Does the Winter or Pell and Gregory Classification System Indicate the Apical Position of Impacted Mandibular Third Molars?

Development and validation of a deep learning algorithm for the classification of the level of surgical difficulty in impacted mandibular third molar surgery

The aim of this study was to develop and validate a convolutional neural network (CNN) algorithm for the detection of impacted mandibular third molars in panoramic radiographs and the classification of the surgical extraction difficulty level. A dataset of 1730 panoramic radiographs was collected; 1300 images were allocated to training and 430 to testing. The performance of the model was evaluated using the confusion matrix for multiclass classification, and the actual scores were compared to those of two human experts. The area under the precision-recall curve of the YOLOv5 model ranged from 72% to 89% across the variables in the surgical difficulty index. The area under the receiver operating characteristic curve showed promising results of the YOLOv5 model for classifying third molars into three surgical difficulty levels (micro-average AUC 87%). Furthermore, the algorithm scores demonstrated good agreement with the human experts. In conclusion, the YOLOv5 model has the potential to accurately detect and classify the position of mandibular third molars, with high performance for every criterion in radiographic images. The proposed model could serve as an aid in improving clinician performance and could be integrated into a screening system.

Removal of Horizontally Impacted Mandibular Third Molar through Buccal Plate Extirpation and Replacement - An Evaluative Study

BACKGROUND

An impacted lower wisdom tooth is a common condition encountered in oral surgery. A horizontally impacted lower third molar is associated with more bone removal compared to mesioangular and distoangular impactions.

OBJECTIVE

The goal was to minimize overall bone removal without compromising the function of the inferior alveolar nerve.

MATERIALS AND METHODS

Twenty-five patients, between 18 and 46 years old, participated in the study-20 females and five males. All patients attended a private clinic with the intention of having their impacted teeth removed. A portion of the buccal cortex, with specific dimensions, was removed from a position lateral to the horizontally impacted wisdom tooth. This was preserved in a sterile wet pack and refixed after tooth removal to minimize bone loss.

RESULTS

A majority of cases involved females (80%) and males (20%). The primary assessment criterion was the viability of the buccal cortex and the presence of any associated complications. One male patient was found to have lost the buccal cortex (accounting for 4% of cases). Two patients complained of temporary paraesthesia, which resolved within 4 months.

STATISTICAL ANALYSIS

The data were collected and compiled in Microsoft Excel. The Mann-Whitney U test for nonparametric data was used to analyse descriptive data. The level of statistical significance was set at P < 0.05.

CONCLUSION

The removal of a small part of the buccal cortex lateral to a horizontally impacted lower third molar is highly predictable when conducted with precision. This is particularly true when the tissue is secured properly, which can subsequently reduce the amount of bone removed.

Prevalence of distal caries in second molar associated with impacted mandibular third molar and the position and level of impaction: a systematic review and meta-analysis

OBJECTIVES

The primary objective of this systematic review was to analyze the overall prevalence of distal caries in mandibular second molars (MSMs) associated with the presence of impacted mandibular third molars (IMTMs). Secondary objectives were to determine how IMTM position and level of impaction influence the occurrence of distal caries.

MATERIALS AND METHODS

PRISMA guidelines were followed. An automated search was conducted as well as a manual search for relevant clinical articles. The review included studies reporting IMTM and adjacent MSM presenting distal caries published in the last ten years. The quality of evidence was evaluated using the Newcastle-Ottawa Quality Assessment Scale.

RESULTS

Thirteen studies met the inclusion criteria and underwent analysis; they included a total of 13,788 patients. The overall prevalence of caries in MSMs adjacent to IMTMs was 29.89% (CI 95%: 21.05 - 38.74%; p < 0.001). Following Winter's classification, the mesioangular position was the most frequently associated with caries with 43.37% (CI 95%: 33.03 - 53.70%; p < 0.001). Following Pell & Gregory classification, position A was the most frequently associated with caries with 33.97% (CI 95%: 24.06 - 43.89%; p < 0.001).

CONCLUSIONS

IMTMs in mesioangulated positions, especially if accompanied by level A impaction, present the highest risk of MSM distal caries.

CLINICAL RELEVANCE

Knowing which positions and level of IMTMs are most frequently associated with distal caries in MSMs is crucial to implementing preventive measures.

REVIEW REGISTRATION

This systematic review was registered in the International Prospective Register of Systematic Reviews (PROSPERO). Reg. number: CRD42023393143.

Multivariable Analysis of Correlation Between Anatomical Features of Mandibular Third Molars and Pericoronitis

Objective: The correlation between anatomy features of impacted mandibular third molars (M3Ms) and prevalence of pericoronitis was only interpreted using univariate analysis. This study investigated this correlation using multivariable analysis to determine the relationship between pericoronitis prevalence and the M3Ms' anatomical features. Methods: This cross-sectional study recruited 245 patients with 338 impacted M3Ms. One researcher collected participants' demographic characteristics such as sexes, age, side, and pericoronitis condition. The radiographic characteristics of M3Ms, including eruption direction and impacted levels according to Pell-Gregory classification, were assessed based on their orthopantomograms. Initially, univariate analyses were used to determine potential demographic and radiographic factors that correlated to pericoronitis. These factors were, then, analyzes using Firth's logistic regression. Results: No significant difference was found between non- and pericoronitis groups about sexes, age, side (p  > 0.05). The univariate analyses showed that proportion of vertical impacted levels and eruption direction of M3Ms were significantly different between non- and pericoronitis groups. Firth's logistic regression analysis indicated that M3Ms with impacted level A were more likely to suffer from pericoronitis than ones at level B (odds ratio (OR) = 3.34), wheraes M3Ms impacted level II had higher risk of pericorinitis than ones at level I (OR = 1.63). Vertical M3Ms were more likely to develop pericoronitis than horizontal (OR = 5.78) ones. Conclusion: M3M angulation and impacted level are significant factors relating to pericoronitis prevalence. M3Ms with vertical eruption, vertically level A, and horizontally level B are more likely to have pericoronitis.

Screening Female Patients With Autonomic Nervous System Imbalance Using the Toho Medical Index Before Tooth Extraction

OBJECTIVE

Imbalanced autonomic nervous system (ANS) activity raises concerns about the development of systemic complications during dental treatment. The purpose of this study was to determine whether a psychological test (Toho Medical Index (TMI)) prior to the impacted mandibular third molar extraction can identify patients with potentially imbalanced autonomic function.

MATERIALS AND METHODS

In this prospective study, 34 healthy adult patients with no history of systemic disease were assigned to either the autonomic imbalance group (type II, III, IV) or the control group (type I) based on the results of the TMI. We evaluated sympathetic nervous system activity (low/high frequency (LF/HF)), parasympathetic nervous activity, heart rate (HR), and systolic blood pressure (SBP) values before extraction of the impacted mandibular third molar.

RESULTS

LF/HF and SBP in the autonomic imbalance group were significantly higher preoperatively than those in the control group. In addition, preoperative HF values were significantly lower in the autonomic imbalance group compared to those in controls (Mann-Whitney U test, p < 0.05); no significant group differences in HR were found (Mann-Whitney U test, p < 0.05).

CONCLUSION

ANS activity before extraction of the impacted mandibular third molar was assessed subjectively using the TMI and objectively using HR variability analysis. Our findings suggest that some patients do not have symptoms specific to dysautonomia but have an imbalance of autonomic function before extraction of the impacted mandibular third molar, and TMI can identify such patients.

The agreement of panoramic radiography with cone-beam computed tomography in classifying impacted lower third molars: a systematic review

BACKGROUND

This systematic review aimed to determine whether cone-beam computed tomography (CBCT) and panoramic radiography (PR) yield consistent results in determining the degree of impacted lower third molar teeth based on existing classification parameters.

METHODS

A comprehensive literature search was conducted of PubMed, Embase, Cochrane, and PLOS One, adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Additionally, a manual search was also carried out. There were no restrictions on publication dates, allowing a broader scope of literature. Only articles published in English were eligible for inclusion. Furthermore, all studies that compared the outcomes of CBCT and panoramic images concerning the position of impacted teeth, according to the Winter and the Pell & Gregory classifications, were included.

RESULTS

Four studies met the inclusion criteria. One study used the Pell & Gregory classification to assess differences, finding a significant result (P< 0.001). Two studies used both the Winter and the Pell & Gregory classifications. In these assessments, one study found no significant differences in the Winter classification (p= 1.000) or the Pell & Gregory assessment (p= 0.500). However, another study identified significant differences using both the winter and the Pell & Gregory classifications (P< 0.001). One study conducted an assessment using only Winter classification and found no significant differences between PR and CBCT (P> 0.05).

CONCLUSION

There are inter-modality differences in the agreement concerning the degree of impaction of the third molar when using CBCT compared with panoramic imaging across various classification levels. Improved assessment methods are necessary to determine the most appropriate imaging modality for therapeutic management.

Incidence of caries and pathological findings in different positions of impacted third molars: A retrospective analysis

OBJECTIVES

Impacted third molars(3 M), commonly known as wisdom teeth, are prone to caries and pathological formations depending on their position in the jaw. This study aimed to determine and compare the incidence of caries, pathological formations, and the superposition of the roots of the mandibular impacted third molar over the mandibular canal in different positions of impacted 3Ms.

METERIALS AND METHODS

This retrospective study was conducted on orthopantomographs of patients who presented with 3 M complaints at the Tokat Gaziosmanpaşa University Oral and Maxillofacial Surgery Department between 2019 and 2023. The 3 M were classified according to their position by two researchers independently and were evaluated for caries, pathology, and nerve superposition. The position of the 3Ms classified using Pell and Gregory and Winter's classifications. The primary outcome variable was the presence of caries in the 3 M The secondary outcome variable was the presence of pathological formations around the 3 M The tertiary outcome variable was the superposition of the roots of the mandibular 3 M over the mandibular canal.

RESULTS

A total of 7,038 patients were included in the study, with 53.74 % being female. The mean age was 32.15±7.2 years. The highest incidence of caries was associated with the vertical position in both maxillary and mandibular 3Ms (right maxillary: 9.98 %, P < 0.001; left maxillary: 12.74 %, P < 0.001; left mandibular: 11.66 %, p = 0.003; right mandibular: 11.69 %, p = 0.031). Pathological formations were most commonly observed in the vertical position, but the highest incidence was found in the horizontal or mesioangular positions (right maxillary: 36.84 %, p < 0.001; left maxillary: 40 %, p < 0.001; left mandibular: 62.04 %, p < 0.001; right mandibular: 62.25 %, p < 0.001). Nerve superposition was most common in the vertical position but was highest in the distoangular position (left mandibular: 74.69 %, p < 0.001; right mandibular: 76.66 %, p < 0.001).

CONCLUSIONS

The position of 3Ms plays a critical role in the development of complications such as caries and pathological formations. Prophylactic extraction may be considered more seriously in cases where the position of the tooth poses a higher risk of complications.

Evaluation of the Inferior Alveolar Canal Course in Relation to Fully and Partially Impacted Lower Third Molar Roots via Cone-Beam Computed Tomography

INTRODUCTION

Impacted mandibular third molars are frequently encountered in dentistry. As extraction is often the treatment of choice, knowledge of the proximity and relationship of the inferior alveolar canal (IAC) with the tooth is essential. This study was designed to determine the course of the IAC in cases of impacted lower third molars.

METHODS

Cone-beam computed tomography (CBCT) imaging of 103 patients (mean age: 37 years, range: 22-82 years) with 140 impacted lower third molars from 2016 to 2017 was evaluated. The number of roots, type of impaction according to Winter's classification, positional relationship of the IAC in relation to the roots, and shape of the canal were examined.

RESULTS

The most common type of impaction was mesioangular, two-rooted molars. Most often, the canal ran below and in contact with the root, and the canal was most commonly oval-shaped. The type of impaction and the number of roots did not depend on sex. Single-rooted (p = 0.025) and distoangularly impacted (p = 0.019) molars were more common in older patients. There was a significant relationship between the number of roots and the canal running between the roots (p < 0.0001).

CONCLUSIONS

There was no relationship between the shape of the IAC and the number of roots or type of impaction. Based on these results, the interesting correlation between age, type of impaction, and number of roots requires further investigation and explanation. The frequency of canals in contact with the root further emphasizes the importance of CBCT imaging for preoperative visualization.

Radiological findings associated with postoperative wound infection after extraction of impacted mandibular third molar: A retrospective study

INTRODUCTION

Studies directly relating radiological findings to the risk of postoperative wound infection (PWI) in impacted mandibular third molars (M3) are limited and poorly understood. This study aimed to clarify the radiological risk of PWI.

MATERIALS AND METHODS

Twenty-six patients who developed PWI after M3 extraction were retrospectively analyzed using orthopantomography (OPG) and computed tomography (CT) before M3 extraction to determine the association between M3 impaction status and PWI. These were compared with an equal number of non-infected groups. Moreover, the possibility of assessing the same risk in OPG as in CT imaging was examined.

RESULTS

Multivariate analysis identified class III and position B of the Pell and Gregory classification system as independent risk factors for PWI. On CT, an axial overlap distance (AOD) >3.5 mm was significantly associated with PWI. Furthermore, the sagittal overlap distance (SOD) and AOD of the OPG were significantly greater in group III-B. A strong positive correlation was observed between SOD and AOD.

CONCLUSION

These results indicate that class III, position B, and an AOD >3.5 mm may be novel risk factors for M3 PWI. The strong correlation between SOD and AOD suggests that the risk assessment for PWI can be performed by evaluating OPG alone.

Impacted mandibular third molars: a comparison of orthopantomography and cone-beam computed tomography imaging in predicting surgical difficulty

BACKGROUND

This study investigated the predictive value of orthopantomography (OPG) for the difficulty of extracting impacted mandibular third molars, in comparison with cone-beam computed tomography (CBCT).

METHODS

In this descriptive quantitative investigation, two oral and maxillofacial radiologists evaluated OPG and three-dimensional CBCT images according to the Pell-Gregory and Winter classifications. The results for the classification were compared using the chi-square test, and the prediction of difficulty was assessed using the Pederson scale, with a significance level of p< 0.05.

RESULTS

The study included 30 patients (14 men and 16 women), providing a total of 53 samples of impacted mandibular third molars. Of these, 30 (56.6%) were from the right side and 23 (43.4%) from the left. There was a statistically significant difference between the OPG and CBCT images concerning their relation to the mandibular ramus (p< 0.05). However, evaluations based on occlusal lines and angulation showed no significant differences (p> 0.05). According to the Pederson scale, significant differences were observed between OPG and CBCT in predicting extraction difficulty (p< 0.05).

CONCLUSION

CBCT offered a more accurate assessment of the surgical difficulty associated with mandibular third molars than OPG. OPG views frequently failed to adequately visualize the region of the mandibular ramus, influencing the perceived difficulty of mandibular third molar surgery. In certain cases, the use of CBCT imaging is crucial.

Distribution and impaction patterns of third molars in a sample of German population: Retrospective analysis in a high turnover maxillofacial department

BACKGROUND

The surgical removal of impacted third molars is considered a routine procedure for oral and maxillofacial surgeons. However, the distribution of impacted molars varies among different populations. A study into impaction patterns in the German population is currently not described. The aim of this retrospective study is to determine patterns of impacted third molars in a sample of German population, to identify gender and age specific differences as well as further risk factors for impacted molar extraction and to compare these results with other studies.

MATERIALS AND METHODS

The clinical findings and digital panoramic radiographs of 84 patients with a total of 243 impacted third molars that had been subjected for tooth extraction, from January to September 2023, were collected and analyzed. All third molars were analyzed according to Winter´s angulation, Pell and Gregory Score of depth and relationship to ramus. Furthermore, inferior alveolar nerve and maxillary sinus proximity were identified through a newly developed risk score and an analysis of patient´s gender and age regarding impaction patterns was performed.

RESULTS

No significant gender specific differences were found regarding the impaction patterns. Third molar angulations significantly differed regarding patient´s age (cut-off 26 years). In comparison, third molar depth, bone coverage, nerve approximity and angulation patterns differed from the results of other populations.

CONCLUSION

The results of this study can serve as a baseline for further studies of third molar impactions in the German population to minimize perioperative complications in impacted third molar surgery.

Estimating the Extraction Time of an Upper Third Molar: Proposal and Validation of Results

Background: Numerous studies in the literature have aimed to evaluate the difficulty level of removing third molars. However, most of these studies have focused on the lower third molars, which can lead to complications. There is a lack of a method to determine the complexity of upper third molar extraction. Therefore, this study's objective was to develop an equation using multiple linear regression to estimate the extraction time of an upper third molar based on its complexity. Methods: This study involved patients enrolled in the Master of Oral Surgery program at the University of Seville. To determine their relationship with surgical time, the researchers analyzed various factors, such as depth, root morphology, and the need for odontosection. They then validated their findings by studying patients treated at Palmaplanas Hospital in Mallorca. Results: The cohort analysis from the University of Seville revealed significant associations between surgical time and the identified factors. A regression equation design was performed to predict the total duration of surgical intervention for wisdom teeth extraction. This equation incorporates several independent variables, represented by Xi, together with a constant term, C, and the corresponding coefficients, Bi, which weight the impact of each variable on the intervention time. The results are as follows: -0.312 (spatial relationship), 0.651 (depth), -0.443 (bone and mucosa integrity), 0.214 (roots), -0.745 (ostectomy), 0.713 (odontosection), and -0.426 (suture). Upon application of the statistical methodology to the Palmaplanas Hospital cohort, a regression coefficient of 0.770 was determined. This indicates a strong correlation between the input data and the estimated surgical time. Conclusions: In conclusion, the proposed formula demonstrates notable validity in predicting the surgical time required to extract upper third molars.

Root volume measurements of maxillary canines and lateral incisors in patients with unilateral maxillary canine impaction

OBJECTIVE

This study aimed to assess root volumes of maxillary canines and adjacent lateral incisors in patients with unilateral maxillary canine impaction.

METHODS

This cross-sectional study was performed on cone-beam computed tomography (CBCT) scans of 100 patients (49 females and 51 males) with unilateral maxillary canine impaction. The images were loaded in Planmeca Romexis Viewer, and root layers between the cementoenamel junction and apex were reconstructed at 600-µm intervals. At each layer, the root boundary was marked, and finally, the root volume was calculated by multiplying the layers' area by the thickness of 600 µm. The root size of canines and lateral incisors was compared between the impaction and normal eruption sides.

RESULTS

Sixty-two patients showed buccal canine impaction, and 38 presented palatal impaction. The mean root volume of canines on the impaction side was significantly greater than that on the normal eruption side; either the tooth was buccally or palatally impacted (p<0.001). The lateral incisors on the side of buccally-impacted canines showed a significantly smaller root volume than that of the contralateral side (p<0.001). However, there was no significant difference in the root size of lateral incisors between the two sides in cases presenting palatal canine impaction (p=0.177).

CONCLUSION

The difference in root volume of canines between the two sides can serve as an indicator of canine impaction. The reduction in the root size of the lateral incisor on the side of the buccally impacted canine may be due to root resorption created by pressure from the canine's crown.

A finite element analysis on the indication for extracting partially impacted mandibular third molars considering mandibular trauma

BACKGROUND

Patients presenting with partially impacted lower third molars (M3) have a higher likelihood of experiencing angle fractures while simultaneously decreasing the risk of condylar fractures. However, the specific biomechanical mechanism responsible for this occurrence remains unclear. Moreover, there is an ongoing debate regarding whether the removal of M3s might actually increase the risk of condylar fractures. This study aimed to evaluate how the presence of M3s influences mandibular fractures resulting from blows to the symphysis and lateral mandibular body, and to determine the indication for extracting M3s in such cases.

METHODS

Models of the mandible with a partially M3-impacted model (M3I), M3-extracted model (M3E), and M3-absent model (M3A) were generated using a computer. A traumatic blown force of 2000 N was applied to the symphysis and the right body of the mandible. Von Mises and principal stresses were analyzed, and failure indexes were determined. Two cases of mandibular linear fractures were chosen for model verification and interpretation.

RESULTS

When force was applied to the symphysis, the condylar region exhibited the highest stress levels, while stress in the mandibular angle region was much less regardless of the M3 state. On applying the force to the right mandibular body, stress in the condylar region decreased while stress in the mandibular body increased, especially in the blown regions. Impacted tooth or cavity formation post-M3 extraction led to uneven stress distribution on the blown side of the mandible, increasing the risk of mandibular angle fractures. In cases where M3 was absent or the extraction socket had healed, stress from lateral traumatic blown force was evenly distributed along both the inner and outer oblique lines of the mandible, thereby reducing the risk of mandibular fractures.

CONCLUSIONS

The reduced risk of condylar fractures in patients with partially impacted lower M3s and mandibular angle fractures is mainly due to lateral blows on the mandible, which generate less stress in the condylar region than blows on the mandibular symphysis, rather than being caused by the M3 itself. Extraction of the lower M3 can decrease the risk of mandibular fractures, with a minor influence on condylar fractures.

Removal of Horizontally Impacted Mandibular Third Molars Using the Three-Piece or T-Shaped Tooth Sectioning Method

BACKGROUND

The extraction of horizontally impacted mandibular third molars (HM3) can be a complicated surgery. Appropriate tooth sectioning methods can reduce the operation time and postoperative complications.

PURPOSE

The current study compares operative time and postoperative pain between HM3 removed using the three-piece or T-shaped tooth sectioning techniques.

STUDY DESIGN, SETTING, SAMPLE

A randomized single-blind prospective clinical trial on HM3 extraction was carried out between June and December 2022 in the Department of Oral and Maxillofacial Surgery, the Affiliated Stomatological Hospital, Southwest Medical University. Patients with local or systemic infection, poor oral hygiene, and systemic disease were excluded.

PREDICTOR VARIABLE

The predictor variable was the tooth sectioning method. The subjects were randomized to a three-piece or T-shaped group.

MAIN OUTCOME VARIABLE(S)

The primary outcome variables were the operative time and postoperative pain measured using a visual analog scale (VAS). The secondary outcome variables were the rates of primary bleeding, mouth opening reduction, swelling, patient satisfaction measured using a VAS, and quality of life measured using a postoperative symptom severity scale.

COVARIATES

The covariates included age, sex, side and classification of HM3, and the relationship of HM3 to the inferior alveolar nerve canal.

ANALYSES

The data were analyzed using the independent samples t-test, paired t-test, χ2, and rank sum test. A significance level set at P < .05.

RESULTS

The sample included 60 patients in the three-piece group and 66 patients in the T-shaped group. The operative time of the three-piece group (14.73 ± 3.21 minutes) was shorter than that of the T-shaped group (19.25 ± 4.29 minutes) (P < .05). On days 3 and 7, VAS of pain were 2.24 ± 1.89 and 0.15 ± 0.40 in the three-piece group and 3.95 ± 2.44 and 0.48 ± 0.68 in the T-shaped group (P < .05). The VAS of patient satisfaction in the three-piece group (6.05 ± 1.29) was better than the T-shaped group (4.90 ± 1.05) on day 7 (P < .05).

CONCLUSION AND RELEVANCE

The three-piece tooth sectioning for HM3 removal was associated with shorter duration, slighter postoperative symptoms, and higher patient satisfaction and may be considered as a recommended practice for dentists.

Association of indications for mandibular third molar coronectomy and the Pell and Gregory and the Winter classification systems

PURPOSE

The purpose of this study was to determine how the surgeon's decision to perform a mandibular third molar coronectomy or surgical removal is associated with the impaction pattern as classified using Pell and Gregory or Winter's system.

METHODS

This observational, cross-sectional study was conducted on 813 mandibular third molars belonging to 565 patients. All patients were referred for removal of the mandibular third molar and had radiographic signs indicating a close relationship with the inferior alveolar nerve. Panoramic images were classified according to the impaction pattern.

RESULTS

A coronectomy was performed on 492 (60.5%) mandibular third molars. Most impacted mandibular third molars were class IIB with a mesioangular inclination. A significant association was found between the Pell and Gregory classification and the surgeon's choice (p = 0.002). Winter's classification was not significantly associated with surgeon choice (p = 0.425).

CONCLUSION

Mandibular third molar coronectomy is chosen more frequently than surgical removal if molars are class III and position B.

TRIAL REGISTRATION NUMBER

Not applicable.

Evaluation of anatomical relationships in the mandibular third molar region based on its angulation and depth of impaction: a CBCT-based study

PURPOSE

The aim of this study is to evaluate the relationship between the inclination/impaction depth and root proximity to the inferior alveolar canal/lingual plate on a millimeter scale using CBCT scans.

METHODS

340 CBCT scans of the mandibular third molar (M3) of 219 patients were evaluated for this cross-sectional study. After adjustment of the 3D orientation of the individual's jaws, the study variables including the angulation between M3 and second molar (M2)/occlusal plane (OP), and the distance of mesial (M)/distal (D) roots of M3 from the inferior alveolar canal (IAC) and lingual plate (LP) were measured. Winter's classification was used for the specification of teeth angulation. The vertical position of each M3 was then evaluated using the 3D view window (based on Pell & Gregory classification). The Spearman correlation coefficient was used for reporting the correlation between quantitative variables. The One-way ANOVA test and the Welch analysis were used for inter-group comparisons. Finally, a multivariant analysis of variances was performed.

RESULTS

Most third molars had a mesioangular inclination (52.1%), and vertical inclination (25.9%) was in second place. There was no significant correlation between angulation and age or the D/LP. A strong positive correlation between M3:M2 and M3:OP was observed (0.983). Furthermore, there was a weak negative correlation between M/IAC or M/LP and angulation (- 0.16 and - 0.13, respectively). Concerning Winter's classification, the relationship between D/IAC and angulation was statistically significant (P = 0.003). Furthermore, teeth in position A had lesser inclination compared to those with B or C positions. Multivariate analysis revealed that there was no statistically significant relationship between particular combinations of inclination-impaction depth and proximity of the M3 roots to the IAC or LP (P = 0.211).

CONCLUSIONS

The findings of the current study revealed that there is a strong correlation between M3:M2 and M3:OP. The D/IAC was the only variable that had a significant relationship with the angulation of these teeth. Moreover, the roots of horizontally inclined teeth with position A were the closest to the LP and the farthermost to the IAC.

Mandibular Canal Branching Assessed With Cone-Beam Computed Tomography

This study aimed to evaluate the prevalence and type of mandibular canal branching in a sample of the Iranian population through cone-beam computed tomography (CBCT) images. This cross-sectional study was performed on CBCT records of 300 patients (112 males and 188 females; mean age 30.14 ± 10.96 y). The presence of mandibular canal branch (MCB) was evaluated by reconstructing multiple panoramic views and buccolingual cross-sections, according to Naitoh's classification. The prevalence of MCB, the type of MCB, and the demographic information of all patients were recorded. The maximum number of branching and the maximum type of branching were also registered for each patient. Mandibular canal branching was observed in 131(43.7%) of 300 CBCT images without side or sex differences ( P > 0.05). The most frequent type was dental, followed by the retromolar, forward, and buccolingual types, respectively. There was a statistically higher frequency of retromolar canal in females than in males (odds ratio: 1.14 ± 4.25; P = 0.013). About 46% of patients with MCB had more than one accessory canal and 29% displayed more than one type of MCB. The coincidence of dental and retromolar canals in a patient was the most prevalent combination. Considering the relatively high prevalence of MCB (43.7%), it is recommended to keep in mind the possibility of anatomical variations of the inferior alveolar nerve during dental procedures to avoid postsurgical complications. The high possibility of observing multiple numbers and types of branching in the patients should also be considered during preoperative assessments.

Radiographic evaluation of mandibular third molars: an ex vivo comparative study between multilayer and conventional panoramic radiography

OBJECTIVES

To compare the multilayer panoramic radiography (MPAN) and conventional panoramic radiography (CPAN) in the evaluation of mandibular third molars using cone-beam computed tomography (CBCT) as a reference.

METHODS

CPAN, MPAN, and CBCT scans from 33 dry human mandibles were acquired using the OP300 Maxio unit, totalizing 56 mandibular third molars to be evaluated. Three examiners evaluated each third molar according to their position, depth of impaction in the mandibular ramus, proximity between the dental root apexes and the mandibular canal, and the presence of radiographic signs of proximity to the mandibular canal. In addition, when there was a distance between the root apexes and the mandibular canal, it was measured. As a reference, these same parameters were assessed in the CBCT scans by a fourth examiner. For the statistical analysis, the weighted Kappa, Bland Altman, and Wilcoxon tests were performed (α = 0.05).

RESULTS

The agreement between the assessments performed in the panoramic modalities with the CBCT ranged from 66.1% to 100.0% for the categorical variables. Overall, the agreement values of CPAN and MPAN with CBCT were similar. The distances between the dental root apex and the mandibular canal for both CPAN and MPAN were significantly underestimated compared to CBCT (p < 0.05). The intra- and interexaminer agreements of the examiners ranged from poor to almost perfect; in general, the agreements were higher in the evaluation performed in the MPAN than in the CPAN.

CONCLUSIONS

The MPAN performs similarly to CPAN for evaluating mandibular third molars and their proximity relationship to the mandibular canal.

CLINICAL RELEVANCE

Preoperative evaluation of lower mandibular third molars is usually performed using CPAN. Recently, a new tool, MPAN, was developed, which has not yet been tested for the evaluation of mandibular third molars and showed similar performance to CPAN in the present study. Future studies using MPAN are encouraged to evaluate other diagnostic tasks.

Assessment and Correlation of Variation in Lingual Cortical Plate Thickness with Different Angulations of Impacted Mandibular Third Molar Using Cone Beam Computed Tomography in North Indian Population

Purpose

The extraction of impacted mandibular third molar is associated with various types of intraoperative and postoperative complications, one of them is injury to lingual nerve. The present study aims to assess and correlate the variation in lingual cortical plate thickness with different angulations and determine the topographic relationship between the root apex of impacted mandibular third molar and lingual cortical plate using Cone Beam Computed Tomography (CBCT).

Methods

This prospective cohort study enrolled 140 patients with impacted mandibular third molars who underwent preoperative CBCT imaging. The CBCT images were used to evaluate the outcome variables such as lingual cortical plate thickness and topographical relationship between root apex of impacted mandibular third molar and lingual cortical plate. The predictor variables included age, gender, inclination of third molar, mesiodistal angle, buccolingual angle and lingual plate morphology.

Results

The temporary lingual nerve paresthesia was reported by 1 patient (0.71%) out of 140 patients. The lingual bone in distoangular and vertical impacted third molar was found to be 1.20 times thicker than mesioangular and horizontal teeth. Lingual bone thinning at mid-root level was observed in maximum number of cases with mesioangular teeth (68.5%), whereas horizontal impacted teeth showed lingual bone thinning (90.9%) at root apex level. The mean buccolingual angle of impacted mandibular third molar was found to be significantly associated with lingual bone perforation (p value = 0.0258). The morphology of lingual plate was observed as undercut type (37.14%) followed by slanted (36.43%), parallel (19.29%) and round type (7.14%).

Conclusion

Increase in buccolingual angle of impacted mandibular third molar decreases lingual bone thickness which is the natural barrier for protecting injury to lingual nerve. Also undercut and slanted lingual plate shapes were recognised as risk factors for contact/perforation between root apex and lingual plate. Therefore, proper screening and planning of high risk patients before third molar extraction is crucial.

Mandibular third molar extraction: perceived surgical difficulty in relation to professional training

BACKGROUND

Establishing the level of surgical difficulty pre-operatively is an essential step in ensuring correct treatment planning. This study set out to determine whether the knowledge and experience acquired by dentists who had received different levels of training influenced, firstly, the perceived levels of difficulty of a variety of cases of mandibular third molar (MTM) extraction and, secondly, the perceived difficulty deriving from a series of factors (patient-related factors, anatomical and radiographic factors, operative factors).

METHODS

This cross-sectional, descriptive, observational study took the form of a survey. Using a visual analog scale (VAS), participants evaluated both the perceived difficulty of 30 cases of MTM extraction described by means of digital panoramic radiographs and the perceived difficulty deriving from a series of factors conditioning MTM extraction. The results underwent statistical analysis with SPSS Statistics 28.0 software. Non-parametric tests (Mann Whitney test for independent samples and the Kruskal-Wallis test) were applied.

RESULTS

A total of 389 surveys were available for analysis. Dental practioners with no surgical training saw the intervention as presenting greater difficulty. Professionals with postgraduate training in oral surgery considered patient-related factors more important than operative factors, in contrast to dentists who had not received oral surgery training.

CONCLUSIONS

Dental training has a signficant influence on the perceived difficulty of MTM extraction and also affects opinions about which factors have greater or lesser influence on surgical difficulty.

Comparison between the Flapless Surgical Approach and a Novel Single Incision Access in Terms of Recovery Time and Comfort after Extraction of Impacted Inferior Third Molars: A Randomised, Blinded, Split-Mouth Controlled Clinical Trial

The recent attention to quality of life and oral health care procedures reflects a renewed 'patient-based' approach to dealing with non-life-threatening conditions. In the current study, we proposed a novel surgical approach to the extraction of impacted inferior third molars (iMs3) through a randomised, blinded, split-mouth controlled clinical trial following the CONSORT guidelines. The novel surgical procedure, hereinafter referred to as single incision access (SIA), will be compared with our previously described flapless surgical approach (FSA). The predictor variable was the novel SIA approach, involving access through a single incision without removal of soft tissue, on the impacted iMs3. The primary endpoint was the acceleration of the iMs3 extraction healing time. The secondary endpoints were the incidences of pain and oedema as well as gum health (pocket probing depth and attached gingiva). The study was carried out on 84 teeth of 42 patients with both iMs3 impacted. The cohort was composed of 42% Caucasian males and 58% Caucasian females, aged 23.8 ± 7.9 (17-49) years. We observed faster recovery/wound-healing on the SIA side (33.6 ± 4.3 days) than at the FSA side (42.1 ± 5.4 days; p < 0.05). The FSA approach confirmed the evidence previously detected concerning early post-surgery improvement in terms of attached gingiva and reduced oedema and pain, with respect to the traditional envelope flap. The novel SIA approach follows the early positive post-surgery FSA results.

Orthodontic treatment of substituting third molars for missing permanent molars

INTRODUCTION

This study aimed to evaluate the orthodontic effect and efficiency of substituting third molars for missing first or second permanent molars systematically.

METHODS

Forty-six patients (69 third molars total) with missing permanent molars replaced by third molars were selected. The angulation, crown-to-root ratio, and periodontal condition of the third molars before and after treatment were compared. The American Board of Orthodontics Objective Grading System was used to evaluate the alignment and occlusion of third molars after treatment. The duration of orthodontic treatment and third molar replacement therapy were also recorded.

RESULTS

The average orthodontic treatment time was 33.9 ± 5.6 months, and the average angulation change of third molars during treatment was 49.8 ± 29.8°. The average height of mesial alveolar bone increased by 4.8 ± 0.5 mm in patients whose third molars were mesially inclined or horizontally impacted. The root length of adult patients decreased by 0.72 ± 0.02 mm on average, and the average gingival recession was 0.10 mm, both of which were not statistically significant. The average score for each third molar evaluated by the American Board of Orthodontics Objective Grading System was 1.8 ± 0.5 points.

CONCLUSIONS

If the indications and timing of treatment were well-controlled, third molars would be excellent substitutes for missing first or second permanent molars through the orthodontic method.

The Radiological Evaluation of Mandibular Canal Related Variables in Mandibular Third Molar Region: a Retrospective Multicenter Study

OBJECTIVES

The aim of this retrospective study was to investigate anatomical structure of mandibular canal and the factors those increase the possibility of inferior alveolar nerve damage in mandibular third molar region of Turkish population.

MATERIAL AND METHODS

Overall 320 participants with 436 mandibular third molars were included from four different study centers. Following variables were measured: type and depth of third molar impaction, position of mandibular canal in relation to third molars, morphology of mandibular canal, cortication status of mandibular canal, possible contact between the third molars and mandibular canal, thickness and density of superior, buccal, and lingual mandibular canal wall, bucco-lingual and apico-coronal mandibular canal diameters on cone-beam computed tomography scans.

RESULTS

Lingual mandibular canal wall density and thickness were decreased significantly as the impaction depth of mandibular third molar was increased (P = 0.045, P = 0.001 respectively). Highest buccal mandibular canal wall density and thickness were observed in lingual position of mandibular canal in relation to mandibular third molar (P = 0.021, P = 0.034 respectively). Mandibular canal with oval/round morphology had higher apico-coronal diameter in comparison to tear drop and dumbbell morphologies (P = 0.018). Additionally, mandibular canals with observed cortication border and no contact with mandibular third molar had denser and thicker lingual mandibular canal wall (P = 0.003, P = 0.001 respectively).

CONCLUSIONS

Buccal and lingual mandibular canal wall density, thickness and mandibular canal diameter may be related with high-risk indicators of inferior alveolar nerve injury.

[Frequency of retained third molars in relation to facial biotype. a cross-sectional study]

Objective

This study aims to determine the frequency of retained third molars in relation to facial biotype, the data were collected by using the patients' 2D studies (panoramic and cephalometric) attending the imaging center ZETA-EXMED in the period November 2018 to December 2021, in the city of Lima, Peru.

Methods

The type of study used for this research are observational, descriptive, cross-sectional, and retrospective. For the present study, 6000 cases were evaluated, each case consists of one panoramic radiographic image and one cephalometric image, both taken to the patient on the same date, of these, only 150 cases that met the selection criteria were included in this study. Measurements about frequency of retained third molars in relation to facial biotype were done by a trained and calibrated researcher, using NemoCeph software for the cephalometric tracing. The statistical analysis was done using SPSS program version 1.0.0.1401 (SPSS Inc., USA) and the Chi square test (p <0.05).

Results

Of the 150 cases observed, 91 were women (60.66%) and 59 were men (39.33%). According to the results, dolichofacial biotype had the highest frequency among males with a total of 27 cases (45.80%), while the brachyfacial biotype was more prevalent among females, with a total of 35 cases (38.50%). In addition, out of the total number of retained third molars evaluated (403 pieces), 141 were present in cases with dolichofacial biotype, followed by the mesofacial biotype with 139 pieces and finally the brachyfacial biotype with 123 pieces. Regarding the evaluation of retained third molars according to their position and facial biotype, 63 retained third molars were found in mesioangulated position and 28 retained third molars in dolichofacial / distoangular position, followed by 48 pieces in the vertical position in brachyfacial.

Conclusions

There is not significant association between the quantity of retained third molars and their positions, in relation to facial biotype, although there is a significant association between facial biotype and the patient's sex, so it was concluded that Dolichofacial biotype has the highest frequency in males, while the Brachyfacial biotype is seen more frequently among females.

Effect of antibiotic prophylaxis for preventing infectious complications following impacted mandibular third molar surgery. A randomized controlled trial

Background

The objective of this study was to determine the effect of antibiotic prophylaxis in preventing postoperative infections after extraction of impacted mandibular third molars.

Material and Methods

A Parallel-group, randomized, blind, placebo-controlled trial was performed. 154 patients were randomly allocated to 2 groups; experimental (n=77) receiving 2g amoxicillin 1 hour prior to surgery and control (n=77) receiving placebo. Primary outcome was postoperative infections and secondary outcome was the need for rescue analgesia.

Results

4.5% of patients developed postoperative infections, five patients of the control group (4 alveolar osteitis, 1 surgical site infection) and two of the experimental group (1 alveolar osteitis, 1 surgical site infection). Difference between groups was not statistically significant, RR=0.4 (95%CI 0.08-1.99, 𝘱=0.41) NNTB=26. Rescue analgesia intake was significantly higher in the control group (41 vs 18 patients of experimental group) RR=0.49 (95%CI 0.32-0.75, 𝘱<0.05) NNTB=3.

Conclusions

The use of 2g amoxicillin 1 hour before surgery was not effective in significantly reducing the risk of postoperative infections from impacted mandibular third molars extraction, when compared to placebo. Nevertheless, antibiotic prophylaxis was associated with a reduced need for rescue analgesia.

Key words:Antibiotic prophylaxis, third molar, tooth extraction, impacted tooth, dry socket, surgical wound infection, oral surgery.

Efficacy and Safety of Concentrated Growth Factor Fibrin on the Extraction of Mandibular Third Molars: A Prospective, Randomized, Double-Blind Controlled Clinical Study

PURPOSE

To investigate the efficacy and safety of concentrated growth factor fibrin (CGF) for the extraction of mandibular third molars.

PATIENTS AND METHODS

This was a randomized, double-blind, and controlled clinical study. Patients who underwent mandibular impacted tooth extraction were randomly divided into 2 groups. In the CGF group, the tooth extraction fossa was utilized to place CGF gel. In the control group, the fossa was filled with serum. The visual analogue scale (VAS), reductions in swelling and trismus, incidence of postoperative dry socket, distal periodontal depth and bone regeneration of the second molar, and bone density (BMD) of the extraction fossa at 24 weeks were evaluated.

RESULTS

One hundred eighteen patients were enrolled in this study. There was no significant difference in baseline clinical characteristics between the 2 groups. The pain score of the CGF group was significantly lower than that of the control group at 2, 24, and 48 hours after operation. There was no significant difference in the reduction in swelling or trismus between the 2 groups. There were no cases of dry socket in the CGF group and 3 cases of dry socket in the control group. The periodontal probing depth and bone regeneration of the second molar when the socket was implanted with CGF were better than those that healed naturally (P < .05). The bone mineral density of each group was significantly increased at 24 weeks but was significantly different between groups (P < .05).

CONCLUSION

CGF can effectively reduce reactive tooth extraction pain and help avoid dry sockets. It can promote periodontal tissue and bone healing in distal and extracted sockets.

Comparison of Submucosal With Intramuscular or Intravenous Administration of Dexamethasone for Third Molar Surgeries: A Systematic Review and Meta-Analysis

Objective: The study aimed to review evidence on the efficacy of submucosal (SM) administration vs. intravenous (IV) or intramuscular (IM) route of injections of dexamethasone for improving outcomes after mandibular third molar surgery. Methods: PubMed, Embase, CENTRAL, and Google Scholar were searched for randomized controlled trials (RCTs) up to 20th May 2021. Early (2-3 days) and late (7 days) outcomes were compared between SM vs. IV or IM dexamethasone. Quality of evidence was assessed based on GRADE. Results: Thirteen trials were included in the systematic review and 10 in the meta-analysis. Meta-analysis indicated a significant reduction in early pain with IV dexamethasone but no such difference for late pain compared to the SM group. There was no difference in early and late swelling scores between the SM and IV groups. Pooled analysis indicated no significant difference in early and late trismus between SM and IV groups. Comparing SM with IM dexamethasone, there was no significant difference in early and late pain scores. Swelling in the early and late postoperative periods was not significantly different between the two groups. There was no significant difference in early and late trismus between SM and IM groups. The quality of evidence was low for all outcomes. Conclusion: Low-quality evidence suggests that SM infiltration of dexamethasone results in similar outcomes as compared to IV or IM administration of the drug after third molar surgeries. Further high-quality RCTs are needed to corroborate the current conclusions.

The influence of flap design on patients' experiencing pain, swelling, and trismus after mandibular third molar surgery: a scoping systematic review

Third molar removal surgery usually comes accompanied by postoperative discomfort, which could be influenced by the surgical approach chosen. This scoping systematic review aimed at compiling the available evidence focused on the influence of flap design, including envelope flap (EF), triangular flap (TF), and modified triangular flap (MTF), on postoperative pain, swelling, and trismus, as primary outcome measures, and any result mentioning healing promotion or delay, as secondary outcome measure, after mandibular third molar extraction surgery. An electronic search, complemented by a manual search, of articles published from 1999 to 2020 was conducted in the Medline (PubMed), EMBASE and Web of Science databases including human randomized controlled trials, prospective, and retrospective studies with at least 15 patients. The risk of bias of the included studies was assessed either with the Cochrane's Risk of Bias tool or with the Newcastle-Ottawa scale. Every step of the review was performed independently and in duplicate. The initial electronic search recovered 2102 articles. After applying the inclusion criteria, 12 articles were included. For patient's perceived postoperative pain, TF and MTF frequently reported better results than EF. For swelling, the literature is divided, despite a trend favoring EF. For trismus, data showed that its occurrence is mostly associated with the duration of the surgery rather than with the chosen flap. For healing, the limited data is inconclusive. Finally, randomized studies showed a high risk of bias, whereas nonrandomized studies were mostly of good quality and low risk of bias. Although there was no clear consensus regarding the influence of different flap designs for third mandibular molar extraction on postoperative clinical morbidities; the surgeon's experience, estimated surgical difficulty, molar position and orientation, and surg ery duration should be considered when choosing among the different flap designs.

Flapless Surgical Approach to Extract Impacted Inferior Third Molars: A Retrospective Clinical Study

This study aimed to compare a flapless surgical approach (FSA) with a traditional envelope flap (traditional approach (TA)). Every patient was treated with two approaches: TA and FSA. The primary outcome variables were both the discomfort during the post-operative convalescence and the correct final recovery of the impacted area. The secondary outcome variable was the average duration of the surgery. Post-operative pain and oedema were recorded. The measurements of soft tissue interface toward the distobuccal edge of the second molar were taken by periodontal probe before surgery (baseline) and 8 weeks after surgery. Statistical software was used to evaluate the data; a p-value < 0.05 was considered statistically significant. Twenty-four teeth of 12 patients (six Caucasian males and six Caucasian females, aged 23 ± 4 (17-30) years) with both lower impacted third molars (Ms3) were analysed. Considering an alpha error 0.05 that sample size allows power from 0.80 to 0.90, depending on the variable evaluated. Concerning attached gingiva, oedema and pain, the linear mixed model resulted in a statistically significant difference between the TA and FSA (p = 0.003; p < 0.01; and p = 0.018, respectively). Conversely, the model did not show a difference (p = 0.322) if pocket probing depth was considered. The FSA procedure was faster (p < 0.05) than the TA procedure (17 min and 8 s (±6 s) vs. 28 min and 6 s (±4 s), respectively). The results suggest that the FSA could be a suitable option for improving the surgical removal of lower Ms3. However, additional randomized controlled trial studies are necessary to confirm the reliability of our procedure and to verify its suitability in more complex Ms3 classifications.

Specific oral and maxillofacial identifiers in panoramic radiographs used for human identification

Radiographically assisted dental identification is an important means for individual identification. Specific identifiers help to quickly filter some of the possible corresponding AM and PM images at the beginning. The study seeks specific oral and maxillofacial identifiers in panoramic radiographs. A total of 920 panoramic radiographs from 460 live patients were used. The most recent radiograph served as the surrogate post-mortem (PM) record of an unidentified person, and the earliest radiograph served as the ante-mortem (AM) record of the same person. We evaluated the following four groups of identifiers of the images: (1) dental morphology, tooth number, and position; (2) dental treatment and pathology; (3) morphological identifiers of the jaw; and (4) pathological identifiers of the jaw. The ratio of each identifier being identified simultaneously in the AM and PM databases was determined. Specific identifiers were defined as those that appeared at low frequency (ratio: 0%-0.250%). A total of 18 specific oral and maxillofacial identifiers were determined. The specific identifiers were a retained deciduous tooth (0.011%), S-shaped deflection of a tooth root (0.012%), distal deflection of tooth root (0.017%), inverted impaction (0.018%), malposition (0.038%), supernumerary teeth (0.061%), mesial deflection of tooth root (0.092%), microdontia (0.136%), buccal/lingual impaction (0.188%), cementoma (0.002%), hypercementosis (0.002%), continuous crown (0.004%), pulp calcification (0.023%), attrition (0.030%), residual root (0.106%), root resorption (0.137%), implant (0.156%), and osteomyelitis (0.002%). Identifiers of the teeth and jaw can be used for human identification, and dental identifiers are more specific than identifiers of jaw.

Positional Differences of the Mandibular Canal in Relation to Permanent Mandibular First Molars with Eruption Disturbances in Children

Eruption disturbances in permanent mandibular first molars (PM1s) are uncommon. This retrospective study aimed to investigate differences in the position of the mandibular canal in relation to PM1s, with or without, eruption disturbances. Panoramic and cross-sectional views were reconstructed from cone-beam computed tomography imaging of children with PM1 eruption disturbances. Distances from the most inferior margin of the mandible to the center of the mandibular canal (M-C) and from the outer margin of the lingual cortex to the center of the mandibular canal (L-C) were measured for normally erupted PM1s (normal group) and for PM1s with eruption disturbances (ED group) and compared using independent t-tests. The mean M-C was significantly shorter in the ED group (4.86 ± 1.07 mm) than in the normal group (6.56 ± 1.06 mm) (p < 0.05). The mean L-C was also significantly shorter in the ED group (2.74 ± 0.74 mm) than in the normal group (3.09 ± 0.71 mm) (p < 0.05). This study demonstrated that the mandibular canal tended to be positioned more inferiorly in relation to PM1s with eruption disturbances than normally erupted PM1s in children. Clinicians should be aware of this positional deviation when managing children with PM1 eruption disturbances.