OBJECTIVE: To investigate the prevalence of tooth agenesis and associated dental anomalies in Latvian adolescent dental patients and compare it to other European countries.
METHODS: Cross-sectional study of 2692 11-to-14-year-old patients (39.9% males and 60.1% females) attending Riga Stradins University Institute of Stomatology with panoramic radiographs taken between August 2020 and September 2021. Patients with any genetic syndromes were excluded. Data on tooth agenesis (excluding third molars) and other dental anomalies were recorded.
RESULTS: The prevalence of tooth agenesis in Latvian adolescent dental patients was 9.3% with no statistically significant difference between genders (χ2 test, p = 0.472). The most commonly missing teeth were mandibular second premolars, followed by upper lateral incisors and upper second premolars. There was a statistically significant association with the presence of other dental anomalies in tooth agenesis patients (p < 0.001).
CONCLUSIONS: This study found that the prevalence of non-syndromic tooth agenesis in Latvian adolescent dental patients was 9.3% with no statistically significant differences between the genders. Patients with tooth agenesis have a statistically significant possibility of the presence of other dental anomalies (p < 0.001).

The gradual movement of a tooth away from the occlusal plane is called infraocclusion or reinclusion. Reincluded teeth are most often deciduous molars, and permanent teeth are less frequently affected. Depending on the level of the infraocclusion, the severity of the disorder is classified as mild, moderate, or severe. The etiology of the phenomenon is not fully known. Tooth submerging can lead to serious complications, such as abnormal position of adjacent teeth, displacement of the bud of the permanent successor, shortening of the dental arch, or developmental disturbances of alveolar process. Early diagnosis of the tooth infraocclusion and regular monitoring of its progression help to avoid serious permanent sequelae. The treatment of reinclusion often involves only observation. However, in some cases, the therapeutic procedure requires interdisciplinary treatment by specialists from various fields of dentistry. This study presents current methods of diagnosis and treatment of patients with submerged teeth.

Hypodontia is an inherited condition involving the absence of one to six teeth. The permanent dentition is the most frequently affected; however, it may also affect the primary dentition. A congenitally missing tooth (CMT) is the most common dental abnormality, with the missing mandibular second premolar, maxillary lateral incisor, maxillary second premolar, and mandibular central incisor accounting for 90% of CMT in hypodontia studies. The etiology of CMT has been attributed to environmental and genetic contributing factors, with the latter having a strong influence. It may occur in isolation or in association with syndromes. Congenitally missing mandibular incisor is more common in the Asian population and females. Depending on the number and location of missing teeth, hypodontia may be a considerable issue for the clinician since it may impact occlusal balance, mastication, speech, and esthetics and often requires a multidisciplinary approach. Missing mandibular incisors are of particular interest to orthodontists because of the possibility of mandibular retrognathism, the potential for the development of malocclusion, and difficulty in achieving a balanced occlusion. This case report describes the skeletal and dental features of a nonsyndromic familial occurrence of missing mandibular incisors in three generations. A comprehensive literature search was also performed to review the familial cases with missing mandibular incisors.
UNASSIGNED: Selvaraj M, Sennimalai K, Samrit VD, et al. A Rare Incidence of Nonsyndromic Mandibular Incisor Agenesis in a Three-generation Family: Case Report and Literature Review. Int J Clin Pediatr Dent 2023;16(2):388-395.

Mutations in PAX9 are the most common genetic cause of tooth agenesis (TA). The aim of this study was to systematically review the profiles of the TA and PAX9 variants and establish their genotype-phenotype correlation. Forty articles were eligible for 178 patients and 61 mutations (26 in frame and 32 null mutations). PAX9 mutations predominantly affected molars, mostly the second molar, and the mandibular first premolar was the least affected. More missing teeth were found in the maxilla than the mandible, and with null mutations than in-frame mutations. The number of missing teeth was correlated with the locations of the in-frame mutations with the C-terminus mutations demonstrating the fewest missing teeth. The null mutation location did not influence the number of missing teeth. Null mutations in all locations predominantly affected molars. For the in-frame mutations, a missing second molar was commonly associated with mutations in the highly conserved paired DNA-binding domain, particularly the linking peptide (100% prevalence). In contrast, C-terminus mutations were rarely associated with missing second molars and anterior teeth, but were commonly related to an absent second premolar. These finding indicate that the mutation type and position contribute to different degrees of loss of PAX9 function that further differentially influences the manifestations of TA. This study provides novel information on the correlation of the PAX9 genotype-phenotype, aiding in the genetic counseling for TA.

Oligodontia is a developmental dental anomaly defined by the absence of 6 or more permanent teeth, excluding the third molars. We performed a review with a systematic approach and proposed a guideline for the choice of the bone augmentation surgery. The different bone augmentation technique terms were searched in the PubMed and Science Direct database. Clinical studies were eligible if they reported on pre-implant surgery in patients with oligodontia. The database search yielded 400 studies after duplicates removed. Thirty studies were finally included, involving 410 patients. Sixty-three sinus lifts were performed in 37 patients with no failure. Thirteen out of 33 patients with iliac bone transplantation and two out of 24 with parietal bone transplantation had resorption, one out of 4 patients who received allogeneic bone block had complete failure. Seventy-eight patients underwent guided bone regeneration, none had bone loss. No failure was found with the alveolar distraction osteogenesis technique. Four out of thirteen patients developed permanent hypoesthesia after inferior alveolar nerve transposition. The cumulative implant survival rate was 94.4% after bone augmentation procedures. Extensive edentulous areas should be grafted with parietal bone, as iliac grafts present a greater risk of resorption. Smaller edentulous areas should be treated by endobuccal harvesting or guided bone regeneration. Osteogenesis distraction and nerve transposition are effective surgeries for medium-to-large mandibular edentulous spaces. The implant survival rate is not significantly different between implants placed in grafted and nongrafted bone, the appropriate choice of bone augmentation technique can reduce the risk of peri‑implant bone resorption.

The objective of this systematic review was to determine the orthodontic and dentofacial orthopedic treatments carried out in patients with ectodermal dysplasia to facilitate functional and aesthetic rehabilitation.
The systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement. We systematically searched PubMed, Web of Science, Scopus, Scielo, LILACS, EBSCOhost and Embase databases up to 6 January 2022. We included articles describing patients with any type of ectodermal dysplasia who received orthodontic or dentofacial orthopedic treatment to facilitate functional and aesthetic oral rehabilitation. The search was not restricted by language or year of publication. The quality of the studies was assessed using the Joanna Briggs Institute Quality Assessment Scale of the University of Adelaide for case series and case reports. The review was registered at the University of York Centre for reviews (CRD42021288030).
Of the initial 403 studies found, 29 met the inclusion criteria. After applying the quality scale, 23 were left for review-21 case reports and 2 case series. The initial age of patients ranged from 34 months to 24 years. Thirteen studies were on hypohidrotic and/or anhidrotic ectodermal dysplasia, of which two were X-chromosome linked. In one study, the patient had Wiktop syndrome, and in nine the type of ectodermal dysplasia was not specified. The duration of treatment was 7 weeks to 10 years. The treatments described were: fixed orthodontic appliances or simple acrylic plates designed for tooth movement, including leveling and aligning, closing of diastemata, retraction of impacted teeth in the dental arch; clear aligners; fixed and/or removable appliances for the correction of skeletal and/or dentoalveolar relationships; palatal expanders in combination with face masks for orthopedic traction of the maxilla; and orthognathic surgery. Only three studies provided cephalometric data.
The level of evidence of the articles reviewed was low and most orthopedic and dentofacial orthodontic treatments described were focused on correcting dental malpositioning and jaw asymmetries and not on stimulating growth from an early age. Studies with greater scientific evidence are needed to determine the best treatment for these patients.

Hypodontia (tooth agenesis) is regarded as the most common congenital dental anomaly. The present review discusses the epidemiological characteristics of congenitally missing second permanent molars (CMSPMs) within a systematic review of the literature. The review was based on Pubmed library associated with the search of various scientific databases or academic resources, improved by hand search of reference lists. The terms \'hypodontia\' or \'anodontia\' in combination with \'prevalence\' or \'epidemiology\' were searched in the data sources for studies published between January 2001 and December 2020. Abstracts of non-English papers were also analyzed. The inclusion criteria were as follows: i) Study provided precise data about CMSPMs, even if no second permanent molar was reportedly missing; ii) the number of CMSPMs distributed by jaw was provided and iii) studies on subjects >3 years were used. The exclusion criteria were as follows: i) Studies on patients with history of trauma of the maxilla or the mandible, any type of syndrome affecting bone metabolism, metabolic disorders, previous extraction or tooth loss due to dental caries, cleft lip and palate; ii) studies performed on cohorts of patients with hypodontia and iii) studies reporting data including third molars, except for those that presented sufficient data to perform correct calculations. A total of 79 studies were selected, accumulating a population of 281,968 people, with an average sample size of 3,524.60±11,255.25. The prevalence of CMSPMs (IpHSPM) was 2.79±3.16% among all missing teeth (1.03±1.59% for upper CMSPMs and 1.76±2.32% for lower CMSPMs; P=0.011). There were no significant differences (P=0.250) in IpHSPM between men (1.59±1.52%) and women (2.13±1.67%). However, significant differences were recorded between continents. Furthermore, lower CMSPMs were found more frequently in orthodontic samples (P=0.033). The prevalence of CMSPMs is low compared with the overall prevalence of CM teeth. Despite the rarity of these anomalies, early detection is important to enable practitioners to plan and start treatment at the best time for optimal results.

Dentists may encounter patients with numerical dental anomalies in clinical practice and understanding of these conditions would allow early detection as well as intervention. The absence of one or more teeth congenitally is referred as hypodontia. This dental anomaly is rarely reported in primary dentition and the most commonly affected teeth in the primary dentition are mandibular lateral incisors and primary canines are remarkably very rare and this entity has not been often reported. This case study was aimed to report a 3-year-old Indian girl with the absence of three canines primary dentition and also evaluate the overall dental development pattern of developing permanent teeth. Furthermore, a new finding for pediatric dentists that the development of permanent canines in case of missing primary canines.

Ectodermal dysplasia-syndactyly syndrome 1 (EDSS1) is characterized by cutaneous syndactyly of the toes and fingers and abnormalities of the hair and teeth, variably associated with nail dystrophy and palmoplantar keratoderma (PPK). EDSS1 is caused by biallelic mutations in the NECTIN4 gene, encoding the adherens junction component nectin-4. Nine EDSS1 cases have been described to date. We report a 5.5-year-old female child affected with EDSS1 due to the novel homozygous frameshift mutation c.1150delC (p.Gln384ArgfsTer7) in the NECTIN4 gene. The patient presents brittle scalp hair, sparse eyebrows and eyelashes, widely spaced conical teeth and dental agenesis, as well as toenail dystrophy and mild PPK. She has minimal proximal syndactyly limited to toes 2-3, which makes the phenotype of our patient peculiar as the overt involvement of both fingers and toes is typical of EDSS1. All previously described mutations are located in the nectin-4 extracellular portion, whereas p.Gln384ArgfsTer7 occurs within the cytoplasmic domain of the protein. This mutation is predicted to affect the interaction with afadin, suggesting that impaired afadin activation is sufficient to determine EDSS1. Our case, which represents the first report of a NECTIN4 mutation with toe-only minimal syndactyly, expands the phenotypic and molecular spectrum of EDSS1.

Different genes and loci that are associated with non-syndromic developmental tooth agenesis (TA) have the same causation pathway in the development of tumours including breast cancer (BC), epithelial ovarian cancer (EOC), colorectal cancer (CRC) and lung cancer (LC).
To assess the link between TA and the development of cancer.
This registered review included a comprehensive search of electronic databases (Cochrane Central Register of Controlled Trials [CENTRAL], LILACS, Scopus, Web of Science and Medline via Ovid) until 1 April 2020, supplemented by manual, grey literature and reference lists search. There was no restriction in term of date of publication, gender, race or type of hypodontia.
The primary outcome was the relationship between TA and cancer. The secondary outcome was to identify the genetic correlation between TA and cancer.
Study selection, data extraction and risk of bias assessment were performed independently and induplicate by two reviewers, with disputes resolved by a third reviewer.
Eight studies with a moderate-high risk of bias were included in the final review, with a total of 5821 participants. Due to the heterogeneity among the included studies, the data were presented narratively. Limited studies reported a high prevalence of EOC (19.2%-20%) and CRC (82%-100%) in individuals with TA (depending on the study) compared to those without TA (3% for EOC and 0% for CRC). While others reported a weak correlation between EOC and CRC and TA (P > 0.05). Weak evidence suggested a strong correlation between breast, cervical uterine and prostate cancers and TA (P < 0.05).
Though low-quality evidence suggests a link between TA and cancer, it was not possible to verify that TA can hold a predictive value as a marker for cancers. Further research is needed to confirm the association.
PROSPERO (CRD42020139751).