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.
CONCLUSIONS: 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.

Dental trauma is one of the most common injuries encountered in the younger population. This can have a long-term impact on the patient\'s overall quality of life as they may have to deal with the sequelae of these injuries for years to come. Young boys experience dental trauma more frequently than young girls and one of the most common outcomes of these injuries are fractured teeth. This first paper in a two-part review series aims to provide an overview of dental trauma followed by a discussion on management of fractured teeth, associated pulpal complications and resorption. These can be uncomplicated fractures involving enamel and/or dentine, or complicated fractures involving enamel, dentine and pulp. They can involve the crown, the crown and root together, or present solely as root fractures. Pulpal complications can lead to pulp necrosis or pulp canal obliteration. Resorption can be internal or external, inflammatory, or replacement type. The management of each of these injuries begins with a thorough assessment followed by initiating emergency treatment to stabilise the presenting condition. This is followed by a long-term treatment plan which aims to address the patients\' aesthetic and functional requirements and provide the patient with the most suitable treatment outcome in the hope to improve their sense of wellbeing and overall quality of life.

The dentition is critical to animal survival and teeth are present in modern vertebrates including teleost fish, sharks, amphibians, mammals and reptiles. The developmental processes that give rise to teeth are not just preserved through evolution but also share high level of similarity with the embryogenesis of other ectodermal organs. In this review we go beyond the embryonic phase of tooth development to life-long tooth replacement. We will address the origins of successional teeth, the location of putative tissue-resident stem cells, how de novo tooth formation continues throughout life and how teeth are shed in a spatially and temporally controlled manner. We review the evidence that the dental epithelium, which is the earliest recognizable dental structure in the reptilian dentition, serves as a putative niche for tissue-resident epithelial stem cells and recent molecular findings from transcriptomics carried out in reptilian dentitions. We discuss how odontoclasts resorb the primary tooth allowing eruption of the successional tooth. The reptiles, particularly lizards, are emerging as some of the most accessible animals to study tooth replacement which has relevance to evolution of the dentition and human dental disorders.

The study aim was to assess the volumetric, linear, and morphological changes of the maxillary incisor, canine, and premolar roots following Le Fort I osteotomy. Sixty patients (585 teeth) were included retrospectively from among individuals who underwent combined orthodontics and orthognathic surgery. The study group comprised 30 patients who underwent orthodontics and one-piece Le Fort I osteotomy, while the control group consisted of 30 patients who underwent orthodontics and bilateral sagittal split osteotomy but no maxillary surgery. CBCT scans were obtained at four time points: preoperative, 6 months, 1 year, and 2 years postoperative. A fully automated three-dimensional evaluation protocol was utilized to assess root changes of the maxillary teeth. Significant differences in the apical and middle parts of the teeth were observed between the study and control groups at 1 and 2 years postoperative, with greater percentage changes in the study group (all P < 0.05). Greater root remodelling in the canines, first and second premolars was observed in the study group (all P < 0.005). Spearman correlation analysis indicated a positive relationship between root remodelling and maxillary advancement, with larger advancements contributing to increased root remodelling in the apical and middle root parts (both P < 0.05). These findings can be valuable for surgeons and orthodontists in evaluating root changes.

Tooth resorption refers to the loss of the organic and inorganic components of tooth structure by clastic cells. The complex and multifaceted nature of its aetiology, along with the several classification schemes published in the area, are likely to create confusion amongst researchers and clinicians, and may lead to compromised treatment decisions. Therefore, this paper will categorise and address tooth resorption based on aetiology in order to help clinicians diagnose and filter treatment options based on the pathophysiology of the resorption at hand. With recent advancements in the literature, the purpose of this paper is to provide clinicians with a current, clinically relevant summary of the various forms of tooth resorption, with a focus on aetiologically driven treatment strategies and suggestions that facilitate their recognition, diagnosis and management.

Tooth resorption (TR) is one of the most common dental diseases of cats. It is a painful condition leading to tooth loss. The etiology of TR remains unclear, but old age, breed, other oral and dental diseases, and environmental factors are suspected predisposing factors. In our study, we used part of the data from the extensive feline health online survey of 8115 Finnish cats. As TR is difficult to detect and as the feline health survey included diagnoses defined by both veterinarians and the owners, we limited our study to a subpopulation of cats diagnosed with oral or dental disease by a veterinarian and had dental examination or surgery under sedation (n=944). We utilized case-control study analysed by multivariable logistic regression to determine the risk factors and breed variation of feline TR. The 202 cats diagnosed with TR were defined as TR cases and the remaining 742 cats as controls. The frequency of veterinarian-diagnosed TR was 3.9% in the health survey data (316/8115) and 21% in the subpopulation (202/944). The risk of TR increased with age (14.7% in youngest and 25.3% in oldest age group). Our finding that TR was significantly associated with gingivitis or periodontitis in cats that had also calculus (OR: 2.49 and 3.70, respectively) suggests that inflammatory changes caused by calculus increase the risk of TR. We found that Cornish Rex, European, and Ragdoll are at higher risk for TR (OR: 2.44, 2.98 and 2.90, respectively). Exotic-Persians breed group had lower risk (OR: 0.28). TR was not observed in Turkish van or Devon Rex. The differences between breeds highlight a genetic contribution. In addition, female cats that had food available constantly had significantly less TR than female cats that had feeding times (OR: 0.44). The underlying reasons for this remain unexplained in our study.

OBJECTIVE: Pre-eruptive intramural resorption (PEIR) is defined as an abnormal, well-circumscribed radiolucency within the coronal dentin of the tooth, which is often overlooked in plain radiographs. This study aimed to investigate the prevalence of PEIR and its related factors using cone-beam computed tomography (CBCT).
METHODS: CBCT images of 590 unerupted teeth were evaluated for the presence of PEIR, location of PEIR, number of lesions in the affected tooth, PEIR score, tooth angulation, tooth position, and pericoronal space. Binary logistic tests were used to analyze the association between the characteristics of PEIR and the patient\'s demographic data and related factors.
RESULTS: The tooth prevalence of PEIR was 13.6% among unerupted teeth. However, it was noteworthy that 19.2% of the unerupted teeth with PEIR were planned to be kept. PEIR was significantly associated with transverse (p = 0.020), inverted-angulated (p = 0.035), and centrally-positioned teeth (p = 0.043). The severity of PEIR was more pronounced in teeth with distal (p = 0.019), lingual (p = 0.023), or inverted-angulated (p = 0.040) positions, and in the absence of pericoronal space (p = 0.036).
CONCLUSIONS: PEIR should be suspected in transverse, inverted-angulated, centrally positioned unerupted teeth, particularly in molars, with no pericoronal space. Further monitoring through CBCT is recommended in such cases.
CONCLUSIONS: The management of unerupted teeth does not always involve surgical removal. Instead, they could be utilized for artificial eruption or tooth transplantation. The present study emphasizes the significance of early detection of PEIR. Clinical recommendations for screening PEIR in unerupted teeth are also proposed, which can be applied to routine plain radiographs.

OBJECTIVE: Root resorption in permanent teeth is a common pathological process that often follows dental trauma or orthodontic treatment. More rarely, root resorption is a feature of genetic disorders and can help with diagnosis. Thus, the present review aims to determine which genetic disorders could induce pathological root resorptions and thus which mutated genes could be associated with them.
METHODS: We conducted a systematic review following the PRISMA guidelines. Articles describing root resorptions in patients with genetic disorders were included from PubMed, Embase, Web of Science, and Google Scholar. We synthesized the genetic disorder, the type, severity, and extent of the resorptions, as well as the other systemic and oral symptoms and histological features.
RESULTS: The synthetic analysis included 25 studies among 937 identified records. We analyzed 21 case reports, three case series, and one cohort study. Overall, we highlighted 14 different pathologies with described root resorptions. Depending on the pathology, the sites of resorption, their extent, and their severity showed differences.
CONCLUSIONS: With 14 genetic pathologies suspected to induce root resorptions, our findings are significant and enrich a previous classification. Among them, three metabolic disorders, three calcium-phosphorus metabolism disorders, and osteolysis disorders were identified.

OBJECTIVE: To explore the genetic background and clinical phenotypes of multiple idiopathic cervical root resorption (MICRR) in a Chinese family.
METHODS: The proband and his three family members were clinically examined and had radiographs taken with a radiovisiography (RVG) system and CBCT to define the diagnosis of MICRR. Genomic DNA (gDNA) was extracted from peripheral blood samples of the patient, his father, mother and younger sister for whole exome sequencing (WES). The pathogenicity of rare variants with minor allele frequency (MAF) less than 0.005 were analysed following possible inheritance patterns, predicted results from 12 software programs, the American College of Medical Genetics (ACMG) 2015 criteria, and information from ClinVar, OMIM and HGMD databases as well as gene function.
RESULTS: The proband presented the typical MICRR phenotypes such as thin cervical pulp wall and apple core-like lesions in radiographs. Following the recessive inheritance pattern, WES analysis identified SHROOM2, SYTL5, MAGED1 and FLNA with a higher chance of causing MICRR. Four genes with compound heterozygous variants and another 27 genes with de novo variants either in autosomal-dominant or autosomal-recessive pattern were also found to have the potential pathogenicity.
CONCLUSIONS: A total of 35 novel potential pathogenic genes were found to be associated with MICRR from a Chinese family through WES. The new genetic background of MICRR may be helpful for clinical and molecular diagnosis.

OBJECTIVE: To estimate the relative diagnostic sensitivity and specificity of oral clinical examination, full-mouth dental radiography, and cone-beam CT for the detection of tooth resorption in cats, and to estimate the prevalence of tooth resorption in unowned, unsocialised cats in Denmark.
METHODS: Cadavers of 144 adult cats underwent an oral examination, full-mouth dental radiography, and cone-beam CT. Sensitivity and specificity of the three tests, along with the true prevalence, overall and stratified by sex and tooth location, were estimated using latent class methods.
RESULTS: We found cone-beam CT to be the superior image modality, with a sensitivity of 99.5% and a specificity of 99.8%. Dental radiography had a sensitivity of 78.9% and a specificity of 100%, and oral clinical examination had a sensitivity of only 36.0% and specificity of 99.9%. We estimated the prevalence of tooth resorption among unowned unsocialised cats in Denmark to be 40% of adult individuals, and 6.1% of teeth.
CONCLUSIONS: When dealing with tooth resorption, cone-beam CT can help the operator to find and treat affected teeth that could otherwise go undiagnosed. The prevalence of tooth resorption among unowned, unsocialised cats in Denmark does not appear to differ from other populations of cats.