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Abstract Objective: Considering that the available studies on prevalence of malocclusions are local or national-based, this study aimed to pool data to determine the distribution of malocclusion traits worldwide in mixed and permanent dentitions. Methods: An electronic search was conducted using PubMed, Embase and Google Scholar search engines, to retrieve data on malocclusion prevalence for both mixed and permanent dentitions, up to December 2016. Results: Out of 2,977 retrieved studies, 53 were included. In permanent dentition, the global distributions of Class I, Class II, and Class III malocclusion were 74.7% [31 - 97%], 19.56% [2 - 63%] and 5.93% [1 - 20%], respectively. In mixed dentition, the distributions of these malocclusions were 73% [40 - 96%], 23% [2 - 58%] and 4% [0.7 - 13%]. Regarding vertical malocclusions, the observed deep overbite and open bite were 21.98% and 4.93%, respectively. Posterior crossbite affected 9.39% of the sample. Africans showed the highest prevalence of Class I and open bite in permanent dentition (89% and 8%, respectively), and in mixed dentition (93% and 10%, respectively), while Caucasians showed the highest prevalence of Class II in permanent dentition (23%) and mixed dentition (26%). Class III malocclusion in mixed dentition was highly prevalent among Mongoloids. Conclusion: Worldwide, in mixed and permanent dentitions, Angle Class I malocclusion is more prevalent than Class II, specifically among Africans; the least prevalent was Class III, although higher among Mongoloids in mixed dentition. In vertical dimension, open bite was highest among Mongoloids in mixed dentition. Posterior crossbite was more prevalent in permanent dentition in Europe. Resumo Objetivo: considerando-se que os estudos disponíveis sobre a prevalência das más oclusões são de base local ou nacional, esse estudo teve como objetivo reunir dados para determinar a distribuição dos tipos de má oclusão em uma escala global, nas dentições permanente e mista. Métodos: foi realizada uma busca eletrônica através das ferramentas de pesquisa do PubMed, Embase e Google Acadêmico, para reunir estudos publicados até dezembro de 2016 sobre a prevalência das más oclusões, tanto na dentição permanente quanto na dentição mista. Resultados: dos 2.977 estudos encontrados, 53 foram analisados. Na dentição permanente, a distribuição mundial das más oclusões de Classe I, II e III foi, respectivamente, de 74,7% [31 - 97%], 19,56% [2 - 63%] e 5,93% [1 - 20%]. Na dentição mista, a distribuição dessas más oclusões foi de 73% [40 - 96%], 23% [2 - 58%] e 4% [0,7 - 13%]. Em relação às más oclusões verticais, observou-se prevalência de 21,98% de sobremordida profunda e 4,93% de mordida aberta. A mordida cruzada posterior afetou 9,39% da amostra. Os africanos mostraram a maior prevalência de Classe I e mordida aberta na dentição permanente (89% e 8%, respectivamente) e na dentição mista (93% e 10% respectivamente), enquanto os caucasianos apresentaram a maior prevalência de Classe II na dentição permanente (23%) e na dentição mista (26%). A má oclusão de Classe III na dentição mista foi mais prevalente entre xantodermas. Conclusão: mundialmente, nas dentições mista e permanente, as más oclusões de Classe I de Angle são mais prevalentes do que as de Classe II, especificamente entre os africanos; a menos prevalente foi a Classe III, ainda que mais prevalente entre os xantodermas na dentição mista. Na dimensão vertical, as mordidas abertas foram mais prevalentes entre xantodermas na dentição mista. A mordida cruzada posterior apresentou maior prevalência na dentição permanente na Europa.

Background While artificial intelligence-driven approaches have shown great promise in dental diagnosis and treatment planning, most research focuses on dental radiographs. Only three studies have explored automated tooth numbering in oral photographs, all focusing on permanent dentition. Our study aimed to introduce an automated system for detection and numbering of teeth across mixed and permanent dentitions in occlusal photographs. Methods A total of 3215 occlusal view images of maxilla and mandible were included. Five senior dental students, trained under the guidance of an associate professor in dental public health, annotated the dataset. Samples were distributed across the training, validation, and test sets using a ratio of 7:1.5:1.5, respectively. We employed two separate convolutional neural network (CNN) models working in conjunction. The first model detected tooth presence and position, generating bounding boxes, while the second model localized these boxes, conducted classification, and assigned tooth numbers. Python and YOLOv8 were utilized in model development. Overall performance was assessed using sensitivity, precision, and F1 score. Results The model demonstrated a sensitivity of 99.89% and an overall precision of 95.72% across all tooth types, with an F1 score of 97.76%. Misclassifications were primarily observed in underrepresented teeth, including primary incisors and permanent third molars. Among primary teeth, maxillary molars showed the highest performance, with precisions above 94%, 100% sensitivities, and F1 scores exceeding 97%. The mandibular primary canine showed the lowest results, with a precision of 88.52% and an F1 score of 93.91%. Conclusion Our study advances dental diagnostics by developing a highly precise artificial intelligence model for detecting and numbering primary and permanent teeth on occlusal photographs. The model’s performance, highlights its potential for real-world applications, including tele-dentistry and epidemiological studies in underserved areas. The model could be integrated with other systems to identify dental problems such as caries and orthodontic issues.

Background The differential impact of maxillary first molar distalization on the three-dimensional displacement of the maxillary second molars during crown formation (Nolla 4–6 stages) and root development (Nolla 7–8 stages) remains unclear. Furthermore, the influence of two stages on the three-dimensional displacement of the first molars and central incisors, as well as the actual distal displacement and displacement rate of the first molars requires further investigation. Method 36 patients were equally divided into Nolla 4–6 stages group ( aged 8.50 ± 0.92 years) and Nolla 7–8 stages group ( aged 11.27 ± 0.67 years). CBCT data were analyzed before and after distalization. Normally distributed data were analyzed using paired sample T-tests, with significance set at P <  0.05. Result (1) After distalization in Nolla 4–6 and Nolla 7–8 stages groups, the first and second molars showed buccal movement, distobuccal rotation and crown distal inclination ( P <  0.05). Proclination of the maxillary central incisors was found. (2) Compared to Nolla 4–6 stages group, the degree of distobuccal rotation and crown distal inclination of second molars, distobuccal rotation of first molars and proclination of central incisors were smaller and the realization rate was larger in Nolla 7–8 stages group ( P <  0.05). Conclusions Clear aligners can effectively distalize maxillary first molars when second molars are unerupted. However, the movement of molars and central incisor, the actual displacement and realization rate of first molars are different in Nolla 4–6 and Nolla 7–8 stages. Treatment plans should be tailored to the developmental stage of the second molars to enhance efficiency and ensure optimal dental and maxillofacial health in children.

Background Impacts of the developmental stages of maxillary second molars, methods for distalization of the maxillary first molars, Class II traction application, and different traction modes on three-dimensional molar movements, anchorage tooth displacement, and stress distribution remains poorly understood. Method Patients with maxillary second molars in Nolla 4–6 and 7–8 stages were selected for 3D finite element modeling. We analyzed three-dimensional movements and stress distribution in maxillary and mandibular dentitions after unilateral and bilateral distalization of maxillary first molars using clear aligners, with no traction and three types of Class II traction. Results In Nolla 4–6 and 7–8 stages, after bilateral molar distalization, maxillary anterior labial inclination, tooth, periodontal membrane and alveolar bone stress were more significant. Movements of maxillary first molars were greater in Nolla 7–8 stages regardless of unilateral or bilateral molar distalization. Either unilateral or bilateral molar distalization, Angel button group provided better anchorage control for central incisors. Precision incision group provided superior anchorage control for lateral incisors and achieved the largest distal movements of maxillary first molars. Lingual button group provided anchorage control for deciduous or permanent canines. Molar distalization modes had no effect on mandibular dentition. Movements and maximum periodontal membrane stress values of mandibular dentition were the smallest in the Angel button group. Conclusion When moving molars distally, it's necessary to consider the development of maxillary second molar and evaluate the distalization modes, Class II traction modes and the influence on anchorage teeth, to design personalized treatment plan.

Patients with a mixed dentition can present for dental treatment with a nonvital primary tooth. The treatment of choice is often extraction, with the subsequent space presenting a cosmetic issue or requiring a space maintainer to preserve arch integrity for the erupting permanent teeth. Presented is a nonsurgical alternative treatment that saves the tooth, is less invasive, and may be preferred by some patients and their families. It is a procedure that may often be overlooked but can be included in the armamentarium of general dentists, pediatric dentists and endodontists.

The national prevalence of dental caries in Nigeria is currently unknown. The objective of this systematic review and meta-analysis was to determine the prevalence of dental caries in the primary, mixed and permanent dentition among residents in urban, rural and semi-urban Nigeria. A systematic search was conducted in PubMed, Web of Science, Scopus, CINAHL and Embase databases and Google Scholar for studies published between January 2001 and December 2023 reporting the prevalence of dental caries in Nigeria. The review was registered with PROSPERO (CRD42022362019) and conducted in accordance with the PRISMA guidelines. Data extracted included study design, sample size, age of participants, and study location. Study quality and risk of bias were assessed. A random-effects meta-analysis was performed to estimate pooled prevalence. A total of 1,010 records were identified, of which 52 studies were included in the systematic review and 35 were eligible for meta-analysis. Most studies were conducted in Southwestern Nigeria. The overall pooled prevalence of dental caries in Nigeria was 17% (95% CI: 14%-21%; I² = 97%). The pooled prevalence was 16% (95% CI: 10%-24%; I² = 98%) in primary dentition, 16% (95% CI: 11%-23%; I² = 97%) in mixed dentition, and 20% (95% CI: 16%-26%; I² = 96%) in permanent dentition. By setting, the pooled prevalence was 22% (95% CI: 7%-52%; I² = 98%) in rural areas, 17% (95% CI: 14%-22%; I² = 97%) in semi-urban areas, and 14% (95% CI: 6%-29%; I² = 98%) in urban areas. Substantial heterogeneity was observed across studies. Dental caries remains a significant public health concern in Nigeria, affecting approximately one in five individuals. Although variations were observed across dentition types and geographic settings, substantial heterogeneity indicates diverse epidemiological contexts across the country. Strengthened preventive strategies and improved access to oral healthcare services are needed to address the burden of dental caries nationwide.