Boundary of mandibular molar distalization in orthodontic treatment: A systematic review and meta-analysis.

To explore the mandibular retromolar space length (MRSL), initial root-inner cortex contact percentage (IRCCP), and the various factors that influence mandibular molar distalization. Searches were undertaken in PubMed, EMBASE, Web of Science, Cochrane Library, Scopus, and grey literature (Google Scholar and OpenGrey) for eligible cross-sectional observational studies measuring the MRSL and IRCCP in healthy adult patients. The risk of bias and evidence quality were evaluated using the Joanna Briggs Institute's checklist and GRADE framework. Thirteen studies involving 1169 patients were included for qualitative synthesis. Seven of these studies were eligible for quantitative analysis. Meta-analysis showed that the mean MRSL at the subfurcation-6 mm plane in Asian normodivergent cases was 3.78 mm (95% confidence interval [CI]: 2.81-4.35; I2 = 79.7%) for skeletal Class-I malocclusions, 3.02 mm (95% CI: 2.10-3.94; I2 = 62.5%) for Class-II, and 4.43 mm (95% CI: 3.14-5.73; I2 = 75.1%) for Class-III. The mean MRSL at the sub-cementoenamel junction (CEJ)-10 mm plane for Asian, Class-I, normodivergent cases was 3.28 mm (95% CI: 2.44-4.12; I2 = 68.9%). The mean IRCCP for Asian, Class-I, normodivergent cases was 27.2% (95% CI: 0.22-0.32; I2 = 0%). In Asian normodivergent cases, MRSL ranges from 3.28 to 4.43 mm with a 27.2% IRCCP for Class-I. Cone-beam computed tomography imaging is recommended for measuring the MRSL in the apex region particularly before molar distalization. Factors influencing MRSL and IRCCP include different races, skeletal patterns, facial types, and third-molar status.

Variations in the alveolar bone morphology in maxillary molar area: a retrospective CBCT study.

BACKGROUND: This study quantitatively analyzed the anatomic structure of the alveolar bone in the maxillary molar region at three potential locations for Temporary Anchorage Device (TAD) placement. Additionally, the study compared the variability in this region across different age groups, sagittal skeletal patterns, vertical facial types, and sexes. METHODS: In this retrospective cone-beam computed tomography study, the buccal alveolar bone was analyzed in the posterior molar area of 200 patients, the measurement items include buccal alveolar bone height, alveolar bone thickness, interradicular distance, and maxillary retromolar space. RESULTS: Buccal alveolar height was greatest in the U56 region. The interradicular space was largest in the U56 region and increased from the alveolar crest to the sinus floor. Buccal alveolar bone thickness was highest in the U67 region and generally increased from the alveolar crest to the sinus floor. The maxillary retromolar space gradually increased from the alveolar crest to the root apex. CONCLUSIONS: TADs are safest when placed in the buccal area between the maxillary second premolar and the first molar, particularly at the 9 mm plane. The U67 region is the optimal safe zone for TAD placement for maxillary dentition distalization. TADs placement in adolescents can be challenging. Maxillary third molar extraction can be considered for maxillary dentition distalization.

Assessment of mandibular retromolar space in adults with regard to third molar eruption status.

OBJECTIVE: The aim of this study was to compare the difference in length and width of the mandibular retromolar space (RMS) stratified by the different eruption and impaction statuses of the third molars in patients with skeletal Class I malocclusion. MATERIALS AND METHODS: The right mandibular RMS in 186 adult patients categorized according to the different statuses of the third molar was analyzed by using cone-beam computed tomography (CBCT). The shortest distances between the inner lingual cortex of the mandibular body and second molar root were measured parallel to the posterior occlusal line (POL) at depths of 2, 4, 6, 8, and 10 mm (mandibular retromolar space length in root level, RLin2,4,6,8,10) on the axial slices with the cementoenamel junction (CEJ) as the reference level. The width of the RMS and second molar root was measured vertical to the POL at the terminal point of the molar distalization at depths of 2, 4, 6, 8, and 10 mm (width of the mandibular retromolar space, BW2,4,6,8,10/ width of the second molar distal root, TW2,4,6,8,10) from the CEJ. RESULTS: RL in different measurement planes was 2.72 ± 2.22 ~ 3.74 ± 2.26 for Group A, 5.27 ± 1.68 ~ 9.10 ± 2.04 for Group B, 1.94 ± 2.34 ~ 5.71 ± 4.37 for Group C, 1.83 ± 2.95 ~ 5.05 ± 4.24 for Group D, and 5.93 ± 3.97 ~ 10.52 ± 2.16 for Group E. The BW measurement results for A ~ E group were 9.71 ± 1.41 ~ 10.51 ± 1.81, 9.83 ± 1.39 ~ 12.55 ± 2.11, 9.96 ± 1.21 ~ 12.17 ± 1.62, 9.82 ± 1.47 ~ 12.28 ± 2.77, and 10.02 ± 1.20 ~ 12.75 ± 0.82, respectively. There was no significant difference between men and women in any measurements (P > 0.05). Patients with normal third molars erupted and those vertically impacted possessed larger RMS lengths than those in which the third molars were missing, horizontally impacted or mesially impacted (P < 0.05). In each measurement plane, TW was significantly smaller than BW (P < 0.05). CONCLUSIONS: Sex had no effect on the length or width of the mandibular RMS. Different statuses of third molars can also differentially affect the mandibular RMS. The mandibular RMS width is not a limit for mandibular molar distalization. CLINICAL RELEVANCE: When considering the distalization of mandibular molars, more attention should be directed to the lingual cortex of the mandible, and CBCT scans are recommended for patients who require significant mandibular molar distalization. The mandible buccal shelf and retromolar area maybe a safe zone to insert the miniscrew for molar distalization.

Three-dimensional analysis of the relationship between mandibular retromolar space and positional traits of third molars in non-hyperdivergent adults.

BACKGROUND: The anatomical position of the mandibular third molars (M3s) is located in the distal-most portions of the molar area. In some previous literature, researchers evaluated the relationship between retromolar space (RS) and different classifications of M3 in three­dimensional (3D) cone-beam computed tomography (CBCT). METHODS: Two hundred six M3s from 103 patients were included. M3s were grouped according to four classification criteria: PG-A/B/C, PG-I/II/III, mesiodistal angle and buccolingual angle. 3D hard tissue models were reconstructed by CBCT digital imaging. RS was measured respectively by utilizing the fitting WALA ridge plane (WP) which was fitted by the least square method and the occlusal plane (OP) as reference planes. SPSS (version 26) was used to analyze the data. RESULTS: In all criteria evaluated, RS decreased steadily from the crown to the root (P < 0.05), the minimum was at the root tip. From PG-A classification, PG-B classification to PG-C classification and from PG-I classification, PG-II classification to PG-III classification, RS both appeared a diminishing tendency (P < 0.05). As the degree of mesial tilt decreased, RS appeared an increasing trend (P < 0.05). RS in classification criteria of buccolingual angle had no statistical difference (P > 0.05). CONCLUSIONS: RS was associated with positional classifications of the M3. In the clinic, RS can be evaluated by watching the Pell&Gregory classification and mesial angle of M3.

Correlation of mandibular third molar orientation and available retromolar space with arch length discrepancy in subjects with different growth pattern.

Aim and Objective: To evaluate, compare, and correlate the mandibular third molar orientation and available retromolar space with arch length discrepancy in subjects with skeletal class II malocclusion and different growth pattern. Material and Method: A total of 250 patients (age >18 yrs) having skeletal class II malocclusion (based on YEN angle and WITS appraisal) were divided into two groups. Both the groups (Group I with erupted mandibular third molars {N = 150} and Group II with impacted mandibular third molars {N = 100}) were subdivided into subgroups IA (n = 71), IB (n = 19), IC (n = 71) and Group IIA (n = 54), IIB (n = 30) and IIC (n = 16) for normo-, hypo- and hyperdivergent growth patterns, respectively (based on Jarabak ratio and Sn-Go-Gn angle). Four parameters, that is, retromolar space, width of third molar, third molar angulation, and mandibular incisor angulation were measured on orthopantomogram whereas arch length discrepancy was calculated with the help of lateral cephalogram and study model. Intragroup, intergroup comparisons (using unpaired Student's 't' test), and Pearson's correlation coefficient for assessed parameters were obtained. Result: Third molar angulation and retromolar space were significantly higher in Group I than in Group II (hyperdivergent pattern of Group II had highest value). The width of third molar was less than retromolar space in Group II and vice versa for Group I. Mandibular incisor angulation and arch length discrepancy were more in Group II than in Group I, but difference was statistically nonsignificant. Strong positive correlation was observed for mandibular third molar angulation and available retromolar space in normo- and hyperdivergent growth patterns. Conclusion: Lack of retromolar space along with increased amount of arch length discrepancy and mandibular incisor angulation is responsible for increased chances of third molar impaction in some subjects with class II malocclusion.

Influence and Impact of Mandibular Ramal Dimensions on the Incidence of Lower Third Molar Impaction: A Prospective Study.

Context: The incidence of third molar impaction is very frequent in the dental arch; however, the etiology remains unclear. Assessment of ramal parameters might aid in deducing the chance of the lower third molar being impacted. Aims: To investigate the mandibular ramus features that could contribute to the etiology of mandibular third molar impaction. Settings and Design: A prospective study. Methods and Materials: In total 1,125 patients (568 males and 557 females) who satisfied the inclusion and exclusion criteria were included in the study. Six linear and four angular measurements such as ramal height, ramal width, mandibular body length, third molar width, the body of mandible width, retromolar space, angle of the impacted tooth, the angle between condyle and coronoid process, gonial angle, and inclination of the lower posterior teeth were made using digital panoramic radiographs and recorded. Also, the occurrence of impacted lower third molar was noted. Statistical Analysis Used: Comparisons between groups were done using Student's t-test. Pearson correlation was used to assess the degree of relationship between retromolar space and mandibular measurements. Results: Control group showed significantly greater measurements in most of the variables, whereas the impacted group showed no significant difference. A significant correlation of retromolar space is found with body height, third molar width, and angle of impaction. Conclusions: The present study found that the configuration of the mandibular ramus appears to be discrete in many aspects in the erupted other than impacted lower third molars subjects, which might be a possible cause for the impaction.

A longitudinal assessment of sex differences in the growth of the mandibular retromolar space.

OBJECTIVE: To assess longitudinal variation in patterns of retromolar space growth, with regard to sex and cervical vertebrae maturation. DESIGN: We utilized serial lateral cephalograms from three craniofacial growth studies (Denver, Iowa, Oregon), measuring retromolar space and cervical vertebrae maturation in 99 subjects (56% male) from 8 to 18 years of age for each subject. Repeated measures ANOVA and a linear mixed effects model were used to assess retromolar space growth through time. RESULTS: Our analyses revealed an average increase in retromolar space of 8.73 mm from 8 to 18 years. While t-tests failed to find differences in retromolar space growth between males and females at the measured age points, repeated measures ANOVA and linear mixed effects models revealed modest differences in growth trends between sexes, with females having more growth earlier but a younger age of deceleration of growth (between 12 and 14 years of age). CONCLUSIONS: Our results confirm large increases in retromolar space through growth, reaching an average of 1.38 mm/year around puberty. Importantly, we add to the conversation regarding sex differences, showing differences in timing of growth. This highlights the importance of using longitudinal data and analytical approaches to address questions of this nature.

Mandibular retromolar space in adults with different sagittal skeletal patterns.

OBJECTIVES: To analyze the mandibular retromolar space among normal-divergent adult patients with different sagittal skeletal patterns by cone-beam computed tomography (CBCT). MATERIALS AND METHODS: CBCTs of a total of 120 normal-divergent adult patients were investigated. Patients were categorized into the following three groups according to their ANB angle: skeletal Class I (48 patients), skeletal Class II (36 patients), and skeletal Class III (36 patients). Four different planes parallel to the mandibular occlusal plane were used to measure the retromolar space. The retromolar space was measured by two reference lines and then compared between different sagittal skeletal patterns groups. The incidence of root contact with the inner lingual cortex was compared among the three groups. RESULTS: The retromolar space of the Class III patients was significantly larger than that of Class I patients and Class II patients. Compared with Class I and Class III patients, Class II patients had a smaller retromolar space and higher incidence of contact with the inner cortex of the mandible. CONCLUSIONS: Class III patients had a larger retromolar space than Class I patients and Class II patients in four different planes. The mandibular retromolar space should be evaluated by CBCT in patients who need mandibular molar distalization.

Effects of Angle class II correction with the Forsus fatigue resistant device on mandibular third molars : A retrospective study.

PURPOSE: The goal was to evaluate the effects of Angle class II malocclusion treatment using the Forsus fatigue resistant device (FRD, 3M, St. Paul, MN, USA) on the position and angulation of mandibular third molars and retromolar space. PATIENTS AND METHODS: In all, 58 class II patients (mean age 13.6 ± 1.8 years) treated with the FRD (FRD group) were compared with 51 class I patients (mean age 13.5 ± 1.6 years) who underwent orthodontic treatment (control group). A total of 109 mandibular third molars in the FRD group and 91 in the control group were evaluated. Changes in the retromolar space, angulation of the second (É£) and third molars (ß), and the angle between these teeth (α) were assessed with panoramic radiographs taken at the beginning and the end of the treatment. Data were statistically analyzed. RESULTS: At the end of the treatment, there were significant increases in É£ and ß in the FRD group and É£ in the control group (p < 0.05). The decrease in α in the FRD group and increase in the control group were not significant (p > 0.05); however, this change led to a small significant change between the groups (p < 0.05). The retromolar space significantly increased in the FRD group compared to the control group (p < 0.05). No significant correlation was found between retromolar space and third molar uprighting in any of the groups (p > 0.05). CONCLUSION: Class II correction with FRD led to mesialization of the lower arch which provided an increase in the retromolar space. Little improvement in the uprighting of the third molars occurred.

Quantitative evaluation of retromolar space in adults with different vertical facial types.

OBJECTIVE: To investigate the differences in mandibular retromolar space among skeletal Class I subjects with different vertical divergence using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: A total of 123 skeletal Class I patients (aged 20-40 years) were categorized into hypodivergent, normodivergent, and hyperdivergent groups based on S-N/Go-Me and facial height index (FHI). Mandibular retromolar space was measured at four planes parallel to the occlusal plane along the sagittal line and molar cuspal line, respectively. The mandibular retromolar space was compared among the three vertical groups. RESULTS: The hyperdivergent group had a significantly smaller mandibular retromolar space compared with the other two groups, while the hypodivergent group had the largest retromolar space. In addition, the hyperdivergent group had a larger number of subjects whose roots contacted the lingual cortex of the mandibular body. CONCLUSIONS: The hyperdivergent group tends to exhibit the smallest mandibular retromolar space and highest risk of cortex contact. Clinicians should keep in mind that successful molar distalization requires sufficient retromolar space, especially for hyperdivergent subjects, which should be verified with CBCT.

Bone availability for mandibular molar distalization in adults with mandibular prognathism.

OBJECTIVES: To investigate the retromolar space available for molar distalization in patients with mandibular prognathism. MATERIALS AND METHODS: Using cone-beam computed tomography, the posterior mandibular dimensions in 110 consecutive patients with Class I or Class III malocclusion were measured (mean age, 27.0 ± 7.1 years). The shortest linear distances from the distal root of the right mandibular second molar to the inner border of the mandibular cortex were measured at the level of root furcation and 2, 4, and 6 mm apical to the furcation along the sagittal line and the posterior line of occlusion. The retromolar distances were compared between the Class I and Class III malocclusion groups using general linear mixed models. RESULTS: The retromolar space measured through the sagittal line showed no significant intergroup difference. Among the distances measured through the posterior line of occlusion, the space measured at depths 0 and 2 mm to the furcation were significantly greater in the Class III group than in the Class I group. CONCLUSIONS: Patients with Class III malocclusion have greater retromolar space for mandibular molar distalization along the posterior line of occlusion only at the level of the second molar furcation.

The effect of first and second premolar extractions on third molars: A retrospective longitudinal study.

OBJECTIVES: To analyse the effect of first and second premolar extractions on eruption space for upper and lower third molars and on third molar position and angulation during orthodontic treatment. METHODS: The sample consisted of 296 patients of which 218 patients were orthodontically treated without extraction and 78 patients with extraction of first or second premolars. The eruption space for third molars was measured on pre- and posttreatment lateral cephalograms, whereas the angulation, vertical position, the relation with the mandibular canal and the mineralization status of third molars were evaluated using pre- and posttreatment panoramic radiographs. All data were statistically analyzed. RESULTS: The increase in eruption space and the change in vertical position of upper and lower third molars significantly differed between patients treated with and without premolar extractions, whereas the change in angulation, relationship with the mandibular canal and mineralization status of the third molars did not significantly differ between patients treated with and without premolar extractions. CONCLUSIONS: The retromolar space and the position of third molars significantly change during orthodontic treatment in growing patients. Premolar extractions have a positive influence on the eruption space and vertical position of third molars, whereas they do not influence the angular changes of third molars. Due to the retrospective character of the study, these conclusions should be carefully considered. Further prospective research is necessary for better insights into this complex topic. CLINICAL SIGNIFICANCE: This study stresses the importance of considering the possible effects of orthodontic treatment on third molars during treatment planning.

Influence of orthodontic premolar extraction therapy on the eruption of the third molars: A systematic review of the literature.

BACKGROUND: Through a systematic literature review, the authors assess the effect of premolar extractions on third-molar (M3) eruption considering eruption rate, retromolar space, and molar angulation. TYPES OF STUDIES REVIEWED: The authors performed a systematic search using MEDLINE and Web of Science databases up through April 2017 to identify quality studies available comparing M3 eruption between a group with premolar extraction and a group without premolar extraction. RESULTS: Twelve comparative retrospective cohort studies met all the inclusion criteria. The authors found in 5 studies comparing the rate of M3 eruption that there were significantly higher results in the group with extractions. They found in 5 studies comparing the evolution of the retromolar space significantly higher results in the group with extractions. Lastly, concerning the uprighting of the M3 during treatment, the authors found only 2 studies showing significant differences between the 2 groups, each time in favor of the group with extractions. CONCLUSIONS AND PRACTICAL IMPLICATIONS: The dental literature on premolar extraction related to the eruption of the M3 is composed of average-quality retrospective studies. Premolar extraction significantly improves the chances of M3 eruption, but the level of evidence of comparative retrospective cohort studies is low. Clinicians must continue to rely on their judgment regarding premolar extraction on a case-by-case basis until the evidence is stronger. Retrospective studies with standardized protocols and more detailed methodologies are required to obtain higher levels of evidence.

Measurement of retromolar space dimensions using dental pantomograms for intubation feasibility.

BACKGROUND: The purpose of this study was to measure the dimensions of the retromolar space of a patient population. If the dimensions were found to exceed the outside diameters of commonly used tracheal tubes, the results could increase use of the retromolar approach for oral intubation in patients with trismus. METHODS: We reviewed 311 dental pantomograms. Retromolar space height was measured from the lowest point of the maxillary tuberosity to the mandibular alveolar ridge. Width was measured from the last mandibular molar to the junction of the anterior border of the ramus with the body of the mandible. RESULTS: Mean height and width were 17.87 mm and 17.48 mm for the right space and 18.07 mm and 16.51 mm for the left. CONCLUSION: These dimensions were usually larger than the outside diameters of commonly used tracheal tubes. The retromolar approach can be considered an option for flexible fiberoptic intubation in patients with trismus. © 2015 Wiley Periodicals, Inc. Head Neck 38: E638-E642, 2016.

Association between mandibular third molar formation and retromolar space.

OBJECTIVE: To assess the association between formation stages of the mandibular third molars and the space distal to the permanent molars (retromolar space). MATERIALS AND METHODS: The material included pretreatment lateral cephalographs of 96 orthodontic patients (49 males, 47 females; 8-18 years old). The molar formation stage was assessed through the method of Nolla, which rates the degree of calcification on a scale of 10 stages. The retromolar space was measured from the most concave point of the anterior border of the ramus to the distal surface of the first molar (used because the second molars had not yet erupted in the younger patients). Statistical analyses included t-tests and analyses of variance for group differences and the Pearson product moment to gauge associations among variables. RESULTS: The formation stage advanced with age, but wide standard deviations were noted. Similarly, the retromolar distance increased with age and was greatest between 10 and 12 years. The correlation between retromolar space and developmental stage was high (r  =  0.85). On average, an increase of 5 mm of retromolar space corresponds to a 1.8 stage in tooth maturation. CONCLUSIONS: The correlation between third molar mineralization and available retromolar space essentially represents the association between one biologic age (dental formation) and another growth-related event (mandibular skeletal growth). The findings do not necessarily reflect successful emergence or nonimpaction of the molars. Longitudinal data are needed to determine such outcomes.

Modificaciones del espacio óseo posterior para terceros molares desde la infancia hasta la adolescencia / Modifications of the posterior bony space for third molars from childhood to adolescence

Introducción: Del crecimiento de los maxilares depende en gran medida la correcta disposición de los dientes, especialmente de los terceros molares, que son los últimos en brotar. Objetivo: Estimar los cambios en el espacio óseo posterior según la edad y su relación con variables epidemiológicas. Métodos: Se realizó un estudio observacional, descriptivo y transversal en niños pertenecientes al Policlínico Docente "José Martí Pérez" de Santiago de Cuba, de mayo de 2016 a febrero de 2017, para lo cual se utilizaron radiografías panorámicas en las mediciones, analizadas según las variables edad, sexo y color de la piel. Resultados: Sobresalió que la diferencia del espacio óseo posterior de la infancia a la adolescencia fue de 9 mm para el molar 18, de 8,1 para el 28, de 12,5 para el 38 y de 11,5 para el 48; no se observaron diferencias significativas en cuanto a sexo y color de la piel. Conclusiones: Con la evaluación de la magnitud dimensional de dicho espacio es posible predecir el crecimiento de los maxilares para dar ubicación a los terceros molares en el transcurso de la infancia a la adolescencia.

Introduction: The correct disposition of teeth depends in great measure on the growth of maxillary, especially the third molars that are the last ones in eruption. Objective: To estimate the changes in the posterior bony space according to age and its relationship with epidemic variables. Methods: An observational, descriptive and cross-sectional study was carried out in children belonging to José Martí Pérez Teaching Polyclinic in Santiago de Cuba, from May, 2016 to February, 2017, for which panoramic X-rays were used in the measures, analyzed according to age, sex and color of the skin. Results: It was remarkable that the difference of the posterior bony space from childhood to adolescence was 9 mm for 18 molar, of 8.1 for 28 molar, of 12.5 for 38 molar and of 11.5 for 48 molar; significant differences were not observed between sex and color of the skin. Conclusions: With the evaluation of the dimensional magnitude of this space it is possible to predict the growth of the maxillary to give location to the third molars during the course from the childhood to the adolescence.

Características anatomorradiográficas de los terceros molares en adolescentes de la enseñanza preuniversitaria / Anatomo-radiographic characteristics of third molars in senior high school students

RESUMEN Introducción: Las retenciones dentarias afectan al 17 % de los pacientes a nivel mundial y están consideradas actualmente como un síndrome, en que los terceros molares ocupan el primer lugar y cuya extirpación quirúrgica deviene la intervención más comúnmente practicada por los cirujanos maxilofaciales. Objetivo: Describir las características anatomorradiográficas de los terceros molares, así como su posible relación con variables epidemiológicas de interés. Métodos: Se realizó un estudio observacional, descriptivo y transversal en escolares del Instituto Preuniversitario "Antonio Alomá Serrano", perteneciente al área de salud del Policlínico Docente Asistencial "José Martí" de Santiago de Cuba, durante el período comprendido desde mayo de 2016 hasta febrero de 2017. Se utilizaron radiografías panorámicas indicadas a estos pacientes, en las que se efectuaron el análisis y la clasificación. Resultados: La mayoría de los dientes se encontraban en clase I (52,6 por ciento), clase C (51,9 por ciento), posición C (82,2 por ciento), verticales (47,7 por ciento) y sin aproximación sinusal (89,5 por ciento). Además se observaron relaciones significativas entre la edad y el color de la piel con respecto al espacio retromolar y la inclinación dentaria de este grupo molar, y entre el sexo y la inclinación. Conclusiones: Los terceros molares son los dientes con mayor variabilidad en cuanto a posición e inclinación intraósea y en edades avanzadas se logra suficiente espacio retromolar y verticalización en la mayoría de ellos(AU)

ABSTRACT Introduction: Tooth impaction affects 17 % of patients worldwide. It is currently considered to be a syndrome in which third molars occupy the first place. Surgical removal is the most common intervention performed by maxillofacial surgeons. Objective: Describe the anatomo-radiographic characteristics of third molars and their possible relationship to epidemiological variables of interest. Methods: A cross-sectional observational descriptive study was conducted of students from Antonio Alomá Serrano Senior High School, from the health area of José Martí University Polyclinic in Santiago de Cuba, from May 2016 to February 2017. The study was based on panoramic radiographs, which were analyzed and classified. Results: Most teeth were class I (52.6 percent), class C (51.9 percent), position C (82.2 percent), vertical (47.7 percent) and without sinus approach (89.5 percent). Significant relationships were found between age and skin color with respect to retromolar space and tooth inclination of this molar group, and between sex and inclination. Conclusions: Third molars are the teeth showing the greatest variability in terms of intraosseous inclination and position. In advanced ages most of them achieve enough retromolar space and verticalization(AU)

Alterações da região retromolar decorrentes do crescimento mandibular / Retromolar space changes associated with mandibular growth

Objetivo: as modificações regionais inerentes ao processo de crescimento mandibular, como a reabsorção da borda anterior do ramo, determinam o aumento do espaço na região retromolar e mostram a necessidade ou não de exodontia dos terceiros molares. O objetivo deste trabalho foi avaliar, quantitativamente, o crescimento anteroposterior da região retromolar mandibular e verificar a ocorrência de dimorfismo sexual dessa variável. Material e métodos: foram utilizadas telerradiografias obtidas em norma lateral de 45 jovens, de ambos os sexos, leucodermas, entre nove e 11 anos de idade, mesofaciais, com perfis faciais harmônicos e oclusão normal. Foi aferido o espaço retromolar ao longo do plano oclusal funcional, entre a borda anterior do ramo da mandíbula e a face distal do primeiro molar inferior. Os dados obtidos submeteram-se, primeiramente, ao teste t de Student, para verificar o erro sistemático, e ao teste de correlação para o erro casual, ambos intraexaminador, indicando ausência de erro do método. Empregou-se o teste de Tukey, para comparar as medidas obtidas nas diferentes idades, e a análise de variância, para verificar a ocorrência de dimorfismo sexual. Resultados e conclusão: verificou-se um crescimento da região retromolar de 3,29 mm, entre os nove e os 11 anos. Nas idades de dez aos 11 anos ocorreu um aumento de 2,55 mm, sendo estatisticamente maior do que o constatado dos nove aos dez anos, de 0,74 mm. A análise de variância indicou ausência de dimorfismo sexual.

Objective: regional mandibular growth changes as the resorption of the anterior ramus border that increases the retromolar space determining if lower third molars need to be removed or not. The aim of this study was to evaluate, quantitatively, the mandibular alveolar sagital growth and also if sexual dimorphism was present. Material and methods: lateral cephalograms of 45 Brazilian Caucasian children of both genders, aging from 9 to 11 years, with balanced faces and good occlusion were used. The retromolar mandibular space was measured at the functional occlusal plane, from the anterior border of the ramus to the distal aspect of the lower first molar. The data was firstly examined about systematic and random intra-examiner errors through Student's "t" test and correlation test, respectively. In order to compare the data among different ages and occurrence of sexual dimorphism Anova and Tukey's test were performed. Results and conclusions: it was found an increase of 3.29 mm in the mandibular retromolar space from 9 to 11 years of age. Between 10 and 11 years there was an increase of 2.55 mm, statistically greater than those verified from 9 to 10 years of age, which was 0.74 mm. Anova demonstrated no sexual dimorphism.