Incisor Malocclusion Research Articles

Radiological, histological and clinical side effects of incisor trimming in rabbits.

Incisor malocclusion in rabbits (Oryctolagus cuniculus) is a common clinical problem seen in general practice. Given that the growth rate is about 2 mm per week, a lack of wear quickly leads to feeding difficulties and soft tissue injuries. Therefore, pathologically elongated incisors must be shortened every three to six weeks. The goal of this study was to assess the potential adverse effects on dental and periodontal tissues associated with the three most commonly used trimming methods: nail cutter, diamond-coated cutting disc and diamond burr. The left mandibular incisor of 28 healthy New Zealand rabbits was subjected to four trimmings with one of the three cutting methods. After the fattening period, the mandibles were collected and both mandibular incisors were investigated on dental radiographs, micro-computed tomography scans and histological sections. Dental and periodontal tissue changes were evaluated. This study allowed a more accurate statement of the potential short-term adverse effects of the three trimming methods. At the clinical level, the nail cutter caused the formation of an irregular occlusal surface with sharp edges. Both engine-drive methods allowed the attainment of a smooth surface but the disc was less accurate. Histological evaluation revealed that the primary modifications, including coronal fractures, periodontal ligament widening and inflammation, reparative osteodentine, paracementosis and biofilm accumulation, were found in the nail cutter group.

Clinical condition of teeth and dentition in children and adolescents with cerebral palsy

BACKGROUND: Literature and statistical data reveal the increasing incidence of psychoneurological diseases (PND) and thus dental pathologies with PND in children and adolescents. Thus, the authors examined the structures and frequency of dental defects and deformities in patients with PND. Children and adolescents with PND aged 718 years are at high risk for the development of dental pathologies, and oxidative stress and immune system disorder present major associations with the pathogenesis of dental pathologies.
 AIM: To determine the structure and frequency of dental defects and deformities in children and adolescents with PND and study the etiopathogenetic factors and mechanism of pathology formation to guide the development of preventive measures.
 MATERIAL AND METHODS: The study comprehensively analyzed the data of 299 patients aged 718 years, of which 143 were diagnosed with PND based on the International Classification of Disease 10th Revision (main group; МG) and 156 somatically healthy patients with dental pathologies (control group; CG). The participants were divided into two subgroups: 75 patients aged 712 years (52.44%; МG-1) and 68 patients aged 1318 years (47.55%; МG-2) from the main group (MG) and 65 (41.66%; CG-1) and 91 (58.33%; CG-2) patients from the CG of the respective age groups.
 RESULTS: The incidence rates of caries in the temporary teeth of MG-1 and CG-1 were 97.33% and 84.61% and in the permanent teeth of MG-2 and CG-2 were 95.58 and 87.91%, respectively. In the pre-eruptive period, the rates of dental lesions were as follows: hypoplasia, 20.97%; impaired dentition, 49.65%; primary adentia, 47.55%; anomalies of the completeness of teeth, 64.33%; endemic fluorosis of teeth, 2.79% in patients with PND; and 12.17%, 12.17%, 26.92%, 11.53%, and 0.6% in children and adolescents in CG, respectively (p 0.0001): disappearance of dental hard tissues, 9.09%; dental injuries, 24.47%; enamel necrosis, 7.7%; enamel erosion, 17.5% of patients with MG. In children and adolescents of CG, only tooth trauma was noted in 7.7% and enamel necrosis in 1.3%. In patients with PND, 49.6% had distal occlusion; 37.8%, cross occlusion; 31.6%, neutral occlusion; 29.9%, deep incisor occlusion; 25.9%, deep incisor malocclusion; 54.5%, narrowing of the lower dentition; 43.3%, crowding of teeth in the lower jaw; 26.6%, diastemas; and tremas, 23.8%.
 CONCLUSION: Non-carious lesions of the teeth and a shift in the timing of the development of temporary and permanent teeth are more common in MG than in CG and lead to impaired dental anatomy and disrupt the aesthetics of smiles, speech, etc. Moreover, hypertrophic gingivitis and local periodontitis were characteristic of children with severe PND, who are at high risk for dental pathologies associated with oxidative stress and genetically related immune system disorders, especially in older children with PND.

Incisor Malocclusion Using Cut-out Method and Convolutional Neural Network

Malocclusion is a condition of misaligned teeth or irregular occlusion of the upper and lower jaws. This condition leads to poor performance of vital functions such as chewing. A common procedure in orthodontic treatment for malocclusion is a conventional diagnostic procedure where a dental health professional takes dental x-rays to examine the teeth to diagnose malocclusion. However, the manual orthodontic diagnostic procedure by dental experts to identify malocclusion is time-consuming and vulnerable to expert bias that results in delayed treatment completion time. Recently, artificial intelligence technology in imageprocessing has gained attention in orthodontics treatment, accelerating the diagnosis and treatment process. However, several issues concerning the dental images as input of the classification model may affect the accuracy of the classification. In addition, unstructured images with varying sizes and the problem of a machine learning algorithm that does not focus on the region of interest (ROI) for incisor features bring challenges in delivering the treatment. This study has developed a malocclusion classification model using the cut-out method and Convolutional Neural Network (CNN). The cut-out method restructures the input images by standardising the sizes and highlighting the incisor sections of the images which assisted the CNN in accurately classifying the malocclusion. From the results, the implementation of the cut-out method generates higher accuracy across all classes of malocclusion compared to the non-implementation of the cut-out method.

The Challenging Biomechanics in a Maxillary Lateral Incisor and Canine Transposition Malocclusion

The Challenging Biomechanics in a Maxillary Lateral Incisor and Canine Transposition Malocclusion

Veterinary care of hamsters. Part 2: diagnostics, diseases

Hamsters are very popular pets in the UK and owner expectations regarding advice and treatment for their pets are increasing. Hamsters are frequently seen in general veterinary practice and may be presented for routine procedures such as health checks, but are more often presented for treatment of illnesses. As hamsters are prey species they instinctively hide any signs of illness and so often present later into a disease process. Conditions frequently observed in hamsters include diarrhoea, skin wounds, incisor malocclusion, weight loss and neoplasia.

Measurement of forces and moments around the maxillary arch for treatment of a simulated lingual incisor and high canine malocclusion using straight and mushroom archwires in fixed lingual appliances.

An Orthodontic SIMulator (OSIM) was used to investigate the propagation of forces and moments around a simulated archform for a gingival displaced canine and lingual displaced lateral incisor using fixed lingual orthodontic appliances. In-Ovation L self-ligating lingual brackets were bonded to anatomically shaped teeth on the OSIM, and the teeth were positioned such that a G4 NiTi 0.016" large maxillary mushroom archwire could be ligated in passive position. Each trial consisted of two movements: a 3mm lingual displacement of the 1-2 lateral incisor at 0.2 mm increments, and a 1.5 mm gingival displacement of the 2-3 canine at 0.15 mm increments (n = 50). Anterior brackets were repositioned to accommodate G4 NiTi 0.016" universal straight archwires (n = 50). Tests were completed at 37°C, and force and moment data in all directions was collected for each tooth around the arch at all increments. In general, the straight archwire produced significantly larger forces and moments at the centre of resistance for teeth of interest than did mushroom archwires. Specifically, the straight archwire produced 2.62 N and 3.81 N more force in the direction of tooth movement on the tooth being moved for a gingival displaced canine and lingual displaced lateral incisor, respectively, as compared to mushroom archwires. Results from this study suggest that mushroom archwires may provide better mechanics for movement of teeth in the anterior segment when using a round archwire; however, only biomechanical data was considered in this study and there are many factors that need to be considered in treatment planning.

Disrupted mitochondrial function in the Opa3L122P mouse model for Costeff Syndrome impairs skeletal integrity.

Mitochondrial dysfunction connects metabolic disturbance with numerous pathologies, but the significance of mitochondrial activity in bone remains unclear. We have, therefore, characterized the skeletal phenotype in the Opa3L122P mouse model for Costeff syndrome, in which a missense mutation of the mitochondrial membrane protein, Opa3, impairs mitochondrial activity resulting in visual and metabolic dysfunction. Although widely expressed in the developing normal mouse head, Opa3 expression was restricted after E14.5 to the retina, brain, teeth and mandibular bone. Opa3 was also expressed in adult tibiae, including at the trabecular surfaces and in cortical osteocytes, epiphyseal chondrocytes, marrow adipocytes and mesenchymal stem cell rosettes. Opa3L122P mice displayed craniofacial abnormalities, including undergrowth of the lower mandible, accompanied in some individuals by cranial asymmetry and incisor malocclusion. Opa3L122P mice showed an 8-fold elevation in tibial marrow adiposity, due largely to increased adipogenesis. In addition, femoral length and cortical diameter and wall thickness were reduced, the weakening of the calcified tissue and the geometric component of strength reducing overall cortical strength in Opa3L122P mice by 65%. In lumbar vertebrae reduced vertebral body area and wall thickness were accompanied by a proportionate reduction in marrow adiposity. Although the total biomechanical strength of lumbar vertebrae was reduced by 35%, the strength of the calcified tissue (σmax) was proportionate to a 38% increase in trabecular number. Thus, mitochondrial function is important for the development and maintenance of skeletal integrity, impaired bone growth and strength, particularly in limb bones, representing a significant new feature of the Costeff syndrome phenotype.

Dental Disease and Periodontitis in a Guinea Pig (Cavia porcellus)

A 6-year-old intact male guinea pig was referred with a 5-day history of reduced food intake and weight loss. Incisor teeth were clipped with nail clippers at another veterinary clinic 4 days earlier. Owing to a poor prognosis and the health status of the animal, the owner elected for euthanasia. Based on the postmortem results of the oral cavity examination, micro–computed tomography analysis, bacteriology, and histopathology, iatrogenic incisor malocclusion, incisor enamel fractures, dental disease, hepatic lipidosis, chronic purulent gingivitis/periodontitis caused by Fusobacterium nucleatum and Prevotella buccae, and dental caries were determined to be the final, postmortem diagnoses. Patients with acquired dental disease should be screened carefully for periodontitis, as periodontal disease is progressive in nature and early detection, diagnosis, and treatment are essential.

TNF Accelerates Death of Mandibular Condyle Chondrocytes in Rats with Biomechanical Stimulation-Induced Temporomandibular Joint Disease.

ObjectiveTo determine if temporomandibular joint chondrocyte apoptosis is induced in rats with dental biomechanical stimulation and what a role TNF takes.MethodsThirty-two rats were divided into 4 groups (n = 8/group) and exposed to incisor mal-occlusion induced by unilateral anterior crossbite biomechanical stimulation. Two groups were sampled at 2 or 4 weeks. The other two groups were treated with local injections of a TNF inhibitor or PBS into the temporomandibular joints area at 2 weeks and then sampled at 4 weeks. Twenty-four rats either served as unilateral anterior crossbite mock operation controls (n = 8/group) with sampling at 2 or 4 weeks or received a local injection of the TNF inhibitor at 2 weeks with sampling at 4 weeks. Chondrocytes were isolated from the temporomandibular joints of 6 additional rats and treated with TNF in vitro. Joint samples were assessed using Hematoxylin&eosin, Safranin O, TUNEL and immunohistochemistry staining, real-time PCR, fluorogenic activity assays and Western blot analyses. The isolated chondrocytes were also analyzed by flow cytometry.ResultsUnilateral anterior crossbite stimulation led to temporomandibular joint cartilage degradation, associated with an increase in TUNEL-positive chondrocytes number, caspase-9 expression levels, and the release of cytochrome c from mitochondria at 2 weeks without changes in TNF and caspase-8 levels until after 4 weeks. TNF stimulated apoptosis of the isolated chondrocytes and up-regulated caspase-8 expression, but did not change caspase-9 expression levels. Local injection of TNF inhibitor down-regulated caspase-8 expression and reduced TUNEL-positive cell number, but did not reverse cartilage thickness reduction, caspase-9 up-regulation or cytochrome c release.ConclusionsUnilateral anterior crossbite stimulation induces mitochondrion-mediated apoptosis of articular chondrocytes. TNF accelerated the unilateral anterior crossbite induced chondrocytes apoptosis via death-receptor pathway. However, anti-TNF therapy does not prevent cartilage loss in this model of temporomandibular joint.

Measurement of Incisor Overjet and Physiological Diastemata Parameters in Quarter Horse Foals.

Cephalometric studies are important to quantify abnormalities of jaw length and positioning. In this study, 4 to 7-month-old Quarter horse foals (n = 51) were examined to determine overjet (horizontal overlap) prevalence and measure the size of the physiological diastemata. Results were analyzed in relation to age, sex, and lineage. Another aim of this study was to develop a simple field technique for measuring incisor malocclusion and physiological diastemata dimensions that could be used to monitor the growth of the rostral components of maxilla, incisive bone, and mandible. The overall prevalence of overjet lesions in these foals was 51%. Females were overrepresented (61.5%). Overjet occurred more commonly in show foals (50% prevalence) than other working (7.7%) and race (42.3%) lineage foals. Significant differences were found between maxillary and mandibular physiological diastemata lengths in foals of all ages and, as expected, there was a positive statistical correlation between age and maxillary and mandibular physiological diastemata measurements. Incisor overjet was present in 44.4% of 4-month-old foals, 45.5% of 5-month-old foals, 58.3% of 6-month-old foals, and 60% of 7-month-old foals. There was a weak positive correlation between age and the presence of incisor overjet. It was concluded that incisor overiet was common among Quarter horse foals, especially those from show and race lineages. The field technique for physiological diastema measurements was considered effective.

Mechanical Forces Exacerbate Periodontal Defects in Bsp-null Mice

Bone sialoprotein (BSP) is an acidic phosphoprotein with collagen-binding, cell attachment, and hydroxyapatite-nucleating properties. BSP expression in mineralized tissues is upregulated at onset of mineralization. Bsp-null (Bsp-/-) mice exhibit reductions in bone mineral density, bone turnover, osteoclast activation, and impaired bone healing. Furthermore, Bsp-/- mice have marked periodontal tissue breakdown, with a lack of acellular cementum leading to periodontal ligament detachment, extensive alveolar bone and tooth root resorption, and incisor malocclusion. We hypothesized that altered mechanical stress from mastication contributes to periodontal destruction observed in Bsp-/- mice. This hypothesis was tested by comparing Bsp-/- and wild-type mice fed with standard hard pellet diet or soft powder diet. Dentoalveolar tissues were analyzed using histology and micro–computed tomography. By 8 wk of age, Bsp-/- mice exhibited molar and incisor malocclusion regardless of diet. Bsp-/- mice with hard pellet diet exhibited high incidence (30%) of severe incisor malocclusion, 10% lower body weight, 3% reduced femur length, and 30% elevated serum alkaline phosphatase activity compared to wild type. Soft powder diet reduced severe incisor malocclusion incidence to 3% in Bsp-/- mice, supporting the hypothesis that occlusal loading contributed to the malocclusion phenotype. Furthermore, Bsp-/- mice in the soft powder diet group featured normal body weight, long bone length, and serum alkaline phosphatase activity, suggesting that tooth dysfunction and malnutrition contribute to growth and skeletal defects reported in Bsp-/- mice. Bsp-/- incisors also erupt at a slower rate, which likely leads to the observed thickened dentin and enhanced mineralization of dentin and enamel toward the apical end. We propose that the decrease in eruption rate is due to a lack of acellular cementum and associated defective periodontal attachment. These data demonstrate the importance of BSP in maintaining proper periodontal function and alveolar bone remodeling and point to dental dysfunction as causative factor of skeletal defects observed in Bsp-/- mice.

Changes of Temporomandibular Joint and Semaphorin 4D/Plexin-B1 Expression in a Mouse Model of Incisor Malocclusion

To investigate the changes in condylar cartilage and subchondral bone of the temporomandibular joint (TMJ) in a mouse model of incisor malocclusion. By bonding a single (single group) or a pair (pair group) of metal tube(s) to the left incisor(s), a crossbite-like relationship was created between left-side incisors in mice. The morphological changes in the TMJ condyles were examined by hematoxylin and eosin and toluidine blue staining. Indices of osteoclastic activity, including tartrate-resistant acid phosphatase (TRAP) staining and macrophage colony stimulating factor (M-CSF) were investigated by histochemistry or real-time polymerase chain reaction (PCR). The osteoblastic activity was indexed by osteocalcin expression. Expressions of semaphorin 4D and its receptor, Plexin-B1, were detected by real-time PCR. Two-way analysis of variance was used to assess the differences between groups. One week and 3 weeks after bonding the metal tube(s), cartilage degradation and subchondral bone loss were evident histologically. Both indices of osteoclastic activity (TRAP and M-CSF) were significantly increased in cartilage and subchondral bone after bonding the metal tube(s). Osteocalcin expression in cartilage was significantly increased at week 3, while its expression in subchondral bone was significantly increased at week 1 but decreased at week 3. The semaphorin 4D expression in cartilage and subchondral bone was significantly decreased at week 1 but significantly increased at week 3. For Plexin-B1 expression, a significant increase was detected in subchondral bone at week 3. Bonding a single or a pair of metal tube(s) to left incisor(s) is capable of inducing remodeling in the TMJ, which involved cartilage degradation and alteration of osteoclastic and osteoblastic activity.

A restorative approach to the clinical and aesthetic management of adult patients with class ii division 2 incisor malocclusions

A Class II division 2 incisor malocclusion may be a cause of aesthetic and/or functional concern for some affected patients. Their particular concerns may include dark spaces around the misaligned teeth or uneven gingival contours. Orthodontic and/or orthognathic treatment can address some of these problems but frequently involves lengthy and expensive treatment in the adult dentition. Sadly, such treatment often produces an unstable result, with significant drawbacks such as the requirement for long-term retention. This article aims to describe alternative strategies for managing patients with this incisor malocclusion. This paper outlines a quicker, pragmatic and minimally destructive restorative treatment alternative to conventional orthodontic treatment and the associated long-term retention.

Deficiency in Acellular Cementum and Periodontal Attachment in Bsp Null Mice

Bone sialoprotein (BSP) is an extracellular matrix protein found in mineralized tissues of the skeleton and dentition. BSP is multifunctional, affecting cell attachment and signaling through an RGD integrin-binding region, and acting as a positive regulator for mineral precipitation by nucleating hydroxyapatite crystals. BSP is present in cementum, the hard tissue covering the tooth root that anchors periodontal ligament (PDL) attachment. To test our hypothesis that BSP plays an important role in cementogenesis, we analyzed tooth development in a Bsp null (-/-) mouse model. Developmental analysis by histology, histochemistry, and SEM revealed a significant reduction in acellular cementum formation on Bsp-/- mouse molar and incisor roots, and the cementum deposited appeared hypomineralized. Structural defects in cementum-PDL interfaces in Bsp-/- mice caused PDL detachment, likely contributing to the high incidence of incisor malocclusion. Loss of BSP caused progressively disorganized PDL and significantly increased epithelial down-growth with aging. Bsp-/- mice displayed extensive root and alveolar bone resorption, mediated by increased RANKL and the presence of osteoclasts. Results collected here suggest that BSP plays a non-redundant role in acellular cementum formation, likely involved in initiating mineralization on the root surface. Through its importance to cementum integrity, BSP is essential for periodontal function.

Common Dental Disorders of the Degu (Octodon Degus)

Dental disease is prevalent in the captive degu (Octodon degus), yet little has been documented on the variety of disorders in this species. In this internet-based study, dental cases presented over a 7-year period were collated, analyzed, and grouped. Of the 137 total cases, the most common dental disorder of the degu was found to be molar malocclusion (42.3 %). Other disorders documented included enamel decoloration (13.1%), molar elodontoma (8.0%), enamel hypoplasia (6.6%), incisor tooth fracture (6.6%), incisor malocclusion (3.6%), oral abscess (2.2%), and impacted molar teeth (0.7%). Details of each condition, pathogenesis, and clinical signs are described. Age was found not to be a significant predictor of dental disease in the degu.

Má oclusão Classe I de Angle com agenesia de incisivos laterais

O planejamento ortodôntico de pacientes com agenesia de incisivos laterais envolve considerações estéticas e funcionais de grande relevância para um resultado clínico satisfatório. Tanto o fechamento dos espaços correspondentes aos dentes ausentes quanto sua abertura ou manutenção oferecem vantagens e desvantagens que devem ser avaliadas de acordo com as características individuais do paciente. Fatores importantes que influenciam o planejamento são o padrão esquelético, o tipo de má oclusão e a coloração e forma dos caninos, dentre outros. Neste artigo, teve-se como objetivo relatar o tratamento de uma paciente com má oclusão Classe I de Angle, agenesia de incisivos laterais, sobressaliência e sobremordida diminuídas, tendência à mordida aberta e mordida cruzada.A abordagem clínica foi realizada com expansão maxilar, seguida de fechamento dos espaços, com auxílio de ancoragem esquelética extrabucal. Esse caso foi apresentado à diretoria do Board Brasileiro de Ortodontia e Ortopedia Facial (BBO), como parte dos requisitos para a obtenção do título de Diplomado pelo BBO.

Acquired incisor malocclusion in an adult rabbit buck. A case report

A rare case of dental malocclusion in an adult white chinchilla rabbit buck is reported. A diagnosis of acquired incisor malocclusion was made based on the history, physical examination of the rabbit and postmortem examination of the skull. To the best of our knowledge, this appears to be the first reported case of this condition in Nigeria. It is suggested that the condition may be more common among rabbits in Nigeria and elsewhere than the paucity of reports on the incidence. Measures to be adopted in order to forestall dental malocclusion in rabbits are discussed. Keywords: Malocclusion, rabbit, incisor.

Spontaneous dwarf rat: A novel model for aging research

Dwarf animal models can provide new models for aging research. For the spontaneous dwarf rat (SDR), a dwarf strain derived from the Sprague-Dawley (SD) rat, no data relevant to aging research are available. The present study aimed to examine its growth, hormonal background, lifespan and age-related diseases. Male SDR and SD rats were used for growth comparison and for immunohistochemistry and plasma hormonal analysis. SDR of each sex were maintained until natural death and then inspected pathologically. SDR showed an apparent dwarfism in their youth. Immunohistochemistry indicated that the development of growth hormone (GH)-positive cells in the pituitary was insufficient in SDR. In SDR, plasma GH levels were lower than in SD rats. Moreover, both insulin-like growth factor-1 (IGF-1) and insulin levels were decreased compared to levels in SD rats. Male and female SDR showed a mean lifespan of 29.3 +/- 3.3 and 26.8 +/- 5.3 months, respectively. The main neoplastic lesions in SDR were pituitary and mammary tumors. Major non-neoplastic lesions were incisor malocclusion, heart disease, chronic nephropathy (male) and cerebral hemorrhage (female). Most cases of chronic nephropathy were mild. Compared with longevity data and pathological data reported for SD rats, the lifespan in SDR was increased by 20-40% in males and 10-20% in females, and SDR had characteristic decreases in pituitary and mammary tumors as well as in severe chronic nephropathy. The SDR, differing in endocrinology, longevity and pathology from the SD rat, is potentially a new animal model for aging research.

Incisor adjustment in rabbits

Rabbit incisor teeth are open-rooted and, in healthy animals, grow continuously. Incisor adjustments are often necessary to maintain the health and well-being of rabbits with incisor malocclusion. This column will describe some techniques used to manage incisor malocclusion in the rabbit.

Tooth size discrepancies in female patients with palatally impacted canines

Abstract Background Small upper lateral incisors in patients with palatally impacted canines may contribute to inter-arch tooth size discrepancies. Aim To compare the Bolton ratios in female patients with and without unilateral palatally impacted canines. Methods The pretreatment dental casts of 30 female patients with unilateral palatally impacted canines (Impaction group) and 30 female patients without palatally impacted canines (Control group) were used. The latter were matched for age and incisor malocclusion with the Impaction group. The anterior and overall Bolton ratios were calculated for each group. Results Although the total width of the upper anterior teeth in the Impaction group was significantly smaller than the total width of the upper anterior teeth in the Control group (p = 0.029), there was no significant difference between the mesio-distal widths of the lower anterior teeth in the two groups. Furthermore, there were no significant group differences in either the mean anterior Bolton ratio (p = 0.156) or the overall Bolton ratio (p = 0.652). Conclusion Females patients with palatally impacted canines may not have more inter-arch tooth size discrepancies than female patients without palatally impacted canines.