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).

OBJECTIVE: It is traditionally considered that breaking bad news to patients does not represent a cause for concern for dental professionals. However, there are situations where they will be confronted with this task, as in the case of rare dental diseases. Little information is available regarding the feelings of healthcare professionals on this subject. There are no qualitative studies that explore how a diagnosis of oligodontia is announced to patients by dentists and orthodontists. The aim of our study is to explore the difficulties and ethical issues experienced by dental health professionals when they have to announce a diagnosis of oligodontia to a patient and their family.
METHODS: This study relied on a qualitative research method using focus groups of dentists and orthodontists and a thematic analysis procedure.
RESULTS: The difficulties experienced could be summarised within five topics: organisational difficulties, difficulties with the management of dental treatment and with the administrative management associated with this anomaly, difficulties with the content of the announcement, and relational difficulties. These could be grouped in two categories: practical difficulties and ethical difficulties.
CONCLUSIONS: This survey allowed us to understand the difficulties encountered by dentists and orthodontists when announcing oligodontia. The participants felt uncomfortable with this task and were under stress. They reported difficulties in delivering the medical information and in adapting to the message. It is essential that dental professionals develop skills in medical communication.

Dental agenesis (DA) in the permanent dentition is one of the most common dental anomalies, with a prevalence up to 2-10%. Therefore, the aim of this retrospective study was to investigate the prevalence and therapeutic treatment of DA in healthy children (HC) compared to children with systemic disease or congenital malformation (SD/CM).
Out of 3407 patients treated at the Department of Paediatric Dentistry of the Justus Liebig University Giessen (Germany) between January 2015 and December 2020, a total of 1067 patients (594 female, 473 male) aged between 4.5 and 18 years were included in this study due to DA. Besides the patients\' general medical history and therapeutic treatments, panoramic radiographs were analysed.
In contrast to the HC group with 9.7% DA, the SD/CM group showed a significantly higher prevalence of DA (19.8%; p < 0.05). The latter group was further classified into children with ectodermal dysplasia (4.4%), down syndrome (8.2%), cleft lip and palate (4.4%), intellectual disability/developmental delay (16.4%), and other genetic/organic diseases without intellectual disability (45.9%). Regarding therapeutic treatments, the HC group (59.5%) was significantly more often treated with an orthodontic gap opening compared to the SD/CM group (42.6%; p < 0.05), followed by orthodontic gap closing 36.5% in the HC group and 22.9% in the SD/CM group (p < 0.05), whereas no treatment was predominantly performed in the SD/CM group (37.7%) compared to the HC group (4%; p < 0.05). Furthermore, 50% in the SD/CM group required general anaesthesia for therapeutic treatment (vs. 8.1% in the HC group; p < 0.05).
Children with SD/CM suffered more often from DA compared to HC that underlines multi- and interdisciplinary treatment of utmost importance. Furthermore, due to intellectual disability, common treatment methods can be complicated by insufficient compliance. This fact underlines the importance of an early attempt to establish the necessary cooperation enabling children with SD/CM to receive therapy.

the aim of this study was to report and assess the management and implant rehabilitation of oligodontia patients since its recognition in 2012 by french authorities in the nomenclature.
we conducted a retrospective study in the Maxillofacial Surgery and Stomatology Department of the Lille University Hospital between January 2012 and May 2022. Patients had to present an oligodontia recognized under the ALD31 in adulthood, and to have benefited from a pre-implant/implant surgical treatment in the unit.
a total of 106 patients were included in the study. The mean number of agenesis was 12 per patient. The most missing teeth are the ones at the end of the series. After a pre-implant surgery phase including orthognathic surgery and/or bone grafting, 97 patients benefited from implant placements. The mean age for this phase was 19.38. A total of 688 implants were placed. The median number of implants placed was 6 per patient and 5 patients presented implant failures after or during the osseointegration phase (16 implants lost). The implant success rate was 97.6%. 78 patients benefited from rehabilitations by fixed implant-supported prostheses and 3 by implant-supported mandibular removable prostheses.
The described care pathway seems to us adapted to the patients followed in our department, with good functional and esthetic results. It would be necessary to evaluate on a national scale to adapt the management process.

OBJECTIVE: To investigate the pathogenic gene of a patient with nonsyndromic oligodontia, and analyze its possible pathogenic mechanism.
METHODS: The variant was detected by whole exome sequencing (WES) and Sanger sequencing in a family with oligodontia. Bioinformatic and structural analyses were used to analyze variant. Functional studies including western blotting and immunofluorescent analyses and luciferase reporter assay were conducted to explore the functional effects.
RESULTS: We identified a novel frameshift variant of PAX9 (c.491-510delGCCCT-ATCACGGCGGCGGCC, p.P165Qfs*145) outside the DNA-binding domain causing an autosomal-dominant nonsyndromic oligodontia in a Chinese family. Bioinformatic and structural analyses revealed that the variant is pathogenic and conserved evolutionarily, and the changes might affect protein stability or folding. Functional studies demonstrate dramatically reduced ability in activating transcription activity of BMP4 promoter and a marked decrease in protein production, as evaluated by western blotting and immunofluorescent analyses.
CONCLUSIONS: We found a novel frameshift variant of PAX9 causing nonsyndromic oligodontia in a Chinese family. Our findings indicate that frameshift variants cause loss of function of PAX9 protein during the patterning of the dentition and the subsequent tooth agenesis, providing new molecular insights into the role of frameshift variant of PAX9 and broaden the pathogenic spectrum of PAX9 variants.

X-linked hypohidrotic ectodermal dysplasia (XLHED) is caused by pathogenic variants of the gene EDA disrupting the prenatal development of ectodermal derivatives. Cardinal symptoms are hypotrichosis, lack of teeth, and hypo- or anhidrosis, but the disease may also evoke other clinical problems. This study aimed at investigating the clinical course of XLHED in early childhood as the basis for an evaluation of the efficacy of potential treatments.
25 children (19 boys and 6 girls between 11 and 35 months of age) with genetically confirmed XLHED were enrolled in a long-term natural history study. Clinical data were collected both retrospectively using parent questionnaires and medical records (pregnancy, birth, infancy) and prospectively until the age of 60 months. General development, dentition, sweating ability, ocular, respiratory, and skin involvement were assessed by standardized clinical examination and yearly quantitative surveys.
All male subjects suffered from persistent anhidrosis and heat intolerance, although a few sweat ducts were detected in some patients. Sweating ability of girls with XLHED ranged from strongly reduced to almost normal. In the male subjects, 1-12 deciduous teeth erupted and 0-8 tooth germs of the permanent dentition became detectable. Tooth numbers were higher but variable in the female group. Most affected boys had no more than three if any Meibomian glands per eyelid, most girls had fewer than 10. Many male subjects developed additional, sometimes severe health issues, such as obstructive airway conditions, chronic eczema, or dry eye disease. Adverse events included various XLHED-related infections, unexplained fever, allergic reactions, and retardation of psychomotor development.
This first comprehensive study of the course of XLHED confirmed the early involvement of multiple organs, pointing to the need of early therapeutic intervention.

There is need to get insight into condition-specific oral health-related quality of life in Dutch children with oligodontia. Between October 2014 and March 2017, 11-17-year-old oligodontia patients were approached to join a study assessing the impact of oligodontia on condition-specific oral health-related quality of life (OHrQoL). The patients received a condition-specific OHrQoL questionnaire prior to the start of orthodontic treatment. Non-oligodontia children in the same age group, but also requiring orthodontic treatment, were approached to serve as a control. The Fisher\'s Exact Test was used for comparison purposes with the control group because of the small group sizes. Furthermore, subgroup analyses were performed for gender, age, number of congenitally missing teeth, tooth agenesis in the aesthetic region, orthodontic classification and microdontia via independent t-tests. p-values of <0.05 were considered statistically significant. Twenty-eight oligodontia patients and 23 controls agreed to participate. The oligodontia patients\' scores were comparable to the controls except for the items about dental appearance and treatment complexity. The impact of oligodontia on OHrQoL in youngsters is limited and mainly concerns dental appearance and the complexity of the treatment.

BACKGROUND: The purpose of this cross-sectional study was to investigate the effects of congenitally missing teeth on craniofacial morphology and to characterize the features of maxillofacial morphology of oligodontia patients associated with individual skeletal maturity by assessment with the cervical vertebrae maturation (CVM) method.
METHODS: A total of 106 non-syndromic Japanese patients with congenitally missing teeth (except for third molars) were selected and categorized into two groups according to the severity of congenitally missing teeth (hypodontia group, 1-5 missing teeth [n = 56]; oligodontia group, ≥ 6 missing teeth [n = 50]). A control group included orthodontic patients without either skeletal disharmony or congenitally missing teeth (n = 63). Subjects in oligodontia and control groups were further categorized into two subgroups on the basis of cervical stage (CS): stage I (CS2 or 3; n = 27 and n = 31, respectively) and stage II (CS4 or above; n = 23 and n = 32, respectively). Lateral cephalograms were analyzed by using eight angular and eight linear measurements. Z-scores were formulated on the basis of age and sex and were matched to the Japanese norm. Tukey tests and t tests were performed.
RESULTS: Compared with the control group, the hypodontia group had significantly smaller U1 to FH plane angle and A-B plane angle; U1-L1 was significantly larger. The oligodontia group had significantly smaller ANS-Me, L1 to mandibular plane angle, and Ptm-A; U1-L1 was significantly larger. At stage I, the oligodontia group had significantly smaller ANS-Me, gonial angle, and ANS-U1. At stage II, the oligodontia group had significantly smaller U1 to FH plane angle, L1 to mandibular plane angle, Ptm-A, and Go-Pog; it also had significantly larger U1-L1.
CONCLUSIONS: The present study suggested that skeletal patterns differ along with the number of congenitally missing teeth and that, in oligodontia patients, skeletal patterns differ before and after growth peak. It is important to consider the skeletal characteristics of tooth agenesis patients when designing a treatment plan.

OBJECTIVE: Neural tube defects may increase the risk of an abnormal development of skull, vertebral column and teeth formation, including dental agenesis in non syndromic patients. The association between the presence of a congenital Dental Agenesis (DA) and the Atlantooccipital Ligament (AOL) calcification, known as \"Ponticulus Posticus\" (PP), as possible links can be investigated.
METHODS: After a systematic review of the scientific literature on this topic, two independent examiners assessed the AOL calcification in lateral cephalograms of 350 non syndromic patients(7-21 years old). The results were compared with a control group (non syndromic patients, without congenital missing teeth).
RESULTS: The 16.3% of the population studied by cephalometric analysis revealed a prevalence rate of PP (both complete and partial) with a slight male predominance is seen, not statistically significant (χ square test = 0.09; p= 0.76). In both sexes complete PP is more observed. In the patients affected by DA the frequency of PP is the 66.6% (both complete than partial). The χ square test with Yates correction showed a significative difference(χ= 66.20; p value= 0.00) between PP in patients with DA compared to not affected by DA.
CONCLUSIONS: PP is not an uncommon anomaly. Since orofacial pain like migraine and other symptoms are often associated to PP, during routine radiographic examination, if detected, it should be documented in patients\' health record and with symptoms, further investigation should be sought for. These findings encourage to think there\'s an association between DA in non syndromic patients and neuro-crestal cells defects.

Non-syndromic tooth agenesis (NSTA) is the most common developmental anomaly in humans. Several studies have been conducted on dental agenesis and numerous genes have been identified. However, the pathogenic mechanisms responsible for NSTA are not clearly understood. We studied a group of 28 patients with sporadic NSTA and nine patients with a family history of tooth agenesis. We focused on four genes - paired box 9 (PAX9), Wnt family member 10A (WNT10A), msh homeobox 1 (MSX1), and axin 2 (AXIN2) - using direct Sanger sequencing of the exons and intron-exon boundaries. The most prevalent variants identified in PAX9 and AXIN2 genes were analyzed using the chi-square test. The sequencing results revealed a number of variants in the AXIN2 gene, including one novel missense mutation in one patient with agenesis of a single second premolar. We also identified one variant in the AXIN2 gene as being a putative risk factor for tooth agenesis. Only one missense mutation was identified in the WNT10A gene and this mutation was found in two patients. Interestingly, WNT10A is reported as the most prevalent gene mutated in the European population with NSTA.