Can adjunctive corticosteroid therapy improve patient-centered outcomes following third molar surgery? A systematic review.

BACKGROUND: Third molar surgery is frequently associated with postoperative discomfort such as pain, edema and trismus. We aimed to evaluate the current evidence on the efficacy of adjunctive corticosteroid therapy in improving patient-centered outcomes following third molar surgery. MATERIAL AND METHODS: This systematic review assessed and searched PubMed, Google scholar, Scopus, web of science, clinicaltrials.gov and Cochrane central for controlled trials, up to May 2021. The primary outcome measures were patient-centered outcomes such as quality of life following the use of adjunctive corticosteroid therapy in third molar removal. Only randomized controlled trials published in English language were included. RESULTS: A total of 355 studies were initially identified, and 12 studies were finally included. The results showed that both methylprednisolone and dexamethasone decreased postoperative side effects such as pain, trismus, and edema and consequently were improving patient reported outcomes. In this regard, none of the included papers reported any significant statistical difference between these two drugs (p > 0.05). The analysis regarding the route of administration for the corticosteroids showed that local and intravenous injection of dexamethasone had equivalent effects, and both methods showed better results as compared to simple oral administration. CONCLUSIONS: Adjunctive use of corticosteroid drugs may improve patient-centered outcomes following third molar surgery. However, there is no significant difference between drugs and routs of administration. Comparing various administration routs, local submucosal injection of dexamethasone seems to be a straightforward, painless and cost-effective adjunctive therapy.

Efficacy of a topical gel containing chitosan, chlorhexidine, allantoin and dexpanthenol for pain and inflammation control after third molar surgery: A randomized and placebo-controlled clinical trial.

BACKGROUND: The aim of this study was to evaluate and compare the postoperative effect of a topic gel containing chlorhexidine, chitosan, allantoine and dexpanthenol versus a placebo for pain and inflammation control after third molar surgery. MATERIAL AND METHODS: A gel combining 0.2% chlorhexdine, 0.5% chitosan, 5% dexpanthenol, 0.15% allantoin and 0.01% sodium saccharin was selected for this split mouth randomized controlled and double-blind trial including 36 patients with bilaterally and symmetrically impacted lower third molars. The teeth (n=72) were randomly divided into two groups before surgical removal: control group (CG; in which a placebo was given) and experimental group (EG). Swelling, trismus, postoperative pain, wound healing and complications were measured and recorded in order to evaluate differences between the placebo and experimental product. RESULTS: Five patients suffered from an alveolitis in the CG (13.9%), and none in the study group (0%), but no statistically significant difference was found (p=0.063). From day 0 to day 7, trismus and swelling were significantly less pronounced in the EG, and wound healing was considered 'good' in 22.2% for the CG and 97.2% for the EG (p<0.001). Mean VAS scores during the seven postoperative days were statistically lower in the study (2.56±1,19) compared to the placebo group (3.25±1.6) (p=0.002). The mean consumption of analgesic pills during the first 92 hours was also statistically lower in the EG (0.26±0.51) in comparison to the CG (0.56±0.67) (p=0.003). CONCLUSIONS: The use of an experimental gel containing chlorhexidine, chitosan, allantoine and dexpanthenol seems to significantly reduce postoperative pain, trismus and signs of inflammation. Future studies should further evaluate, if the gel is effective in dry socket preventing after third molar removal.

Medication-related osteonecrosis of the jaws (MRONJ) in cancer patients treated with denosumab VS. zoledronic acid: A systematic review and meta-analysis.

BACKGROUND: The aim of the present study was to analyse the incidence, risk ratio (RR) and prognoses of two types of medication-related osteonecrosis of the jaws (MRONJ): denosumab-related osteonecrosis of the jaws (DRONJ) and Bisphosphonate-Related Osteonecrosis of the Jaws (BRONJ) in cancer patients under treatment with denosumab or zoledronic acid (ZA). MATERIAL AND METHODS: An electronic and manual search was conducted for randomized controlled trials (RCTs) until May 2019. Assessment of the identified studies, risk of bias and data extraction were performed independently by two reviewers. The incidence of DRONJ and BRONJ and the RR to develop MRONJ were calculated at 1 year, 2 years and 3 years of exposure. It was also calculated the odds ratio (OR) of their respective prognoses. They were calculated normalizing the values of the individual studies to 1 year, 2 years or 3 years when necessary through robust regression models using a statistical program. RESULTS: From 1.277 references identified, 8 RCTs were included, which comprised a total of 13.857 patients with a variety of neoplasms. The incidence of DRONJ in cancer patients under treatment with denosumab ranged from 0.5 to 2.1% after 1 year, 1.1 to 3.0% after 2 years, and 1.3 to 3.2% after 3 years of exposure. The incidence of BRONJ in cancer patients under treatment with ZA ranged from 0.4 to 1.6% after 1 year of exposure, 0.8 to 2.1% after 2 years, and 1.0 to 2.3% after 3 years of exposure. Statistically significant differences were found between denosumab and ZA in the risk of developing MRONJ after 1, 2 and 3 years of exposure. Nevertheless, there were no significant differences in terms of patient prognosis. CONCLUSIONS: Denosumab is associated with a significantly higher risk of developing MRONJ compared to ZA. Nevertheless, no differences were found in its prognoses.

Determination of the occlusal vertical dimension in edentulous patients using lateral cephalograms.

The determination of the occlusal vertical dimension (OVD) in edentulous patients is based on clinical assessment with high variability. This study tested the hypothesis: The average OVD in edentulous patients with conventional dentures is too low compared to orthodontic norms, when only clinical parameters are used for the determination of the OVD. Edentulous patients with conventional full dentures were enrolled. Clinical parameters were judged by two senior prosthodontists. Digital lateral cephalograms were taken and served to calculate the OVD according to the lower face height angle (ANS-Xi-D) taking tooth-independent facial growth patterns into account. The ANS-Xi-D angle was compared with reference values by applying one-sample mean comparison tests. Thirty-six participants (17 female, 19 male; mean age 65.3 ± 10.6 years) were enrolled in this study. Clinically, the OVD of four dentures was judged too low, in one case too high, and in the other 31 cases as correct. The mean ANS-Xi-D angle was 48.28°±4.86 and statistically not different to the norm value of 49°±4 (n.s.). There was a tendency that the ANS-Xi-D angle was different between participants with different tooth-independent facial growth patterns (ANOVA, P = .0548). Predominantly, clinically sufficient prostheses show adequate ANS-Xi-D angles. Short-face type denture patients are often restored to comply with mesiofacial norms. The determination of the OVD based on lateral cephalography is not recommendable to be a standard diagnostic parameter. Orthodontic norms are derived from dentate cohorts and might not take the continuing facial growth and other confounding factors of edentulous subjects into account.

Patent nasopalatine ducts: an update of the literature and a series of new cases.

PURPOSE: The objective of this review is to present an update and summary of clinical findings of cases with a patent nasopalatine duct (NPD) reported in the literature from 1881 to 2016. METHODS: Previous articles and reviews about patent NPDs were studied and copies of all original publications were obtained for data verification. Furthermore, a literature search was conducted. In addition, the study sample was complemented with four cases recently seen in our institution. RESULTS: Ten out of 67 published cases were to be excluded for this analysis due to misinterpretation or misreporting in previous articles. Overall, 57 cases with NPD patency could be analyzed. Males outnumbered females in a ratio of 2:1. The mean age (when this information was available) was 34.1 ± 17.6 years (range 6-69 years). NPDs were located bilaterally (60%), unilaterally (20%) or centrally (20%). Complete or partial patency was reported in 73.9 and 26.1%, respectively. 74.1% of patients presented a variety of clinical signs and symptoms. The ability of the patient to produce a squeaky or whistling sound was the most frequent clinical finding (23.8%). CONCLUSIONS: Caution must be exercised when reading review articles about NPD patency since wrong data have been copied in several subsequent publications. Since epidemiological data are missing with regard to patent NPDs, age and gender predilections are not warranted. Bilateral occurrence and full patency were prevailing features in the evaluated case reports of patent NPDs.

Agreement between 2D and 3D radiographic outcome assessment one year after periapical surgery.

AIM: To compare 2D with 3D radiography in assessing the treatment outcome 1 year after periapical surgery. METHODOLOGY: In this prospective study, periapical radiographs (PA) and cone beam computed tomography (CBCT) were performed 1 year after periapical surgery. Three calibrated observers independently evaluated the radiographs for the presence and type of periapical radiolucencies. Ratings in PA were compared to those in bucco-lingual and mesio-distal CBCT images (coronal and sagittal planes), and the ratings of the latter two were also compared between each other. Further, maximum size diameters of radiolucencies were measured on CBCT scans, and the calculated means were correlated with the types of radiolucency. Statistical analysis was completed using Friedman rank sum tests, the Wilcoxon signed rank test and the Pearson correlation coefficient. RESULTS: A total of 61 roots in 54 patients were eligible for the final assessment. On average, the intra-observer ratings were identical in 59.6% when comparing PA and CBCT (kappa 0.112 to 0.192). A very high intra-observer agreement (93.4%) was noted when comparing bucco-lingual and mesio-distal CBCT ratings (kappa 0.797 to 1). Interobserver agreement was higher for PA (68.8%) than for CBCT (bucco-lingual 45.9%, mesio-distal 47.5%), but without reaching significant differences. The calculated mean size of persistent radiolucencies in CBCT scans correlated well with the assigned types of radiolucency. CONCLUSION: CBCT images showed in nearly a third of the evaluated cases a worse situation than PA. There is a need to define criteria to assess the 'radiographic healing' in CBCT following periapical surgery.

Efficacy of topical tacrolimus for oral lichen planus: real-life experience in a retrospective cohort of patients with a review of the literature.

BACKGROUND AND OBJECTIVE: Management of oral lichen planus (OLP) is challenging and therapeutic options are limited. The use of topical tacrolimus has shown promising results. We reviewed our daily life experience with topical tacrolimus in OLP patients. METHODS: This retrospective unicentre study included all 21 patients with OLP, which were evaluated over a 53-month period and treated with topical tacrolimus. Patients were initially given a topical preparation of 0.1% tacrolimus twice daily. The response to treatment was assessed using a 4-point scale at month 2 and 6: complete response of affected area (CR), major remission (>50%, MR), partial remission (25-50%, PR) and either no response (<25%) or worsening. The pain score was also assessed using a 3-point scale. RESULTS: Four of 21 patients (19%) showed a CR at month 2, whereas at month 6, 7 (33%) had a CR. For patients who reported MR (n = 2) and PR (n = 8) at month 2, the therapy was continued. Of those, at 6 months, three patients showed a CR, while four maintained a PR. The pain score improved during treatment. After 2 months of therapy, eight of 10 patients with an initial high pain score achieved a significant improvement. In patients starting with moderate pain an improvement was observed in one of seven patients. Overall, for three patients there was a complete loss of pain, while in nine there was a reduction. Except for transitory burning sensation and altered taste sensation, no relevant side-effects were reported. CONCLUSION: This retrospective analysis confirms that topical tacrolimus is a valuable therapeutic option in severe or treatment-resistant OLP. Our findings in daily practice suggested nevertheless that the efficacy of topical tacrolimus is overestimated with regard to both complete response and pain reduction.

Three-dimensional study of nasopalatine canal morphology: a descriptive retrospective analysis using cone-beam computed tomography.

PURPOSE: For dental implant treatment planning and placement, a precise anatomic description of the nasopalatine canal (NC) is necessary. This descriptive retrospective study evaluated dimensions of the NC and buccal bone plate (BBP) and the tridimensional association of the anatomic variants of NC, using cone-beam computed tomography (CBCT). METHODS: This study included 230 CBCTs. Sagittal slices were used for measurements of the NC and BBP and to evaluate shape and direction-course of the NC. Coronal slices were used to assess NC shape and axial slices to assess number of incisive foramina and foramina of Stenson. RESULTS: Mean NC length was 12.34 ± 2.79 mm, statistically significant differences were detected between genders (p < 0.001). Mean BBP length was 20.87 ± 3.68 mm, statistically significant differences were found for the dental status (p < 0.001) and mean BBP width was 6.83 ± 1.28 mm, significant differences were detected between genders (p < 0.001). Mean nasopalatine angle was 73.33° ± 8.11°, significant differences were found in sagittal and coronal classifications. The most prevalent canal was: cylindrical sagittal shape (48.2 %); slanted-straight direction-course (57.6 %); Ya-type coronal shape (42.4 %); and one foramen incisive with two Stenson's foramina (1-2) (50.9 %). Sagittal shape was associated with sagittal direction-course (p < 0.001). Coronal shape was associated with axial classification (p < 0.001). CONCLUSIONS: The NC anatomy is highly variable. Gender is related to the NC length and BBP width, while dental status is related to BBP length. There was an association between the different sagittal classifications of the NC and between the coronal shape and axial classification.

Verruciformes Xanthom an der linken Wange bei einer 56-jährigen Patientin - Diagnostik, Therapie und Nachsorge

The oral verruciform xanthoma (OVX) is a rare, benign lesion that occurs predominantly in the masticatory region of the oral cavity. The OVX is small, slow growing, and mostly free of clinical symptoms. The exact pathogenesis is unknown, and a viral etiology such as from a human papillomavirus (HPV) infection has not been proven. Although primarily observed in healthy individuals, there have been cases in patients with autoimmune diseases and with chronic graft-versus-host disease (GvHD). The treatment of choice is complete excision of the lesion. This case report showcases a successful surgical removal of an oral verruciform xanthoma on the left buccal mucosa in a 56-year-old patient with GvHD 14 years after allo-genic stem cell transplantation due to a Non-Hodgkin lymphoma.

Bone apposition to a titanium-zirconium alloy implant, as compared to two other titanium-containing implants.

Implants made of commercially pure titanium (cpTi) are widely and successfully used in dentistry. For certain indications, diameter-reduced Ti alloy implants with improved mechanical strength are highly desirable. The aim was to compare the osseointegration of titanium-zirconium (TiZr) and cpTi implants with a modified sandblasted and acid-etched (SLActive) surface and with a Ti6Al4V alloy that was sand-blasted and acid-washed. Cylindrical implants with two, 0.75 mm deep, circumferential grooves were placed in the maxilla of miniature pigs and allowed to heal for 1, 2, 4 and 8 weeks. Undecalcified toluidine blue-stained ground sections were produced. Surface topography, area fraction of tissue components, and bone-to-implant contact (BIC) were determined. All materials showed significantly different surface roughness parameters. The amount of new bone within the implant grooves increased over time, without significant differences between materials. However, BIC values were significantly related to the implant material and the healing period. For TiZr and cpTi implants, the BIC increased over time, reaching values of 59.38 % and 76.15 % after 2 weeks, and 74.50 % and 84.67 % after 8 weeks, respectively. In contrast, the BIC for Ti6Al4V implants peaked with 42.29 % after 2 weeks followed by a decline to 28.60 % at 8 weeks. Significantly more surface was covered by multinucleated giant cells on Ti6Al4V implants after 4 and 8 weeks. In conclusion, TiZr and cpTi implants showed faster osseointegration than Ti6Al4V implants. Both chemistry and surface topography might have influenced the results. The use of diameter-reduced TiZr implants in more challenging clinical situations warrants further documentation in long-term clinical studies.

Oral mucosal morphea: a new variant.

Morphea is a cutaneous disorder characterized by an excessive collagen deposition. While in almost all cases the sclerosing process exclusively affects the skin, there are anecdotal cases in which associated mucosal involvement has been described. We here report the case of a woman developing a whitish indurated plaque over the left upper vestibular mucosa and hard palate leading to dental mobility and exposure of the roots of several teeth. Cone beam computed tomography of the left maxilla showed bone resorption involving the upper cuspid to the second molar region with widened periodontal ligament spaces, while light microscopy studies demonstrated epithelial atrophy and fibrosis of the dermis extending into the submucosa with hyalinization of subepithelial collagen. Our observation expands the spectrum of clinical presentations of morphea and provides the first example of isolated oral morphea. Its recognition is important to avoid significant local complications.

A systematic review of medical interventions for oral submucous fibrosis and future research opportunities.

Oral Diseases (2011) 17 (Suppl. 1), 42-57 Oral submucous fibrosis (OSF) is a chronic, insidious disease caused by areca nut use, and is associated with both significant morbidity (including pain and reduced oral opening) and an increased risk for malignancy. This systematic review explored and updated the current medical (i.e., non-surgical) interventions available for the management of OSF. Of the 27 published medical interventions, there were four randomized controlled trials. The overall quality of these randomized controlled studies was assessed using the GRADE approach and significant limitations that challenged the conclusions were found. However, this review was valuable in terms of identifying opportunities to provide recommendations for future research, in terms of the populations to research, the types of interventions needed, the types of outcomes to be measured, the study designs needed, and the infrastructure required to conduct studies. The next step is to initiate a pathway for a low-cost research plan leading to the development of a brief protocol for future clinical trials in this field, with an emphasis on conducting studies in regions of the world where OSF is prevalent.

Incidental maxillary sinus findings in orthodontic patients: a radiographic analysis using cone-beam computed tomography (CBCT).

UNLABELLED: To determine the frequency of incidental maxillary sinus findings using cone-beam computed tomography (CBCT) images made for orthodontic purposes. SETTING AND SAMPLE POPULATION: One hundred thirty-nine consecutive CBCTs from 134 patients treated at the Department of Orthodontics and Dentofacial Orthopedics, University of Bern, Bern, Switzerland. Indications for CBCT imaging included the localization of impacted teeth and root resorption related to impacted teeth. MATERIAL AND METHODS POPULATION: Two experienced observers reviewed the CBCT scans (fields of view: 4 × 4/6 × 6/8 × 8 cm) and recorded all incidental maxillary sinus findings according to standardized categories. The patient's age and gender, the size of the field of view, the season of CBCT image taking, and the thickness of the Schneiderian membrane were evaluated to identify potential influencing factors. RESULTS: In 65 CBCTs (46.8%), incidental maxillary sinus findings were found (interrater classification agreement of 95.7%/95% CI: 90.9-97.9%). Three types of incidental findings were diagnosed: flat mucosal thickening (23.7%), polypoid mucosal thickening (19.4%), and signs of acute sinusitis (3.6%). There was no correlation between the field of view of the CBCT and the number of incidental findings inside the field. There was no correlation between the season during which the CBCT was made and the number of incidental findings. The mean thickness of the mucosal lining in the maxillary sinus was 1.58 mm (95% CI: 1.17-1.98 mm). CONCLUSIONS: A high percentage of the CBCTs made for orthodontic diagnostic purposes exhibit incidental maxillary sinus findings not associated with the primary indication.

[Oral medicine: a specialty placed between medicine and dentistry]. / Orale Medizin : Interdisziplinäre Zusammenarbeit zwischen Medizin und Zahnmedizin.

Oral medicine is a dental specialty that bridges the traditional areas of health between dentistry and medicine. International descriptions reflect this and oral medicine is defined as "the dental speciality placed at the interface between medicine and dentistry and is concerned with the diagnosis and management of (non-dental) pathology affecting the oral and maxillofacial region." Oral medicine specialists provide clinical care to patients with a wide variety of orofacial conditions, including oral mucosal diseases, orofacial pain syndromes, salivary gland disorders, and oral manifestations of systemic diseases. There is a growing need to implement this specialty globally: due to the rapid progress in both medicine and dentistry, and to the growing percentage of senior citizens in many countries, the adequate diagnosis and treatment of oral diseases will become even more complex in the future. In this article, the authors' intention is to point out that oral medicine is neither a recognized specialty nor a distinct field of study in Germany, Austria, or Switzerland; thus, the need for postgraduate training in this field in countries where oral medicine is not a specialization is emphasized.

Disruptive Innovation in Dentistry: What It Is and What Could Be Next.

Dentistry is a technically oriented profession, and the health care sector is significantly influenced by the ubiquitous trend of digitalization. Some of these digital developments have the potential to result in disruptive changes for dental practice, while others may turn out to be just a pipedream. This Discovery! essay focuses on innovations built on artificial intelligence (AI) as the center-technology influencing 1) dental eHealth data management, 2) clinical and technical health care applications, and 3) services and operations. AI systems enable personalized dental medicine workflows by analyzing all eHealth data gathered from an individual patient. Besides dental-specific data, this also includes genomic, proteomic, and metabolomic information and therefore facilitates optimized and personalized treatment strategies and risk management. Based on the power of AI, the triangular frame of "data"/"health care"/"service" is supplemented by technological advancements in the field of social media, Internet of things, augmented and virtual reality, rapid prototyping, and intraoral optical scanning as well as teledentistry. Innovation continues to be critical to tackle dental problems until its routine implementation based on sound scientific evidence. Novel technologies must be viewed critically in relation to the cost-benefit ratio and the ethical implications of a misleading diagnosis or treatment produced by AI algorithms. Highly sensitive eHealth data must be handled responsibly to enable the immense benefits of these technologies to be realized for society. The focus on patient-centered research and the development of personalized dental medicine have the potential to improve individual and public health, as well as clarify the interconnectivity of disease in a more cost-effective way.

A randomized controlled trial comparing surgical excisional biopsies using CO2 laser, Er:YAG laser and scalpel.

This randomized controlled trial (RCT) (ClinicalTrials.gov ID: NCT03001791) compared excisional biopsies of fibrous hyperplasia performed using a CO2 laser (140Hz, 400µs, 33mJ), Er:YAG laser (35Hz, 297µs, 200mJ, air-water cooling), or scalpel (15c blade). Clinical parameters recorded were duration of the intervention, intraoperative bleeding, need for electrocauterization and/or suturing, postoperative side effects, complications, pain, and intake of analgesics. Histopathological linear measurements of the thermal damage zone were performed on the laser biopsies. Results showed that the duration of the intervention was significantly shorter for both lasers compared to the scalpel (P<0.001). Intraoperative bleeding occurred less frequently with the CO2 laser (P<0.001). Additional electrocautery was used in 92% of Er:YAG laser interventions (P<0.001). Postsurgical complications, pain, and the intake of analgesics did not differ between the groups. The measured thermal damage zones differed significantly between the CO2 laser (median of 72.6µm) and Er:YAG laser (30.9µm) (P<0.001). This RCT showed that CO2 laser, Er:YAG laser, and scalpel are all adequate for excisional biopsies of small lesions in the oral mucosa. While patient postoperative morbidity is similar, the ideal instrument can be selected according to the surgical advantages preferred for the individual situation.

Risk factors for external root resorption of maxillary second molars due to impacted third molars as evaluated using cone beam computed tomography.

The purpose of this retrospective study was to evaluate risk factors for external root resorption (ERR) on maxillary second molars (MxM2) in association with impacted third molars (MxM3) using cone beam computed tomography (CBCT) scans. The angles between the axes of MxM2/MxM3 (inclination) were measured. Further, ERR on MxM2 was classified as absent, slight, moderate, or severe. Contact location between MxM3 and MxM2, the size of the dental follicle, type of impaction, root formation, and patient demographic characteristics were also assessed. Half of the 84 MxM2 showed ERR (slight 36.9%, moderate 6.0%, severe 7.1%). Patient age was a significant factor for the presence of ERR (P = 0.03). The inclination was also a relevant factor, with transverse MxM3 exhibiting the highest risk of ERR (P = 0.02). The cervical third (28.6%) showed a significantly lower risk percentage of ERR compared to the apical (73.7%) and middle thirds (60.6%) of the root (P = 0.004). Based on these findings, clinicians assessing the need for surgical removal should be able to selectively identify impacted MxM3 at risk of causing ERR on MxM2 early on, especially when the MxM3 is located in close contact with the apical and middle thirds of the MxM2 roots and has a transverse inclination.

Incidence of bleeding after minor oral surgery in patients on dual antiplatelet therapy: a systematic review and meta-analysis.

Bleeding is a feared complication of minor oral surgery in patients on treatment with antiplatelet agents and there is no agreed strategy regarding the cessation or not of antiplatelet treatment. The aim of this systematic review was to evaluate bleeding with minor oral surgery in patients on dual antiplatelet therapy (DAPT), single antiplatelet therapy (SAPT), or no antiplatelet therapy (no APT). The PubMed, Embase, Web of Science, and Cochrane Library databases were screened. Sixteen studies were included. DAPT was continued in all studies. The perioperative bleeding risk was significantly higher for DAPT than for SAPT (risk ratio (RR) 10.16, P= 0.010; risk difference (RD) 0.35, P= 0.269), but not higher compared to no APT (RR 6.50, P= 0.057; RD 0.19, P= 0.060). The postoperative bleeding risk was significantly elevated for DAPT compared to SAPT (RR 2.61, P= 0.010) and no APT (RR 3.63, P= 0.035), but only by 1% (RD 0.01, P= 0.103) and 1% (RD 0.01, P= 0.421), respectively. Clinically, this may be considered quite similar. Additionally, local haemostatic measures could control all reported bleeding and no lethal events occurred. Therefore, DAPT interruption is not advised before minor oral surgery.

Risk factors for root resorption of second molars associated with impacted mandibular third molars.

External root resorption (ERR) affecting mandibular second molars (M2) may occur when the adjacent third molar (M3) is impacted in close proximity. This retrospective cohort study aimed to assess the presence, severity, and location of ERR on M2 due to M3 using cone beam computed tomography (CBCT) scans and to identify associated factors. The angle between the axis of M2 and M3 was measured. ERR on M2 was classified as absent, slight, moderate, or severe. The location of contact between M3 and M2, the size of the dental follicle, and patient demographic characteristics were recorded. A total of 433 patients with 640 M3 were included. A male predilection was found with regard to ERR (P=0.0004). ERR was identified on 31.9% of M2 and was slight in 30.2%, moderate in 1.4%, and severe in 0.3% of cases. The presence of ERR was associated with direct contact between M2 and M3 (P<0.0001), the angle between M2 and M3 (P<0.0001), the inclination of M3 (P=0.001), and the location of contact (P=0.0005). This study showed ERR to be a frequent finding. ERR is associated with a mesioangular position of M3 in more than one third of cases, and a proximity ≤0.5mm between M2 and M3 favours ERR.