Influence of the tooth section technique in alveolar nerve damage after surgery of impacted lower third molars

Research on a novel digital tooth sectioning guide system for tooth sectioning during mandibular third molar extraction: An in vitro study

OBJECTIVE

To construct a novel portable tooth sectioning guide to improve the accuracy of mandibular third molar extraction.

METHODS

First, 72 samples of an identical 3D-printed double-rooted mandibular third molar were obtained and used in 36 mandibular models. Three different models were constructed (class B vertical, mesial, and horizontal impaction). Then, we made the tooth sectioning guides. mimicking clinical tooth sectioning conditions, two dental surgeons with different levels of experience used both the digital guided technique and the traditional empirical technique during surgery. Accuracy indicators, including apical deviation and angle deviation, were analyzed and compared on postoperative cone-beam computed tomographic scanning and via image reconstruction. Descriptive statistical analyses were performed. A p-value of 0.05 indicated statistically significant differences among the groups.

RESULTS

Overall, the mean apical deviation of experienced/inexperienced operators using the conventional section technique was 1.120 mm (0.7 mm, 2.3 mm) and 1.54± 0.84 mm, respectively. Correspondingly, the mean apical deviation under the guided section technique was 0.28 mm (0.2 mm, 0.4 mm) and 0.32±0.16 mm, respectively. The mean angle deviations of experienced/inexperienced operators under the conventional section technique were 8.015° (3.5°, 10.5°) and 6.570° (5.5°, 14.9°). Correspondingly, the mean apical deviation using the guided section technique was 1.880° (0.4°, 2.9°) and 1.470° (0.7°, 3.1°), respectively. The conventional and guided techniques were significantly different (P < 0.001).

CONCLUSIONS

In the digital guide technique, sectioning is more predictable and accurate, and the success of the operation is achievable with different proficiencies among dental surgeons.

CLINICAL SIGNIFICANCE

This technique will not only reduce the difficulty of tooth extraction but also reduce the risk of damage to the surrounding soft and hard tissues, especially damage to the inferior alveolar nerve.

Do anatomical variations of the mandibular canal pose an increased risk of inferior alveolar nerve injury after third molar removal?

OBJECTIVES

The present study aimed to assess whether anatomical variations of the mandibular canal are associated with neurosensory disturbances of the inferior alveolar nerve (IAN) following mandibular third molar removal.

METHODS

Two observers compared the detection of third molar root-nerve relations and bifurcations of the mandibular canal on panoramic radiographs and CBCT images of 201 patients undergoing removal of 357 mandibular third molars. Potential neurosensory disturbances of the IAN were surveyed ten days after surgery. Fisher's Exact was performed to correlate presence of canal variations to postoperative neurosensory disturbances. Positive and negative predictive values (PPV, NPV) and likelihood ratios (LR + , LR-) were calculated.

RESULTS

Thirteen patients reported postoperative altered sensation of the lower lip, with 2 of them having mandibular canal bifurcations on the ipsilateral side of the injury. Fisher's Exact showed that the studied mandibular canal variations were not related to postoperative neurosensory disturbances. CBCT was superior in visualization of anatomical variations of the mandibular canal. Prevalence of bifurcations was 14% on CBCT and 7% on panoramic radiographs. In both imaging modalities and for all parameters, PPVs were low (0.04 - 0.06) and NPVs were high (0.92 - 0.98), with LR ranging around 1.

CONCLUSION

In the present study, the assessed mandibular canal variations had limited predictive value for IAN neurosensory disturbances following third molar removal.

CLINICAL RELEVANCE

While a close relation between the third molar and the mandibular canal remains a high risk factor, mandibular canal variations did not pose an increased risk of postoperative IAN injury after third molar removal.

CBCT Radiological Features as Predictors of Nerve Injuries in Third Molar Extractions: Multicenter Prospective Study on a Northeastern Italian Population

Background: Neurological alterations are one of the main complications occurring after the third molar extractions. The aim of this prospective multicenter cohort study was to find out Cone Beam Computed Tomography (CBCT) features and distribution of neurological complications in patients undergoing lower third molar surgery and to determine the radiological and patient-related factors that could be correlated to the occurrence of inferior alveolar and lingual nerves injury. Material and Methods: 378 patients who underwent lower third molar extraction from March 2018 to March 2019 were included. Clinical and radiological data were collected. CBCT features were recorded following Maglione et al. classification. Symptoms and characteristics of patients who experienced neurological alterations were evaluated. Results: 193 patients needed a second-level radiological exam (CBCT). In these patients, the most common feature was Maglione class 3: a higher frequency of apical or buccal mandibular canals in direct contact with the tooth was observed. 3.17% of the patients developed a neurological complication. Maglione class 4, increased age, and operative time were all positively correlated with neurological alterations. Conclusions: while the buccal or apical position of the mandibular canal was the more common findings, the lingual position was found to have a higher correlation with a negative outcome. Age and operative time were also found to be risk factors for developing nerve injury in the considered population.

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.

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.

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

OBJECTIVES

The root anatomy and position of mandibular third molars are important factors in assessing the level of difficulty of surgical removal procedures. In this light, this study aims to identify the most frequent position and the root anatomy of mandibular third molars.

METHODS

The study sample comprised 1205 mandibular third molars from 710 panoramic radiographs evaluated. Regarding the position, all of them were based on Pell and Gregory's and Winter's classifications. The root anatomy was classified according to the type and number of roots, as well as the presence of laceration, fusion, or divergence. Gender and the quadrant were also considered. Following an interexaminer analysis, a statistical analysis was performed using the Kappa test.

RESULTS

The results showed that the IA (40.3%) and mesioangular (53.8%) position was predominant in mandibular third molars. Regarding the anatomy, the most common were two roots (98.3%), of the conical simple type (88.9%), with absence of laceration (89.2%), divergence (84%), and fusion (80%).

CONCLUSION

The present study showed that the most prevalent mandibular third molar type in Brazilian patients was the IA and mesioangular position, with simple root anatomy. The result of this study can assist oral surgeons to better plan and assess the level of difficulty of surgical removal procedures.

Prevention of neurological injuries during mandibular third molar surgery: technical notes

Surgery to the mandibular third molar is common, and injuries to the inferior alveolar nerve and the lingual nerve are well-recognized complications of this procedure. The aim of these technical notes is to describe operative measures for reducing neurological complications during mandibular third molar surgery. The following procedure should be used to prevent damage to the inferior alveolar nerve: a well-designed mucoperiosteal flap, to obtain appropriate access to the surgical area; a conservative ostectomy on the distal and distal-lingual side; tooth sectioning, to facilitate its removal by decreasing the retention zones; tooth dislocation in the path of withdrawal imposed by the curvature of the root apex; and careful socket debridement, when the roots of the extracted tooth are in intimate contact with the mandibular canal. To prevent injury to the lingual nerve, it is important (I) to assess the integrity of the mandibular inner cortex and exclude the presence of fenestration, which could cause the dislocation of the tooth or its fragment into the sublingual or submandibular space; (II) to avoid inappropriate or excessive dislocation proceedings, in order to prevent lingual cortex fracture; (III) to perform horizontal mesial-distal crown sectioning of the lingually inclined tooth; (IV) to protect the lingual flap with a retractor showing the cortical ridge; and (V) to pass the suture not too apically and from the inner side in a buccal-lingual direction in the retromolar area.

Coronectomy; Good or Bad?

The removal of mandibular third molars can be complicated by injury to the inferior alveolar nerve (IAN). Coronectomy retains the tooth root; this method has been found to be preferable to extraction in the context of mandibular third molars. A failed coronectomy may cause mobilization of these roots, thereby requiring a subsequent extraction. Having undergone a previous coronectomy, extraction is then safer as the roots usually migrate away from the IAN. Computed tomography is more accurate than radiography when imaging mandibular third molars pre-operatively owing to its three-dimensional nature. Longer studies need to be conducted to evaluate the long term benefits of coronectomy. CPD/CLINICAL RELEVANCE: The removal of mandibular third molars can be complicated by the presence of the close lying inferior alveolar nerve. Coronectomy can be useful in this setting and therefore it is important to be aware of the pros and cons of this technique.

Influence of tooth sectioning technique and various risk factors in reducing the IAN injury following surgical removal of an impacted mandibular third molar

A prospective study on 100 patients presented with a mesioangular impacted mandibular third molar in close proximity to the inferior alveolar nerve canal (IANC) was done to evaluate the efficacy of tooth sectioning in reducing the incidence of inferior alveolar nerve (IAN) injury during their surgical removal. The patients were divided into two groups: group A, where tooth sectioning was not performed, and group B, where tooth sectioning was performed. Patients were recalled 7 days, 15 days, 30 days, 3 months, and 6 months postoperatively for evaluation of nerve injury and its recovery. A total of 13 patients suffered from nerve damage out of which 10 patients (10/50 or 20 %) belonged to group A and 3 patients (3/50 or 6 %) belonged to group B. All patients showed complete recovery from nerve damage within 6 months except 1 patient. The result of the study showed that tooth sectioning significantly reduces the incidence of nerve damage by 14 %. Deviation of the IANC, increased depth of the impacted tooth, intraoperative hemorrhage within socket/nerve exposure, and increased duration of procedure were found to be the significant risk factors associated with nerve injury.

Surgical techniques for the removal of mandibular wisdom teeth

BACKGROUND

The surgical removal of mandibular wisdom teeth is one of the most common operations undertaken in oral and maxillofacial surgery. The most common indication for surgery is infection about a partially erupted tooth that is impacted against bone or soft tissues. Other indications include unrestorable caries, pulpal and periapical pathology, fracture of the tooth and cyst development, amongst others. Most commonly the benefits of surgical removal of a wisdom tooth include alleviation of the symptoms and signs of pericoronitis and its potential consequences. However, surgery is frequently associated with postoperative pain, swelling and trismus. Less commonly complications include infection, including dry socket, trigeminal nerve injuries and rarely fracture of the mandible.

OBJECTIVES

To compare the relative benefits and risks of different techniques for undertaking various aspects or stages of the surgical extraction of mandibular wisdom teeth.

SEARCH METHODS

We searched the Cochrane Oral Health Group's Trials Register (to 21 March 2014), CENTRAL (The Cochrane Library 2014, Issue 1), MEDLINE (OVID) (1946 to 21 March 2014) and EMBASE (OVID) (1980 to 21 March 2014). We searched ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform for ongoing trials. There were no restrictions regarding language or date of publication in the electronic searches.

SELECTION CRITERIA

RCTs comparing surgical techniques for removal of mandibular wisdom teeth.

DATA COLLECTION AND ANALYSIS

Two review authors conducted assessment of relevance, risk of bias and data extraction. Study authors were contacted for additional information. RRs were used for dichotomous data and MDs for continuous data, unless the event rate was very low and Peto ORs were used. The pairing of the split-mouth studies was taken into account in the analysis for both dichotomous and continuous outcomes, and parallel group and split-mouth studies were combined using the generic inverse variance method. Random-effects models were used provided there were more than three studies (fixed-effect models otherwise).

MAIN RESULTS

A total of 35 trials (2569 patients) were included. The interventions under consideration fell into seven broad categories, with many comparisons including only a small number of trials. Twenty-one of the trials were assessed at high risk of bias, the remaining 14 as unclear. The results are described in the summary of findings tables.Triangular flaps were associated with a 71% reduction in alveolar osteitis at one week (RR 0.29, 95% CI 0.11 to 0.78; three trials, moderate quality) and reduction in pain at 24 hours (MD -0.21, 95% CI -0.32 to -0.10; two trials, moderate quality) compared with envelope flaps. There was no evidence of a difference in overall infection rates, in maximum mouth opening or in permanent sensation. However, there was some evidence that residual swelling after one week was slightly increased in the triangular flap groups compared to envelope flap types (MD 0.66 mm, 95% CI 0.26 to 1.07; two trials, low quality). We found no data on temporary sensation, or adverse events.There was low quality evidence from two studies, looking at the use of a retractor during third molar surgery, to indicate more cases of temporary altered sensation (up to one month) when a retractor was used (Peto OR 5.19, 95% CI 1.38 to 19.49; two trials, low quality). One study reported that this did not persist for more than six months in either group. We found no data for use of a retractor on other primary outcomes or adverse effects (including fracture of the mandible).Due to the small number of studies, the different comparisons evaluated, the variable outcomes reported and the paucity of useful data for all primary outcomes we were not able to draw any conclusions concerning bone removal in third molar surgery.There was insufficient evidence from single studies of very low quality on irrigation method (manual versus mechanical) or irrigation volume (low or high) to determine whether there were differences or not for the outcomes of alveolar osteitis or postoperative infection. We found no data for any of the other primary outcomes.There was insufficient evidence (low to very low quality) that any wound closure technique (primary versus secondary) was superior to another for the outcomes of alveolar osteitis, postoperative infection or maximum mouth opening achieved after seven days, or reactionary bleeding. There was evidence that secondary wound closure was associated with reduced pain at 24 hours (MD 0.79, 95% CI 0.35 to 1.24; four trials, moderate quality) and slightly reduced swelling after one week (MD 0.33, 95% CI 0.09 to 0.57; seven trials, moderate quality).We found no data on other primary outcomes.There was some evidence that the use of a surgical drain was associated with less postoperative swelling (MD -0.90, 95% CI -1.62 to -0.19; five trials, moderate quality) and greater maximum mouth opening one week after surgery (MD 3.72 mm, 95% CI 2.84 to 4.59; two trials, moderate quality). There was insufficient evidence from a single study (low quality) to determine whether the presence of a drain made any difference to pain at 24 hours postoperation. There were no data for the other primary outcomes.Although two RCTs compared coronectomy with complete extraction, flaws in the design and the unit of analysis of these studies meant that there were no reliable data available for inclusion.

AUTHORS' CONCLUSIONS

The thirty-five included trials looked at a range of different surgical techniques. The comparisons related to seven broad aspects of the surgical procedures for impacted mandibular third molars: type of surgical flap raised, use of retractors, techniques for bone removal, wound irrigation, wound closure, wound drainage, and complete/incomplete tooth removal. The quality of the body of evidence for each of these comparisons was very low to moderate due to the small number of trials and patients, and the majority of the trials being at high risk of bias (65%) with the remainder at unclear risk of bias.The evidence for making changes to surgical practice is therefore limited. However, it is useful to describe the state of the research evidence supporting practice so that surgeons can make an informed choice in adopting new techniques, or continuing with established techniques.

Removal of impacted mandibular third molars using an inward fragmentation technique (IFT) - Method and first results

PURPOSE

Conventional surgical extraction of impacted mandibular third molars (M3M) requires a lateral flap reflection in conjunction with lateral bone removal for outward mobilization of the tooth. The aim of this report is to outline a novel inward fragmentation technique (IFT) in conjunction with an occlusal miniflap approach to reduce the amount of bone removal to a minimum.

PATIENTS AND METHODS

Seventeen consecutive patients (7 men and 10 women; mean age 24.4 years, range 18-36 years) required the extraction of 21-impacted M3M with a close relationship to the inferior alveolar nerve (IAN). Occlusal miniflaps were used and only occlusal bone removal was performed to expose the M3M under endoscopic vision. A central space-making cavity was created followed by inward fragmentation and mobilization of the crown and subsequent root removal through the space created.

RESULTS

20 of 21 sites healed uneventfully, one late infection was observed, no permanent neurosensory lesion occurred. The mean preoperative buccal bone height was 15.5 (11-18) mm and the postoperative buccal bone height 14.7 (11-17) mm. On the 2nd day, the mean swelling level was 1.38 (0-2) on a 4 point scale, the pain level was 2.30 (0-5) on a 10 cm VAS, mean pain duration was 2.04 days.

CONCLUSION

An inward fragmentation technique allows preservation of >90% of the buccal bone height adjacent to mandibular third molars and may reduce postoperative morbidity without raising the risk of IAN lesions.

Assessment of factors associated with surgical difficulty during removal of impacted lower third molars

PURPOSE

The aim of the present study was to adjust a multivariate model to explain each of the response variables for the occurrence of surgical difficulty during the removal of impacted lower third molars.

PATIENTS AND METHODS

A prospective cohort study was carried out involving patients submitted to at least one surgical removal of an impacted lower third molar. A total of 285 patients fulfilled the eligibility criteria and 473 surgeries were performed. Preoperative variables indicative of surgical difficulty were recorded. All surgical procedures were performed under the same conditions by two surgeons who were unaware of the data collected in the pre-selection phase. Either Pearson's chi-square test or Fisher's exact test was used for the data analysis (P<5.0%).

RESULTS

Root number (P((1)) < 0.004*) and morphology (P((1)) < 0.031*), tooth position (P((1)) = 0.001*), periodontal space (P((2)) < 0.004*) and second molar relation (P((1)) = 0.001*) were significant predictors of surgical difficulty, whereas patient age (P((1)) = 0.097), gender (P((1)) = 0.470), body mass index (P((1)) = 0.719), associated pathologies (P((1)) = 0.237), relation with mandibular canal (P((1)) = 0.384) and width of 3rd molar crown (P((1)) = 0.154) were not significant predictors.

CONCLUSION

Many factors contribute to surgical difficulty, but considering these factors individually, some are only determinants of either difficulty or complications. Thus, not all significant predictors of surgical difficulty should be considered indicators of complications.

Necessity of 3D visualization for the removal of lower wisdom teeth: required sample size to prove non-inferiority of panoramic radiography compared to CBCT

The availability of cone beam computed tomography (CBCT) and the numbers of CBCT scans rise constantly, increasing the radiation burden to the patient. A growing discussion is noticeable if a CBCT scan prior to the surgical removal of wisdom teeth may be indicated. We aimed to confirm non-inferiority with respect to damage of the inferior alveolar nerve in patients diagnosed by panoramic radiography compared to CBCT in a prospective randomized controlled multicentre trial. Sample size (number of required third molar removals) was calculated for the study and control groups as 183,474 comparing temporary and 649,036 comparing permanent neurosensory disturbances of the inferior alveolar nerve. Modifying parameter values resulted in sample sizes ranging from 39,584 to 245,724 respectively 140,024 to 869,250. To conduct a clinical study to prove a potential benefit from CBCT scans prior to surgical removal of lower wisdom teeth with respect to the most important parameter, i.e., nerval damage, is almost impossible due to the very large sample sizes required. This fact vice versa indicates that CBCT scans should only be performed in high risk wisdom tooth removals.

Paresthesias in dentistry

Alterations to normal oral sensory function can occur following restorative and surgical dental procedures. Paresthesia is defined as an abnormal sensation, such as burning, pricking, tickling, or tingling. Paresthesias are one of the more general groupings of nerve disorders known as neuropathies. This article reviews the extent of this oral complication as it relates to dental and surgical procedures, with specific emphasis on paresthesias associated with local anesthesia administration. This review establishes a working definition for paresthesia as it relates to surgical trauma and local anesthesia administration, describes the potential causes for paresthesia in dentistry, assesses the incidence of paresthesias associated with surgery and local anesthesia administration, addresses the strengths and weaknesses in research findings, and presents recommendations for the use of local anesthetics in clinical practice.

Risk factors associated with injury to the inferior alveolar and lingual nerves following third molar surgery-revisited

OBJECTIVE

Earlier reports, including a preliminary study within our unit, have shown that the surgeon's experience is one of the most influential factors in determining the likelihood of both permanent inferior alveolar nerve (IAN) and lingual nerve (LN) paresthesia, following third molar surgery. The effect of this and other factors influencing such prevalence are assessed in this study.

STUDY DESIGN

This prospective study involved 3236 patients who underwent surgical removal of impacted third molars. Patients' demographics and radiological parameters were recorded along with the grade of the treating surgeon. The prevalence of inferior alveolar and lingual nerves paresthesia at 1 month, 6 months, and 18 to 24 months postoperatively were also traced.

RESULTS

At 1 month postoperatively, the incidence of IAN paresthesia was 1.5% and the LN was 1.8%. These figures decreased over time and 18 to 24 months postoperatively, the incidence of permanent dysfunction of the IAN was 0.6% and LN was 1.1%. With regard to inferior alveolar nerve paresthesia, risk factors included the patient's age (26-30 years), horizontally impacted teeth, close radiographic proximity to the inferior alveolar canal (IAC), and treatment by trainee surgeons. With regard to the lingual nerve, risk factors included male patients, distoangular impactions, close radiographic proximity to the IAC, and treatment by trainee surgeons.

CONCLUSION

One of the main risk factors of developing permanent sensory dysfunction in the distribution of these nerves is related to the surgical skills/experience of the operator. Other factors are associated with the type of impaction and the radiographic proximity of the tooth to the inferior alveolar nerve. Such long-term complications can affect the patient's quality of life; the impact on profession, education, and research is unknown.