Prevalence and characteristics of and risk factors for impacted teeth with ankylosis and replacement resorption - a retrospective, 3D-radiographic assessment.

BACKGROUND: Large variation in the prevalence of ankylosis and replacement resorption (ARR) is reported in the literature and most studies have relatively small patient numbers. The present retrospective study aimed to provide an overview on prevalence, location of, and associated risk factors with ARR based on a large sample of computed tomography (CT) / cone beam computed tomography (CBCT) scans of impacted teeth. The results should allow clinicians to better estimate the risk of ARR at impacted teeth. METHODS: The CT/CBCT scans of 5764 patients of a single center in Central Europe were screened with predefined eligibility criteria. The following parameters were recorded for the finally included population: gender, age, tooth type/position, number of impacted teeth per patient, and presence/absence of ARR. For teeth with ARR the tooth location in reference to the dental arch, tooth angulation, and part of the tooth affected by ARR were additionally registered. RESULTS: Altogether, 4142 patients with 7170 impacted teeth were included. ARR was diagnosed at 187 impacted teeth (2.6%) of 157 patients (3.7%); 58% of these patients were female and the number of teeth with ARR per patient ranged from 1 to 10. Depending on the tooth type the prevalence ranged from 0 (upper first premolars, lower central and lateral incisors) to 41.2% (upper first molars). ARR was detected at the crown (57.2%), root (32.1%), or at both (10.7%). After correcting for confounders, the odds for ARR significantly increased with higher age; further, incisors and first/second molars had the highest odds for ARR, while wisdom teeth had the lowest. More specifically, for 20-year-old patients the risk for ARR at impacted incisors and first/second molars ranged from 7.7 to 10.8%, but it approximately tripled to 27.3-35.5% for 40-year-old patients. In addition, female patients had significantly less often ARR at the root, while with increasing age the root was significantly more often affected by ARR than the crown. CONCLUSION: ARR at impacted teeth is indeed a rare event, i.e., only 2.6% of 7170 impacted teeth were ankylosed with signs of replacement resorption. On the patient level, higher age significantly increased the odds for ARR and on the tooth level, incisors and first/second molars had the highest odds for ARR, while wisdom teeth had the lowest.

Prevalence and Characterization of External Cervical Resorption Using Cone Beam Computed Tomography.

INTRODUCTION: The aim of this study was to assess the prevalence of external cervical resorption (ECR) and characterize the cases of ECR using cone beam computed tomography (CBCT). METHODS: High-resolution CBCT scans of 6216 patients (2280 males and 3936 females), consecutively acquired during the period July 2021 to March 2022, were analyzed. Identified cases of ECR were characterized by 3 evaluators regarding lesion height, circumferential spread, portal of entry proximity to root canal, stage, location, and width. RESULTS: In a total of 38 patients and 40 teeth, ECR cases demonstrated an incidence of 0.61%. The median age of the patients was 39 years. Prevalence of ERC was 0.78% among males and 0.50% among females. The most affected teeth were the maxillary incisors and canines. The most frequent characteristics of the lesion were: extension up to the cervical third (47.5%), more than 270° circumferential spread (42.55%), probable pulpal involvement (57.5%), progressive stage (65%), supracrestal (52.1%) and mesial (34.7%) localization of >1 mm in size (52.1%) portals of entry. Cases with greater longitudinal involvement also showed greater circumferential progression (P = .008). There was no association between portal of entry location and bone crest or ECR reparative phase (P = .42). Inter-rater agreement ranged from good to very good. No association between portal of entry and ECR progression was observed. CONCLUSIONS: ECR showed low prevalence in the Brazilian population, affecting mostly anterior maxillary teeth of patients within a wide age range. CBCT allowed characterization of ECR lesions with good interobserver agreement.

Relationship between the impacted mandibular third molar and adjacent second molar' external root resorption by cone-bean computed tomography analysis.

BACKGROUND: The relationship between the impacted mandibular third molar (IMTM) and the external root resorption (ERR) of the mandibular second molar (MSM) was analysed with cone-beam computed tomography (CBCT). The risk factors affecting the ERR of the MSM were examined to provide a reference. MATERIAL AND METHODS: A total of 327 patients (total: 578 teeth) admitted to the Affiliated Hospital of Yanbian University for IMTM extraction from January 2017 to December 2019 was chosen and divided according to gender and age. The correlation between the IMTM and ERR of MSM was analysed, including inclination angle, impaction direction and depth. The relationship of mandibular ascending ramus classification with ERR of MSM was also analysed. In addition, the correlation between the MTM impaction type and the severity of ERR was analysed. RESULTS: The incidence of ERR of MSM in male patients was higher than in females (27.9% vs.17.6%, p = 0.018). The occurrence and the site of ERR showed statistical differences in the inclination angle [(≤20°, 3.6%) vs. (21°-40°, 27.1%) vs. (41°-60°, 27.6%) vs. (61°-80°, 25.6%) vs. (>80°, 31.7%), p <0.001], impaction direction [(Vertical, 1.1%) vs. (Mesial, 32.7%) vs. (Horizontal, 25.3%), p <0.001] and depth of MTM [(Low position, 38.6%) vs. (Median position, 32.0%) vs. (High position, 13.7%), p <0.001]. Also, there was a significant difference in the mandibular ascending ramus type [(Class I, 17.4%) vs. (Class II, 32.3%) vs. (Class III, 44.9%), p <0.001]. In addition, the severity of ERR showed statistical differences in the mesial (40.9%, p<0.05), lower impaction (54.5%, p<0.05) depth of MTM and type III of mandibular ascending ramus (63.6%, p<0.05). CONCLUSIONS: The inclination angle, impaction direction, and depth of MTM were the influencing factors for the occurrence and site of ERR. Also, mandibular ascending ramus type was the impact fact. For MTM with mesioangular, lower impaction, and mandibular ascending ramus with type III, the ERR of the MSM was severer.

The effect of impacted third molars on second molar external root resorption, a cross-sectional cone beam computed tomography study

Background: Third molars have the highest prevalence of impaction in teeth and can cause pathological damage on the adjacent second molars. This study aims to evaluate the effects of factors related to impacted third molars on external root resorption (ERR) in adjacent second molars using cone-beam computed tomography (CBCT). Material and Methods: In CBCTs, the effect of impacted third molars on the root surface of adjacent second molars was investigated. Inclusion criteria for subjects were being older than 16 and younger than 55, presence of at least one impacted third molar and adjacent second molar. Exclusion criteria were pathology, a follicle gap greater than 5 mm, crowned second molar, severe decay, an artifact on a radiologic image, and previous surgery on the second or third molars. The investigations were made based on age range, gender, tooth inclination, Pell-Gregory classification, retention type, contact area, root formation, pericoronal width, and tooth absence on the same quadrant for potential risk factors. The collected data were statistically analyzed with R software. The Chi-Square test was used to find out any significant difference. Logistic regression analyses were done for potential risk factors for ERR. Results: A total of 437 impacted third molars and adjacent second molars were investigated using CBCT. Of these, 381 met the inclusion criteria. Mesioangular and horizontal inclination, Pell-Gregory Class B-C, contact area, and retention type were found the statistically potential risk factors for ERR. Conclusions: The impacted third molar with horizontal or mesioangular position, and osseous retention, with Pell and Gregory Class B and C, are more likely to cause external root resorption in adjacent second molars. (AU)

The effect of impacted third molars on second molar external root resorption, a cross-sectional cone beam computed tomography study.

BACKGROUND: Third molars have the highest prevalence of impaction in teeth and can cause pathological damage on the adjacent second molars. This study aims to evaluate the effects of factors related to impacted third molars on external root resorption (ERR) in adjacent second molars using cone-beam computed tomography (CBCT). MATERIAL AND METHODS: In CBCTs, the effect of impacted third molars on the root surface of adjacent second molars was investigated. Inclusion criteria for subjects were being older than 16 and younger than 55, presence of at least one impacted third molar and adjacent second molar. Exclusion criteria were pathology, a follicle gap greater than 5 mm, crowned second molar, severe decay, an artifact on a radiologic image, and previous surgery on the second or third molars. The investigations were made based on age range, gender, tooth inclination, Pell-Gregory classification, retention type, contact area, root formation, pericoronal width, and tooth absence on the same quadrant for potential risk factors. The collected data were statistically analyzed with R software. The Chi-Square test was used to find out any significant difference. Logistic regression analyses were done for potential risk factors for ERR. RESULTS: A total of 437 impacted third molars and adjacent second molars were investigated using CBCT. Of these, 381 met the inclusion criteria. Mesioangular and horizontal inclination, Pell-Gregory Class B-C, contact area, and retention type were found the statistically potential risk factors for ERR. CONCLUSIONS: The impacted third molar with horizontal or mesioangular position, and osseous retention, with Pell and Gregory Class B and C, are more likely to cause external root resorption in adjacent second molars.

The prevalence, characteristics, and risk factors of external cervical resorption: a retrospective practice-based study.

OBJECTIVES: External cervical root resorption (ECR) is a poorly understood and aggressive form of resorption. The purpose of this study was to examine the prevalence, characteristics, and risk factors associated with the occurrence of ECR in patients seeking endodontic care from private practice settings. MATERIALS AND METHODS: Records of 343 patients with 390 teeth diagnosed with ECR were identified from 3 private endodontic practices from 2008 to 2022. The patients' demographic information, systemic conditions, and dental history were recorded. The characteristics of the cases including Heithersay classification, pulpal and periapical status, and their management were documented. The association between case severity and potential predisposing factors was examined using chi-square analysis. RESULTS: The overall prevalence of ECR among patients seeking endodontic care was low (< 1%). However, there was a greater than twofold increase in the pooled prevalence from 2016 to 2021 (0.99%) compared to the data from 2010 to 2015 (0.46%). The most commonly affected teeth were anterior teeth (48.7%). Class II (30.0%) and class III (45.4%) defects were the most often identified. Patients with a history of trauma or orthodontic treatment were significantly more likely to be diagnosed with severe cervical resorption (class III or IV) (p < 0.05). CONCLUSIONS: There has been an increase in the prevalence of ECR in patients seeking endodontic care. A history of orthodontic treatment and traumatic dental mechanical injuries may predict the severity of resorption. CLINICAL RELEVANCE: The upward trend in the occurrence of ECR warrants close monitoring of the patients at high risk of developing the condition to facilitate early detection and management.

Reprint of: Prevalence and Characteristics of Root Resorption Identified in Cone-Beam Computed Tomography Scans.

INTRODUCTION: Root resorption is a destructive process that compromises tooth structure and can result in tooth loss. Often it remains asymptomatic and is an incidental finding on radiographic examinations. The purpose of this study was to determine prevalence and characteristics of root resorption in patients referred for cone-beam computed tomography (CBCT) imaging for a variety of indications. METHODS: The study included CBCT scans of 1086 consecutive patients referred for CBCT imaging over an 18-month period. A total of 1148 scans were acquired. Data were abstracted from radiology reports, and prevalence estimates of resorption were computed for the aggregate sample and also across specific indications. RESULTS: Resorption was identified in 171 patients (15.7%, 95% CI: 13.6%-17.9%) and in 249 teeth with a prevalence range of 2.6%-92.3% across specific indications. An 18.7% of the patients had 2 resorption sites whereas 8.8% had 3 or more resorption sites. The majority of affected teeth were anteriors (43.8%), followed by molars (40.6%) and premolars (14.5%). The most prevalent resorption types were external (29.3%), cervical (22.5%), infection-induced apical resorption (13.7%), internal (9.6%), and impacted tooth induced (8.8%). The majority of teeth with resorption did not have prior endodontic treatment (73.9%) and had radiographically normal periapex (69.5%). Of 249 teeth with resorption, 31% presented as incidental finding. The prevalence of incidental findings of resorption increased with age, P < .05, and was significantly lower for anterior teeth (20.2%) as compared to premolars (41.7%) and molars (36.6%), (P < .05). CONCLUSION: The high proportion of incidental findings of resorption detected by CBCT suggests that resorption is not recognized/detected by conventional radiography and therefore remains underdiagnosed.

Prevalence of second molar external root resorption caused by mandibular third molars: a CBCT study.

The aims of this study were to use cone beam computed tomographic (CBCT) scans to assess the prevalence of second molar external root resorption (ERR) caused by impacted mandibular third molars and to associate the location and severity of ERR with the third molar position using 2 classification systems-1 proposed by Pell and Gregory and the other proposed by Winter. In this cross-sectional study, 2 calibrated observers evaluated a total of 107 CBCT scans (71 female and 36 male patients). After the presence or absence of ERR was determined, ERR was classified according to its location (cervical, middle, apical third, or root apex) and severity (mild, moderate, or severe resorption). The data were assessed with the Pearson chi-square test, the chi-square test for linear trend, and Poisson regression analysis. The significance level was set at P < 0.05. The prevalence of second molar ERR in the sample as a whole was 47.7% (n = 51). The prevalence was significantly higher (69.4%) for male patients (P = 0.002; Pearson chi-square test). The probability that ERR would affect the second molar was 1.71 times greater when the third molar exhibited the Pell and Gregory class IC position (95% CI, 1.27-2.31) and 1.64 times greater when the third molar exhibited the Winter mesioangular position (95% CI, 1.38-1.95). There was a statistically significant association between ERR location and severity; the cervical third was the most affected by mild ERR and the middle third was the most affected by severe ERR. The prevalence of mandibular second molar ERR caused by impacted third molars is high, especially in male patients. Mandibular third molars in the Pell and Gregory class IC position or Winter mesioangular position demonstrated greater potential to result in ERR of the adjacent second molar.

Is it necessary to remove bone-impacted teeth? A retrospective study.

BACKGROUND: In clinical practice, it is risky to extract bone-impacted teeth and they're prone to a variety of complications, such as pathological fracture, adjacent tooth fracture, maxillary sinus perforation, and so on, making it difficult for clinicians to decide whether to extract them. PURPOSE: In order to illustrate our opinions on the possibility of extracting full third molars (M3), 360 examples of complete third molars were analyzed in this study. MATERIALS AND METHOD: We investigated 2189 patients, and 261 of them provided CBCT images of 360 teeth. assessing the degree of second molar(M2) root absorption in connection to age, impacted relationship, contact part, calculating the odds ratio (OR) and 95% confidence interval using the Logistic regression analysis equation. RESULT: Bone-impacted M3 occurred in 11.92% (261/2189) of patients with "impacted teeth" diagnoses. There was a significant difference between the occurrence of M2ERR and the contact parts (P value<0.001), and only the type of vertical impaction differed significantly from Level 3 (P < 0.05). CONCLUSIONS: 1) M3 should be removed if root resorption has not occurred in M2. 2) Root resorption is more likely to occur when M3 crown and M2 apical contact. 3) Enough experience, precise preoperative assessment can reduce the dangers to a minimum.

Prevalence and Characteristics of Root Resorption Identified in Cone-Beam Computed Tomography Scans.

INTRODUCTION: Root resorption is a destructive process that compromises tooth structure and can result in tooth loss. Often it remains asymptomatic and is an incidental finding on radiographic examinations. The purpose of this study was to determine prevalence and characteristics of root resorption in patients referred for cone-beam computed tomography (CBCT) imaging for a variety of indications. METHODS: The study included CBCT scans of 1086 consecutive patients referred for CBCT imaging over an 18-month period. A total of 1148 scans were acquired. Data were abstracted from radiology reports, and prevalence estimates of resorption were computed for the aggregate sample and also across specific indications. RESULTS: Resorption was identified in 171 patients (15.7%, 95% CI: 13.6%-17.9%) and in 249 teeth with a prevalence range of 2.6%-92.3% across specific indications. An 18.7% of the patients had 2 resorption sites whereas 8.8% had 3 or more resorption sites. The majority of affected teeth were anteriors (43.8%), followed by molars (40.6%) and premolars (14.5%). The most prevalent resorption types were external (29.3%), cervical (22.5%), infection-induced apical resorption (13.7%), internal (9.6%), and impacted tooth induced (8.8%). The majority of teeth with resorption did not have prior endodontic treatment (73.9%) and had radiographically normal periapex (69.5%). Of 249 teeth with resorption, 31% presented as incidental finding. The prevalence of incidental findings of resorption increased with age, P < .05, and was significantly lower for anterior teeth (20.2%) as compared to premolars (41.7%) and molars (36.6%), (P < .05). CONCLUSION: The high proportion of incidental findings of resorption detected by CBCT suggests that resorption is not recognized/detected by conventional radiography and therefore remains underdiagnosed.

Does exogenous female sex hormone administration affect the rate of tooth movement and root resorption? A systematic review of animal studies.

BACKGROUND: The long-term use of contraceptive methods that contain estrogens, progestogens or combinations of the above among women aged 15 to 49 years is extensive. Both estrogens and progestogens affect bone metabolism. OBJECTIVE: To systematically investigate and appraise the quality of the available evidence from animal studies regarding the impact of exogenous administration of female sex hormones on the rate of orthodontic tooth movement and root resorption. SEARCH METHODS: Search without restriction in seven databases (including grey literature) and hand searching were performed until May 2021. SELECTION CRITERIA: We looked for controlled animal studies investigating the effect from exogenous administration of formulations containing female sex hormones on the rate of orthodontic tooth movement and root resorption. DATA COLLECTION AND ANALYSIS: After study retrieval and selection, relevant data was extracted, and the risk of bias was assessed using the SYRCLE's Risk of Bias Tool. The quality of available evidence was assessed with the Grades of Recommendation, Assessment, Development, and Evaluation. RESULTS: Three studies were identified, all being at unclear risk of bias. Overall, administration of progesterone and the combinations of estradiol with norgestrel and desogestrel were shown to significantly decrease the rate of orthodontic tooth movement when given for longer periods (>3 weeks). Inconsistent information was detected for shorter periods of consumption. Estradiol, with desogestrel use, resulted in less root resorption. The quality of the available evidence was considered to be low. CONCLUSIONS: Exogenous administration of female sex hormones may decelerate in the long term the rate of tooth movement and decrease orthodontically induced root resorption in animals. Until more information becomes available, an orthodontist should be able to identify a patient consuming such substances and understand the potential clinical implications and adverse effects that may arise. REGISTRATION: PROSPERO: CRD42017078208; https://clinicaltrials.gov/.

Frequency and association of maxillary ectopic canine with incisor root resorption and dental agenesis.

OBJECTIVE: To assess the frequency of maxillary ectopic canine both buccally and palatally displaced with incisor root resorption and dental agenesis. METHODS: The cross-sectional study was conducted from April 8 to June 29, 2019, at the Department of Orthodontics, Dr. Ishrat Ul Ebad Khan Institute of Oral Health Sciences, and Dow Dental College, Dow University Of Health Sciences, Karachi, and comprised orthodontic patients diagnosed with maxillary ectopic canine eruption. Root resorption and agenesis were diagnosed on panoramic films. Root resorption was further confirmed by periapical radiographs. Data was analysed using SPSS 21. RESULTS: Of the 98 subjects, 86(87.8%) had buccally displaced canines of which 38(44.2%) were associated with root resorption, while 12(12.2%) patients had palatally displaced canines of which 10(83.3%) had root resorption (p=0.011). Overall, 30(30.6%) lateral incisors were resorbed, 7(7.1%) both central and lateral incisors, 5(5.1%) premolars, and 6(6.1%) both lateral incisors and premolars were resorbed. Agenesis was detected in 10 (10.2%) subjects (p=0.62). CONCLUSIONS: There was found to be no association of maxillary ectopic canines with incisor root resorption and dental agenesis.

Ectopic eruption of maxillary permanent first molars: Predictive factors for self-corrected and impacted outcome.

OBJECTIVE: The aim of this study was to describe the occurrence, angulation and mesialisation ratio of the ectopic eruption of the maxillary permanent first molar (PFM) and its correlation with the pathological resorption of maxillary primary second molar (PSM). METHODS: This retrospective study was performed using the subsequent panoramic radiographs of 11.924 child patients aged 6-10 years. Ectopic eruption status is categorised as self-corrected and impacted types. To evaluate the differences between the two groups (self-corrected and impacted), the angulation of PFM, mesialisation ratio of PFM, and degree of adjacent PSM root resorption were also assessed. The data were statistically analysed using ANOVA and chi-square tests. Pearson correlation was used to analyse whether a quantitative relationship exists between PFM mesialisation ratio and PSM root resorption. RESULTS: Ectopic eruption frequency was determined as 0.83%. The distribution of ectopic eruption according to gender shows a higher prevalence in males than females. In most cases of ectopic eruption, the eruption status was impacted. The impacted PFMs showed more negative vertical and positive horizontal angle between the PSM and PFM. There was no significant difference between eruption status and angles. Mesialisation ratio of impacted PFMs was significantly higher than self-corrected PFMs. There was significant difference between the PFM mesialisation ratio and the degree of PSM root resorption. CONCLUSION: Even if eruption disturbances do not occur frequently, making an early diagnosis is important to begin treatment at an optimal time. Although the relationship between horizontal and vertical angles and the ectopic eruption pattern is controversial, it is one of the clinical determinants. The mesialisation ratio of the impacted type was significantly higher than the self-corrected type. Self-correction of PFM was reduced in PSM with grade III and IV root resorption.

External Cervical Resorption: A Retrospective Case-Control Study.

INTRODUCTION: The current retrospective case-control study examined the potential systemic and local risk factors in relationship to external cervical resorption (ECR). The study hypothesis stated that both local and systemic risks are associated with higher ECR rates. METHODS: The ECR group included data about 76 patients (98 teeth) diagnosed with ECR at the university graduate endodontics clinic from 2008-2018. An equivalent comparative control group without ECR was composed of the same pool of patients and matched with cases by sex and age. Information about dental and medical history, including potential local risk factors (bruxism, trauma, eruption disorders, extraction of an adjacent tooth, orthodontics, and restorations) and systemic risk factors (medical conditions, medication, and allergies), was collected for both groups. Data were analyzed at tooth and patient levels. The chi-square test or Fisher exact test compared proportions between the 2 study groups. RESULTS: The overall ECR prevalence among endodontic patients during the 10-year follow-up was 2.3%. ECR was most frequent in maxillary anterior teeth (31.6%), and the Heithersay class 2 was the most frequent (38.8%) ECR diagnosis. Diabetes was the only significant systemic risk factor (P < .05). Trauma, as a local risk factor, was significantly (P < .05) more frequently reported in cases than in controls. CONCLUSIONS: The study hypothesis stating that both systemic and local risk factors were associated with higher ECR rates was partly confirmed, as one systemic (diabetes) and one local (trauma) risk factor were associated with higher ECR rates.

A retrospective study: Do all impacted teeth cause pathology?

OBJECTIVE: The objective of this study is to determine the incidence of impacted teeth and the frequency of pathologies they caused by cone beam computed tomography (CBCT) retrospectively. MATERIALS AND METHODS: In this study, 608 patients' CBCT images were analyzed retrospectively. Detected impacted teeth were classified as incisor, canine, premolar, molar, third molar, and supernumerary teeth. The pathologies caused by impacted teeth are classified as cysts or tumors, tooth decay, root resorptions, and periodontal bone loss. RESULTS: Impacted teeth were detected in 34.37% of the 608 CBCT images included in the study. The distribution of impacted teeth was 9.4% incisor, 29.4% canine, 9.9% premolar, 2.9% molar, 9.3% supernumerary, and 39.9% third molar teeth. Approximately 63.7% of the impacted teeth caused a pathology. The pathology that was most commonly caused by impacted teeth was periodontal bone loss (44.4%), and respectively others were root resorptions (33.3%), cysts or tumors (8.6%), and tooth decay (2.3%). The most common cause of this pathology was right mandibular third molar teeth. CONCLUSION: Impacted teeth were common and they often caused a pathology. CBCT is a useful device to assess the impacted teeth. When the impacted teeth are evaluated, each tooth should be assessed within itself. If the impacted teeth are not caused by pathology, they can be kept under control.

External root resorption in maxillary and mandibular second molars associated with impacted third molars: a cone-beam computed tomographic study.

OBJECTIVE: To separately investigate the prevalence and risk factors of external root resorption (ERR) in maxillary and mandibular second molars (M2s) adjacent to impacted third molars (M3s). MATERIALS AND METHODS: CBCT scans involving 184 maxillary and 323 mandibular impacted M3s were included. Age, gender, the impaction status of M3, the presence, severity, and location of ERR in M2 were assessed. Risk factors were identified by multivariate logistic regression analyses. RESULTS: The prevalence of ERR was 32.6% in maxillary and 52.9% in mandibular M2s (P < 0.001). Mesio-angulated and deeply impacted M3s were identified as risk factors for both ERR in maxillary and mandibular M2s (P < 0.05). Besides, age over 25 increased the risk of ERR in maxillary M2s (P < 0.05). ERR in maxillary M2s was overall more severe than that in mandibular M2s (P < 0.001). For maxillary M2s, ERR mostly occurred at the apical third, while the mandibular M2s ERR was most frequently detected at the cervical third. CONCLUSIONS: ERR occurring in M2s adjacent to impacted M3s is common, especially in mandibular M2s. ERR in maxillary M2s cannot be neglected because of its relatively high severity. Mesial angulation and impaction depth of M3 are significantly associated with ERR in M2s. For ERR in maxillary M2s, age is another predictive parameter. CLINICAL RELEVANCE: Considering the presence of ERR is associated with M3s' impaction, watchful monitoring or prophylactic removal of impacted M3s should be deliberated especially for the patients over 25 years and with mesially inclined and deeply positioned M3s.

Incidence of Root Resorption after the Replantation of Avulsed Teeth: A Meta-analysis.

INTRODUCTION: An avulsion injury is a serious trauma to pulp and periodontal tissues. After avulsion and replantation, teeth are at risk of infection and root resorption, which may affect treatment outcome and survival rate. Thus, the purpose of this systematic review was to evaluate the incidence of root resorption after the replantation of avulsed teeth. METHODS: Two reviewers searched 7 electronic databases for observational studies involving human subjects that evaluated the incidence of root resorption after tooth avulsion. Risk of bias (RoB) was evaluated using the Meta-Analysis of Statistics Assessment and Review Instrument, and the quality of available evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation tool. RESULTS: Of the 1507 articles, 23 met the inclusion criteria. A meta-analysis was conducted and showed that the incidence of internal root resorption was 1.2% (95% confidence interval [CI], 0.02-5.50). Regarding external root resorption, the incidence of surface root resorption was 13.3% (95% CI, 6.21-22.62), that of inflammatory root resorption was 23.2% (95% CI, 13.94-34.19), and that of replacement root resorption was 51.0% (95% CI, 40.10-62.00). Two studies presented a high RoB, 16 had a moderate RoB, and 11 had a low RoB. The overall level of evidence identified was very low. CONCLUSIONS: The incidence of root resorption after avulsion and replantation in descending order was replacement root resorption > inflammatory root resorption > surface root resorption > internal root resorption.

Apical root resorption during orthodontic treatment with clear aligners: A retrospective study using cone-beam computed tomography.

INTRODUCTION: We aimed to investigate the incidence and severity of orthodontically induced inflammatory root resorption (OIIRR) on maxillary incisors with clear aligner therapy using cone-beam computed tomography and to identify possible risk factors. METHODS: The root lengths of maxillary incisors were measured on orthogonal images from pretreatment and posttreatment cone-beam computed tomography examinations of 160 patients who received comprehensive orthodontic treatment with clear aligners. RESULTS: Mean absolute reductions in root length varied between 0.47 ± 0.61 mm and 0.55 ± 0.70 mm and were not significantly different between maxillary central and lateral incisors. The prevalence of severe OIIRR, defined as both maxillary central incisors experiencing greater than a 25% reduction in root length, was found to be 1.25%. Potential risk factors included sex, malocclusion, crowding, and posttreatment approximation of apices to the cortical plates. Race, interproximal reduction, previous trauma to the teeth, elastics, age, treatment duration, and pretreatment approximation of apices to the cortical plates did not significantly affect the amount of OIIRR. CONCLUSIONS: Comprehensive treatment with clear aligners resulted in minimal root resorption. Sex, malocclusion, crowding, and posttreatment approximation to the cortical plates significantly affected the percentage of change in root length. Posttreatment approximation of root apices to the palatal cortical plate showed the strongest association for increased OIIRR.

Association of sickle cell haemoglobinopathies with dental and jaw bone abnormalities.

OBJECTIVE: To estimate the association between sickle cell anaemia and trait with dental and jaw bone abnormalities. SUBJECTS AND METHODS: Subjects (n = 369) were allocated to three groups: sickle cell anaemia, trait and control. Dental shape, number, size and position and changes in pulp chamber, root and periapex were analysed by intra-oral periapical radiographs. Integrity of lamina dura, quality of cancellous bone and bone trabeculation were also evaluated. Prevalence ratios (PR) were calculated (α = 0.05). RESULTS: Sickle cell anaemia had higher prevalence (PR:8.31) and number of teeth (PR:13.40) with external resorption; higher number of teeth with pulp calcification; partial and total loss of lamina dura; and higher prevalence of changes in trabecular structure of maxilla (PR:6.45) and mandible (PR:5.34). Sickle cell trait showed higher prevalence (PR:1.26) and higher number of teeth (PR:1.98) with partial loss of lamina dura; higher number of teeth with hypercementosis, changes in shape, size, periapex, total loss of lamina dura; and higher prevalence of changes in mandibular trabecular bone (PR:1.43). CONCLUSION: Pulp calcification and external resorption of the root were the most frequent dental alterations in sickle cell anaemia group, while in trait was higher frequency of changes in shape, size, periapex and root. Jaw bone changes were most prevalent in both homozygous and heterozygous subjects.