PROPHYLACTIC VS. SYMPTOMATIC THIRD MOLAR REMOVAL: EFFECTS ON PATIENT POSTOPERATIVE MORBIDITY

Automatic detection of the third molar and mandibular canal on panoramic radiographs based on deep learning

PURPOSE

This study aims to develop a deep learning framework for the automatic detection of the position relationship between the mandibular third molar (M3) and the mandibular canal (MC) on panoramic radiographs (PRs), to assist doctors in assessing and planning appropriate surgical interventions.

METHODS

Datasets D1 and D2 were obtained by collecting 253 PRs from a hospitals and 197 PRs from online platforms. The RPIFormer model proposed in this study was trained and validated on D1 to create a segmentation model. The CycleGAN model was trained and validated on both D1 and D2 to develop an image enhancement model. Ultimately, the segmentation and enhancement models were integrated with an object detection model to create a fully automated framework for M3 and MC detection in PRs. Experimental evaluation included calculating Dice coefficient, IoU, Recall, and Precision during the process.

RESULTS

The RPIFormer model proposed in this study achieved an average Dice coefficient of 92.56 % for segmenting M3 and MC, representing a 3.06 % improvement over the previous best study. The deep learning framework developed in this research enables automatic detection of M3 and MC in PRs without manual cropping, demonstrating superior detection accuracy and generalization capability.

CONCLUSION

The framework developed in this study can be applied to PRs captured in different hospitals without the need for model fine-tuning. This feature is significant for aiding doctors in accurately assessing the spatial relationship between M3 and MC, thereby determining the optimal treatment plan to ensure patients' oral health and surgical safety.

The Accuracy of Bone Assessment Distal to Lower Second Molars Using Panoramic Radiography: A Systematic Review and Meta-Analysis

Panoramic radiography (OPG) evaluates mandibular third molar impaction (MTMI). This systematic review aimed to investigate the diagnostic accuracy of OPG in detecting bone loss distal to the lower second molars. The associated bone loss with different impaction positions and the most prevalent positions of MTMI were investigated as secondary outcomes. In January 2023, PubMed, Scopus, and Cochrane were searched to identify studies published between January 2012 and January 2023. Two examiners blindly selected the eligible studies for data extraction and quality assessment. Of 427 studies, 8 were suitable for data extraction. All studies reported bone loss distal to the second molar using OPG, ranging from 4.9 to 62.9%. The most frequent position of MTMI is mesioangular. The distal bone loss in the vertical and horizontal positions is statistically significant compared to typically positioned third molars and those that are fully erupted or impacted, but in a normal orientation (p-value 0.005 and 0.02, respectively). Bone loss was not statistically significant in the mesioangular position compared to other impacted positions (p-value 0.14). The risk of bias ranges between 66 and 88%. Despite its limitations, OPG is still considered a valuable tool to assess bone loss distal to the lower second molar in cases of an impacted mandibular third molar.

Efficacy of Hydrocortisone, Povidone-Iodine, and Normal Saline as an Irrigating Solution During Surgical Removal of Impacted Mandibular Third Molars: A Randomized Controlled Trial

Background The surgical removal of mandibular third molars is one of the most common procedures in dentistry. Researchers have extensively studied the treatment of postoperative sequelae such as pain, edema, trismus, and alveolar osteitis throughout the past six decades. Many approaches have been used to address clinical difficulties after third molar surgery, including various flap designs and irrigating solutions. The aim of this study was to compare the effects of three irrigating solutions, hydrocortisone, povidone-iodine, and normal saline, on pain, trismus, and edema following surgical removal of the impacted mandibular third molar. Methodology The study involved 105 participants who required surgical extraction of mandibular third molars. The patients' ages ranged from 18 to 40 years, and they fulfilled the inclusion criteria. Using a simple random sampling technique, they were divided into three groups (group 1: hydrocortisone, group 2: povidone-iodine, group 3: normal saline). The parameters evaluated were edema, pain, and trismus on the second and seventh postoperative days. All data were input into Microsoft Excel (Microsoft® Corp., Redmond, USA) worksheets and analyzed using Stata 17.0 (StataCorp LLC, College Station, USA). The visual analog scale (VAS) score was used to measure postoperative pain, and postoperative swelling was measured using linear measurements from four fixed anatomical points and compared to preoperative values. To assess trismus, the inter-incisal distance was measured in millimeters with a caliper. A p-value of <0.01 was considered statistically significant. Results The mean VAS score for pain in group 1 was lower than the other two groups. The effect of group 1 was significant on the second postoperative day but insignificant on the seventh postoperative day for swelling. The effect of all three groups on trismus was significant on the second and seventh days. Conclusions Hydrocortisone as an irrigating solution showed promising results in managing postoperative swelling in the first 48 hours, but its effect gradually declined by the seventh postoperative day. Additionally, it was effective in controlling postoperative pain and trismus. This suggests that utilizing hydrocortisone as an irrigating solution, compared to povidone-iodine, has been proven to be a significantly effective option in reducing postoperative pain, edema, and trismus resulting from the surgical removal of impacted teeth.

A retrospective longitudinal assessment of artificial intelligence-assisted radiographic prediction of lower third molar eruption

Prediction of lower third molar eruption is crucial for its timely extraction. Therefore, the primary aim of this study was to investigate the prediction of lower third molar eruption and its uprighting with the assistance of an artificial intelligence (AI) tool. The secondary aim was identifying the incidence of fully erupted lower third molars with hygienic cleansability. In total, 771 patients having two panoramic radiographs were recruited, where the first radiograph was acquired at 8-15 years of age (T1) and the second acquisition was between 16 and 23 years (T2). The predictive model for third molar eruption could not be obtained as few teeth reached full eruption. However, uprighting model at T2 showed that in cases with sufficient retromolar space, an initial angulation of < 32° predicted uprighting. Full eruption was observed for 13.9% of the teeth, and only 1.7% showed hygienic cleansability. The predictions model of third molar uprighting could act as a valuable aid for guiding a clinician with the decision-making process of extracting third molars which fail to erupt in an upright fashion. In addition, a low incidence of fully erupted molars with hygienic cleansability suggest that a clinician might opt for prophylactic extraction.

Risk assessment of inferior alveolar nerve injury after wisdom tooth removal using 3D AI-driven models: A within-patient study

OBJECTIVE

To compare a three-dimensional (3D) artificial intelligence (AI)- driven model with panoramic radiography (PANO) and cone-beam computed tomography (CBCT) in assessing the risk of inferior alveolar nerve (IAN) injury after mandibular wisdom tooth (M3M) removal through a within-patient controlled trial.

METHODS

From a database of 6,010 patients undergoing M3M surgery, 25 patients met the inclusion criteria of bilateral M3M removal with postoperative unilateral IAN injury. In this within-patient controlled trial, preoperative PANO and CBCT images were available, while 3D-AI models of the mandibular canal and teeth were generated from the CBCT images using the Virtual Patient Creator AI platform (Relu BV, Leuven, Belgium). Five examiners, who were blinded to surgical outcomes, assessed the imaging modalities and assigned scores indicating the risk level of IAN injury (high, medium, or low risk). Sensitivity, specificity, and area under receiver operating curve (AUC) for IAN risk assessment were calculated for each imaging modality.

RESULTS

For IAN injury risk assessment after M3M removal, sensitivity was 0.87 for 3D-AI, 0.89 for CBCT versus 0.73 for PANO. Furthermore, the AUC and specificity values were 0.63 and 0.39 for 3D-AI, 0.58 and 0.28 for CBCT, and 0.57 and 0.41 for PANO, respectively. There was no statistically significant difference (p>0.05) among the imaging modalities for any diagnostic parameters.

CONCLUSION

This within-patient controlled trial study revealed that risk assessment for IAN injury after M3M removal was rather similar for 3D-AI, PANO, and CBCT, with a sensitivity for injury prediction reaching up to 0.87 for 3D-AI and 0.89 for CBCT.

CLINICAL SIGNIFICANCE

This within-patient trial is pioneering in exploring the application of 3D AI-driven models for assessing IAN injury risk after M3M removal. The present results indicate that AI-powered 3D models based on CBCT might facilitate IAN risk assessment of M3M removal.

Factors affecting number of third molars extracted in a single visit

OBJECTIVE

This cross-sectional study evaluated the number and characteristics of third molars extracted in a single visit in primary care and their associations with patient's age and sex and operator's experience.

MATERIALS AND METHODS

The data included all appointments where routine and surgical extractions of third molars were performed in 2016 in primary care of the City of Helsinki. Statistics included χ2 and Mann-Whitney U tests, and binomial logistic regression.

RESULTS

In total of 10,894 appointments, the number of extracted third molars was 12,728, yielding an average of 1.2 third molars per visit. Mean age of patients (55% women, 45% men) at extraction was 32.2 years (range 12 - 97 years). Most appointments (83.7%, n = 9,118) comprised extraction of one, 15.8% two, 0.4% three, and 0.1% four third molars. Number of teeth extracted at a time did not differ by sex. Increasing age was associated with a reduction in the likelihood of several third molar extractions in a visit (OR 0.96; 95% confidence interval (CI) 0.96-0.97). Multiple third molars were extracted significantly more likely if the operator was experienced (OR 2.32; 95%CI 1.90-2.84). Multiple extractions were also associated with the mandible, operative extractions, unerupted teeth and caries.

CONCLUSIONS

Third molars were typically extracted one at a time. In health care units, it is appropriate to consider extraction of several third molars in a single visit, if need for extraction of other third molars exist. Concentrating the extractions of younger patients on experienced operators would reduce the number of patients' visits.

Improvement of the Impacted Level of Lower Third Molars After Orthodontic Treatment

OBJECTIVES

The early or delayed surgical removal of an asymptomatic lower third molar (M3) in orthodontic patients remains controversial. This study aimed to determine the changes in the impacted level of M3 such as angulation, vertical position, and eruption space, after orthodontic treatment in 3 groups, namely non-extraction (NE), first premolar (P1) extraction, and second premolar (P2) extraction.

METHODS

Relevant angles and distances related to 334 M3s from 180 orthodontic patients were assessed pre- and posttreatment. Angle between lower second molar (M2) and M3 (M3-M2) was used for evaluating M3 angulation. For M3 vertical position, distances from occlusal plane to the highest cuspid (Cus-OP) and fissure (Fis-OP) of M3 were used. Distances from the distal surface of M2 to anterior border (J-DM2) and centre (Xi-DM2) of the ramus were used for assessing M3 eruption space. Pre- and posttreatment values of the angle and distance in each group were compared using a paired-sample t test. Measurements of the 3 groups were compared using analysis of variance. Hence, multiple linear regression (MLR) analysis was used to determine significant factors that impacted changes in M3s' related measurements. Independent factors used for MLR analysis included sex, treatment starting age, pretreatment respective angle/distance, and premolar extraction (NE/P1/P2).

RESULTS

M3 angulation, vertical position, and eruption space at posttreatment were significantly different from those at pretreatment in all 3 groups. MLR analysis showed that P2 extraction significantly improved M3 vertical position (P < .05) and eruption space (P < .001). P1 extraction significantly decreased Cus-OP (P = .014) and eruption space (P < .001). Treatment starting age was significant factor that affected Cus-OP (P = .001) and M3 eruption space (P < .001).

CONCLUSIONS

After orthodontic treatment, M3 angulation, vertical position, and eruption space changed in favour of the impacted level. These changes in the 3 groups were clearer in order: NE, P1, and P2, respectively.

The Association Between Skeletal Facial Types and Third Molars Impaction in a Saudi Arabian Subpopulation: A CBCT Study

Purpose

To assess the state of mandibular and maxillary third molars in relation to different facial types in a Saudi population using cone-beam computed tomography (CBCT) records.

Patients and Methods

A retrospective study was performed on CBCTs. Statistical analysis determined the relationship between impacted maxillary and mandibular third molars and different skeletal facial types. The degree of third molar impaction was evaluated.

Results

A total of 198 CBCTs from subjects were evaluated, with a mean age of 34.2 years. Archer II classification was found to be significantly associated with all skeletal profiles. The incidence of mesioangular impactions in lower third molar showed a notable increase in the brachyfacial group, which was statistically significant.

Conclusion

In conclusion, this study demonstrates that different facial types are associated with the angulation of third molar impactions.

Nd:YAG laser therapy on postoperative pain, swelling, and trismus after mandibular third molar surgery: a randomized double-blinded clinical study

This study aims to evaluate the effect of Nd:YAG laser therapy (NdLT) on postoperative pain, swelling, and trismus after mandibular third molar (M3) surgery. Three hundred patients were randomly divided into the Nd group (n = 100), medication group (n = 100), and Nd+medication (Nd+m) group (n = 100). The WHARFE classification system was used to assess surgical difficulty. After surgery, the Nd group was irradiated by the Nd:YAG laser in very long-pulsed mode (VLP, pulse duration 1 ms, 20 Hz, 4 W, R21-C3) in 6 regions of the extraction socket with a total energy of 300 J. For the medication group, dexamethasone 0.75 mg and loxoprofen 60 mg were prescribed immediately and every 12 h thereafter for 3 days. The Nd+m group received both treatments mentioned above. Pain assessment was performed at 6, 24, 48, and 72 h postoperatively using the visual analog scale (VAS). Swelling was evaluated by changes in the distance from (1) the tragus to the labial commissure, (2) the tragus to the pogonion, and (3) the mandibular angle to the lateral canthus preoperatively and 72 h postoperatively. Trismus was assessed by the change in maximum mouth opening. Groups Nd and Nd+m had lower VAS scores at 6 h, 24 h, and 48 h (F = 13.80, p = 0.00), but the difference between the two groups was not significant (F = 1.34, p = 0.11). However, no significant difference was observed at 72 h (p = 0.10). There was no significant difference in swelling or trismus among the three groups (p > 0.05). NdLT is an effective approach to improve complications after M3 surgery.

Third molar position after completion of orthodontic treatment: a prospective follow-up

OBJECTIVES

To prospectively follow up a previously reported sample, analyzing (1) changes in third molar (M3) position after completion of 2 different types of orthodontic treatment: (2) non-extraction treatment with (HG) vs without cervical headgear (non-HG) and (3) first or second premolar extractions (PM1-2) compared to a non-extraction group (NE).

METHODS

A total of 474 patients were prospectively followed up. Panoramic radiographs were taken pre- (T1), post-treatment (T2) and at follow-up (T3). T3 records (a mean of three years after treatment) were available for 135 (HG vs non-HG) and 134 patients (PM1-2 vs NE), respectively. Angulation, vertical position, relation with the mandibular canal and mineralization status of M3 at T2 and T3 were statistically compared.

RESULTS

The HG group presented more M3 with ideal vertical orientation at T3. In NE-cases, further improvement in angulation and orientation can be expected after debonding, as well as a deterioration in the relationship with the mandibular canal. Extractions accelerated upper M3 vertical eruption and PM2 extractions led to long-term larger lower retromolar spaces.

CONCLUSIONS

The use of cervical headgear increased upper M3 uprighting three years after debonding, while little changes in M3 position were found after orthodontic treatment with extractions. However, PM2 extractions led to larger retromolar spaces and better M3 angulation in the long term.

Positional assessment of lower third molar and mandibular canal using explainable artificial intelligence

OBJECTIVE

The aim of this study is to automatically assess the positional relationship between lower third molars (M3i) and the mandibular canal (MC) based on the panoramic radiograph(s) (PR(s)).

MATERIAL AND METHODS

A total of 1444 M3s were manually annotated and labeled on 863 PRs as a reference. A deep-learning approach, based on MobileNet-V2 combination with a skeletonization algorithm and a signed distance method, was trained and validated on 733 PRs with 1227 M3s to classify the positional relationship between M3i and MC into three categories. Subsequently, the trained algorithm was applied to a test set consisting of 130 PRs (217 M3s). Accuracy, precision, sensitivity, specificity, negative predictive value, and F1-score were calculated.

RESULTS

The proposed method achieved a weighted accuracy of 0.951, precision of 0.943, sensitivity of 0.941, specificity of 0.800, negative predictive value of 0.865 and an F1-score of 0.938.

CONCLUSION

AI-enhanced assessment of PRs can objectively, accurately, and reproducibly determine the positional relationship between M3i and MC.

CLINICAL SIGNIFICANCE

The use of such an explainable AI system can assist clinicians in the intuitive positional assessment of lower third molars and mandibular canals. Further research is required to automatically assess the risk of alveolar nerve injury on panoramic radiographs.

Fully Guided Tooth Bud Ablation in Pigs Results in Complete Tooth Bud Removal and Molar Agenesis

PURPOSE

Fully guided microwave tooth bud ablation has the potential to become a minimally invasive means for managing third molars in adolescent patients. If developed, this new modality could provide improved outcomes and reduced complications compared to traditional third molar management strategies. The purpose of this 28-day longitudinal characterization study was to determine if the healing response following fully guided microwave ablation of second molar tooth buds in juvenile pigs would result in the complete removal of targeted tooth bud tissues, molar agenesis, and no significant collateral tissue damage.

METHODS

Investigators performed fully guided microwave ablation on 24 mandibular second molar tooth buds (#18 and #31) in seven-week-old pigs. Postablation healing assessment consisted of radiographic and histological evaluation of 3 subcohorts (consisting of 4 animals each) at 7-, 14- and 28-days post ablation. Controls were untreated, opposing maxillary second molar tooth buds. Neurological assessment was performed to determine if there was any detectible loss of inferior alveolar nerve function.

RESULTS

Healing processes were nearly complete at 28 days post ablation. While one tooth bud was identified as partially ablated at 14 days post treatment, all treated tooth bud tissues were replaced with trabecular new bone formation by the end of this study. There was no detectible loss of inferior alveolar nerve function. The thermal dosing strategy used in this study appears to deliver prescribed ablation volumes and-within the context of this animal model-there was no detected collateral tissue damage.

CONCLUSIONS

The results of this study confirm the hypothesis that healing processes following fully guided tooth bud ablation resulted in removal of targeted tooth bud tissues, complete molar agenesis, and trabecular new bone growth at 28-days post treatment.

Surgical experience and patient morbidity after third molar removal

OBJECTIVES

The present study aimed to assess differences in patients' postoperative morbidity after third molar removal in relation to the surgeon's level of experience and other intraoperative factors.

MATERIAL AND METHODS

Patients admitted for prophylactic removal of asymptomatic third molars were prospectively followed up on day 3 and 10 after surgery in the context of the M3BE-study. Uni- and multivariable logistic regression was performed to assess the associations between surgeon's (in)experience and postoperative discomfort. Other contributing factors were gender, age, extraction method (osteotomy or not), and number of extractions and involved jaws.

RESULTS

In total, 7 senior surgeons and 28 surgical residents operated 2560 patients (8672 third molars). Differences in postoperative morbidity on day 3 and 10 after surgery were small. The results showed no significant associations between surgeon's inexperience and postoperative discomfort (pain, trismus, swelling), except for persistent pain (day 10; OR 1.468; p = 0.0016). No effect was observed on the occurrence of postoperative nerve complications. It was shown that postoperative morbidity was more dependent on factors like age, gender, number of extractions and intraoperative osteotomy.

CONCLUSION

We may conclude that patient recovery following third molar removal is affected by other factors than surgical experience. However, surgical residents seemed to cause significantly more persisting pain problems 10 days after surgery.