Position Of Mandibular Third Molars Research Articles

Radiographic study of mandibular third molars: evaluation of the position and root anatomy in Brazilian population.

The root anatomy and position of mandibular third molars are important factors in assessing the level of difficulty of surgical removal procedures. In this light, this study aims to identify the most frequent position and the root anatomy of mandibular third molars. The study sample comprised 1205 mandibular third molars from 710 panoramic radiographs evaluated. Regarding the position, all of them were based on Pell and Gregory's and Winter's classifications. The root anatomy was classified according to the type and number of roots, as well as the presence of laceration, fusion, or divergence. Gender and the quadrant were also considered. Following an interexaminer analysis, a statistical analysis was performed using the Kappa test. The results showed that the IA (40.3%) and mesioangular (53.8%) position was predominant in mandibular third molars. Regarding the anatomy, the most common were two roots (98.3%), of the conical simple type (88.9%), with absence of laceration (89.2%), divergence (84%), and fusion (80%). The present study showed that the most prevalent mandibular third molar type in Brazilian patients was the IA and mesioangular position, with simple root anatomy. The result of this study can assist oral surgeons to better plan and assess the level of difficulty of surgical removal procedures.

Association between impacted mandibular third molars and distal caries in second molars-A radiographic study

Objective: The aim of this study was to evaluate the incidence of caries on distal aspect of mandibular second molars in patients with impacted mandibular third molars using cone beam computed tomography (CBCT) radiography and to identify its association with angular position and depth of the impacted mandibular third molars based on the classification by Pell and Gregory. Methods: Maxillofacial cone beam computed tomography scan records of 35 patients with impacted third molars presenting to the Department of Oral and Maxillofacial Surgery, Saveetha dental college and Hospital were collected and assessed. Using CBCT the radiographic angulation and depth of mandibular third molar impaction were determined and compared to determine the relationship with incidence of caries on the distal surface of the second molar. Data were checked using Sirona software, statistically analyzed and results obtained. Results: Mesioangular position was the most common type of impaction with a distribution of 56% among all the impactions. According to this study results, 45.7% cases showed caries on the distal aspect of mandibular second molars. The incidence of caries was highest with mesioangularly impacted third molars (62%). A majority of these mesioangular cases were Level A and Class I as per the Pell and Gregory classification. Conclusion: The prophylactic extraction of mesioangular impacted mandibular third molars is indicated if the angulation in CBCT is between 30° and 70° and is justified by the incidence of distal caries in the second molars.

The predictivity of mandibular third molar position as a risk indicator for pericoronitis: A prospective study.

Aim:The aim of this study was to describe the characteristics of the mandibular third molar at highest risk for acute pericoronitis using clinical and radiographic analysis.Materials and Methods:A total of 120 patients ranging in age from 18 to 55 years suffering from pericoronitis were examined. Subjective and objective observations were recorded that included the age, gender, angulation of partially impacted mandibular third molar, the frequency of pericoronitis in a year, the presence of impinging maxillary third molar, the extent of soft tissue coverage over the impacted mandibular third molar, the clinical signs evaluated in the patient, the class and position of the impacted mandibular third molar, and the presence of distal radiolucency with respect to the impacted mandibular third molar.Results:The results obtained in the study indicate that pericoronitis is associated more in the age group of 26–35 years and is more commonly reported in the female gender. Distoangular partially impacted mandibular third molars impacted at Class II and position B seem to be at the highest risk of developing pericoronitis.Conclusion:The results obtained in the study indicate that pericoronitis is associated more in the age group of 26-35 years and is more commonly reported in the female gender. Distoangular partially impacted mandibular third molars impacted at class II and position B seem to be at the highest risk of developing pericoronitis.

Impact of informed consent on patient decisions regarding third molar removal.

We investigated whether the order in which patients learned about complication risks affected their anxiety about and willingness to undergo the removal of their third molar. In total, 171 patients (65 males, 106 females) were included in the study. The distributions of gender and the position of mandibular third molars were recorded. The Amsterdam Preoperative Anxiety and Information Scale and Spielberger's State-Trait Anxiety Inventory were used to evaluate anxiety. Associations of anxiety with timing (pre/post), gender, and the order in which the information was presented in the consent form were analyzed. The most common angulations were horizontal (26.3%) and mesioangular (60.2%), and these were more common in women. All patients obtained significantly higher anxiety scores after reading the consent form. There was no significant difference in anxiety scores, according to the order of information. In total, 88 patients underwent surgery, whereas 83 postponed the extraction after reading the consent form. Women were significantly more anxious than men before the procedure. Patients showed lower anxiety levels after the procedure (P < 0.05). Increased anxiety was not associated with the order in which information was presented in the informed consent form. However, the informed consent form itself was a major contributor to increased patient anxiety. Further studies regarding the contents of consent forms and their effects on patient anxiety and decisions regarding third molar removal are needed.

Predicting pathology in impacted mandibular third molars

Introduction: The rising incidence of the impacted mandibular third molars and their association with pathologies is now considered a public health problem. Aims and Objectives: The objective of this study was to assess the position of impacted mandibular third molars that are prone to developing pathologies and to determine the frequency and type of pathological conditions associated with these impacted teeth to facilitate planning for their prophylactic removal. Materials and Methods: Consecutive panoramic radiographs and clinical examination of 300 patients with impacted mandibular third molars were collected. They were segregated according to Pell and Gregory’s classification, Winter’s classification, and according to their state of eruption. These were correlated with associated pathologies based on clinical and radiological criteria. Statistical Analysis Used: Descriptive statistics included computation of percentages, mean, and standard deviations. The statistical test applied for the analysis was Pearson’s Chi-square test (χ2). For this test, confidence interval and P value were set at 93% and ≤0.03, respectively. Results: The pathology most commonly associated with impacted third molars was pericoronitis, which had the highest frequency of occurrence in partially erupted, distoangular, and IA positioned (as per Pell and Gregory classification) impacted teeth. Impacted mandibular third molars, which were in IA position, placed mesially, and partially erupted, were prone to develop pathologies such as dental caries and periodontitis. Conclusion: The clinical and radiographical features of impacted third molar may be correlated to the development of their pathological complications. The partially impacted mandibular third molars with mesioangularly aligned in IA position have the highest potential to cause pathological complications.

Incidence of distal caries in mandibular second molars due to impacted third molars: Nonintervention strategy of asymptomatic third molars causes harm? A retrospective study.

Background:Removal of impacted third molars is the most common oral surgical procedure. Many investigators have questioned the necessity of removal in patients who are free of symptoms or associated pathologies.Aim:The aim of this retrospective study was to evaluate the incidence of caries on distal aspect of mandibular second molars in patients referred for corresponding third molar assessment and to identify its association with angular position and depth of the impacted mandibular third molars based on the classification of Pell and Gregory.Methodology:Records of 150 patients with impacted third molar presenting to the Department of Oral and Maxillofacial Surgery, Sri Rajiv Gandhi College of Dental Sciences and Hospital, were assessed retrospectively. The radiographic angulation and depth of mandibular third molar impaction were determined and compared to determine the relationship with incidence of caries on the distal surface of the second molar.Results:According to this study results, 37.5% cases show caries on the distal aspect of mandibular second molars. The incidence of caries with mesioangular impacted third molars was 55%. A majority of these mesioangular cases were Level B and Class I as per the Pell and Gregory classification.Conclusion:The prophylactic extraction of mandibular third molars is indicated if the angulation is between 30° and 70° and is justified by incidence of distal caries in the second molars.

Evaluation of Mandibular Third Molar Position by Using Space-Width Ratio Method

Background: The prediction of changes in the mandibular third molar position and eruption is an important clinical concern because third molar retention may be beneficial for orthodontic anchorage. The aims of this study were to assess the mandibular third molar position by using medical CT scan and lateral reconstructed radiograph and evaluate gender differences. Materials and Methods: The sample of present study consisted of 39 patients (18 males and 21 females) with age range 11-15 years who were attending at Al-Suwayra General Hospital/ the Computerized Tomography department. The distance from anterior edge of ramus to distal surface of permanent mandibular second molar and mesio-distal width of developing mandibular third molar were measured in both three dimensional volumetric and two dimensional CT derived lateral images. The statistical analyses included: means, standard deviations. Paired t-test was used to compare between the two methods and independent t-test was used in verifying the genders difference. Results: The results showed that there was high significant method difference between 3D CT and 2D image and gender differences were observed in values of linear measurements of present study, as males showed higher mean values than females. Conclusion: There is high accuracy of measurement on CT images, so C.T. scan is advisable during the diagnosis and treatment plan of orthodontic cases.

A multi-centre retrospective study of mandibular fractures: do occlusal support and the mandibular third molar affect mandibular angle and condylar fractures?

This retrospective study was performed to investigate the influence of occlusal support and the presence, state, and position of mandibular third molars on the incidence of mandibular angle and condylar fractures. The following variables were investigated: age, sex, cause of fracture, presence and state (impaction, angulation, and the number of roots) of the mandibular third molars, site of the mandibular fracture, presence of occlusal support, duration of intermaxillary fixation, and postoperative complications. Various risk factors for mandibular angle and condylar fractures were investigated by univariate analysis. The risk of mandibular angle fracture was significantly higher in patients with occlusal support and mandibular third molars. The risk of condylar fracture was significantly higher in patients without occlusal support or mandibular third molars. The position and angulation of the mandibular third molars were not significant risk factors in mandibular angle and condylar fractures. This study demonstrated the influence of occlusal support and the presence of mandibular third molars on the incidence of mandibular angle and condylar fractures. The presence of occlusal support may be a more important factor affecting mandibular angle or condylar fractures than the position of the mandibular third molars.

Difficulty index in extraction of impacted mandibular third molars and their post-operative complications

Background: Although the removal of impacted mandibular third molars is a common minor oral surgical procedure, the extraction of these teeth can present with certain post–operative complications. Koerner KR proposed a Difficulty Index Scale for removal of these teeth on the basis of local anatomy and radiographs, which were helpful in predicting the difficulty that would be encountered intra-operatively, as well as the post-operative complications. Objective: To study the different post-operative complications in the removal of impacted mandibular third molars calculating their difficulty index value. Method: A total of 119 patients, 79 females and 40 males who underwent extraction of their impacted third molars were selected over a one year period. Data were collected prospectively, according to the angulation, depth and position of the impacted mandibular third molars and their difficulty index calculated. This was further correlated with the postoperative complications encountered. Results: Mesio-angular impaction (43.7%), with level A (66.4%) and Class I (70.6%) impaction were the major type of impaction seen. The difficulty index showed that majority were in the moderately difficult category (51.2%), with swelling and trismus seen to increase as the difficulty index value increased. Females were affected more than males, with swelling (Odds ratio 2.206) and trismus (Odds ratio 2.570) seen to be significantly more. Conclusion: Surgical removal of impacted mandibular third molars causes post-operative complications and special care is required in their removal, especially in females. The Difficulty Index, as described by Koerner KR can be used as a tool for predicting the frequency of the post-operative complications, especially swelling and trismus. DOI: http://dx.doi.org/10.3126/jkmc.v3i1.10918 Journal of Kathmandu Medical College Vol. 3, No. 1, Issue 7, Jan.-Mar., 2014, Page: 14-20

The Effect Of Class III Orthopedic Treatment On Position And Development Of Impacted Mandibular Third Molar: A Longitudinal Study

The third molars, and particularly those in the lower jaw, are the most frequently impacted teeth. The reason for third molar impaction, particularly of the lower molars is not absolutely clear. Several factors such as morphology, mesiodistal width of teeth, alveolar arch space behind the second molars, unfavorable path of eruption, and unsatisfactory uprighting during eruption have been associated with third molar impaction. While different methods have been developed to predict whether a molar will erupt or become impacted, no model has been able to reliably predict whether a molar will erupt or become retained. Yet, the risk of third molar impaction was reduced by an increase in retromolar space due to mandibular first premolar extraction1 and mesial molar movement2 during orthodontic treatments. However, we are aware of no studies evaluating the effect of Class III orthopedic treatment on the position and development of mandibular third molars, and retromolar space. The purpose of this study is to evaluate and to compare the position, inclintion of mandibular right and left third molars after Class III orthopedic treatment and long term follow-up.

Impacted mandibular third molars and their influence on mandibular angle and condyle fractures – A retrospective study

BackgroundPrevious retrospective analyses prove that impacted mandibular third molars (M3s) increase the risk of angle fractures and decrease the risk of concomitant fractures to the condyle. Study designA retrospective cohort was designed for patients reported to the Department of Oral and Maxillofacial Surgery from January 2011 till June 2013. The study variables are presence or absence of third molar, if it is present, their position, classified using the Pell and Gregory system; angulation, classified using Shiller's method. The outcome variables were angle and condyle fractures. Materials and methodsHospital records and panoramic radiographs were used to determine and classify these variables.The study sample comprised of 118 mandibular angle and condyle fractures in 110 patients.Database was constructed and analysed using SPSS version 10.0. ConclusionThis present retrospective study concluded that the presence of impacted third molar predisposes the angle to fracture and reduces the risk of a concomitant condylar fracture. However absence of impacted third molar increases the risk of condylar fracture. The highest incidence of angle fracture was observed in position A impacted mandibular third molars. And there is no significant relationship, concerning ramus position and angulation of impacted mandibular third molars with the angle fracture.

Position of impacted mandibular third molar in different skeletal facial types: First radiographic evaluation in a group of Iranian patients

PurposeThis study was performed to evaluate the position of impacted mandibular third molars in different skeletal facial types among a group of Iranian patients.Materials and MethodsA total of 400 mandibular third molars in 200 subjects with different types of facial growth were radiographically investigated for their positions according to their types of facial growth on the basis of the β angle. The subjects were divided into three groups (class I, II, and III) according to ANB angle, representing the anteroposterior relationship of the maxilla to the mandible. Meanwhile, the subjects were also divided into three groups (long, normal, and short face) according to the angle between the stella-nasion and mandibular plane (SNGoGn angle). ANOVA was used for statistical analysis.ResultsThe mean β angle showed no significant difference among class I, II, and III malocclusions (df=2, F=0.669, p=0.513). The same results were also found in short, normal, and long faces (df=1.842, F=2, p=0.160). The mesioangular position was the most frequent one in almost all of the facial growth patterns. Distoangular and horizontal positions of impaction were not found in the subjects with class III and normal faces. In the long facial growth pattern, the frequency of vertical and distoangular positions were not different.ConclusionIn almost all of the skeletal facial types, the mesioangular impaction of the mandibular third molar was the most prevalent position, followed by the horizontal position. In addition, β angle showed no significant difference in different types of facial growth.

Changes in the Position of Mandibular Third Molars Following Extraction and Non-Extraction Orthodontic Treatments

Introduction: Impaction of third molars can be associated with a number of sequelae, each requiring a different type of treatment. The purpose of this study was to assess the changes in the position of lower third molars following extraction and non-extraction orthodontic treatments. Methods: Pre- and post-treatment panoramic radiographs of 26 class I malocclusion patients (4 male and 22 female) who were treated on a non-extraction basis were compared with those of 30 class I malocclusion patients (5 male and 25 female) who received orthodontic treatment following the extraction of all first premolars. In each group, the lower third molar angulations and their distance from the lower border of the mandible were assessed. Results: Paired t-tests and independent t-tests detected significant changes in the position of the lower third molars in the extraction group. Both the left and right molars became more upright and their distance from the lower border of the mandible increased. Similar changes were only seen in the position of the right mandibular third molars in the non-extraction group. Conclusion: Tooth extractions can bring about favorable changes in the position of mandibular third molars and possibly reduce their incidence of impaction

Evaluation of Mandibular Third Molar Positions in Various Vertical Skeletal Malocclusions

Introduction: The purpose of this study was to evaluate the relationship between the position of mandibular third molar (M3) and vertical skeletal malocclusions. Methods: Materials for the study consisted of panoramic radiographs and lateral cephalograms of 73 fifteen to nineteen-year-old class I patients (girls=66%, boys= 34%). Patients were classified into three groups based on four vertical cephalometric indices: FMA, PFH/AFH, LAFH/TAFH, and Y-axis. Analysis of the position of mandibular M3 and its relation to the bone and other teeth were determined by three variables on panoramic view: evaluation of the space for mandibular M3, vertical position of the mandibular M3 in relation to occlusal plane, and spatial relationship between the mandibular second molar (M2) and M3. Results: In girls, there was a significant relationship between the retromolar space in both sides of the jaw and different vertical skeletal malocclusions (P<0.001 and P=0.001, respectively). In boys, significant relationship existed between the retromolar space in both sides of the jaw, spatial relationship between the mandibular M2 and mandibular M3 in the left side of the jaw and various vertical skeletal malocclusions (P=0.021, P=0.026, and P=0.017, respectively). Conclusion: The present study showed significant correlation between the retromolar space and various vertical skeletal malocclusions in boys and girls.

Remoción de terceros molares mandibulares con asistencia endoscópica. Nota técnica de un nuevo procedimiento quirúrgico para prevenir lesiones del NAI y formación de defectos óseos

Anatomic variability of the position of mandibular third molars represents significant challenges associated with its depth and angulation. The most common complications of conventional surgical procedure are related to extensive osteotomy and poor visualization, which can cause postsurgical effects such as inflammation, pain, trismus, reversible and irreversible lesions of the inferior alveolar nerve (IAN) or lingual nerve, fracture risk and formation of a deep periodontal defect on the distal aspect of the second molar. The implementation of rigid endoscopy in optics has allowed to use this technology via a minimally invasive approach to remove third molars by a minimally occlusal flapless ostectomy, preserving the buccal and lingual walls through direct and magnified visualization of the surgical site, adaptable to the patient's movements during the surgery. In this report, we present a new and minimally invasive procedure through endoscopic assistance for bone conservation in the removal of third molars at risk of inferior alveolar nerve injury

Comparison of Orthopantomography and Computed Tomography Image for Assessing the Relationship between Impacted Mandibular Third Molar and Mandibular Canal

Permanent mandibular third molar are most commonly impacted teeth. In planning the surgical removal of mandibular third molar, correct diagnosis requires not only their precise spatial location, but also a thorough and accurate assessment of the intimate relationship with adjacent anatomical structures. Various imaging modalities have been used for localizing the mandibular third molar but not satisfactorily. This prospective study of 30 patients with 42 impacted mandibular third molars was carried out with the aim of finding evidence for justifying the use of computed tomography and orthopantomography as a diagnostic modality, prior to surgical intervention of impacted mandibular third molar. Subjective evaluation of the CT and OPG images by two observed had shown that there was significant difference between the CT and OPG for radiographic visibility of mandibular canal in relation to third molar. Data analysis was done with Chi-square test (X(2)) and z-test to find the significant difference between the two radiographic modalities OPG and CT in localizing special relationship of impacted mandibular third molar. The comparison of OPG and CT showed z-value >1.5 in darkening of roots (1.98), deflection of root (2.00) interruption of z-value = 0 in narrowing of canal and dark, bifid apexes. Also it showed p-value <0.05 in all the radiographic signs except narrowing of mandibular canal and and dark and bifid apexes. The spiral CT image provides a unique opportunity to determine the exact position of impacted mandibular third molar and their relationship to adjacent structure in all three planes. Computed tomography is highly instrumental in depicting the relationship of mandibular third molar with inferior alveolar nerve canal before treatment and accurate appraisal of the several aspects can be made regarding prognosis.

A comparative evaluation of film and digital panoramic radiographs in the assessment of position and morphology of impacted mandibular third molars

Digital photo stimulable phosphor (PSP)-based radiography has many known theoretical advantages over conventional film radiography but its diagnostic efficacy has to be assessed clinically. This study compared the efficiency of conventional film-based panoramic radiographs with that of digital PSP-based panoramic radiographs in the assessment of position and morphology of impacted mandibular third molars. We selected a total of 80 impacted mandibular third molars that fulfilled the inclusion and exclusion criteria of this study. Both conventional film-based panoramic radiographs and digital PSP-based panoramic radiographs were taken of all the study samples and the teeth were later surgically removed. Conventional film-based and digital PSP-based panoramic radiographs were compared for their relative efficiencies in the assessment of impaction status, position of tooth, number of roots, root morphology, and proximity to mandibular canal of impacted mandibular third molars. An oral surgeon graded these same factors during/after surgical exploration and this assessment was considered the gold standard. The data obtained were statistically analyzed using descriptive statistics, chi-square test, and McNemar's test. There was no statistically significant difference between conventional film-based radiographic assessment and digital PSP-based panoramic radiographic assessment of impaction status, position of tooth, number of roots, and proximity to mandibular canal of impacted mandibular third molars (P>0.05). However, there was significant difference between the two methods with regard to assessment of root morphology of impacted mandibular third molars (P=0.00). Conventional film-based panoramic radiographs and digital PSP-based panoramic radiographs were comparable in their accuracy in the preoperative study of impacted mandibular third molar with regard to impaction status, tooth position, number of roots, and proximity to the mandibular canal. Digital PSP-based panoramic radiographs were more accurate than conventional film-based panoramic radiographs in the assessment of root morphology of impacted mandibular third molars. Hence, we conclude that digital PSP-based panoramic radiographs can be used as an effective alternative to conventional film-based panoramic radiographs for assessment of position and morphology of impacted mandibular third molars.

A Study on the Impact of Mandibular Third Molars on Angle Fractures

This study evaluated the relationship between the status and position of mandibular third molars and angle fractures. In a total of 2,033 patients with a mandibular fracture, 532 (26%) had angle fractures, and 1,466 (72%) had retained their lower third molars. The most frequent cause for mandibular fracture was road traffic accident (64%), followed by assault (19%). Of 341 patients with an unerupted third molar, mandibular angle fracture was evident in 249 patients (73%). Only 62 patients (9.4%) with a completely erupted third molar had angle fractures, whereas 83 patients (17.6%) with partially erupted third molars had angle fractures. Our study confirmed an increased risk of angle fractures in the presence of a lower third molar, as well as a variable risk for angle fracture, depending on the third molar's position.

Clinical evaluation of the effects of radiographic distortion on the position and classification of mandibular third molars

Panoramic radiographs are routinely employed for surgical planning of unerupted third molars. The objective of this study was to evaluate distortions in the position of mandibular third molars on panoramic radiographs. Panoramic radiographs of 14 patients with indication for extraction of the mandibular third molars were used. Transurgical impressions of the crowns of the teeth to be extracted and adjacent second molars (n=19) were achieved with addition silicone and poured with type IV plaster for comparison of the inclinations of the third molars on the radiographs and study casts. There was a mean difference of -5.37 degrees between the position of the third molar on the panoramic radiograph and on the study cast (standard deviation 1.46, P<0.05, Student's t-test). There is distortion in the position of teeth on the panoramic radiograph, which may influence the surgical planning; however, this does not invalidate it as the main tool for diagnosis and surgical planning of mandibular third molars.

下顎智歯抜歯後に発症した下唇知覚鈍麻についての検討

Removal of mandibular third molars is one of the most common operations in oral surgery. Hypoesthesia of the lower lip occurring after the extraction of third molars is a serious complication, requiring a prolonged time for recovery. In this study, we investigated factors potentially affecting the incidence of hypoesthesia.A total of 781 mandibular third molars extracted at our clinic in 2002 were examined. There were 17 cases (2.2%) of hypoesthesia of the lower lip. There was no relation of gender, difficulty of extraction, or the skill of the operator to the incidence of hypoesthesia. In contrast, the incidence of hypoesthesia strongly correlated with age and the root position of mandibular third molars with respect to the mandibular canal.Eleven of the 17 cases of hypoesthesia (64.7%) resolved within 1 month, and 16 of the 17 cases (94.1%) resolved within 6 months. The patients who had hypoesthesia for more than 1 monthwere significantly older than those who recovered from hypoesthesia within 1 month and were all female.These results might be useful when informing patients about potential complications of tooth extraction.