A randomised controlled clinical trial to compare the incidence of injury to the inferior alveolar nerve as a result of coronectomy and removal of mandibular third molars

Neurological Complications following Surgical Treatments of the Lower Molars

Aim

The current review aims to explore postoperative neurological complications in third molar extractive surgery.

Materials and Methods

The PRISMA protocols were followed when conducting this review. We found a total of 2,250 articles that matched our topic using the Boolean keywords, mandibular nerve complications AND oral surgery, from PubMed (1,083), Scopus (435), and Web of Science (732), with the filters of English language articles, time range January 1, 2003, to September 30, 2023, and human studies. After 762 duplicates were eliminated, there remained 1,488 articles. Eleven final articles were deemed of the highest relevance to our topic by eliminating articles in animals, non-English language, reviews, meta-analysis, and off-topic. A potential risk in the third molar extraction was temporary loss of sensibility often caused by mild compression or irritation of the mandibular nerve. This typically resolves within weeks or months, but in severe cases, recovery might take longer. Permanent loss of sensation can occur, indicating significant nerve damage and lasting effects on touch, temperature, or pain perception.

Conclusions

Various treatments exist for nerve damage, including low-level laser therapy, pain management medications, or physical therapy. While these therapies may improve neurosensory impairment, patients often report a decline in their quality of life.

The success rates and outcomes of mandibular third molar coronectomy: 167 cases

PURPOSE

The purpose of this study was to assess success rates and to report complications of coronectomy of mandibular third molars (M3M), including intra-operative failure, pain, infection, dry socket, inferior dental alveolar (IAN) and lingual nerve (LN) injuries and re-operation rates.

METHODS

Retrospective analysis of 167 coronectomies completed between January 2017 to December 2022 was undertaken.

RESULTS

The success of coronectomy was 93%. Intra-operative failure was reported to be 3.6% (n = 8). Complications accounted for pain (15%, n = 24), infection (9%, n = 15) and dry socket (3.6%, n = 6). Three patients required removal of M3M root at 3 months (n = 2) and 24 months (n = 1), accounting for 1.8% re-operation rate. A total of number of patients who suffered a nerve injury was 12; three of these were permanent (LN - 1.2%, n = 2; IAN - 0.6%, n = 1), nine were temporary (IAN - 1.2%; n = 2, LN - 2.4%; n = 4; site not specified - 1.8%, n = 3). No patients with intra-operative failure and re-operation suffered IAN or LN injury post-operatively.

CONCLUSION

Coronectomy offers a successful strategy for management of high risk M3M. The treatment outcomes can be improved with careful case selection and adjusting surgical technique, including assessment of root morphology, incomplete crown sectioning technique and avoidance of lingual retraction. Reporting of coronectomy success as a factor of surgical outcome, presence or absence of permanent IAN injury, persistent symptoms or any other long-standing complications (such as LN injury), and the need for re-operation accounting for root migration status may be a useful tool to measure coronectomy outcomes.

Effect of mineralized dentin matrix on the prognosis of bone defect and retained root after coronectomy

OBJECTIVE

To investigate the impact of mineralized dentin matrix (MDM) on the prognosis on bone regeneration and migration of retained roots after coronectomy.

MATERIALS AND METHODS

Patients were divided into three groups based on the type of bone graft after coronectomy: Group C (n = 20, collagen), Group T (n = 20, tricalcium phosphate (TCP) + collagen), and Group D (n = 20, MDM + collagen). CBCT scans, conducted immediately and 6 months after surgery, were analyzed using digital software. Primary outcomes, including changes in bone defect depth and retained root migration distance, were evaluated 6 months after surgery.

RESULTS

After 6 months, both Groups D and T exhibited greater reduction of the bone defect and lesser retained root migration than Group C (p < 0.001). Group D had greater regenerated bone volume in the distal 2 mm (73 mm3 vs. 57 mm3, p = 0.011) and lesser root migration (2.18 mm vs. 2.96 mm, p < 0.001) than Group T. The proportion of completely bone embedded retained roots was also greater in Group D than in Group C (70.0% vs. 42.1%, p = 0.003).

CONCLUSIONS

MDM is an appropriate graft material for improving bone defect healing and reducing retained root migration after coronectomy.

CLINICAL RELEVANCE

MDM is an autogenous material prepared chairside, which can significantly improve bone healing and reduce the risk of retained root re-eruption. MDM holds promise as a routine bone substitute material after M3M coronectomy.

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.

Outcomes of Coronectomy and Total Odontectomy of Impacted Mandibular Third Molars

OBJECTIVE

The aim of this research was to evaluate the surgical complications and neurosensory deficits after coronectomy and the complete removal of mandibular third molars.

METHODS

The study sample included patients requiring surgical removal of mandibular third molars. A coronectomy was conducted on 220 teeth showing signs of close proximity to the inferior alveolar canal. A complete extraction was performed on 218 teeth with no risk signs. The patients were evaluated at 1 week and 1, 3, 6, 12, and 24 months after surgery for pain, swelling, neurologic deficit, dry socket, postoperative bleeding, infection, root migration, and eruption.

RESULTS

No significant difference was noted in pain and swelling; however, bleeding and dry socket were significantly higher in the odontectomy group (P = .017). The inferior alveolar nerve deficit was higher in the odontectomy group (3.7%) than the coronectomy group (0.5%) (P = .017). The percentage and distance of root migration of coronectomised teeth at 3, 6, and 12 months were 60% (2.37 ± 0.96 mm), 66% (3.35 ± 0.86 mm), and 74% (3.85 ± 0.93 mm), respectively.

CONCLUSIONS

Coronectomy is a safe procedure and should be performed when the roots are closely associated with the mandibular canal. Although root migration is common, the likelihood of root exposure is low and roots rarely need removal.

Third Molar Coronectomy vs Total Removal in Second Molar Periodontal Healing

OBJECTIVES

The objective of this randomised controlled trial was to compare the periodontal healing at the distal of the adjacent second molar after coronectomy or surgical removal and the surgical morbidities of the 2 techniques.

METHODS

This is a pilot study of a split-mouth randomised clinical trial comparing the periodontal healing of the adjacent second molar after coronectomy or total removal of lower third molars, which was registered with the University of Hong Kong Clinical Trial Centre as HKUCTR-2948 on 21 February 2020. Cone beam computed tomography (CBCT) scans were taken preoperatively and at 6 months postoperatively. Changes in the bone level from the cemento-enamel junction, periodontal probing depth (PPD), and clinical attachment level (CAL) at the distal of the adjacent second molar were compared. Surgical morbidities in terms of pain, infection, neurologic deficit, root exposure, and need for second surgery for removal were assessed.

RESULTS

Forty patients (22 male, 18 female) with mean age of 26.7 years were evaluated at 6 months postoperatively. Both coronectomy and total removal groups demonstrated statistically significant reduction in PPD and CAL. There was an alveolar bone gain of 1.28 ± 0.88 mm in the coronectomy group and 1.13 ± 0.73mm in the control group, which was statistically significant (P < .001 for both groups).

CONCLUSIONS

Early findings show the periodontal healing at the adjacent second molar of coronectomy was as good as that of total removal of lower third molar. There were no differences in terms of surgical morbidities between both groups.

Benefits of Coronectomy in Lower Third Molar Surgery: A Systematic Review and Meta-analysis

PURPOSE

The purpose of this study was to measure and compare coronectomy versus extraction in patients at increased risk for inferior alveolar nerve (IAN) injuries associated with third molar removal in terms of IAN injury and other complications.

METHODS

The review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analyses checklist. We conducted a comprehensive literature search across six databases and the gray literature from July 15 to August 01, 2022. We employed Rayyan software to identify and remove duplicate articles to ensure data integrity. Our research followed the strategy patient (P), intervention (I), comparison (C), outcome (O), and study (S): (P) patients needing lower third molar surgery at higher risk of IAN injury; (I) surgery options, coronectomy or complete extraction; (C) comparisons included reduced risks of nerve injuries, postoperative complications (pain, infection, alveolitis), and increased risks of reoperation, root migration, and extraction; (O) desired outcomes were preventing nerve injuries and reducing other surgical complications; and (S) observational study designs (cohort, case-control). Excluded from consideration were studies involving teeth other than lower third molars, as well as reviews, letters, conference summaries, and personal opinions. To gauge the certainty of evidence, we employed the Grading of Recommendation, Assessment, Development, and Evaluation instrument, selecting the most current papers with the highest levels of evidence for inclusion. The primary outcome variable of our study centered on evaluating the incidence of IAN injury, and secondly, the lingual nerve (LN) injury, the postoperative pain, infection, localized alveolitis, the necessity for surgical reintervention, root migration, and extraction. These assessments were carried out with respect to their chosen operative technique for managing third molars, either coronectomy or extraction, as predictor variables. We also considered covariates such as age, gender, and the presence of systemic diseases in our analysis to account for potential confounding factors. The pooled data underwent rigorous analysis utilizing an inverse variance method with both random and fixed effect models by the "metabin" function in the R program's meta-package. Additionally, we assessed the risk of bias in the selected studies by utilizing the Joanna Briggs Institute's Critical Appraisal Checklist for Studies Reporting Prevalence Data and the Critical Appraisal Checklist for Case Reports.

RESULTS

Of the 1,017 articles found, after applying the inclusion and exclusion criteria, 42 were included in this study (29 cohort and 13 case-control studies), including 3,095 patients from 18 countries. The meta-analysis showed that coronectomy reduced the risk of IAN injury [OR (Odds Ratio): 0.14; 95% CI (confidence intervals): 0.06-0.30; I2 (inconsistency index) = 0%; P = .0001], postoperative pain (OR: 0.97; 95% CI: 0.33-2.86; I2 = 81%; P = .01), and alveolitis (OR: 0.38; 95% CI: 0.13-1.09; I2 = 32.2%; P = .01) when compared to complete tooth extraction. However, it also highlighted a greater risk of reintervention (OR: 5.38; 95% CI: 1.14-25.28; I2 = 0.0%; P = .01).

CONCLUSIONS

This study has demonstrated that coronectomy is associated with a decreased risk for IAN injury and decreased pain and localized alveolitis when compared to complete tooth extraction. However, it is essential to acknowledge the higher likelihood of requiring reintervention with coronectomy. Therefore, clinicians should carefully consider the advantages and potential drawbacks of both techniques and tailor their choices to the unique clinical circumstances of each patient.

miRNA contributes to neuropathic pains

Neuropathic pain (NP) is a kind of chronic pain caused by direct injury to the peripheral or central nervous system (CNS). microRNAs (miRNAs) are small noncoding RNAs that mostly interact with the 3 untranslated region of messenger RNAs (mRNAs) to regulate the expression of multiple genes. NP is characterized by changes in the expression of receptors and mediators, and there is evidence that miRNAs may contribute to some of these alterations. In this review, we aimed to fully comprehend the connection between NP and miRNA; and also, to establish a link between neurology, biology, and dentistry. Studies have shown that targeting miRNAs may be an effective therapeutic strategy for the treatment of chronic pain and potential target for the prevention of NP.

Association of Radiographic Signs in Determining the Proximity of Mandibular Third Molar Roots to the Mandibular Canal and Postoperative Occurrence of Neurosensory Disorders: A Cohort Study

BACKGROUND

The routine oral and maxillofacial procedure involving the surgical removal of impacted mandibular third molars comes with inherent risks to nearby anatomical structures. Proximity of mandibular third molar roots to the inferior alveolar nerve (IAN) poses a significant risk for injury, prompting the need for reliable assessment methods. Radiographic indicators, particularly those observed on intraoral periapical radiographs (IOPARs), offer a dependable means to evaluate proximity.

OBJECTIVES

This study seeks to examine the closeness between the mandibular canal and the roots of mandibular third molars using IOPARs and to assess the incidence of postoperative neurosensory disorders.

METHODS

A cohort of 100 subjects aged 18 to 25, presenting for partially erupted/ impacted mandibular third molar removal, underwent IOPAR examinations. Data analysis employed IBM SPSS Statistics for Windows, Version 12 (Released 2004; IBM Corp., Armonk, New York, United States), calculating frequencies, percentages, means, standard deviations, and ranges. Radiographic signs of proximity were evaluated, and a standardized surgical procedure was performed under local anesthesia. Postoperative neurosensory disorders were assessed using various methods.

RESULTS

Of the evaluated subjects, darkening of the root (52%) was the most prevalent radiographic sign, followed by interruption of the white line of the canal (20%). The prevalence of radiographic signs varied, with none of the patients experiencing narrowing of the root. Postsurgical paraesthesia assessment revealed no nerve sensitivity alterations in any patient.

CONCLUSION

Preoperative radiographic examination is imperative for determining the relationship between mandibular third molar roots and the inferior alveolar canal, aiding in preventing IAN damage during extraction. Contrary to radiographic signs, there was no observed association between impacted mandibular third molar radiographic signs and the occurrence of postoperative neurosensory disorders.

The effect of individual drilling sleeves on the precision of coronectomy tooth sections. An in vitro 3D-printed jaw model experiment

OBJECTIVES

The aim of this in vitro study was to evaluate the effect of a 3D-printed drill sleeve (DS) on the precision and duration of coronectomy sections.

MATERIALS AND METHODS

Thirty-six trainees and oral surgeons performed 72 coronectomy cuts in a 3D-printed, entirely symmetric mandible model. Coronectomy was performed freehand (FH) on one side and with a DS on the other side. The occurrence of "too superficial" (≥ 4 mm unprepared lingual tooth tissue) and "too deep" (drilling ≥ 1 mm deeper as tooth contour) cuts and sectioning times were registered.

RESULTS

In 7 cases, the sections were "too deep" with FH, while none with DS (OR: 18.56; 95%CI: 1.02-338.5; p = 0.048). The deviation between virtually planned and real cut depths was significantly greater in the FH group (1.91 ± 1.62 mm) than in DS group (1.21 ± 0.72 mm) (p < 0.001). A total of 18 "too superficial" buccolingual sections occurred with FH, while 8 cases with DS (OR: 3.50; 95%CI: 1.26-9.72; p = 0.016). Suboptimal sections did not correlate with experience (p = 0.983; p = 0.697). Shortest, suboptimal drillings were most frequently seen distolingually (OR: 6.76; 95% CI: 1.57-29.07; p = 0.01). In the inexperienced group, sectioning time was significantly longer with FH (158.95 ± 125.61 s vs. 106.92 ± 100.79 s; p = 0.038).

CONCLUSIONS

The DS effectively reduced tooth sectioning times by less experienced colleagues. Independently from the level of experience, the use of DS obviated the need for any preparation outside the lingual tooth contour and significantly decreased the occurrence of "too superficial" cuts, leaving thinner unprepared residual tooth tissue lingually.

CLINICAL RELEVANCE

Coronectomy sections may result in lingual hard and soft tissue injury with the possibility of damaging the lingual nerve. The precision of the buccolingual depth-control can be improved, while surgical time can be reduced when applying a drilling sleeve.

What is the Incidence of Late Complications Associated With Lower Third Molar Coronectomy? 10-Year Follow-Up Results

PURPOSE

Coronectomy is an operation to manage impacted third molars (M3s) considered at high risk for mandibular nerve injury but long-term outcomes are still lacking. The purpose of this study was to estimate the risk of late complications occurring within 10 years following lower M3 coronectomy.

METHODS

The investigators designed a prospective cohort study and enrolled a sample of 94 patients treated with coronectomy of third mandibular molars at the Unit of Oral and Maxillofacial Surgery of the University of Bologna, from 2009 to 2012. This follow-up study included all of the patients from the original study who completed 10 years of follow-up. The primary outcome variables is postoperative late complication occurring between 5 and 10 years after coronectomy coded as present or absent. Late complications were defined as root exposure, nerve injury, pulpitis, periapical infection, and reoperation. The secondary outcome variable was probing pocket depth. Covariates examined were age, smoking and type of M3 impaction. Descriptive statistical analyses were performed.

RESULTS

The inception cohort was composed of 94 subjects who had 116 coronectomies (k) completed. The study cohort was composed of subjects with 10 years of follow-up and included 48 subjects (k = 60) with a mean age of 28.99 ± 8.9 years. Between years 5 and 10 of follow-up, 2 subjects (4%) have complications; all root exposures diagnosed at years 8 or 9 after surgery. In another case root removal was required for orthodontics reason. No case of nerve injury to the inferior alveolar nerve occurred, and no periapical infection was observed around the residual roots. The mean 10-year probing pocket depth was 3.31 ± 0.92 mm (1,66-5,66 mm). There were too few complications to identify risk factors for late complications.

CONCLUSIONS

Within all the limitations of this study, the results of this prospective study imply that coronectomy is a useful surgical technique for the treatment of M3s at high neurological risk, to avoid nerve injury to the inferior alveolar nerve. In addition, after coronectomy, retained roots did not develop late infection or periapical infection in the long term. However, in a few cases, removal of retained roots was required at 10 years, due to root migration in the oral cavity. The risk for late complications is uncommon, but persistent.

Extraction of impacted mandibular third molars in close proximity to the inferior alveolar canal with coronectomy-miniscrew traction to avoid nerve injury

OBJECTIVES

Extraction of impacted mandibular third molars (IMTMs) is the most common surgery performed in the Department of Oral and Maxillofacial Surgery. Inferior alveolar nerve (IAN) injury is a rare but severe complication, and the risk is significantly higher in cases of IMTM near the inferior alveolar canal (IAC). The existing surgical method to extract such IMTMs is either not safe enough or is time-consuming. A better surgical design is needed.

MATERIALS AND METHODS

From August 2019 to June 2022, 23 patients underwent IMTM extraction by Dr. Zhao at Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Nanjing University, and were found to have IMTMs in close proximity to the IAC. Due to high IAN injury risk, these patients underwent coronectomy-miniscrew traction to extract their IMTMs.

RESULTS

The time between coronectomy-miniscrew insertion and complete removal of the IMTM was 32.65 ± 2.110 days, which was significantly shorter than that of traditional orthodontic traction. Two-point discrimination testing revealed no IAN injury, and no injury was reported by patients during follow-up. Other complications, such as severe swelling, severe bleeding, dry socket, and limited mouth opening, were not observed. Postoperative pain levels were not significantly higher in the coronectomy-miniscrew traction group than in the traditional IMTM extraction group.

CLINICAL RELEVANCE

For IMTMs that are in close proximity to the IAC and must be extracted, coronectomy-miniscrew traction is a novel approach to minimize the risk of IAN injury in a less time-consuming way with a lower possibility of complications.

Does the "Root Removal First" strategy prevent postoperative complications in the surgical removal of impacted mandibular third molars in the Pell and Gregory class C and horizontal position? - a randomized clinical trial

OBJECTIVE

To evaluate the clinical outcomes of the "Root Removal First" strategy in the surgical removal of impacted mandibular third molar (IMTM) in the class C and horizontal position.

MATERIALS AND METHODS

A total of 274 cases were finally included in the statistics. The positions of IMTM in the horizontal position were confirmed by cone-beam computed tomography (CBCT). Cases were randomly divided into two groups: the "Root Removal First" strategy was applied in the new method (NM) group, and the conventional "Crown Removal First" strategy was executed in the traditional method (TM) group. The clinical information and relevant data upon follow-up were recorded.

RESULTS

The duration of the surgical removal and the incidence rates of lower lip paresthesia in the NM group were significantly lower than those in the TM group. The degree of mobility of the adjacent mandibular second molar (M2) in the NM group was significantly lower than that in the TM group at 30 days and 3 months post-operation. The distal and buccal probing depth of the M2, as well as the exposed root length of M2 in the NM group, were significantly lower than those in the TM group 3 months post-operation.

CONCLUSIONS

The "Root Removal First" strategy can reduce the incidence rate of inferior alveolar nerve injury and periodontal complications of the M2 in the surgical removal of IMTM in class C and horizontal position with high efficiency.

TRIAL REGISTRATION

ChiCTR2000040063.

Early root migration after a mandibular third molar coronectomy

PURPOSE

This prospective cohort study aimed to assess early root migration after a coronectomy of the mandibular third molar at 2 and 6 months after surgery.

METHODS

We included all patients treated with a coronectomy of an impacted mandibular third molar. The primary outcome measure was the extent of postoperative root migration after 2 and 6 months. Migration was measured as the distance between the root complex and a fixed point on the inferior alveolar canal. The secondary aim was to identify factors (age, impaction pattern, and patient sex) that affected the extent of root migration.

RESULTS

One hundred and sixty-five coronectomies were performed in 141 patients (96 females and 45 males; mean age 33.1 years, SD 16.0). The 2-month checkup was completed by 121 patients that received 141 coronectomies. The 6-month check-up was completed by 73 patients that received 80 coronectomies. The mean root migrations were 3.30 mm (SD 2.53 mm) at 2 months and 5.27 mm (SD 3.14 mm) at 6 months. In the 2-6-month interval, the mean root migration was 2.58 mm (SD 2.07 mm). The extents of migration were similar during the 0-2-month interval and the 2-6-month interval (p = 0.529). Younger age was associated with greater root migration, and females experienced significantly greater migrations than males (p = 0.002).

CONCLUSION

Roots migrated more rapidly in the first two postoperative months, compared to the 2-6-month interval. Age was negatively correlated with the extent of root migration, and females showed significantly greater migrations than males.

Does the Tooth Sectioning Method Impact Surgical Removal of the Distoangular Impacted Mandibular Third Molar?

PURPOSE

Distoangular impacted teeth are considered challenging to remove due to their anatomic position. Proper tooth sectioning ensures the removal with minimal bone removal. This study aimed to compare the outcomes of 2 different tooth sectioning methods.

MATERIALS AND METHODS

Patients with distoangular-impacted mandibular third molar were included in this single-blinded randomized controlled trial. Patients with Class III-impacted, grossly decayed teeth and who were ASA III and above were excluded. The subjects were randomly allocated into Group-A conventional method, where tooth sectioning at the cementoenamel junction, and Group B, the modified method, where tooth sectioning removes only the distal portion of the crown. The primary predictor variable was the tooth sectioning method. The primary outcome variable was the operative time and the secondary outcomes included postoperative pain, trismus, and edema assessed on postoperative days 3 and 7. The effect of treatment on operative time was assessed using a t-test and Chi-squared test was used to compare the categorical data.

RESULTS

Thirty eight patients were included in this study. With a 1:1 allocation ratio, 18 (50%) patients were included in each group. No statistically significant differences were observed in the 2 groups for gender allocation (P = .32), age (P = .34), tooth classification (P = .97), and side of extraction (P = .32). The mean operative time was 31.61 ± 14.13 minutes for group A and 22.72 ± 10.79 minutes for group B, at the 95% confidence interval had a P value of .04 (P < .05), favoring group B. Secondary outcomes of pain measured by visual analogue scale 3.83 ± 3.06 for group A and 3.88 ± 3.06 for group B (P = .95), facial edema 22.79 ± 2.08 and 22.88 ± 1.32, respectively (P = .88), and the maximal interincisal opening of 33 ± 8.59 and 31.33 ± 7.42 on day 3 (P = .54) and 36.16 ± 11.62 and 39.05 ± 6.08 on day 7 (P = .36). However, the difference in need for rescue analgesia 2.05 ± 2.15 and 0.44 ± 0.85 (P < .01) was statistically significant, suggesting the superiority of the conventional sectioning method.

CONCLUSIONS

The results show that both methods of tooth sectioning yield comparably acceptable results. However, the tooth removal was faster by the modified sectioning and the need for rescue analgesia was minimal in this group, suggesting it to be a preferred technique over the conventional method.

Neurosensory Deficits of Inferior Alveolar Nerve Following Impacted Mandibular Third Molar Extraction: Comparison of One-Stage Complete Extraction with Two-Stage Partial Coronectomy Surgical Technique

Objectives

Inferior alveolar nerve neurosensory deficit is a worrisome complication of surgical extraction of impacted mandibular third molars. A novel approach using two-stage partial coronectomy has been proposed as an alternative surgical procedure to reduce this complication. This study compared neurosensory deficits of inferior alveolar nerve following impacted mandibular third molar extraction using one-stage complete extraction with the two-stage partial coronectomy technique.

Material and Methods

Subjects with mesioangular or horizontal impacted mandibular third molar with an intimate relationship with inferior dental canal who met the inclusion criteria were recruited for the study. Subjects were divided into one-stage and two-stage partial coronectomy techniques. The subjects were evaluated for the presence of inferior alveolar neurosensory deficit, and the relationships of neurosensory nerve deficit with sex, age and type of impaction.

Results

Neurosensory deficit was observed in 5 subjects (7.8%), with all cases seen in the one-stage group. This difference was statistically significant (p = 0.03). The relationship between the incidence of neurosensory deficit and age, sex, type of impaction, surgical difficulty, operating time and root morphology was not statistically significant (p > 0.05).

Conclusion

Findings from this study suggest partial coronectomy compared to one-stage complete extraction reduces the incidence of Inferior alveolar nerve neurosensory deficit.

Trigeminal Traumatic Neuroma: a Comprehensive Review of the Literature Based On a Rare Case

PURPOSE OF REVIEW

Traumatic neuromas in general, and trigeminal traumatic neuromas in particular, are relatively rare entities originating from a damage to a corresponding nerve or its branches. This manuscript is a comprehensive review of the literature on trigeminal traumatic neuromas based on an interesting and challenging case of bilateral intraoral lesions.

RECENT FINDINGS

The diagnosis for this patient was bilateral trigeminal traumatic neuromas. It is possible that these patients have a genetic predisposition to the development of these lesions. It is a neuropathic pain condition and may mimic dental and other trigeminal pain entities. Topical treatment with lidocaine gel, utilizing a custom-made neurosensory stent, rendered the patient significant and sustained pain relief. Trigeminal traumatic neuromas present a diagnostic challenge even to a seasoned clinician, due to the complex clinical features that may mimic other entities. Topical medications such as local anesthetics may be a good viable alternative to systemic medications to manage the pain associated with the condition. Early identification of the lesion and the associated pain helps in the succinct management of symptomatic trigeminal traumatic neuromas.

Evaluation of the Outcomes of Coronectomy Procedure versus Surgical Extraction of Lower Third Molars Which Have a High Risk for Inferior Alveolar Nerve Injury: A Systematic Review

Results

No study reported permanent inferior alveolar nerve injury (p-IANI) regarding coronectomy; however, transient inferior alveolar nerve injury (t-IANI) was reported in 0–2.20% of successful coronectomy and 0–8% of failed coronectomy. Postextraction t-IANI ranged from 0% to 16.66% while p-IANI from 0% to 3.63%. In 5 studies, root migration occurred in 2% to 85.3% of cases and the distance rate was 2.33–3.43 mm at 6 months postoperatively; then the migration gradually decreased and stopped at 12 months.

Conclusion

This systematic review revealed that coronectomy is an efficient alternative for the management of impacted 3rd M with a high risk of IANI. Patients who got antibiotics postcoronectomy procedures had lower infection rates than those who did not receive antibiotic therapy. We recommend further research on coronectomy with longer follow-up periods to assess the retained roots' long-term outcomes and to assess the effect of antibiotics administration on postcoronectomy infection rate. This systematic review is registered under number CRD42020198394.

Evaluating the presence of IAN injury in patients with juxta-apical radiolucency after third molar surgery: a retrospective cohort study

Background

Juxta-apical radiolucency (JAR) has been presented as a radiographic sign, suggestive of the IAN injury through third molar surgery. This study aimed to evaluate the relation of JAR with IAN injury in cone-beam computed tomography (CBCT) images and to determine whether the presence of JAR is related to tooth angulation, proximity to the mandibular canal, position to the IAN, and thinning of the cortical plates.

Methods

Of an initial sample of 545 mandibular third molars, a total of 75 JAR⁺ and 75 JAR⁻ teeth were evaluated by CBCT. We assessed the relationship between the presence of JAR in cone-beam computed tomography (CBCT) images and the presence of IAN injury after mandibular third molar surgeries. Moreover, we investigated whether the presence of IAN injury is related to tooth angulation, proximity to the mandibular canal, position to the IAN, and thinning of the cortical plates. Descriptive statistics, Chi-square test, and Fisher’s exact test were performed for statistical analysis.

Results

A significant relationship was found between JAR and temporary IAN injury (P = 0.036). However, there was no case of permanent IAN injury. IAN injury showed no significant relationship with the tooth angulation, position to IAN and proximity to the mandibular canal, lingual cortical plate thinning, sex, and age.

Conclusions

JAR is generally in contact with the mandibular canal, and some degree of cortical thinning can be found in most cases. In this study, JAR was significantly related to temporary IAN injury. JAR may increase the risk of nerve injury during the surgical removal of third molars.

Current thinking in lower third molar surgery

The removal of lower third molar teeth is one of the most common surgical procedures performed worldwide, but many concepts in this surgery have been unclear and have engendered different opinions. This paper aims to review current thinking in certain pertinent aspects of this surgery to update the reader on the most current research and synthesise it to make clinical recommendations. Topics covered include preoperative imaging, timing of removal, flap design, lingual retraction, coronectomy, lingual split, closure techniques, and use of antibiotics, steroids, and drains.

Does the Coronectomy a Feasible and Safe Procedure to Avoid the Inferior Alveolar Nerve Injury during Third Molars Extractions? A Systematic Review

This systematic review aimed to review the literature on the coronectomy technique and evaluate the incidence of success and complications as a surgical approach for inferior third molars. Online databases were searched for data on the frequency of inferior alveolar nerve damage, lingual nerve damage, root migration, pain, infection, dry socket, and extraction of the remaining root, and data on the necessity of reintervention were also extracted. Randomized clinical trials, controlled clinical trials, prospective cohort studies, and prospective and retrospective studies with or without the control group were intercepted. This systematic review was registered in PROSPERO (CDR 42020135485). Sixteen papers analyzed 2176 coronectomies in total, and only five of them were judged as appropriate according to methodological quality assessment. The incidence of inferior alveolar nerve injury was documented in 0.59% of the procedures, lingual nerve injury in 0.22%, infection 3.95%, dry socket 1.12%, extraction of the root 5.28%, and reintervention 1.13%. The pain was the most reported, in 22.04% of the population. This study provides an overview of the clinical success and complications of coronectomy, and their prevalence. A coronectomy may be considered a low-risk procedure and an option for treatment to avoid potential damage to nervous structures. However, patients should still undergo a full screening and evaluation of postsurgical procedures.

Is it possible to filter third molar cases with panoramic radiography in which roots surround the inferior alveolar canal? A comparison using cone-beam computed tomography

Inferior alveolar nerve (IAN) entrapment in third molar (M3) roots bears a significant risk for nerve injury. The aim of this study was to identify specific panoramic radiographic (PR) signs that can reliably identify IAN entrapment (IANE) root conformations. In a retrospective case-control study, 10 IANE and 218 non-IANE third molar risk cases were examined by PR and CBCT. The collected data included "classic" specific high-risk panoramic signs, number of M3 roots, extent of inferior alveolar canal (IAC)-root tip overlap, rotated position of M3 and impaction pattern. After bivariate analysis, sensitivity, specificity, positive and negative predictive values, positive likelihood ratios (LR+) and accuracy (area under the curve [AUC]) were calculated for the most significant predictive variables. Interruption of both cortical lines (LR⁺: 43.6; AUC: 96.0%) and upward diversion of the IAC (LR⁺: 36.3; AUC: 96.5%) were the most accurate single signs indicating IANE. Upward diversion combined with root darkening and interruption of the IAC (AUC: 97.4%) and the combination of darkening with interruption and with a rotated M3 (LR⁺:130.8; AUC: 97.8%) were the most accurate combinations predicting IANE. IANE may be correctly filtered with PR when focusing on the signs of upward diversion, darkening, interruption and rotated M3 position, especially in cases involving their multiple (≥3) presence. CBCT evaluation is highly recommended in these cases before partial and total tooth removals.

Factors affecting root migration after coronectomy of the mandibular third molar

Nerve injury especially inferior alveolar nerve (IAN) is the one of the complications that occur when the mandibular third molar (M3) is extracted and in case of high risk patients, coronectomy might be an alternative to tooth extraction. The purpose of this retrospective study was to analyze root migration and its influencing factors at 6 months after coronectomy in both 2- and 3-dimensions using periapical view and cone-beam computed tomography (CBCT). We analyzed 33 cases of root remnant after coronectomy and measured the amount of migration in CBCT. The following factors that could possibly affect root migration were also analyzed: age, gender, number of M3 roots, shape of M3s, Pell, and Gregory classification, mesiodistal (MD) angulation, buccolingual (BL) angulation, contact point with the second molar, root curvature, and complete removal of the coronal portion. Migration of greater than 2 mm was found in 64% of the roots in the 2-dimensional (2D) analysis, and the average root migration was 4.11 mm in the 3-dimensional (3D) analysis. The factors affecting migration were the root morphology, complete removal of the coronal portion, impaction depth, and MD angulation in the 2D analysis, and MD and BL angulation in the 3D analysis. Ensuring sufficient space for root migration especially considering angulation, depth and complete removal of the coronal portion might be important factors after coronectomy of the M3. Root remnant after coronectomy of M3 may migrate in young patients who has sufficient empty coronal space and this may reduce the nerve damage by the separation of IAN and M3.

Displacement of the Inferior Alveolar Bundle Secondary to Post Coronectomy Root Migration: A Case Report

Intentional coronectomy has become a commonplace procedure as an alternative to full third molar removal in order to decrease the occurrence of inferior alveolar nerve (IAN) injury. It is well known that one of the sequelae of this procedure is superior root migration. This is usually not a significant problem as the migrated roots may erupt to a position where they are more readily removed. This report presents a case in which a curvature at the apex of the root displaced the IAN causing neurologic symptoms.

Coronectomy of mandibular third molars: a systematic literature review and case studies

BACKGROUND

Extraction of mandibular third molars (M3M) close to the inferior alveolar nerve (IAN) has a higher risk of neurological disturbance. This review aims to evaluate the evidence supporting the use of the coronectomy technique compared to complete extraction for such M3Ms. Case studies by a specialist oral and maxillofacial surgeon are included to illustrate clinical practice.

METHODS

Three databases (Cochrane Library, Embase, PubMed) were searched (November 2020). Additional articles were sought by hand searching the reference list of included articles. All studies published in English comparing outcomes of coronectomy with complete extraction with at least 50 subjects and 6 months follow-up were included.

RESULTS

Of the six included studies, five reported a lower rate of IAN disturbance after coronectomy compared with complete extraction. There were no reported cases of lingual nerve disturbance. Other outcomes of coronectomy such as pain, infection, alveolar osteitis were either similar or lower compared to complete extraction. There were high rates of root migration but low rates of exposure and reoperation. Follow-up protocols varied considerably.

CONCLUSIONS

There is medium quality evidence to support the option of coronectomy for high risk M3M cases. Further studies to develop follow-up protocols to assist general dental practice is warranted.

Orthodontic Extrusion of Mandibular Third Molar With a Miniscrew and Cross-Arch Elastic

Sensory dysfunction is the most serious complication that occurs after extracting lower third molars in close proximity to the inferior alveolar nerve (IAN). Even experienced surgeons have difficulties in avoiding nerve damage when the root is anatomically adjacent to the nerve canal. A useful method for reducing nerve damage during extraction is to perform orthodontic extrusion, in which the distance between the nerve and the root increased after applying an orthodontic force on the third molar while extruding the tooth. Here, we report the case of a 37-year-old female who presented with a partially erupted left lower third molar and risk of IAN nerve damage because of close anatomical proximity between the nerve and root. She underwent extraction using a miniscrew placed in the maxilla and a routine orthodontic mechanism using a cross-arch elastic band that induced a 3-mm vertical eruption in the impacted third molar without using complex orthodontic devices. In addition, tilting the dental axis to the lingual side resolved the proximity between the IAN and the tooth, thereby allowing extraction to proceed without major complications.

Removal of Horizontally Impacted Mandibular Third Molars With Large Root Bifurcations Using a Modified Tooth Sectioning Method

PURPOSE

The purpose of this study was to introduce the method and first results of a modified tooth sectioning technique for the extraction of horizontally impacted mandibular third molars (M3Ms) with large root bifurcation.

PATIENTS AND METHODS

A total of 300 horizontally impacted M3Ms with large root bifurcation in medically healthy patients were included in this prospective study. Patients were divided into 2 groups: the modified method group (test group), in which the M3M was sectioned between the distal root and the remainder of the tooth at the point of root bifurcation; and the conventional method group (control group), in which the M3M was sectioned between the crown and the root at the cementoenamel junction. Operation duration, postoperative reactions, complications, and patient satisfaction were analyzed and compared between the 2 groups.

RESULTS

Each group included 150 M3Ms which were all successfully extracted. Operation durations in the test and control group were 10.48 ± 3.78 and 15.09 ± 4.24 minutes, respectively (P < .05). The test group had significantly better results than the control group with regard to postoperative reactions and complications (P < .05). Patients in the test group had higher satisfaction ratings regarding operation duration and the healing process than those in the control group (P < .05).

CONCLUSIONS

The modified method of tooth sectioning between the distal root and the remainder of the tooth can efficiently eliminate resistance from the bone and adjacent mandibular second molar and allow for just 1 sectioning of the M3M in most cases, which could make the operation straightforward and safe.

Coronectomy of Mandibular Third Molar: Four Years of Follow-Up of 130 Cases

Inferior wisdom teeth extraction surgery may have some complications that, in some cases, could be prevented by a correct diagnosis and minimal surgery. Coronectomy is a technique used for wisdom teeth surgery where only the crown is extracted and the root/roots are left in situ. This procedure may be controversial, but it could limit the common risks of the extraction procedure. Nowadays, the indication and contraindication of this technique are debated, and clinicians normally extract the entire tooth. The following case series includes the data and follow-up radiographs of 130 patients who received a coronectomy, reporting the safety of the procedure. After a mean follow-up period of four years, no complications occurred. A total of 13 patients showed mobile roots but had no complications or symptoms. The roots migrated in a mesial or coronal direction in 31 patients; in 4 cases, they were removed because of patient preference. Coronectomy is a useful oral surgical procedure in certain complicated cases of mandibular wisdom tooth extraction.

Alternative Approach to Prevent Inferior Alveolar Nerve Injury in Lower Third Molar Surgery: A Pilot Study on Coronectomy

Context:

Injury to inferior alveolar nerve (IAN) in lower third molar (L3M) surgery may lead to unpleasant sensation or anesthesia of lower lip. Considering the quality of life of the patient and the litigations faced by the dentist, alternative treatment approaches to odontectomy have been studied by various researchers. Coronectomy is one such option to prevent the nerve injury.

Aims:

The aim of this study was to assess the efficacy of coronectomy to reduce nerve injury during L3M surgery in high-risk cases as per radiological signs.

Settings and Design:

A pilot study was conducted in the oral surgery department of Rajah Muthiah Dental College, Annamalai Nagar, Chidambaram, India to evaluate coronectomy and its usefulness.

Materials and Methods:

Sixty-five patients who satisfied the inclusion and exclusion criteria for coronectomy were included in the study. The patients were followed up to 1-year period.

Statistical Analysis Used:

Descriptive statistics was used.

Results:

None of the patients in the study group had IAN impairment.

Conclusions:

Coronectomy is a safe alternative for complete odontectomy in high-risk L3M surgery cases. Root migration, infection, and need for second surgery are potential complication. Further studies with more samples and variables need to be performed.

Three-dimensional assessment of root migration and rotation patterns after coronectomy: bone-embedded roots versus soft tissue-covered roots

In this study, a three-dimensional evaluation was performed to explore differences between bone-embedded and soft tissue-covered roots after mandibular third molar (M3M) coronectomy. Patients were recruited according to the results of cone-beam computed tomography, 6 months after coronectomy. Completely bone-embedded M3Ms were assigned to group B, while completely soft tissue-covered M3Ms were assigned to group S. Data were recorded using digital software. A total of 213 M3Ms in 181 patients were investigated, of which 170 were assigned to the two study groups. Age was the primary factor influencing root migration (P<0.001). The smaller the degree of angulation of the M3M, the more likely was the root complex to rotate distally (r=-0.37, P<0.001). The depth of the impacted M3M contributed to the regeneration of new bone (P≤0.008). The length of the root complex (odds ratio 0.82, P=0.048) and distance from the root to the alveolar crest (odds ratio 1.23, P=0.026) were two critical factors influencing whether the root complex was bone-embedded. Ensuring that the length of the root complex is <7.6mm and the distance between the root and alveolar crest is ≥5mm were both found to be critical to the remaining root being completely bone-embedded and thus preventing eruption and the need for secondary surgery.

A systematic review of the complications of high-risk third molar removal and coronectomy: development of a decision tree model and preliminary health economic analysis to assist in treatment planning

Coronectomy is an alternative surgical technique for the management of high-risk third molars. It involves the removal of the crown of a tooth and the deliberate retention of the roots, thereby avoiding injury to the inferior alveolar nerve (IAN). Previous studies have suggested that it reduces the risk of nerve injury when compared with surgical extraction. The purpose of this study was to systematically review the incidence of complications following coronectomy such as IAN injury, pain, dry socket, infection, root migration, and need for re-operation. A comparative cost analysis of coronectomy and surgical extraction was done based on the results of the review. This provides an insight into the economic implications of the two procedures. A search through the MEDLINE database via Ovid, PubMed, Scopus, EMBASE via Ovid, and Web of Science, was carried out to extract randomised and non-randomised controlled trials. Four studies fulfilled the inclusion criteria. A meta-analysis was conducted to measure the overall effect of each outcome. The pooled odds ratio (OR) for IAN injury was 0.16 (95% CI 0.01 to 0.39). Coronectomy reduced this risk by 84%. Dry socket may occur less frequently following coronectomy whereas infection did not show a higher incidence with either intervention. Root migration was found to occur in 13%-85% of cases and the average incidence of re-operation was 2.2%. The ratio of the average costs was 1.12 favouring coronectomy if cone-beam computed tomography (CBCT) was not done prior to the procedure. If a scan was taken routinely for coronectomy, the cost ratio marginally favoured extraction. Coronectomy reduced the risk of nerve injury in high-risk third molars. Definitive conclusions, however, cannot be made for outcomes such as the need for re-operation, which may alter the cost ratio of coronectomy:extraction, as higher quality studies with longer follow-up are needed.

Surgical techniques for the removal of mandibular wisdom teeth

BACKGROUND

Pathology relating to mandibular wisdom teeth is a frequent presentation to oral and maxillofacial surgeons, and surgical removal of mandibular wisdom teeth is a common operation. The indications for surgical removal of these teeth are alleviation of local pain, swelling and trismus, and also the prevention of spread of infection that may occasionally threaten life. Surgery is commonly associated with short-term postoperative pain, swelling and trismus. Less frequently, infection, dry socket (alveolar osteitis) and trigeminal nerve injuries may occur. This review focuses on the optimal methods in order to improve patient experience and minimise postoperative morbidity.

OBJECTIVES

To compare the relative benefits and risks of different techniques for surgical removal of mandibular wisdom teeth.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health Trials Register (to 8 July 2019), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library; 2019, Issue 6), MEDLINE Ovid (1946 to 8 July 2019), and Embase Ovid (1980 to 8 July 2019). We searched ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform for ongoing trials. We placed no restrictions on the language or date of publication.

SELECTION CRITERIA

Randomised controlled trials comparing different surgical techniques for the removal of mandibular wisdom teeth.

DATA COLLECTION AND ANALYSIS

Three review authors were involved in assessing the relevance of identified studies, evaluated the risk of bias in included studies and extracted data. We used risk ratios (RRs) for dichotomous data in parallel-group trials (or Peto odds ratios if the event rate was low), odds ratios (ORs) for dichotomous data in cross-over or split-mouth studies, and mean differences (MDs) for continuous data. We took into account the pairing of the split-mouth studies in our analyses, and combined parallel-group and split-mouth studies using the generic inverse-variance method. We used the fixed-effect model for three studies or fewer, and random-effects model for more than three studies.

MAIN RESULTS

We included 62 trials with 4643 participants. Several of the trials excluded individuals who were not in excellent health. We assessed 33 of the studies (53%) as being at high risk of bias and 29 as unclear. We report results for our primary outcomes below. Comparisons of different suturing techniques and of drain versus no drain did not report any of our primary outcomes. No studies provided useable data for any of our primary outcomes in relation to coronectomy. There is insufficient evidence to determine whether envelope or triangular flap designs led to more alveolar osteitis (OR 0.33, 95% confidence interval (CI) 0.09 to 1.23; 5 studies; low-certainty evidence), wound infection (OR 0.29, 95% CI 0.04 to 2.06; 2 studies; low-certainty evidence), or permanent altered tongue sensation (Peto OR 4.48, 95% CI 0.07 to 286.49; 1 study; very low-certainty evidence). In terms of other adverse effects, two studies reported wound dehiscence at up to 30 days after surgery, but found no difference in risk between interventions. There is insufficient evidence to determine whether the use of a lingual retractor affected the risk of permanent altered sensation compared to not using one (Peto OR 0.14, 95% CI 0.00 to 6.82; 1 study; very low-certainty evidence). None of our other primary outcomes were reported by studies included in this comparison. There is insufficient evidence to determine whether lingual split with chisel is better than a surgical hand-piece for bone removal in terms of wound infection (OR 1.00, 95% CI 0.31 to 3.21; 1 study; very low-certainty evidence). Alveolar osteitis, permanent altered sensation, and other adverse effects were not reported. There is insufficient evidence to determine whether there is any difference in alveolar osteitis according to irrigation method (mechanical versus manual: RR 0.33, 95% CI 0.01 to 8.09; 1 study) or irrigation volume (high versus low; RR 0.52, 95% CI 0.27 to 1.02; 1 study), or whether there is any difference in postoperative infection according to irrigation method (mechanical versus manual: RR 0.50, 95% CI 0.05 to 5.43; 1 study) or irrigation volume (low versus high; RR 0.17, 95% CI 0.02 to 1.37; 1 study) (all very low-certainty evidence). These studies did not report permanent altered sensation and adverse effects. There is insufficient evidence to determine whether primary or secondary wound closure led to more alveolar osteitis (RR 0.99, 95% CI 0.41 to 2.40; 3 studies; low-certainty evidence), wound infection (RR 4.77, 95% CI 0.24 to 96.34; 1 study; very low-certainty evidence), or adverse effects (bleeding) (RR 0.41, 95% CI 0.11 to 1.47; 1 study; very low-certainty evidence). These studies did not report permanent sensation changes. Placing platelet rich plasma (PRP) or platelet rich fibrin (PRF) in sockets may reduce the incidence of alveolar osteitis (OR 0.39, 95% CI 0.22 to 0.67; 2 studies), but the evidence is of low certainty. Our other primary outcomes were not reported.

AUTHORS' CONCLUSIONS

In this 2020 update, we added 27 new studies to the original 35 in the 2014 review. Unfortunately, even with the addition of these studies, we have been unable to draw many meaningful conclusions. The small number of trials evaluating each comparison and reporting our primary outcomes, along with methodological biases in the included trials, means that the body of evidence for each of the nine comparisons evaluated is of low or very low certainty. Participant populations in the trials may not be representative of the general population, or even the population undergoing third molar surgery. Many trials excluded individuals who were not in good health, and several excluded those with active infection or who had deep impactions of their third molars. Consequently, we are unable to make firm recommendations to surgeons to inform their techniques for removal of mandibular third molars. The evidence is uncertain, though we note that there is some limited evidence that placing PRP or PRF in sockets may reduce the incidence of dry socket. The evidence provided in this review may be used as a guide for surgeons when selecting and refining their surgical techniques. Ongoing studies may allow us to provide more definitive conclusions in the future.

Bone regeneration at the distal aspect of the adjacent second molar after lower third molar coronectomy: a long-term analysis

A residual bone defect at the distal aspect of the adjacent second molar may occur after total removal of the lower third molar. Lower third molar coronectomy has been proved to be a safe alternative to total removal, but the extent of bone regeneration at the adjacent tooth after coronectomy is not well reported. The aim of this prospective study was to investigate the long-term bone regeneration at the distal aspect of the adjacent second molar after lower third molar coronectomy. Preoperative and postoperative cone beam computed tomography scans were measured to assess bone regeneration at the distobuccal (DB), mid-distal (MD), and distolingual (DL) aspects of the lower second molar. Forty-eight coronectomies in 37 patients (23 female) with a mean±standard deviation age of 29.1±7.2 years were assessed. The mean follow-up was 93.2±8.7 months. The mean bone level increase at DB, MD, and DL aspects was 3.2±1.6mm, 3.5±1.5mm, and 3.2±1.6mm, respectively; the bone levels were significantly higher than the preoperative measurements (P<0.001). Age and impaction patterns were not factors affecting bone regeneration. Based on this study, it appears that coronectomy of the lower third molar brings favourable bone regeneration at the distal aspect of the adjacent second molar.

Somatosensory changes in Chinese patients after coronectomy vs. total extraction of mandibular third molar: a prospective study

Objectives

This study aimed to quantitatively compare the somatosensory function changes of inferior alveolar nerve (IAN) after mandibular third molar extraction with a surgery protocol of coronectomy, as opposed to the conventional method.

Materials and methods

Patients with a lower third molar directly contacting IAN were recruited and assigned either to a test group (coronectomy group) or a control group (conventional extraction). A standardized quantitative sensory testing (QST) battery was performed for four times: one week before surgery and the second, seventh, and 28th days after surgery. Z-scores and the loss/gain coding system were applied for each participant.

Results

A total of 140 molars (test group: n = 91, control group: n = 49) were enrolled. The sensitivity of the mechanical detection threshold (MDT) and pressure pain threshold (PPT) significantly increased after surgery more than before surgery in both groups (P ≤ 0.001). After the surgery, the sensitivities of the cold detection threshold (CDT), cold pain threshold (CPT), and heat pain threshold (HPT) were significantly higher in the test group than in the control group (P ≤ 0.027). The risk of IANI was significantly larger (P = 0.041) in the test group than in the control group.

Conclusions

QST was a sensitive way to detect somatosensory abnormalities even with no subjective complaint caused by surgery. Coronectomy had less influence on IAN function than conventional total extraction.

Clinical relevance

The somatosensory function changes after mandibular third molar extraction were quantitatively studied, and coronectomy was proved a reliable alternation to reduce IAN injury rate.

Cone beam CT and treatment decision of mandibular third molars: removal vs. coronectomy-a 3-year audit

OBJECTIVES

To assess: (1) the workflow in the treatment decision process of mandibular third molars based on a panoramic image and CBCT and (2) the impact of radiographic markers in CBCT on the decision to perform coronectomy.

METHODS

1437 teeth in 917 patients (mean age 27.8 years, range 18-72) underwent clinical and panoramic examination. If there was an indication for removal of the tooth, and signs of a close relation to the inferior alveolar nerve were present in the panoramic image, a CBCT was performed. Treatment decision based on panoramic image and CBCT was calculated. Statistical analyses were performed to assess whether signs in CBCT had an impact on the treatment decision "coronectomy". Moreover, the actually operated teeth and post-operative sensory disturbances were assessed and discussed in relation to the radiographic method.

RESULTS

Based on the panoramic image, in 462 cases it was decided not to treat, 553 were scheduled for surgery, and 422 referred for a CBCT examination. "No bony separation between the tooth and mandibular canal" seen in CBCT was the main factor influencing the decision to perform a coronectomy (odds ratio = 56.8, p < 0.001). 840 mandibular third molars had undergone surgical intervention, 152 had a coronectomy and 688 were fully removed. Six patients perceived a sensory disturbance of the inferior alveolar nerve: one permanent and five temporary.

CONCLUSION

29% of the examined cases were referred for a CBCT and of these, the majority were scheduled for coronectomy based on the sign "no bony separation between the tooth and mandibular canal" seen in CBCT.

A retrospective cohort study on reasons to retain third molars

The primary goal of this study was to identify and quantify indications for retaining third molars. This retrospective cohort study included 1682 patients (818 male, 864 female; mean age 31 years) who were referred to the University Hospitals Leuven for third molar removal. Eight reasons for retaining the third molars were identified: (1) risk of damaging adjacent structures, (2) compromised health status, (3) adequate space for eruption, (4) third molar serves as abutment tooth, (5) orthodontic reasons, (6) eruption into proper occlusion, (7) symptomless third molars in patients >30 years old, and (8) patient preference. To compare these categories between sex and age groups, a generalized linear model for binary data was fitted with a logit link. A total of 1149 third molars in 548 patients were not extracted. The most frequent reasons for retaining third molar teeth were: eruption into proper occlusion (31.9%), patient preference (31.5%), and symptomless third molars in patients >30 years old (17.5%). Compromised health status and advanced age were often included in the decision regarding whether to retain the third molars. One third of the referred patients had reasons to retain one or more third molars. These findings might facilitate the future development of a consensus statement.

Coronectomy: a retrospective outcome study

PURPOSE

Inferior alveolar nerve (IAN) injury is reported as a complication following surgical removal of lower third molars. In cases where the IAN is intimately related to the roots of the tooth, coronectomy may be performed as an alternative. The objectives of this study were to record operative indications for coronectomy and assess the short- and long-term post-operative outcomes following coronectomy.

METHODS

This retrospective study included patients (19-95 years old) that had coronectomies carried out in the Edinburgh Dental Institute and Chalmers Dental Centre within the last 10 years. The patients were invited by letter to attend a review appointment. High-risk radiographic signs and short- (≤ 3 months) and long-term complications (> 3 months) were recorded.

RESULTS

A total of 124 patients were invited to participate and a total 28 patients returned for review. From the rest of the patients, data was extracted from their dental records. IAN injury was reported in 5 cases (4.3%) as a short-term complication and in 2 cases (3.5%) as a long-term complication. One patient presented with eruption of roots at the review appointment 7 years following surgery. In this study, 'very' long-term complications were recorded as the 28 patients that returned for a review, were seen on an average of 4.8 years post-operation.

CONCLUSIONS

Coronectomy is a relatively safe technique for preservation of the IAN. However, prospective large scale research is needed to more accurately report on the prevalence of short- and long-term complications.