observational cross-sectional study.

Research progress of crown -root ratio in orthodontics

Different types of malocclusion have different craniomaxillofacial morphology and occlusal contact, and the crown-root ratio of teeth is closely related to them. Unhealth crownl-root ratio will affect the long-term stability of teeth. Studies at home and abroad suggest that crown-root ratio has ethnic and gender differences. In orthodontic treatment design, orthodontists should analyze the changes in crown length and crown-root ratio according to the patient's gender, ethnicity and other comprehensive judgments, so as to better estimate the treatment risk, maintain the health of periodontal tissues, and then establish a good occlusal relationship, maintain arch stability, and finally obtain a good treatment effect.

Quantifying health utilities of young adult orthodontic patients using the time trade-off method: a cross-sectional study.

To study the feasibility of time trade-off (TTO) method in quantifying health utility ratings in different types of malocclusion. In this cross-sectional study, 70 orthodontic patients aged 18 years or above, reporting for treatment/consultation, were included and interviewed. Malocclusion-related health utilities were assessed through the TTO method, and oral health-related quality of life was measured with the help of Orthognathic Quality of Life Questionnaire (OQLQ). Angle's classification of malocclusion was recorded. Bivariate analyses and multivariate Poisson's regression were done to find out an association between the oral health utility values, OQLQ and demographic and clinical characteristics. Patients with skeletal Class III malocclusion had lower health utility values than those with Class I and Class II malocclusions (p=0.013). Poisson's regression showed that Angle's Class II division 1 (0.90, CI 0.84 to 0.97), Class III (0.68, CI 0.59 to 0.95) and Skeletal malocclusion (0.79, CI 0.71 to 0.87) and OQLQ scores (1.0, CI 1 to 1.003) were found to be significant predictors of TTO utility scores. TTO utilities were found to be valid and well correlated with clinical findings. Health utilities could serve as useful and reliable markers of health-related quality of life (HRQL) among individuals or communities and help cost-effective preventive or intervention programs planning.

Research progress of temporomandibular joint in adolescent malocclusion

The prevalence of malocclusion in permanent dentition was 72.97%. Temporomandibular joint (TMJ) is one of the most important joints in human body, and its functional structure is the most complex. The shape and position of the temporomandibular joint in patients with malocclusion were affected by occlusal occlusion. This review focuses on the effects of different types of malocclusion on the morphology and function of temporomandibular joint (TMJ) in adolescents.

Research progress on CBCT of temporomandibular joint morphology in children with malocclusion in mixed dentition

Malocclusion is an abnormal development and deformity of maxillofacial structure caused by congenital factors or acquired factors. The morphology and structure of the temporomandibular joint with various malocclusion deformities have their own characteristics, which can seriously affect the physical and mental health of children. With the continuous development of society and economy and the gradual improvement of people's living standard, malocclusion malocclusion in children during dental replacement period has received more attention. CBCT is one of the important imaging methods to examine the morphology and structure of temporomandibular joint. In order to intervene early in children with malocclusion during mixed dentition and to understand the morphological and structural characteristics of temporomandibular joint, imaging is used to review the morphological and structural characteristics and differences of temporomandibular joint in children with different types of malocclusion during in mixed dentition.

Evaluation of Buccal Corridors in Patients Seeking Orthodontic Treatment in Different Types of Malocclusion at Tertiary Care Hospital

There are many factors that make an appealing smile, and the buccal corridor is one of the most crucial smiling characteristics. Objective: To evaluate the width of buccal corridors in patients with different types of malocclusions seeking orthodontic treatment at tertiary care hospital LUMHS Jamshoro/Hyderabad. Methods: 93 subjects were studied. Patients were asked to smile fully to measure buccal corridor width with a vernier caliper. The buccal corridor was estimated by multiplying the maxillary interproximal width by the inner lip corner distance by 100. They were divided into 5 modes by buccal corridor percentage. i-e: Buccal corridor 2% (wide smile), Buccal corridor 10% (nearly a wide smile), Buccal corridor 15% (mediocre smile), Buccal corridor 22% (nearly a narrow smile), Buccal corridor above 22% (narrow smile). Angle's malocclusion classification classified all patients. Results: The mean age was 19.18. Males were 34.4% and females were 65.6%. With various types of buccal corridors among them, 37 participants were in a class I malocclusion, 43 were in the class II and 13 were in the class III malocclusion. 14 participants belongs to medium narrow buccal corridors (15.1%), 18 belongs to the medium buccal corridors (19.4%), 47 belongs to the medium broad buccal corridors (50.5%), and 14 belongs to broad buccal corridors (15.1%). The results showed that there was no significant association between these two variables having p-value 0.207. Conclusion: Medium broad buccal corridors were seen more frequently in various types of malocclusion

Effect of orthodontic treatment with premolar extractions on occlusal planes: A retrospective study.

To figure out whether premolar extractions treatment would influence the cant of the occlusal planes and thus affect dentoskeletal patterns in patients with different types of malocclusions. A total of 140 post-orthodontic treatment subjects (96 females, 44 males) were included in this study, and their lateral cephalograms and demographic information were collected and analysed. The patients were divided into extraction and non-extraction groups. The ANB, SNA, SNB, Wits, Facial Height Index (FHI), SN-MP, SN-AOP, SN-POP and AOP-POP angle were measured on the cephalograms. Other possible confounding factors were recorded. Data were analysed by univariate analysis, stratified analysis, multivariate analysis, and coefficient analysis. After treatment, the changes in the AOP-SN, POP-SN and AOP-POP angle were statistically different between the extraction and non-extraction groups. The results were consistent in different skeletal malocclusions and extent of crowding according to stratified analysis. After adjusting all confounding factors, the cant of the posterior occlusal plane was flattened further by 2.14 degrees in the extraction group than the non-extraction group after orthodontic treatment, and the AOP-SN and AOP-POP angle would further increase by 1.72 and 3.81 degrees, respectively. Although no significant differences were found between the two groups, the SNA, ANB, and Wits in the extraction group decreased more with increased counterclockwise rotation of the mandible. Compared to the non-extraction group, there were more increases in the AOP-SN and AOP-POP angle and more posterior flattening in patients with four premolar extractions despite different types of dentoskeletal malocclusion, which were correlated to the change of variables in sagittal and vertical dimensions such as Wits and FHI.

The Relationship Between Vertical Facial Type and Maxillary Anterior Alveolar Angle in Adults Using Cone-Beam Computed Tomography.

BackgroundCone-beam computed tomography (CBCT) imaging provides detailed and thorough information about the dentofacial complex. However, not all aspects have been yet explored among different types of malocclusion. The maxillary anterior alveolus is one of the components of the maxillary bone which affects the upper lip position and the esthetics of the smile. The inclination of this alveolus may vary between the different vertical growth patterns of patients who may seek orthodontic treatment. The objective of this study was to investigate possible differences in maxillary anterior alveolar angle (MAAA) among orthodontically untreated adults with different vertical facial types in a Syrian sample.MethodsCBCT images of 84 orthodontically untreated adult patients were included. Three groups of vertical facial type (n=28 for each group; 14 males, 14 females) were created using disproportionate multi-stratified random sampling. CBCT-derived lateral cephalograms were used to categorize the patients into three groups. Measurements were made at three regions (region 1 (R1), region 2 (R2), and region 3 (R3)), located in the maxillary anterior alveolar bone using OnDemand3D™ software (Cypermed Inc., Seoul, South Korea).ResultsNo significant differences in the mean MAAA were detected between females and males for the three measured regions in all groups. Analysis of variance showed significant inter-group differences in the MAAA (p<0.05) for all measured regions. The hyperdivergent facial type group had the greatest MAAA mean value of 68.72° (± 6.01), 67.30° (± 4.15), and 68.01° (± 5.12) at R1 in the female, male, and the entire sample of both sexes respectively. Whereas the hypodivergent facial type group had the least mean MAAA values of 58.47° (± 5.34) at R3, 59.83° (± 6.23) at R2, and 59.23° (± 5.75) at R3 in the female, male, and the entire sample of both sexes respectively.ConclusionsThe maxillary anterior alveolar bone was more buccally inclined in the hypodivergent facial type. The MAA bone inclination did not differ between females and males in the same vertical facial type group.

GINGIVAL PHENOTYPE AND FREQUENCY OF RECESSION DURING VARIOUS ANOMALIES OF OCCLUSION

The aim of our research was to determine gingival phenotype and frequency of recession in patients with different types of malocclusion. For this purpose, 174 patients from 20 to 46 years of age were investigated. During our research of gingival phenotype in patients with malocclusion most often thin scalloped biotype was observed - 122 patients (70%), medium thickness – 47 (27,1%), rarely, thick - 4 patients (3,2%) and thick flat - 1 patient (0,6%). According to our data, among investigated patients (174), 75 (43,09%) of them had different type of recession. Whereas RT1 had 43 patients (24,71%), RT2 – 27 patients (15,51%), RT3 only 5 patients (2,87%).In conclusion, it is not rare when gingival phenotypes and recession are combined. Therefore, we should pay more attention during orthodontic treatment of the patients with periodontal disease.

Digital Analysis of Tooth Sizes Among Individuals with Classes I and II Malocclusions in the Kosovo Population - A Pilot Study

Background: This study aimed to evaluate the tooth size discrepancy in patients with different types of malocclusions and compare it with that in patients with normal occlusion, using the three-dimensional (3D) measurement program Maestro Studio. Methods and Results: Patients of both sexes who were aged between 13 and 16 years and who had never received orthodontic treatment were randomly selected. The participants’ mean age was 14.3±1.1 years; 62.0% of patients were girls. Fifty patients were divided into three groups. Group 1 included 16 patients with malocclusion Class I (controls), Group 2 included 19 patients with malocclusion Class II division 1 (II/1), and Group 3 included 15 patients with malocclusion Class II division 2 (II/2). The tooth measurements were made according to the Bolton analysis. Anterior ratio (AR) and overall ratio (OR) were calculated. There was no significant difference in the AR between the groups. However, we found a significant difference in the OR between the groups (P=0.0129). Patients with Class II/2 malocclusion had a significantly lower OR than patients with Class II/1 malocclusion (P=0.0155). However, there was no significant difference in the OR between Class 1 and Class II/1 or Class II/2 malocclusions. Conclusion: Individuals with different malocclusions show different tooth sizes.

Application of the ratio of the radiopaque calcified area to the dental follicle (RCA/DF) for dental age assessment on orthopantomograms

ObjectivesThis study aimed at exploring a new tooth development evaluation method for age assessment and investigating the dynamic alteration and potential trend of tooth development by orthopantomograms (OPGs), in order to provide references for tooth development prediction and forensic purpose. Materials and methodsA total of 132 OPGs of children aged 3–8 years were collected. The developmental stages of the permanent mandibular second molar (M2)were evaluated by experienced examiners according to the Nolla method and Mimics software, respectively. Quantitative analysis of the ratio of the radiopaque calcified area to the dental follicle (RCA/DF) in different stages, ages, sexes and quadrants were evaluated and compared via descriptive statistics and Spearman's correlation coefficient analysis. ResultsThere was a strong, positive correlation between the examiners’ evaluation and mimics analysis results. With the age increased, the Nolla stage of M2 observed by OPGs increased, and the RCA/DF showed increased trends both in males and females. There were significant differences of the RCA/DF of the M2 at various ages. The tooth calcification development of female was 9.08% earlier than that of male between 3 and 8 years old. However, teeth of male seemed to develop faster than that of female during this period. There was no significant difference between left and right quadrant either according to the Nolla stage or RCA/DF. ConclusionsThe RCA/DF value obtained from OPGs of the developmental mandibular second permanent molars could be used as a reliable indicator for tooth maturity and age estimation in children aged 3–8 years. Clinical relevanceAge assessment based on radiographs is considered as a reliable and efficient indicator for judging different types of malocclusion, making suitable orthodontic treatment plan, deciding the extraction time of retained deciduous teeth in clinic practice.