A comparison of radiographically determined periapical healing and tooth survival outcomes of root canal (re)treatment performed in two care pathways within the United Kingdom Armed Forces

AIMS

To compare radiographic periapical healing and tooth survival outcomes of root canal (re)treatment performed within two care pathways (Routine Dental Care and Referred Treatment Pathway), in the United Kingdom Armed Forces (UKAF), and determine the effects of endodontic complexity on outcomes.

METHODOLOGY

This retrospective cohort study included 1466 teeth in 1252 personnel who received root canal (re)treatment between 2015 and 2020. General Dental Practitioners treated 661 teeth (573 patients) (Routine cohort), whilst Dentists with a Special Interest treated 805 teeth (678 patients) (Referred cohort). The latter group were graduates of an MSc programme in Endodontics with 4-8 years of postgraduation experience. Case complexity was retrospectively determined for each tooth using the endodontic component of Restorative Index of Treatment Need (RIOTN) guidelines. Periapical healing was determined using loose radiographic criteria. The data were analysed using chi-square tests, univariate logistic regression and Cox proportional hazards models.

RESULTS

A significantly (p < 0.0001) larger proportion of cases of low complexity had undergone root canal treatment within the Routine versus Referred cohort. The odds of periapical healing was significantly higher within the Referred versus Routine cohort, regardless of analyses using pooled (OR = 1.17; 95% CI: 1.11, 1.22) or moderate complexity (OR = 4.71; 95% CI: 2.73, 8.11) data. Within the Routine cohort, anterior teeth had higher odds of periapical healing than posterior teeth (OR = 1.13; 95% CI: 1.04, 1.22). The 60-month cumulative tooth survival was lower (p = 0.03) in the Routine (90.5%) than the Referred (96.0%) cohort. Within the Routine cohort, the hazard of tooth loss was higher amongst posterior teeth (HR = 4.03; 95% CI: 1.92, 8.45) but lower if posterior teeth had cast restorations (HR = 0.36; 95% CI: 0.19, 0.70). For the Referred cohort, posterior teeth restored with cast restoration (vs not) had significantly lower risk of tooth loss (HR = 0.21; 95% CI: 0.08, 0.55).

CONCLUSIONS

For UKAF patients, root canal (re)treatment provided within the Referred pathway was significantly more likely to achieve periapical healing and better tooth survival than those provided within the Routine pathway. Posterior teeth restored with an indirect restoration had a higher proportion of tooth survival. This study supported the utility of the endodontic component of RIOTN for assessing case complexity.

Antibiotic Over-Prescription by Dentists in the Treatment of Apical Periodontitis: A Systematic Review and Meta-Analysis

After pulp infection and necrosis, the passage of microbial antigens into the periapical space causes apical periodontitis (AP). Most of the clinical forms of AP can be managed without prescribing antibiotics, only with root canal treatment and abscess drainage or, where appropriate, tooth extraction. However, the scientific literature provides evidence of inappropriate antibiotic prescriptions by dentists in the management of apical disease.

OBJECTIVES

The aim of this systematic review and meta-analysis was to analyze the global pattern of antibiotic prescription in the treatment of apical disease.

METHODS

PRISMA Guidelines were followed to carry out this systematic review. The research question was as follows: What is the pattern of antibiotic prescription by dentists in the treatment of the different clinical forms of apical periodontitis? A systematic search was conducted on MEDLINE/PubMed, Wiley Online Database, Web of Science and Scopus. All studies reporting data about the pattern of antibiotic prescription by dentists in the treatment of apical disease were included. The meta-analyses were calculated using the Open Meta Analyst version 10.10 software. Random-effects meta-analyses were performed. The risk of bias was assessed using the Newcastle-Ottawa Scale. The certainty of evidence was assessed using GRADE.

RESULTS

The search strategy identified 96 articles and thirty-nine cross-sectional studies fulfilled the inclusion criteria. The overall percentage of antibiotic prescriptions by dentists in cases of symptomatic AP was 25.8%, and 31.5% in cases of asymptomatic AP with sinus tract present. The percentage of dentists prescribing antibiotics in cases of acute apical abscess with no/mild symptoms was 47.7%, whereas, in cases of acute apical abscess with moderate/severe symptoms, 88.8% of dentists would prescribe antibiotics. Endodontists prescribe antibiotics at a lower rate than general practitioners. The total risk of bias was considered moderate, and the final rating for the certainty of the evidence was low.

CONCLUSIONS

Dentists worldwide are over-prescribing antibiotics in the management of apical disease. It is necessary to improve antibiotic prescribing habits in the treatment of endodontic infections, as well as educational initiatives to encourage the rational and appropriate prescription of antibiotics in periapical diseases.

Magnetic resonance imaging in the diagnosis of periodontal and periapical disease

OBJECTIVES

Early pre-clinical inflammatory changes in periodontal and/or periapical lesions, which typically precede bone loss, are challenging to diagnose using ionizing-radiation-based imaging modalities. MRI provides relevant additional diagnostic information of inflammatory processes in soft and hard tissues. The aim of the present study is to undertake a systematic review of the literature on MRI in the diagnosis of periodontal and/or periapical disease.

METHODS AND MATERIALS

The PubMed/MEDLINE and Scopus bibliographic databases were searched (2000-2021) using the search string: ("MRI" or "magnetic resonance imaging") and ("periodontitis" or "periodontal" or "apical pathology" or "endodontic pathology" or "periapical" or "furcation" or "intrabony"). The search was limited to studies published in English. The studies were assessed independently by three reviewers, focusing on the MRI sequences, imaging modalities (radiographs, cone beam CT (CBCT), and MRI), disease definition, assessed parameters, and outcome measurements.

RESULTS

The search strategy yielded 34 studies, from which 13 were included. Overall, the findings of MRI were in agreement with CBCT. The studies showed that MRI provided diagnostic information of the hard and soft tissue components affected by periodontal and/or periapical disease with a fairly high sensitivity and specificity. However, the assessed parameters (e.g. MRI acquisition protocols, and disease definition) differed substantially.

CONCLUSIONS

The included studies indicate that the use of MRI in the diagnosis of periodontal and/or periapical disease is feasible and promising. More studies are needed to define the accuracy of this non-ionizing-radiation-based diagnostic modality, in the assessment of periodontal and/or periapical lesions.

Treatment outcome of surgical and non-surgical endodontic retreatment of teeth with apical periodontitis

AIMS

To evaluate and compare the treatment outcome of root-filled teeth with apical periodontitis treated either non-surgically or by endodontic microsurgery, and to assess the influence of an intra-radicular post, clinical and demographic factors.

METHODOLOGY

Clinical and radiological data from 1157 patients with apical periodontitis in previously root-filled teeth treated by postgraduate students at the Department of Endodontics, University of Oslo, between September 2010 and January 2020 with recall data at least 11 months from completion were studied. Surgical cases were scored using the Rud/Molven criteria and grouped into success, uncertain or failure at control. Non-surgical cases were scored with the periapical index (PAI) and similarly grouped into success, uncertain or failure at control. Chi-square analyses were used for comparison of subgroups of teeth treated and logistic regression analyses for assessment of the influence of clinical variables.

RESULTS

Non-surgical retreatment was performed on 351 teeth and 107 teeth were treated with endodontic microsurgery, with overall success rates of 65.5% and 77.6%, respectively. The difference was statistically significant. Teeth with an intra-radicular post treated non-surgically (n=30) were successful in 73.3% of cases, whereas teeth with intra-radicular post treated with endodontic microsurgery (n=30) had a lower, 66.7% success rate. The distribution of tooth groups (anterior, premolar and molar) differed significantly between surgical and non-surgical cases, with maxillary anterior and premolar teeth more often treated surgically. Non-surgical retreatment cases were significantly influenced by patients' age (older patients had poorer outcome) and preoperative PAI score (negatively correlated with outcome). Surgical cases were not significantly influenced by the factors studied here.

CONCLUSIONS

The tooth type differed significantly for teeth treated by surgical versus non-surgical methods. Microsurgical treatment with apicectomy and retrograde filling showed significantly better treatment results than non-surgical retreatment of teeth with apical periodontitis, whereas treatment outcome in teeth with posts after non-surgical treatment tended to be better than after surgical treatment. Outcome of non-surgical retreatment was negatively influenced by older age and higher preoperative PAI score.

Nonmalignant nonendodontic lesions mimicking periapical lesions of endodontic origin: A systematic review

The objective of the study is to describe the clinical and radiographic features of nonmalignant nonendodontic periapical lesions (NMNPLs) mimicking lesions of endodontic cause. Five electronic databases, PubMed, Web of Science, Scopus, Embase, and ProQuest, were searched (till July 2021) for case reports, case series, and cross-sectional studies, in English language, reporting NMNPLs, which were clinically and/or radiographically simulating periapical pathosis of endodontic origin. Data extraction was done followed by quality assessment of the included articles using the Joanna Briggs Institute tool for case reports and case series. Seventy-three articles comprising 176 cases were included. Sixty-one articles were case reports, nine articles were case series, and three articles were retrospective studies. Male:female ratio was 1.5:1, with a higher prevalence of lesions occurring in the fourth and second decades of life. The majority of the lesions were located in the anterior maxilla. Radiographically, most of the lesions were well defined, radiolucent, and unilocular. Histologically, 29 different types of NMNPLs were reported, with the most common ones being odontogenic keratocyst (25.56%), dentigerous cyst (17.61%), ameloblastoma (11.36%), nasopalatine duct cyst (10.79%), and adenomatoid odontogenic tumor (5.68%). As all the included studies were observational, the quality of available evidence is considered low. Various features such as loss of tooth vitality, history of trauma, and presence of periapical radiolucency may lead to misdiagnosis of NMNPLs and must be considered during diagnosis of the lesion. Additional imaging modalities and histopathology can aid in right diagnosis.

Endodontic Disinfection for Orthograde Root Canal Treatment in Veterinary Dentistry

Pulp debridement and disinfection in the pulp cavity is a critical step in achieving a successful root canal therapy. Microorganisms remaining in the root canal system after endodontic treatment are a main cause of root canal failure. The challenges faced in endodontic disinfection include the complex anatomy of the root canal system, the existence of a biofilm within the root canal, and the creation of a problematic smear layer during instrumentation of the canal. Historically, sodium hypochlorite and ethylenediaminetetraacetic acid have been utilized as irrigants and still remain as the most effective disinfectants due to their synergistic abilities to eradicate microorganisms, dissolve necrotic debris, and remove the smear layer and biofilm. This article addresses challenges in endodontic disinfection, objectives of endodontic irrigants, properties of an ideal irrigant, currently used irrigants, and irrigant delivery systems utilized in veterinary dentistry.

Association between Endodontically Treated Maxillary and Mandibular Molars with Fused Roots and Periapical Lesions: A Cone-beam Computed Tomography Cross-sectional Study

INTRODUCTION

Fused root variations of the root canal system increase the complexity of the inner root canal system anatomy. The aim of the present study was to determine, in in vivo conditions, the proportion of periapical lesions in association with endodontically treated maxillary and mandibular molars with fused roots presenting previous root canal treatment by assessing preexisting data via cone-beam computed tomographic volumes.

METHODS

A total of 1160 CBCT scans with an overall sample of 20,836 teeth were screened. A global count of 3701 maxillary molars and mandibular second molars were included in the study. The Cohen kappa test and interclass correlation coefficient tested the intra- and interrater reliability, respectively. The percentage of periapical lesions associated with molars with or without root fusion was determined. Proportions were expressed with 95% confidence intervals (CIs). The z test for proportions was used to analyze differences between subgroups, and an odds ratio was calculated in order to understand the association between periapical lesions and root configuration.

RESULTS

Fused molars presented a prevalence of periapical lesions in endodontically treated teeth of 74.0% (95% CI, 65.2%-82.8%), whereas nonfused molars had a proportion of periapical lesions in root canal-treated teeth of 69.5% (95% CI, 65.2%-73.8%; P > .05). Endodontically treated molars with fused roots presented with 1.3 higher odds of being associated with periapical lesions than endodontically treated molars with nonfused roots.

CONCLUSIONS

A tendency of a higher proportion of periapical lesions was found in the fused rooted molars with a history of root canal treatment when compared with nonfused teeth; however, no statistically significant difference was noted.

Genetic and Epigenetic Characterization of Pulpal and Periapical Inflammation

Pulpal and periapical diseases affect a large segment of the population. The role of microbial infections and host effector molecules in these diseases is well established. However, the interaction between host genes and environmental factors in disease susceptibility and progression is less well understood. Studies of genetic polymorphisms in disease relevant genes have suggested that individual predisposition may contribute to susceptibility to pulpal and periapical diseases. Other studies have explored the contribution of epigenetic mechanisms to these diseases. Ongoing research expands the spectrum of non-coding RNAs in pulpal disease to include viral microRNAs as well. This review summarizes recent advances in the genetic and epigenetic characterization of pulpal and periapical disease, with special emphasis on recent data that address the pathogenesis of irreversible pulpal pathosis and apical periodontitis. Specifically, proinflammatory and anti-inflammatory gene expression and gene polymorphism, as well as recent data on DNA methylation and microRNAs are reviewed. Improved understanding of these mechanisms may aid in disease prevention as well as in improved treatment outcomes.

C1 Silencing Attenuates Inflammation and Alveolar Bone Resorption in Endodontic Disease

INTRODUCTION

Endodontic disease, 1 of the most prevalent chronic infectious diseases worldwide, occurs when the dental pulp becomes infected and inflamed, leading to bone destruction around the tooth root, severe pain, and tooth loss. Although many studies have tried to develop therapies to alleviate the bone erosion and inflammation associated with endodontic disease, there is an urgent need for an effective treatment.

METHODS

In this study, we used a gene-based therapy approach by administering recombinant adeno-associated virus (AAV)-mediated Atp6v1c1 knockdown to target both periapical bone resorption and inflammation in the mouse model of endodontic disease.

RESULTS

The results showed that Atp6v1c1 knockdown is simultaneously capable of reducing bone resorption by 70% through impaired osteoclast activation, inhibiting inflammation by decreasing T-cell infiltration in the periapical lesion by 75%, and protecting the periodontal ligament from destruction caused by inflammation. Notably, AAV-mediated gene therapy of Atp6v1c1 knockdown significantly reduced proinflammatory cytokine expression, including tumor necrosis factor α, interleukin 1α, interleukin 17, interleukin 12, and interleukin 6 levels in periapical tissues caused by bacterial infection. Quantitative real-time polymerase chain reaction revealed that Atp6v1c1 knockdown reduced osteoclast-specific functional genes (ie, Ctsk) in periapical tissues.

CONCLUSIONS

Our results showed that AAV-mediated Atp6v1c1 knockdown in periapical tissues slowed endodontic disease progression, prevented bone erosion, and alleviated inflammation in the periapical tissues and periodontal ligament potentially through regulation of toll-like receptor signaling, indicating that targeting Atp6v1c1 may facilitate the design of novel therapeutic approaches to reduce inflammation and bone erosion in endodontic disease.

Immunological profile of teeth with inflammatory periapical disease from chronic liver disease patients

AIM

To evaluate the mRNA expression levels of the cytokines interferon-γ, tumour necrosis factor-α, interleukin (IL)-1β, IL-10, IL-6, VEGF, and AGT and the chemokine CCL2/MCP-1 in periapical interstitial fluid associated with root canal infections before and after the reduction of the bacterial load using a cleaning procedure.

METHODOLOGY

The case group included 11 patients with chronic liver disease, and the control group included 11 healthy patients. Clinical samples were taken from teeth with pulp necrosis. After cleaning and drying the canal, three paper points were introduced into the root canal and passed through the root apex (2 mm) into the periapical tissues for 1 min. The samples were collected immediately after root canal cleaning and 7 days later to characterize those gene expression levels using real-time PCR. The data were subjected to the Shapiro-Wilk and the Wilcoxon tests.

RESULTS

In the control group, significantly increased expression of the pro-inflammatory cytokines IFN-γ and TNF-α was observed in teeth with restrained bacterial loads (day 7) (P < 0.05). Similarly, increased TNF-α expression was found on day 7 in the liver group (P < 0.05). No differences were observed in the expression levels of the IL-1β, IL-10 and, IL-6, MCP-1/CCL-2 and VEGF between the first collection (day 0) and second collection (day 7), over time in either group.

CONCLUSION

Chronic liver disease patients exhibited sufficient immunologic ability showing relatively similar expression levels of cytokines, chemokines and angiogenic factors in periapical samples compared with the responses from no-chronic liver disease patients. The outcomes of this study suggest that liver impairment did not compromise the periapical immune response.

Frequency of Root Canal Treatment among Patients Attending a Teaching Dental Hospital in Dammam, Saudi Arabia

OBJECTIVE

The purpose of the study was to evaluate the frequency and status of root canal-treated teeth in patients treated at the College of Dentistry, University of Dammam in the Eastern Province of Saudi Arabia.

MATERIALS AND METHODS

A total of 3701 patients visited the clinics during the study period. Through the use of radiographs, 161 patients were initially selected who had endodontically treated teeth. However, after applying the inclusion criteria, the total number of eligible cases was reduced to 155. Patients were divided into three groups according to age (children 1-12 years, adults 13-65 years and geriatrics >65 years).

RESULTS

On average, each patient had 2.28 ± 1.88 root canal-treated teeth and 24.02 ± 5.03 teeth without root canal treatment. The average number of endodontically treated teeth increased with an increase in age. The adult group showed the highest number of root-filled teeth 314 (93.4%). Of the 336 endodontically treated teeth, only 75 (22.3%) teeth exhibited periapical radiolucency. First molars (28.43-36.36%) and second premolars (20.1-27.27%) were the most frequently root-filled teeth in both jaws, followed by the first maxillary premolars (11.76%). Periapical lesions showed an almost similar pattern with the highest number of radiolucencies found in the first molars in both jaws (29.3-33.3%) followed by the second premolars in the mandible (30.6%) and first premolars in both jaws (20.8-25%).

CONCLUSION

The first molars and second premolars were the most frequently root-filled teeth in both jaws, followed by maxillary first premolars. Periapical lesions showed an almost similar pattern among teeth with a higher number of radiolucencies found in the first molars in both jaws, followed by the second premolars in the mandible and the first premolars in both jaws.

Post-processing open-source software for the CBCT monitoring of periapical lesions healing following endodontic treatment: technical report of two cases

OBJECTIVES

To describe the use of open-source software for the post-processing of CBCT imaging for the assessment of periapical lesions development after endodontic treatment.

METHODS

CBCT scans were retrieved from endodontic records of two patients. Three-dimensional virtual models, voxel counting, volumetric measurement (mm³) and mean intensity of the periapical lesion were performed with ITK-SNAP v. 3.0 software. Three-dimensional models of the lesions were aligned and overlapped through the MeshLab software, which performed an automatic recording of the anatomical structures, based on the best fit. Qualitative and quantitative analyses of the changes in lesions size after treatment were performed with the 3DMeshMetric software.

RESULTS

The ITK-SNAP v. 3.0 showed the smaller value corresponding to the voxel count and the volume of the lesion segmented in yellow, indicating reduction in volume of the lesion after the treatment. A higher value of the mean intensity of the segmented image in yellow was also observed, which suggested new bone formation. Colour mapping and "point value" tool allowed the visualization of the reduction of periapical lesions in several regions.

CONCLUSIONS

Researchers and clinicians in the monitoring of endodontic periapical lesions have the opportunity to use open-source software.

Association between Odontogenic Conditions and Maxillary Sinus Disease: A Study Using Cone-beam Computed Tomography

INTRODUCTION

The maxillary sinus can be affected by dental infections because of its close relationship with upper teeth. This study aimed to assess the most common types of maxillary sinus alterations and to associate them with odontogenic conditions using cone-beam computed tomographic (CBCT) images.

METHODS

CBCT scans of 400 patients showing sinus disease in 1 or both maxillary sinuses were evaluated. Sinus alteration was considered as follows: generalized or localized mucosal thickening (MT), maxillary sinusitis (MS), and retention cysts (RCs). The odontogenic conditions evaluated were inadequate endodontic treatment, periapical lesions, and periodontal bone loss. Descriptive and multiple logistic regression analyses were performed.

RESULTS

Sinus diseases were observed in 85.9% of the maxillary sinuses. The most prevalent condition was generalized MT (65.2%) followed by localized MT (24.8%), MS (6.4%), and RCs (3.6%). Generalized MT was more related to males (odds ratio = 1.45, P < .05) and periodontal bone loss (P < .05). Localized MT was associated with periapical lesions (odds ratio = 3.09, P < .05) and showed a close anatomic relationship between teeth and the sinus floor (odds ratio = 2.77, P < .05). There were no statistically significant associations between either MS or RCs and the odontogenic conditions studied.

CONCLUSIONS

The most prevalent sinus diseases were the generalized and localized MT, and they were the only ones related to odontogenic conditions (periodontal bone loss and periapical lesions, respectively). We emphasize that CBCT imaging is an appropriate method for evaluating the maxillary sinus findings and their associated odontogenic conditions.

根尖周病中锥形束CT与根尖片识别病损差异的研究进展

With the development of medical radiography, cone beam computed tomography (CBCT) has been widely used in stomatology because of its numerous advantages, such as adequate spatial resolution, low radiation, undistorted three- dimensional tissue information, and good applicability for hard tissue imaging. Traditional periapical radiography is based on two-dimensional image which displays the three-dimensional object and its surrounding structures. Periapical radiography can only show the overlapping mesio-distally direction bone destruction, can't show buccolingual direction bone destruction. As a kind of three-dimensional imaging technology, CBCT can show three-dimensional structure of the organization from sagittal, coronal and axial direction, to overcome the defect of two-dimensional image such as overlap and deformation. CBCT has a unique advantage than periapical radiography in the diagnosis and treatment for periapical disease. This review will summarize the difference between CBCT and periapical radiography in the periapical disease.

Clinical and radiographic assessment of the efficacy of calcium silicate indirect pulp capping: a randomized controlled clinical trial

The aims of this study were to assess the effectiveness of calcium silicate cement (Biodentine) versus glass ionomer cement (GIC; control group) as indirect pulp capping materials in patients with reversible pulpitis and to compare the effectiveness of cone beam computed tomography (CBCT) versus periapical (PA) radiographs in detecting PA changes at baseline (T0) and at 12 mo (T12) postoperatively. Seventy-two restorations (36 Biodentine, 36 Fuji IX) were placed randomly in 53 patients. CBCT/PA radiographs were taken at T0 and T12. Two calibrated examiners assessed the presence/absence and increase/decrease in the size of existing PA radiolucencies under standardized conditions. The Kappa coefficient evaluated statistically the effectiveness of CBCT versus PA radiographs in detecting PA changes. Chi-square/Mann-Whitney tests were used to evaluate the association between PA changes in CBCT with various clinical measures. Significance was predetermined at α = 0.05. Clinical success rates for Biodentine and Fuji IX GIC were 83.3%. CBCT was significantly more effective in detecting PA radiolucencies compared with radiographs (P = 0.0069). Of the teeth, 65.4% and 90.4% were deemed healthy using CBCT and PA radiographs, respectively, at T12. Healing/healed rates were 17.3%/0%, while new/progressed radiolucency were 30.8%/9.6% with CBCT/PA radiographs, respectively. Seventy-one percent of healed lesions had received Biodentine; 88% of new/progressed lesions received Fuji IX GIC. Teeth presenting with an initial CBCT PA lesion had a failure rate of 63%, whereas teeth with no initial lesion had a failure rate of 16%. Although no statistically significant difference was detected in the clinical efficacy of Biodentine/Fuji IX when used as indirect pulp capping materials in patients with reversible pulpitis, CBCT showed a significant difference in that most healed CBCT lesions had received Biodentine while most that did not heal received Fuji IX. Longer-term follow-up is needed to establish their effect on the healing dynamics of PA tissues (ClinicalTrials.gov NCT02201641).

Periapical lesions are not always a sequelae of pulpal necrosis: a retrospective study of 1521 biopsies

AIM

To record the incidence of lesions that were not the sequelae of pulpal necrosis (non-SPN) amongst 1521 biopsies of periapical lesions submitted with a clinical diagnosis of a sequelae of pulpal necrosis (SPN).

METHODOLOGY

A retrospective study of 1521 biopsy request forms of specimens submitted for histopathological examination with a clinical diagnosis 'periapical inflammation', 'periapical abscess', 'periapical granuloma' or 'periapical cyst' during an arbitrarily selected 14-year period was undertaken. Gender and age of the patient, site and maximum diameter of the lesion, symptoms, inclusion of the final diagnosis in the differential diagnosis and specialty of the clinician submitting the biopsy material were recorded in each case. The final diagnosis for each case was extracted from the pathology report, and two groups were formed, SPN and non-SPN lesions. Differences between the respective features of SPN and non-SPN cases were analysed with Yate's chi-square test and t-test (significance level P < 0.05) RESULTS: In 52 of the 1521 cases examined (3.42%), the histological diagnosis was not consistent with a SPN. In most non-SPN cases, the histopathological diagnosis was not included in the differential diagnosis. The keratocystic odontogenic tumour [odontogenic keratocyst (OKC)] was the most frequent non-SPN lesion (34.62%). Other, yet less frequent, non-SPN lesions included glandular odontogenic cysts, lateral periodontal cysts, central ossifying fibromas as well as malignancies (metastatic carcinomas and Langerhans cell histiocytosis).

CONCLUSIONS

Non-SPN lesions appeared in the periapical region mimicking a SPN, although rarely. Most of them were developmental cysts, in particular OKCs, but odontogenic tumours, such as ameloblastoma, or malignant lesions were also diagnosed. Histological examination of tissue harvested from periapical lesions should be performed, in particular when those lesions are large.

Periapical disease and bisphosphonates induce osteonecrosis of the jaws in mice

Osteonecrosis of the jaw (ONJ) is a well-recognized complication of antiresorptive medications, such as bisphosphonates (BPs). Although ONJ is most common after tooth extractions in patients receiving high-dose BPs, many patients do not experience oral trauma. Animal models using tooth extractions and high BP doses recapitulate several clinical, radiographic, and histologic findings of ONJ. We and others have reported on rat models of ONJ using experimental dental disease in the absence of tooth extraction. These models emphasize the importance of dental infection/inflammation for ONJ development. Here, we extend our original report in the rat, and present a mouse model of ONJ in the presence of dental disease. Mice were injected with high dose zoledronic acid and pulpal exposure of mandibular molars was performed to induce periapical disease. After 8 weeks, quantitative and qualitative radiographic and histologic analyses of mouse mandibles were done. Periapical lesions were larger in vehicle-treated versus BP-treated mice. Importantly, radiographic features resembling clinical ONJ, including thickening of the lamina dura, periosteal bone deposition, and increased trabecular density, were seen in the drilled site of BP-treated animals. Histologically, osteonecrosis, periosteal thickening, periosteal bone apposition, epithelial migration, and bone exposure were present in the BP-treated animals in the presence of periapical disease. No difference in tartrate-resistant acid phosphatase (TRAP)+ cell numbers was observed, but round, detached, and removed from the bone surface cells were present in BP-treated animals. Although 88% of the BP-treated animals showed areas of osteonecrosis in the dental disease site, only 33% developed bone exposure, suggesting that osteonecrosis precedes bone exposure. Our data further emphasize the importance of dental disease in ONJ development, provide qualitative and quantitative measures of ONJ, and present a novel mouse ONJ model in the absence of tooth extraction that should be useful in further exploring ONJ pathophysiological mechanisms.