Individual dental and skeletal age assessment according to Demirjian and Baccetti: Updated norm values for Central-European patients

PURPOSE

Chronological age often differs from dental and skeletal age. With orthopantomograms and lateral cephalograms, dental and skeletal development can be determined according to the methods published by Demirjian et al. and Baccetti et al. However, gender and skeletal class as possible confounders were frequently not considered and available norm values are not up-to-date. This retrospective cross-sectional study thus aimed to evaluate effects of skeletal class and gender on dental and skeletal age of growing patients and to generate updated norm values for contemporary Central-European patients.

METHODS

A total of 551 patients were included in the dental and 733 in the skeletal age assessment, respectively. Dental analysis was based on tooth mineralisation stages in orthopantomograms (Demirjian) and skeletal age was defined by cervical vertebrae maturation stages (CVMS) in lateral cephalograms (Baccetti). Skeletal class was determined by the individualised ANB angle of Panagiotidis/Witt. With nonlinear regression analysis a formula for determining dental age was established. Effects of gender and skeletal class were evaluated and updated norm values generated.

RESULTS

Inter- and intrarater reliability tests revealed at least substantial measurement concordance for tooth mineralisation and CVMS. Demirjian stages and CVMS significantly depended on gender with girls developing earlier. Skeletal class significantly affected skeletal age only, but without clinical relevance. Updated norm values for dental age differed significantly from the original values of Demirjian and the values for skeletal age differed from those published by Baccetti.

CONCLUSION

Optimised norms, separated by gender, increase precision in determining individual dental and skeletal age during orthodontic treatment planning. Further studies analysing the effect of skeletal class on dental and skeletal development are needed.

Exploring the sex-associated differences in molars fused roots

BACKGROUND

Human sexual dimorphism is associated with many biological characteristics, including dental variables.

OBJECTIVES

To investigate if molars fused roots present sex-associated differences.

METHODS

Panoramic radiographs were used to investigate the frequency and distribution of permanent molars fused roots. Only patients with all first and second permanent molars were included. Third molars were not investigated. Any molar with roots fused apical to the usual furcal position were considered molar fused roots. Comparisons between males and females were performed using chi-square or Fisher's and Mann-Whitney tests and the established alpha was 5% (p<0.05). Sex-differential liability models were also proposed.

RESULTS

A total of 84 males and 86 females were included and 1360 molars were analyzed. Among them, 46 (26.06%) present at least one molar with fused root. Second maxillary molars were the most affected teeth. There was an association between sex and molars with fused roots. Females had a 3.4 higher chance to present fused roots than males (OR=3.4, CI 95% 1.6-6.8; p=0.0008). The female: male ratio of molars with fused roots was 2.5:1. The number of molars with fused roots ranged from 1 to 6 per patient, and the mean number of Females presented more molars with fused roots (mean = 1.01; standard deviation = 1.52) than males (mean = 0.31; standard deviation = 0.85) (p<0.05).

CONCLUSIONS

Molar fused root of permanent teeth presents sex-associated differences, in which females are more affected than males. Our results support sex-differential liability models for molars fused roots.

Exploring the association between PITX2, third molars agenesis and sella turcica morphology : PITX2, third molars agenesis and sella turcica morphology

OBJECTIVES

PITX2 is required for mammalian development and single nucleotide polymorphisms (SNPs) in this gene could be involved in dental agenesis and sella turcica patterns. Thus, the present study evaluated the association between SNPs in PITX2, third molars agenesis and sella turcica phenotypes.

MATERIALS AND METHODS

The sample consisted of healthy orthodontic German patients with lateral cephalometric radiographs with clearly visualization of the sella turcica, and dental orthopantomograms. The morphological variations of the sella turcica were evaluated using the lateral cephalograms, while third molar agenesis was evaluated using orthopantomograms. DNA isolated from buccal cells was used for genotyping three SNPs in PITX2 (rs3796902, rs1947187, and rs2595110). The analyzes were performed using a significance of 5%. There was no association between third molar agenesis and sella turcica phenotypes (p > 0.05). SNPs in PITX2 were also not associated with third molars agenesis (p > 0.05).

RESULTS

SNPs in PITX2 were associated with sella turcica phenotypes. The rs3796902 was associated with hypertrophic posterior clinoid process (p = 0.013). The rs1947187 and rs2595110 were associated with sella turcica bridge type A (p = 0.013 and p = 0.011, respectively for genotype distribution). Patients that carry the genotypes GG-CC-AG (rs3796902- rs1947187- rs2595110) had 7.2 higher chance to present sella turcica bridge type A (p = 0.002; Odds ratio = 7.2, Confidence interval 95% 2.04-27.04).

CONCLUSIONS

Third molar agenesis was not associated with SNPs in PITX2 and sella turcica phenotypes. SNPs in PITX2 may have an important role in sella turcica pattern.

Oral Cleft Related-Genes may be Involved in Root Curvature of Maxillary Lateral Incisors

The maxilla is formed by the medial nasal and maxillary processes fusion. The dental lamina develops from 2 origins connecting in the lateral incisor. The maxillary lateral incisor region is often affected by dental anomalies and clefting. It is possible that genes involved in oral cleft could also be associated with a variety of phenotypic variations in the maxillary lateral incisor. In this phenotype-genotype study, we explored the association between polymorphisms in the oral-cleft-related genes BMP2 and BMP4 and root curvature of maxillary lateral incisors.

Cross-sectional study.

Universities and private clinics.

Panoramic radiographs and DNA from 231 patients were analyzed.

Schneider method (1971) was applied to estimate the degree of root curvature of the maxillary lateral incisors and to classify the root as straight (5° or less) or curved (higher than 5°). Genetic polymorphisms in BMP2 (rs235768 and rs1005464) and BMP4 (rs17563) were genotyped. Statistical analysis was performed.

A total of 401 teeth (199 left and 202 right) were evaluated. Genetic analysis demonstrated trends toward association for the rs1005464 in BMP2 (P  =  .025) in co-dominant model and in dominant model (P  =  .026) for left incisors. The rs235768 in BMP2 showed trends toward association with the degree of root curvature in left incisors in the recessive model (P  =  .031). rs17563 in BMP4 also showed trends toward association with the degree of the root curvature in left incisors (P  =  .019).

BMP2 (rs235768 and rs1005464) and BMP4 (rs17563) might be involved in maxillary lateral incisor root curvature.

Non-syndromic supernumerary teeth and association with a self-reported family history of cancer

BACKGROUND

Supernumerary teeth are an alteration of dental developmental and result in the formation of teeth above the usual number. Epidemiologic studies suggested that patients with dentofacial anomalies and their family members may present an increased risk of developing cancer, including female breast cancer and gynecologic cancers. These observations indicate that genetic alterations that result in dental anomalies may be related to cancer development. Thus, the aim of the present study was to evaluate the association between supernumerary teeth and a family history of female breast cancer and gynecologic cancers.

METHODS

The diagnosis of supernumerary teeth was based on clinical and radiographic examinations. For data collection, a questionnaire asking for information regarding ethnicity, age, gender, and self-reported family history of cancer up to the second generation was used. Statistical analysis was performed using the Χ2 test and Fisher's exact test with an established α of 5%.

RESULTS

A total of 344 patients were included; 47 of them had one or more non-syndromic supernumerary teeth (not associated with any syndrome or cleft lip and palate) and 297 were control patients. Age, ethnicity, and gender distribution were not statistically different between the group with supernumerary teeth and the control group (p > 0.05). The supernumerary teeth were most commonly observed in the incisors area. Breast cancer (n = 17) was the most commonly self-reported type of cancer, followed by uterine cervical (n = 10), endometrial (n = 2), and ovarian (n = 1) cancers. Endometrial cancer was significantly associated with the diagnosis of supernumerary teeth (p = 0.017).

CONCLUSION

This study suggests that patients with supernumerary teeth possess a higher risk of having family members with endometrial cancer.

[The importance of guidelines in dentistry and dental education]

Evidence-based treatment recommendations are gaining importance within the framework of both medical and dental quality management systems. The scientific findings, which have been evaluated critically by expert committees with regard to their methodological quality, are summarized in easy-to-understand guidelines. All guidelines are evaluated qualitatively in accordance with a balance between consensus and evidence during the drafting process regarding their stages of scientific development. The publication of guidelines and the coordination of guideline development has been carried out by the Association of the Scientific Medical Societies in Germany (AWMF) since its foundation in the 1960s. Forty-four dental guidelines are currently available, which are mostly rated at the highest level (S3) of scientific development. Therefore, recommendations for various treatment protocols are defined for both dental staff at university sites or practices and the implementation of these guidelines into the daily clinical routine is desirable. Poor acceptance and adverse resource requirements are major limitations of the establishment of guidelines with regard to the expansion of evidence-based dentistry. However, these limitations might be overcome by the introduction of basic scientific training within dental universities and increased funding of young researchers in order to ensure high treatment quality and economy in dentistry in the future. Guidelines can facilitate education by providing scientifically validated procedural templates to dental students and assisting educators in meeting the requirements of practical skills.

Impact of Mechanical Strain and Nicotinamide on RUNX2-Deficient Osteoblast Mimicking Cleidocranial Dysplasia

Cleidocranial dysplasia (CCD) is a rare genetic defect caused by a heterozygous mutation of runt-related transcription factor 2 (RUNX2), which is important for osteoblast and skeletal development. RUNX2-deficiency causes extra- and intra-oral malformations that often require orthodontic treatment. Nicotinamide (NAM) affects bone remodelling processes. As these are crucial for orthodontic therapy, NAM could improve orthodontic treatment in CCD patients. This study investigates the effect of NAM in control and RUNX2-deficient osteoblasts under mechanical strain mimicking orthodontic treatment. First, the optimal NAM concentration and the differences in the expression profile of control and RUNX2-deficient osteoblasts were determined. Subsequently, osteoblasts were exposed to tensile and compressive strain with and without NAM, and the expression of genes critically involved in bone remodelling was investigated. NAM increased the expression of bone remodelling genes. RUNX2-deficient osteoblasts expressed more receptor activator of NFkB ligand (RANKL) and interleukin-6 (IL6), but less colony-stimulating factor-1 (CSF1). Most of the positive effects of NAM on bone remodelling genes were impaired by mechanical loading. In conclusion, NAM stimulated osteoblast differentiation by increasing the expression of RUNX2 and regulated the expression of osteoclastogenic factors. However, the positive effects of NAM on bone metabolism were impaired by mechanical loading and RUNX2 deficiency.

Anterior Open Bite Malocclusion: From Clinical Treatment Strategies towards the Dissection of the Genetic Bases of the Disease Using Human and Collaborative Cross Mice Cohorts

Anterior open bite malocclusion is a complex dental condition characterized by a lack of contact or overlap between the upper and lower front teeth. It can lead to difficulties with speech, chewing, and biting. Its etiology is multifactorial, involving a combination of genetic, environmental, and developmental factors. Genetic studies have identified specific genes and signaling pathways involved in jaw growth, tooth eruption, and dental occlusion that may contribute to open bite development. Understanding the genetic and epigenetic factors contributing to skeletal open bite is crucial for developing effective prevention and treatment strategies. A thorough manual search was undertaken along with searches on PubMed, Scopus, Science Direct, and Web of Science for relevant studies published before June 2022. RCTs (clinical trials) and subsequent observational studies comprised the included studies. Orthodontic treatment is the primary approach for managing open bites, often involving braces, clear aligners, or other orthodontic appliances. In addition to orthodontic interventions, adjuvant therapies such as speech therapy and/or physiotherapy may be necessary. In some cases, surgical interventions may be necessary to correct underlying skeletal issues. Advancements in technology, such as 3D printing and computer-assisted design and manufacturing, have improved treatment precision and efficiency. Genetic research using animal models, such as the Collaborative Cross mouse population, offers insights into the genetic components of open bite and potential therapeutic targets. Identifying the underlying genetic factors and understanding their mechanisms can lead to the development of more precise treatments and preventive strategies for open bite. Here, we propose to perform human research using mouse models to generate debatable results. We anticipate that a genome-wide association study (GWAS) search for significant genes and their modifiers, an epigenetics-wide association study (EWAS), RNA-seq analysis, the integration of GWAS and expression-quantitative trait loci (eQTL), and micro-, small-, and long noncoding RNA analysis in tissues associated with open bite in humans and mice will uncover novel genes and genetic factors influencing this phenotype.

Comprehensive Deciphering the Complexity of the Deep Bite: Insight from Animal Model to Human Subjects

Deep bite is a malocclusion phenotype, defined as the misalignment in the vertical dimension of teeth and jaws and characterized by excessive overlap of the upper front teeth over the lower front teeth. Numerous factors, including genetics, environmental factors, and behavioral ones, might contribute to deep bite. In this study, we discuss the current clinical treatment strategies for deep bite, summarize the already published findings of genetic analysis associated with this complex phenotype, and their constraints. Finally, we propose a comprehensive roadmap to facilitate investigations for determining the genetic bases of this complex phenotype development. Initially, human deep bite phenotype, genetics of human deep bite, the prevalence of human deep bite, diagnosis, and treatment of human deep bite were the search terms for published publications. Here, we discuss these findings and their limitations and our view on future strategies for studying the genetic bases of this complex phenotype. New preventative and treatment methods for this widespread dental issue can be developed with the help of an understanding of the genetic and epigenetic variables that influence malocclusion. Additionally, malocclusion treatment may benefit from technological developments like 3D printing and computer-aided design and manufacture (CAD/CAM). These technologies enable the development of personalized surgical and orthodontic guidelines, enhancing the accuracy and effectiveness of treatment. Overall, the most significant results for the patient can only be achieved with a customized treatment plan created by an experienced orthodontic professional. To design a plan that meets the patient's specific requirements and expectations, open communication between the patient and the orthodontist is essential. Here, we propose to conduct a genome-wide association study (GWAS), RNAseq analysis, integrating GWAS and expression quantitative trait loci (eQTL), micro and small RNA, and long noncoding RNA analysis in tissues associated with deep bite malocclusion in human, and complement it by the same approaches in the collaborative cross (CC) mouse model which offer a novel platform for identifying genetic factors as a cause of deep bite in mice, and subsequently can then be translated to humans. An additional direct outcome of this study is discovering novel genetic elements to advance our knowledge of how this malocclusion phenotype develops and open the venue for early identification of patients carrying the susceptible genetic factors so that we can offer early prevention and treatment strategies, a step towards applying a personalized medicine approach.

Narrating the Genetic Landscape of Human Class I Occlusion: A Perspective-Infused Review

This review examines a prevalent condition with multifaceted etiology encompassing genetic, environmental, and oral behavioral factors. It stands as a significant ailment impacting oral functionality, aesthetics, and quality of life. Longitudinal studies indicate that malocclusion in primary dentition may progress to permanent malocclusion. Recognizing and managing malocclusion in primary dentition is gaining prominence. The World Health Organization ranks malocclusions as the third most widespread oral health issue globally. Angle's classification system is widely used to categorize malocclusions, with Class I occlusion considered the norm. However, its prevalence varies across populations due to genetic and examination disparities. Genetic factors, including variants in genes like MSX1, PAX9, and AXIN2, have been associated with an increased risk of Class I occlusion. This review aims to provide a comprehensive overview of clinical strategies for managing Class I occlusion and consolidate genetic insights from both human and murine populations. Additionally, genomic relationships among craniofacial genes will be assessed in individuals with Class I occlusion, along with a murine model, shedding light on phenotype-genotype associations of clinical relevance. The prevalence of Class I occlusion, its impact, and treatment approaches will be discussed, emphasizing the importance of early intervention. Additionally, the role of RNA alterations in skeletal Class I occlusion will be explored, focusing on variations in expression or structure that influence craniofacial development. Mouse models will be highlighted as crucial tools for investigating mandible size and prognathism and conducting QTL analysis to gain deeper genetic insights. This review amalgamates cellular, molecular, and clinical trait data to unravel correlations between malocclusion and Class I phenotypes.

Testosterone suppression impacts craniofacial growth structures during puberty : An animal study

AIM

Hormones play a crucial role in growth development; however, the impact of testosterone suppression (TS) on craniofacial growth during puberty remains inconclusive. This study aimed to evaluate the impact of TS during puberty on cephalometric measurements and histological characteristics of facial growth centers.

MATERIALS AND METHODS

Thirty-six heterogenic Wistar male rats were randomly allocated into experimental orchiectomy (ORX) and control (sham) groups. At an age of 23 days (prepubertal stage), orchiectomy and placebo surgery were performed. Cephalometric measurements were performed via lateral cephalograms during and after puberty. The animals were euthanized at an age of 45 days (pubertal stage) and 73 days (postpubertal stage). Histological slices of the growth centers (condyle, premaxilla, and median palatine suture) were stained with hematoxylin and eosin, and sirius red. Student's t or Mann-Whitney U tests were used to compare linear and angular cephalometric measurements across groups (α error = 5%).

RESULTS

Linear and angular measurements were statistically different in ORX animals (cranial bones, maxilla, and mandible) at 45 days and 73 days. Condylar histology showed a decrease in prechondroblast differentiation and a delay of mineralization in ORX animals. Vascularization of the medium palatine suture was lower in the ORX group at 45 days. Type I and III collagen fiber synthesis was lower in the ORX groups. In the premaxillary suture, collagen fibers were better organized in the sham groups.

CONCLUSIONS

Our results suggest that testosterone suppression affects craniofacial growth during puberty.

The investigation of WNT6 and WNT10A single nucleotide polymorphisms as potential biomarkers for dental pulp calcification in orthodontic patients

The aim of this study is to evaluate if single nucleotide polymorphisms (SNPs) in WNT6 and WNT10A are associated with the risk of dental pulp calcification in orthodontic patients. This cross-sectional study followed the "Strengthening the Reporting of Genetic Association Studies" (STREGA) guidelines. Panoramic radiographs (pre- and post-orthodontic treatment) and genomic DNA from 132 orthodontic patients were studied. Dental pulp calcification (pulp stones and/or pulp space narrowing) was recorded in upper and lower first molars. The SNPs in WNT6 and WNT10A (rs7349332, rs3806557, rs10177996, and rs6754599) were assessed through genotyping analysis using DNA extracted from buccal epithelial cells. The association between pulp calcification and SNPs were analyzed using allelic and genotypic distributions and haplotype frequencies (p<0.05). Prevalence of dental pulp calcification was 42.4% in the 490 studied molars. In the genotypic analysis, the SNPs in WNT10A showed a statistically significant value for molar calcification (p = 0.027 for rs1017799), upper molar calcification (p = 0.040 for rs1017799) (recessive model), and molar calcification (p = 0.046 for rs3806557) (recessive model). In the allelic distribution, the allele C of the SNP rs10177996 in WNT10A was associated with molar calcifications (p = 0.042) and with upper first molar calcification (p = 0.035). Nine combinations of haplotypes showed statistically significant value (p<0.05). The findings of this study indicates that SNPs in WNT10A and WNT6 are associated with dental pulp calcification in molars after orthodontic treatment and may be considered as biomarkers for dental pulp calcification.

Skeletal Class II Malocclusion: From Clinical Treatment Strategies to the Roadmap in Identifying the Genetic Bases of Development in Humans with the Support of the Collaborative Cross Mouse Population

Depending on how severe it is, malocclusion, which may involve misaligned teeth, jaws, or a combination of the two, can hurt a person's overall facial aesthetics. The maxillary molar develops before the mandibular molar in class II malocclusion, which affects 15% of the population in the United States. With a retrusive mandible, patients typically have a convex profile. The goal of this study is to classify the skeletal and dental variability present in class II malocclusion, to reduce heterogeneity, present the current clinical treatment strategies, to summarize the previously published findings of genetic analysis, discuss these findings and their constraints, and finally, propose a comprehensive roadmap to facilitate investigations aimed at determining the genetic bases of malocclusion development using a variety of genomic approaches. To further comprehend the hereditary components involved in the onset and progression of class II malocclusion, a novel animal model for class II malocclusion should be developed while considering the variety of the human population. To overcome the constraints of the previous studies, here, we propose to conduct novel research on humans with the support of mouse models to produce contentious findings. We believe that carrying out a genome-wide association study (GWAS) on a large human cohort to search for significant genes and their modifiers; an epigenetics-wide association study (EWAS); RNA-seq analysis; integrating GWAS and the expression of quantitative trait loci (eQTL); and the testing of microRNAs, small RNAs, and long noncoding RNAs in tissues related to the skeletal class II malocclusion (SCIIMO) phenotype, such as mandibular bone, gum, and jaw in humans and the collaborative cross (CC) mouse model, will identify novel genes and genetic factors affecting this phenotype. We anticipate discovering novel genetic elements to advance our knowledge of how this malocclusion phenotype develops and open the venue for the early identification of patients carrying the susceptible genetic factors so that we can offer early prevention treatment strategies.

Impact of polishing system on surface roughness of different ceramic surfaces after various pretreatments and bracket debonding

OBJECTIVE

Evaluating various polishing methods after bracket debonding and excessive attachment material removal for different ceramics and pretreatments.

MATERIAL AND METHODS

Zirconia (ZrO2), leucite (LEU) and lithium disilicate (LiSi) specimens were pretreated with a) silica coated alumina particles (CoJet); LEU and LiSi additionally with b) hydrofluoric acid (HF), c) Monobond Etch&Prime (MEP), d) silicium carbide grinder (SiC) before bracket bonding, shearing off, ARI evaluation, excessive attachment material removal and polishing with i) Sof-Lex Discs (Soflex), ii) polishing paste (Paste), iii) polishing set (Set). Before/after polishing surface roughness (Ra) was measured with a profilometer. Martens hardness parameter were also assessed.

RESULTS

Irrespective of pretreatment Ra of LEU increased the most, followed by LiSi and ZrO2 (p < 0.001, SiC: p = 0.012), in accordance with the measured Martens hardness parameter. CoJet/SiC caused greater roughness as HF/MEP (p < 0.001). The ZrO2 surface was rougher after polishing with Paste/Set (p < 0.001; p = 0.047). Ra improved in the LEU/CoJet, LEU/SiC and LiSi/SiC groups with Soflex/Set (p < 0.001), in the LiSi/CoJet and LEU/HF groups by Soflex (p = 0.003, p < 0.001) and worsened by Paste (p = 0.017, p < 0.001). Polishing of HF or MEP pretreated LiSi with Set increased Ra (p = 0.001, p < 0.001), so did Paste in the LEU/MEP group (p < 0.001).

CONCLUSIONS

Paste couldn't improve the surfaces. Soflex was the only method decreasing Ra on rough surfaces and not causing roughness worsening. Polishing of LEU/LiSi after MEP, LEU after HF pretreatment doesn´t seem to have any benefit.

CLINICAL RELEVANCE

To avoid long-term damage to ceramic restorations, special attention should be paid to the polishing method after orthodontic treatment.

Impact of genetic variations in the WNT family members and RUNX2 on dental and skeletal maturation: a cross-sectional study

BACKGROUND

This study evaluated if genetic variations in the WNT family members and RUNX2 are associated with craniofacial maturation, investigating dental and skeletal maturity in children and teenagers.

METHODS

Radiographs from pre-orthodontic treatment of Brazilian patients (7 to 17 years-old) were used to assess dental (panoramic radiographs) and skeletal maturity (cephalometric radiographs). The chronological age (CA) was calculated based on the date of birth and the time the radiographs were performed. For the dental maturity analysis, the Demirjian (1973) method was used and a delta [dental age - chronological age (DA-CA)] was calculated. For the skeletal maturity analysis, the Baccetti et al. (2005) method was used and the patients were classified as "delayed skeletal maturation", "advanced skeletal maturation" or "normal skeletal maturation". DNA isolated from buccal cells was used for genotyping of two genetic variations in WNT family genes: rs708111 (G > A) in WNT3A and rs1533767 (G > A) in WNT11; and two genetic variations in RUNX2: rs1200425 (G > A) and rs59983488 (G > T). A statistical analysis was performed and values of p < 0.05 indicated a significant difference.

RESULTS

There were no associations between dental maturity and genotypes (p > 0.05). In the skeletal maturity analysis, the allele A in the rs708111 (WNT3A) was statistically more frequent in patients with delayed skeletal maturation (Prevalence Ratio = 1.6; 95% Confidence Interval = 1.00 to 2.54; p-value = 0.042).

CONCLUSIONS

The rs708111 in the WNT3A gene impacts on skeletal maturation.

Prevalence and local causes for retention of primary teeth and the associated delayed permanent tooth eruption

BACKGROUND

This study aimed to evaluate the prevalence of retained primary teeth (RPT) associated with delayed permanent tooth eruption and the factors associated with this condition in German children.

METHODS

This is a cross-sectional retrospective study that evaluated panoramic radiographs from orthodontic patients. The diagnosis of RPT was established according to Nolla developmental stage. The primary tooth was considered retained when its successor permanent tooth was in Nolla stage 8, 9, or 10. Statistical analysis was performed with an α of 5% (p < 0.05).

RESULTS

A total of 102 children (48 girls and 54 boys), and 574 primary teeth and their respective permanent successor teeth were evaluated. We classified 192 teeth as RPT. Sixty-one (59.8%) children presented one or more RPT. Gender was not significantly different between RPT and control teeth (p = 0.838; odds ratio 0.95, confidence interval 95% 0.44-2.16). In the majority of the RPT cases (68.7%), no clear cause to explain the prolonged retention was identified. The pathological problems most commonly observed with RPT were dental fillings (19.3%), followed by dental caries (4.6%), and ectopic tooth eruption (2.1%).

CONCLUSIONS

The incidence of RPT associated with delayed permanent tooth eruption in German children was high and the most common pathological condition associated with RPT was dental caries.

Validation of a mathematical-geometrical model to calculate the length of an individual anterior arch

PURPOSE

For resolving anterior dental crowding or spacing, it is of key interest in personalised orthodontic diagnostics and treatment planning to predict the extent of space gained or lost in the anterior dental arch by changing incisor inclination or position. To facilitate the determination of anterior arch length (AL) and to predict its alterations following tooth movements, a mathematical-geometrical model, based on a third-degree parabola, was established. The aim of this study was to validate this model and assess its diagnostic precision.

METHODS

This retrospective diagnostic study evaluated 50 randomly chosen dental casts taken before (T0) and after (T1) orthodontic treatment with fixed appliances. Plaster models were digitally photographed, allowing two-dimensional digital measurements of arch width, depth and length. A computer programme based on the mathematical-geometrical model to be validated was created to calculate AL for any given arch width and depth. Mean differences and correlation coefficients as well as Bland-Altman plots were used to compare the measured and the calculated (predicted) AL, evaluating the precision of the model.

RESULTS

Inter- and intrarater reliability tests showed reliable measurements of arch width, depth and length. Measured and calculated (predicted) AL revealed high concordance according to concordance correlation coefficient (CCC), intraclass correlation coefficient (ICC), and Bland-Altman analyses and negligible differences between the mean values.

CONCLUSIONS

The mathematical-geometrical model calculated anterior AL without significant difference to the measured AL, indicating its validity. The model can thus be used clinically for predicting alterations of AL following therapeutic changes of incisor inclination/position.

Assessing the relationship between single nucleotide polymorphisms in Wingless signaling pathway genes and sella turcica morphology

Sella turcica development involves molecular factors and genes responsible for ossification. It is possible that single nucleotide polymorphisms (SNPs) in key genes are involved in morphological variation of sella turcica. Genes belonging to the WNT signaling pathway are involved in the ossification process and are candidates of sella turcica morphology. This study aimed to evaluate if SNPs in WNT6 (rs6754599) and WNT10A (rs10177996 and rs3806557) genes are associated with the calcification and patterns of the sella turcica. Nonsyndromic individuals were included in the research. Cephalometric radiographs were examined and the sella calcification was evaluated and classified according to the calcification of the interclinoid ligament (no calcification, partial calcification, and incomplete calcification) and sella turcica pattern (normal sella turcica, bridge type A-ribbon-like fusion, bridge type B-extension of the clinoid processes, incomplete bridge, hypertrophic posterior clinoid process, hypotrophic posterior clinoid process, irregularity in the posterior part, pyramidal shape of the dorsum, double contour of the floor, oblique anterior wall, and oblique contour of the floor). DNA samples were used to evaluate SNPs in the WNT genes (rs6754599, rs10177996, and rs3806557) using real-time PCR. Chi-square test or Fisher's exact test were used to compare the allele and genotype distributions according to sella turcica phenotypes. The alpha was set as 5% for all comparisons. A total of 169 individuals were included, 133 (78.7%) present sella turcica partially or completely calcified. Sella turcica anomalies were found in 131 individuals (77.5%). Sella turcica bridge type A (27.8%), posterior hypertrophic clinoid process (17.1%), and sella turcica bridge type B (11.2%) were the most prevalent morphological patterns observed. Individuals carrying the TT genotype in rs10177996 (TT vs. CT + CC) had higher chance to present a partially calcified sella turcica (p = 0.047; Odds ratio = 2.27, Confidence Interval 95% 1.01-5.13). In conclusion, the SNP in WNT10A is associated with the calcification phenotype of the sella turcica, the pleiotropic effect of this gene should be taken into consideration in future studies.

Association between craniofacial patterns and third molar agenesis in orthodontic patients

PURPOSE

Third molar agenesis (TMA) is the most common craniofacial anomaly and has been associated with craniofacial patterns in different populations. Therefore, the aim of this retrospective cross-sectional study was to assess a possible association between craniofacial patterns and TMA in German orthodontic patients.

METHODS

Patients undergoing orthodontic treatment with dental records including anamnesis, pretreatment lateral cephalograms and orthopantomograms were evaluated. Cephalometric analyses were conducted digitally and lines, angles and proportions were measured to investigate craniofacial morphology. Skeletal classes were determined by the individualised Wits appraisal and ANB angle. The TMA was identified with the help of orthopantomograms. Patients showing agenesis of at least one third molar were included in the TMA group. Statistical analysis was performed to assess the association between TMA and craniofacial patterns (α of p ≤ 0.05).

RESULTS

A total of 148 patients were included, 40 (27.0%) presented at least one missing tooth (TMA group) and 108 (73.0%) showed full dentition (control group). Skeletal class determined by the individualised Wits appraisal revealed statistical significance between the TMA and control groups (p = 0.022), in which TMA patients were 11 times more likely to present with an individualised skeletal class III (odds ratio 11.3, 95% confidence interval 1.7-139.5). Skeletal cephalometric analysis revealed no statistical differences between TMA and control groups for any further angular, linear and proportional parameters.

CONCLUSION

Third molar agenesis was associated with skeletal class III determined by the individualised Wits appraisal.

Advancing oral immunology for improving oral health

Although substantial progress has been made in dentistry in terms of diagnosis and therapy, current treatment methods in periodontology, orthodontics, endodontics, and oral and maxillofacial surgery, nevertheless, suffer from numerous limitations, some of which are associated with a dramatic reduction in the quality of life. Many general mechanisms of inflammation and immunity also apply to the oral cavity and oral diseases. Nonetheless, there are special features here that are attributable, on the one hand, to developmental biology and, on the other hand, to the specific anatomical situation, which is characterized by a close spatial relationship of soft and hard tissues, exposure to oral microbiota, and to a rapid changing external environment. Currently, a comprehensive and overarching understanding is lacking about how the immune system functions in oral tissues (oral immunology) and how oral immune responses contribute to oral health and disease. Since advances in translational immunology have created a game-changing shift in therapy in rheumatology, allergic diseases, inflammatory bowel disease, and oncology in recent years, it is reasonable to assume that a better understanding of oral immunology might lead to practice-changing diagnostic procedures and therapies in dentistry and thereby also profoundly improve oral health in general.

Effect of genetic polymorphisms rs2301113 and rs2057482 in the expression of HIF-1α protein in periodontal ligament fibroblasts subjected to compressive force

OBJECTIVE

Many genes and signaling molecules are involved in orthodontic tooth movement, with mechanically and hypoxically stabilized HIF-1α having been shown to play a decisive role in periodontal ligament signaling during orthodontic tooth movement. Thus, this in vitro study aimed to investigate if genetic polymorphisms in HIF1A (Hypoxia-inducible factor α-subunits) influence the expression pattern of HIF-1α protein during simulated orthodontic compressive pressure.

METHODOLOGY

Samples from human periodontal ligament fibroblasts were used and their DNA was genotyped using real time Polymerase chain reaction for the genetic polymorphisms rs2301113 and rs2057482 in HIF1A . For cell culture and protein expression experiments, six human periodontal ligament fibroblast cell lines were selected based on the patients' genotype. To simulate orthodontic compressive pressure in fibroblasts, a 2 g/cm2 force was applied under cell culture conditions for 48 hours. Protein expression was evaluated by Western Blot. Paired t-tests were used to compare HIF-1α expression with and without compressive pressure application and unpaired t-tests were used to compare expression between the genotypes in rs2057482 and rs2301113 (p<0.05).

RESULTS

The expression of HIF-1α protein was significantly enhanced by compressive pressure application regardless of the genotype (p<0.0001). The genotypes in the genetic polymorphisms rs2301113 and rs2057482 were not associated with HIF-1α protein expression (p>0.05).

CONCLUSIONS

Our study confirms that compressive pressure application enhances HIF-1α protein expression. We could not prove that the genetic polymorphisms in HIF1A affect HIF-1α protein expression by periodontal ligament fibroblasts during simulated orthodontic compressive force.

Towards Genetic Dissection of Skeletal Class III Malocclusion: A Review of Genetic Variations Underlying the Phenotype in Humans and Future Directions

INTRODUCTION

Skeletal abnormalities and malocclusions have varied features that impact populations globally, impairing aesthetics and lowering life quality. The prevalence of the Skeletal Class III disease is the lowest among all angle malocclusions, with varied prevalence across nations. Environmental, genetic, and societal factors play a role in its numerous etiologies. In this study, we conducted a thorough search across the published data relating to quantitative trait loci (QTL) and the genes associated with Class III progression in humans, discussed these findings and their limitations, and proposed future directions and strategies for studying this phenotype.

METHODS

An inclusive search of published papers in the PubMed and Google Scholar search engines using the following terms: 1. Human skeletal Class III; 2. Genetics of Human skeletal Class III; 3. QTL mapping and gene associated with human skeletal Class III; 4. enriched skeletal Class-III-malocclusion-associated pathways.

RESULTS

Our search has found 53 genes linked with skeletal Class III malocclusion reported in humans, genes associated with epigenetics and phenomena, and the top 20 enriched pathways associated with skeletal Class III malocclusion.

CONCLUSIONS

The human investigations yielded some contentious conclusions. We conducted a genome-wide association study (GWAS), an epigenetics-wide association study (EWAS), RNA-seq analysis, integrating GWAS and expression quantitative trait loci (eQTL), micro- and small-RNA, and long non-coding RNA analysis in tissues connected to skeletal Class III malocclusion phenotype in tissues connected with the skeletal phenotype. Finally, we invite regional, national, and international orthodontists and surgeons to join this effort by contributing human samples with skeletal Class III malocclusion following the accepted Helsinki ethical protocol to challenge these phenomena jointly.

Association between genetic variants in key vitamin-D-pathway genes and external apical root resorption linked to orthodontic treatment

This study evaluated the association between single-nucleotide polymorphisms (SNPs) in vitamin-D-related genes and the amount of external apical root resorption linked to orthodontic treatment. One hundred and forty-three individuals were assessed. The amount of external apical root resorption of upper central incisors (EARR_inc ) and lower first molars (EARR_mol ) were evaluated in radiographs. Seven SNPs were genotyped across four genes including the vitamin D receptor [VDR], group-specific component [GC], cytochrome P450 family 27 subfamily B member 1 [CYP27B1], and cytochrome P450 family 24 subfamily A member 1 [CYP24A1]. Linear regressions were implemented to determine allele-effects on external apical root resorption. Individuals carrying the AA genotype in VDR rs2228570 had a 21% higher EARR_mol than those having AG and GG genotypes (95% CI: 1.03,1.40). EARR_mol in heterozygous rs2228570, was 12% lower than for homozygotes (95%CI: 0.78,0.99). Participants with the CCG haplotype (rs1544410-rs7975232-rs731236) in VDR had an EARR_mol 16% lower than those who did not carry this haplotype. Regarding CYP27B1 rs4646536, EARR_inc in participants who had at least one G allele was 42% lower than for homozygotes AA (95%CI: 0.37,0.93). Although these results did not remain significant after multiple testing adjustment, potential associations may still be suggested. Further replication studies are needed to confirm or refute these findings.

Long-term (≥ 15 years) outcome quality after Class II:1 bionator or Herbst multibracket appliance treatment : A comparison

PURPOSE

To compare the long-term outcome quality (≥ 15 years) of Class II:1 treatment using either a bionator (BIO) or a Herbst-multibracket appliance (HMB).

METHODS

Patients who underwent functional treatment during the ideal treatment period for the respective approach (prepuberty vs. peak/postpeak) were assessed. Inclusion criteria were overjet ≥ 4 mm, skeletal Class II and availability of study casts from before, after and ≥ 15 years after treatment. The study casts were assessed using the Peer Assessment Rating (PAR) index and standard orthodontic cast measurements.

RESULTS

During treatment, PAR score, overjet and sagittal occlusal relationship improved significantly in all groups. Long-term, there was a significant increase of incisor irregularity in the upper (HMB) and lower (BIO) arch and a significant decrease of lower arch width 3 - 3 (BIO). PAR score, overjet, and sagittal occlusal relationship remained stable long-term. Intergroup comparisons revealed significant differences between the BIO and HMB groups in terms of lower arch width (6 - 6), upper and lower arch width (3 + 3/3 - 3) as well as sagittal molar relationship.

CONCLUSIONS

The achieved improvement in PAR score, overjet, and sagittal occlusion remained comparably stable long-term in all groups. The long-term changes are probably a consequence of natural aging.

Twenty-year follow-up of functional treatment with a bionator appliance (part 2): a retrospective cephalometric analysis of skeletal and dentoskeletal changes

OBJECTIVES

To investigate skeletal and dentoskeletal changes 20 years after bionator treatment.

MATERIALS AND METHODS

Analog lateral cephalograms of 18 subjects treated with a bionator appliance during growth were digitized with a transmitted light scanner. Inclusion criteria were: increased overjet (≥4 mm), skeletal Class II, available lateral cephalograms before (T0), after (T1), and 20 years after (T2) treatment with only a Bionator. To assess standard cephalometric parameters, the software ivoris analyze was used. Data were analyzed using Friedman's two-way analysis of variance by ranks followed by Dunn's post hoc tests (P ≤ .05).

RESULTS

During therapy (T0-T1), ANB decreased significantly by 1.9° and remained unchanged long term. SNA slightly decreased (-0.6°) during treatment, SNB and SNPg increased (+1.4°, +1.7°). All three parameters showed a significant increase at T2 (+1.2°, +1.6°, +1.6°). Vertical measurements (ML-NL, ML-NSL, NL-NSL) remained almost unchanged during therapy. NL-NSL also was unchanged during the long-term interval; ML-NSL and ML-NL decreased significantly (-3.4°, -4.9°). During treatment, the maxillary incisors retroclined (OK1-NL: -1.6°, OK1-NA: -0.6°), the mandibular incisors proclined (UK1-ML: +3.5°, UK1-NB: +4.9°), neither significantly. Long term, there was a nonsignificant tendency toward proclination of upper (OK1-NL: +0.1°, OK1-NA: +0.7°) and retroclination of lower incisors (UK1-ML: -1.5°, UK1-NB: -5°).

CONCLUSIONS

Changes of ANB after bionator treatment without additional fixed appliances remained stable after 20 years. The observed long-term changes are probably consequences of well-known physiological and age-related processes.

Impact of PIEZO1-channel on inflammation and osteoclastogenesis mediated via periodontal ligament fibroblasts during mechanical loading

The identification of mechanosensitive ion channels and their importance in innate immunity provides new starting points to elucidate the molecular mechanisms of orthodontic tooth movement. The mechanosensitive electron channel PIEZO1 (Piezo Type Mechanosensitive Ion Channel Component 1) may play a crucial role in orthodontic tooth movement. To investigate the role of the PIEZO1 channel, periodontal ligament fibroblasts (PDLF) were subsequently treated with a PIEZO1 inhibitor (GsMTx) with simultaneous pressure application or with an activator (JEDI2) without mechanical strain. The expression of genes and proteins involved in orthodontic tooth movement was examined by RT-qPCR, Western blot and ELISA. In addition, the effect on PDLF-mediated osteoclastogenesis was investigated in a coculture model using human monocytes. Inhibition of PIEZO1 under pressure application caused a reduction in RANKL (receptor activator of NF-kB ligand) expression, resulting in decreased osteoclastogenesis. On the other hand, activation of PIEZO1 without mechanical strain downregulated OPG (osteoprotegerin), resulting in increased osteoclastogenesis. PIEZO1 appears to play a role in the induction of inflammatory genes. It was also shown to influence osteoclastogenesis.

Impact of different pretreatments and attachment materials on shear bond strength of indirectly bonded brackets using CAD/CAM transfer trays to monolithic zirconia

OBJECTIVE

Investigating the impact of different pretreatment methods, attachment materials and aging regimens on shear bond strength (SBS) between zirconia and indirectly bonded brackets using CAD/CAM transfer trays.

METHODS

Zirconia substrates were conditioned with silica coated alumina (CoJet) and a) Clearfil Ceramic Primer Plus (CF), b) RelyX Ceramic Primer (RXP), c) Futurabond U (FU). Brackets were virtually placed, transfer tray designed (OnyxCeph) and 3D-printed for indirect bonding with a) Transbond LV (TBL), b) Nexus NX3 (NX3), c) Maximum Cure (MC). SBS testing was performed with a universal testing machine after 24 h, 500 thermal cycles, 90 d. Directly bonded brackets to human enamel using Transbond XT Adhesive served as control. The adhesive remnant index (ARI) was evaluated. Data was analyzed with Shapiro-Wilk, Kruskal-Wallis and Dunn's post-hoc test with Bonferroni correction, Chi² test (p < 0.05), and the Weibull modulus was calculated.

RESULTS

SBS ranged from 0.1 to 15.5 MPa and were influenced mostly by the attachment material. NX3 generally showed the highest values (9.5-15.8 MPa). Initially RXP/TBL and FU/TBL presented the lowest values (4.3/4.8 MPa). Aging regimens reduced SBS of MC irrespective of pretreatment, after 90 d values ranged from 0.1 to 0.9 MPa. ARI 1 was predominant in all MC groups and FU/NX3, 2 and 3 in the other groups. Weibull moduli ranged between 0.15 (MC/RXP/500 TC) and 6.24 (NX3/RXP/500 TC).

SIGNIFICANCE

MC seems not to be suitable for indirect bonding using CAD/CAM transfer trays to zirconia. NX3 showed similar SBS values compared to the control, TBL lower.

Dissecting the Complexity of Skeletal-Malocclusion-Associated Phenotypes: Mouse for the Rescue

Skeletal deformities and malocclusions being heterogeneous traits, affect populations worldwide, resulting in compromised esthetics and function and reduced quality of life. Skeletal Class III prevalence is the least common of all angle malocclusion classes, with a frequency of 7.2%, while Class II prevalence is approximately 27% on average, varying in different countries and between ethnic groups. Orthodontic malocclusions and skeletal deformities have multiple etiologies, often affected and underlined by environmental, genetic and social aspects. Here, we have conducted a comprehensive search throughout the published data until the time of writing this review for already reported quantitative trait loci (QTL) and genes associated with the development of skeletal deformation-associated phenotypes in different mouse models. Our search has found 72 significant QTL associated with the size of the mandible, the character, shape, centroid size and facial shape in mouse models. We propose that using the collaborative cross (CC), a highly diverse mouse reference genetic population, may offer a novel venue for identifying genetic factors as a cause for skeletal deformations, which may help to better understand Class III malocclusion-associated phenotype development in mice, which can be subsequently translated to humans. We suggest that by performing a genome-wide association study (GWAS), an epigenetics-wide association study (EWAS), RNAseq analysis, integrating GWAS and expression quantitative trait loci (eQTL), micro and small RNA, and long noncoding RNA analysis in tissues associated with skeletal deformation and Class III malocclusion characterization/phenotypes, including mandibular basic bone, gum, and jaw, in the CC mouse population, we expect to better identify genetic factors and better understand the development of this disease.

Floating norms for individualising the ANB angle and the WITS appraisal in orthodontic cephalometric analysis based on guiding variables

PURPOSE

The sagittal skeletal relationship of maxilla and mandible (skeletal class) can generally be determined via lateral cephalograms (ANB angle or Wits appraisal) by comparing measurements to empirical norms based on the respective population mean. However, values differing from these empirical norms also enable a therapeutically desired, normal class I occlusion depending on individual craniofacial pattern, thus requiring floating norms based on guiding variables. As available regression equations consider only few predictor variables and are not up-to-date regarding a contemporary patient collective, the aim of this study was to establish improved and extended regression equations for individualising the ANB angle and Wits appraisal.

METHODS

This retrospective, cross-sectional multicentre study was based on 71 Caucasian male and female subjects of any age with normal dental occlusion. We cephalometrically analysed digitised pretreatment lateral radiographs and performed multiple linear regression analyses to identify suitable skeletal predictor variables for individualising the ANB angle and Wits appraisal.

RESULTS

Inter- and intrarater reliability tests showed mostly perfect measurement concordance. Both original regression equations by Panagiotidis/Witt and Järvinen could be updated for a contemporary population with new regression coefficients. The equation for individualising the ANB could be further optimised in its prediction reliability by adding the skeletal predictor variables NL-NSL, NSBa, facial axis (Ricketts) and index (Hasund), whereas the recalculated Wits equation could not be further improved by additional guiding variables.

CONCLUSIONS

The improved regression formulae for individualising the ANB angle and Wits appraisal should help to improve the assessment of sagittal skeletal class in clinical orthodontic practice.

Relapse in class II orthognathic surgery: a systematic review

OBJECTIVES

Relapse after orthognathic surgery seems to depend on diverse factors. Proffit et al. postulated in 2007 a "hierarchy of stability" (Head Face Med 6:66, 2007), ranking posttreatment stability after various orthognathic procedures, but no systematically reviewed evidence was provided. Therefore, the aim of this review was to investigate the extent of class II relapse in orthognathic surgery of Angle class II patients depending on the surgical procedure used.

MATERIALS AND METHODS

Seven databases were searched for randomized and controlled clinical trials to compare relapse in surgical procedures for Angle class II patients. After duplicate study selection, data extraction and risk of bias assessment were performed with the ROBINS-I tool as well as data synthesis by frequency distribution, followed by assessment of the quality of evidence with GRADE.

RESULTS

Four non-randomized cohort-studies with a total of 132 patients were included. Bimaxillary procedures as well mandibular advancement procedures proved to be highly stable. Single jaw interventions at the maxilla achieved mostly stable results at sagittal dimension and problematic stability in the vertical dimension. However, there were only limited data available with low quality of evidence.

CONCLUSIONS

Limited existing evidence of low quality partly support the postulated hierarchy of stability of Proffit et al. (Head Face Med 6:66, 2007) and indicates that a surgical correction of class II dysgnathia with bimaxillary procedures and mandibular advancement seems to be highly stable. However, additional studies are needed to address the relation between relapse and surgical orthognathic intervention. Trial registration PROSPERO 2019 CRD42019144873.

Influence of Single-Nucleotide Polymorphisms on Vitamin D Receptor Expression in Periodontal Ligament Fibroblasts as a Response to Orthodontic Compression

This study aimed to evaluate if single-nucleotide polymorphisms (SNPs) in the vitamin D receptor (VDR) gene are associated with gene expression in human periodontal ligament (hPDL) fibroblasts under simulated orthodontic compressive force. hPDL samples from 57 patients were used. A physiological compressive strain was performed to simulate orthodontic tooth movement in pressure areas under cell culture conditions. The RNA from hPDL fibroblasts was isolated to determine the relative gene expression (mRNA) of the VDR. The DNA was also isolated for the genotyping analysis of five SNPs in the VDR gene: BglI (rs739837, G/T), BsmI (rs1544410, T/C), ApaI (rs7975232, A/C), FokI (rs2228570, A/G), and TaqI (rs731236, A/G). Real-time polymerase chain reaction was used for both analyses. Kruskal−Wallis tests were used to compare VDR expression among genotypes of each SNP. A linear regression analysis was performed to evaluate SNP−SNP interaction. An established alpha of 5% was used. The relative mRNA VDR expression according to the genotypes in the SNPs BglI, BsmI, ApaI, FokI, and TaqI was not statistically significantly different (p > 0.05). The SNP−SNP interaction evaluated by regression analysis did not demonstrate any statistically significant association. No association was observed (p > 0.05). In conclusion, the SNPs BglI (rs739837), BsmI (rs1544410), ApaI (rs7975232), FokI (rs2228570), and TaqI (rs731236) did not show an impact on VDR gene expression in hPDL fibroblasts under simulated orthodontic compressive force.

Impact of Leptin on the Expression Profile of Macrophages during Mechanical Strain In Vitro

Childhood obesity is a growing problem in industrial societies and associated with increased leptin levels in serum and salvia. Orthodontic treatment provokes pressure and tension zones within the periodontal ligament, where, in addition to fibroblasts, macrophages are exposed to these mechanical loadings. Given the increasing number of orthodontic patients with these conditions, insights into the effects of elevated leptin levels on the expression profile of macrophages during mechanical strain are of clinical interest. Therefore, the aim of this in vitro study was to assess the influence of leptin on the expression profile of macrophages during simulated orthodontic treatment. RAW264.7 macrophages were incubated with leptin and lipopolysaccharides (LPS) from Porphyromonas gingivalis (P. gingivalis) or with leptin and different types of mechanical strain (tensile, compressive strain). Expression of inflammatory mediators including tumor necrosis factor (TNF), Interleukin-1-B (IL1B), IL6, and prostaglandin endoperoxide synthase (PTGS2) was assessed by RT-qPCR, ELISAs, and immunoblot. Without additional mechanical loading, leptin increased Tnf, Il1b, Il6, and Ptgs2 mRNA in RAW264.7 macrophages by itself and after stimulation with LPS. However, in combination with tensile or compressive strain, leptin reduced the expression and secretion of these inflammatory factors. By itself and in combination with LPS from P. gingivalis, leptin has a pro-inflammatory effect. Both tensile and compressive strain lead to increased expression of inflammatory genes. In contrast to its effect under control conditions or after LPS treatment, leptin showed an anti-inflammatory phenotype after mechanical stress.

A new method for successful indirect bonding in relation to bond strength

The aim of the work was to develop a new transfer method for indirect bonding of brackets to improve the bond strength by applying a uniform contact pressure over the entire dental arch. This has a great potential to reduce the bracket loss rate during clinical treatment. A suitable shape memory polymer (SMP) was selected and prepared in the chemistry laboratory. This SMP applies a force to the brackets during bonding and thus increases the bond strength by applying uniform contact pressure. Various transfer trays were equipped with SMP platelets and the transfer of brackets from the plaster model to the real human tooth model was performed in vitro. The transfer accuracy and bond strength of the bonded brackets were investigated by 3D-overlay and shear tests, respectively. The transfer accuracy was technique sensitive and showed higher accuracy for the trays with SMPs and self-curing silicones than for the vacuum formed trays with SMPs. The bond strength of the indirectly bonded brackets with SMPs was on average 1-2 MPa higher than the bond strength of the brackets indirectly bonded with a conventional two-layer vacuum formed tray without SMPs. Thus, transfer trays with SMPs can provide a significant improvement in bond strength during indirect bonding after appropriate adjustment.

Single Nucleotide Polymorphisms in COX2 Is Associated with Persistent Primary Tooth and Delayed Permanent Tooth Eruption

Persistent primary tooth (PPT) is a prevalent clinical condition that occurs when a primary tooth is over-retained beyond the established period of its normal exfoliation time, remaining in the oral cavity. Many factors could be involved in the risk of PPT; therefore, the aim of this study was to evaluate if single nucleotide polymorphisms (SNPs) in the COX2 gene are associated with PPT. Children undergoing orthodontic treatment were screened. Orthopantomographs were assessed to evaluate PPT according to the Nolla stage of its permanent successor. The primary tooth was considered retained when its successor permanent tooth was in Nolla stage 8 and below the alveolar crypt, Nolla stage 9, or Nolla stage 10. A saliva sample from each child was collected and used for DNA extraction. A real-time PCR of two SNPs, rs689466 (-1195 G/A) and rs5275 (+665 T/C), was performed. A chi-square test was used to compare the allele and genotype distribution. Haplotype analysis was also performed. A total of 100 children were included in the study. Fifty-one had at least one PPT, while 49 children were classified as a control. The number of teeth persistent in the oral cavity ranged from 1 to 8. The genotype distribution was associated with PPT in the co-dominant model (p = 0.006) for SNP rs5275. The individuals that carry two T alleles (TT) compared with the individuals that carry at least one C allele (C + TC) had an almost three times higher chance of presenting with PPT (p = 0.012; OR = 2.99, CI95% 1.28 to 6.95-recessive model). The haplotype C-A for the SNPs rs5275 and rs689466, respectively, was significantly associated (p = 0.042). In conclusion, single nucleotide polymorphisms in the gene encoding for COX2 are associated with persistent primary tooth and may delay permanent tooth eruption.

Ideal treatment timing of orthodontic anomalies-a German clinical S3 practice guideline

Purpose

Ideal treatment timing in orthodontics is controversially discussed depending on the type and extent of the dysgnathia and malocclusion present, especially with regard to efficiency, patient burden and treatment efforts of early compared to regular or late treatment. This German clinical practice guideline aims to clarify, at which time points an orthodontic anomaly can be effectively treated and how treatment efficiency differs depending on treatment timing.

Methods

A systematic literature search was performed in various guideline databases and databases PROSPERO, MEDLINE (PubMed), Cochrane Library, Web of Science, ClinicalTrials.gov and the International Clinical Trials Registry Platform according to a predefined PICO (Population, Intervention, Comparison and Outcomes with added qualitative search terms) search algorithm and strategy. Appraisal of scientific evidence of the individual studies checked for eligibility was carried out according to SIGN (Scottish Intercollegiate Guidelines Network), AMSTAR II (Assessing the Methodological Quality of Systemic Reviews), and AXIS (Appraisal Tool to Assess the Quality of Cross-sectional Studies) tools. Only controlled studies with a high, acceptable or moderate quality (and thus an acceptable risk of bias) were considered.

Results

A total of 309 studies of over 11,000 sources screened were identified to be eligible for inclusion and critically appraised for study quality and risk-of-bias. No relevant guidelines relating to the aims of the present guideline were found. Elected delegates of in total 21 German scientific societies and organizations agreed upon a total of 19 evidence-based statements and recommendations based on a nominal consensus process.

Conclusions

Although most malocclusions can be effectively treated both in the early, late mixed, and permanent dentition, evidence suggests that therapy of a pronounced skeletal or dental class II anomaly can be started early to reduce the risk of dental anterior tooth trauma, whereas in a moderate class II anomaly, therapy can preferably be carried out before or during the pubertal growth peak. Therapy of a skeletal or dental class III anomaly should be started early, as this also reduces the need for later surgery to correct the anomaly. The treatment of a pronounced skeletal or dental transverse anomaly should be started early in the upper jaw in order to utilize the high adaptivity of the maxillary structures in young patients.

Supplementary Information

The online version of this article (10.1007/s00056-022-00409-3) contains supplementary information—the German translation of the article, supplementary tables and references—which is available to authorized users.

Assessing the prevalence of S-shaped root canal and associated genes in humans

BACKGROUND

Multiple signaling molecules have been shown to play crucial roles in dental root development. Therefore, we aimed to investigate the prevalence of S-shaped roots and also to investigate, if single nucleotide polymorphisms (SNPs) in BMP2, BMP4 and SMAD6 are associated with this phenotype in humans.

METHODS

This is a cross-sectional phenotype-genotype association study that used radiographs to determine the phenotypes and DNA to investigate SNPs in candidate genes. During the radiographic exam, teeth presenting root canal(s) doubly curved were considered S-shaped roots. SNPs in BMP2 (rs1005464 and rs235768), BMP4 (rs17563) and SMAD6 (rs2119261 and rs3934908) were blindly genotyped by real-time PCR using TaqMan assay. The relative and absolute frequency of S-shaped roots were calculated. Chi-square test was used to compare the genotype distributions between control and S-shaped groups.

RESULTS

Among the 578 subjects, 61 (10.6%) presented at least one tooth with an S-shaped root. The most commonly affected type of tooth was the premolar. rs1005464 in BMP2 was statistically associated with an S-shaped root (p=0.036). rs235768 in BMP2 was associated with an S-shaped root also in mandibular teeth (p=0.017). A statistical significance was observed for the rs3934908 in SMAD6 (p=0.049) for S-shaped root in the mandible. In the analysis stratified according to the type of tooth, rs235768 in BMP2 was associated with S-shaped roots in premolars (p=0.029).

CONCLUSION

The prevalence of S-shaped roots is 10.6% in permanent teeth. SNPs in BMP2 and SMAD6 could be involved in a higher chance to present S-shaped roots.

Dietary salt and myeloid NFAT5 (nuclear factor of activated T cells 5) impact on the number of bone-remodelling cells and frequency of root resorption during orthodontic tooth movement

PURPOSE

The aim of the study was to investigate the impact of dietary salt and the osmoprotective transcription factor nuclear factor of activated T cells 5 (NFAT5) in myeloid cells on bone remodelling cells as osteocytes, osteoblasts and osteoclasts and on force-induced dental root resorptions in a mouse model.

METHODS

Control mice and mice lacking myeloid NFAT5 (nuclear factor of activated T cells 5) were either kept on low, normal or high salt diets. After one week on the specified diet an elastic band was inserted between the first and second molar to induce orthodontic tooth movement. One week later the mice were euthanised and jaws were fixed for histological analysis. Osteocyte, osteoblast and osteoclast numbers as well as extent of root resorptions were assessed histologically.

RESULTS

Osteocyte number was diminished with high salt diet in wildtype mice. Osteoblast numbers increased with low salt diet in control mice and reduced with high salt diet in mice without NFAT5 in myeloid cells. High salt diet tended to increase osteoclast number in control mice. In mice without myeloid NFAT5, numbers of osteoclasts were reduced under high salt diet. Frequency of force-induced root resorptions tended to be dependent on dietary salt content in control mice.

CONCLUSION

During orthodontic tooth movement dietary salt impacts on the frequency of root resorptions and the number of osteoclasts and osteoblasts in alveolar bone of mice. This can affect bone remodelling during orthodontic treatment. Myeloid NFAT5 impacts on this salt-dependent reaction.

Association of third molar agenesis and microdontia with genetic polymorphisms in vitamin-D-related genes

The present study aimed to evaluate if functional genetic polymorphisms in vitamin-D-related genes are associated with third molar agenesis and third molar microdontia in German orthodontic patients. Pre-orthodontic and follow-up treatment records were evaluated for phenotype definition. Saliva samples were collected for DNA extraction. Eight potential functional genetic polymorphisms in VDR [rs731236 (TaqI), rs7975232 (ApaI), rs2228570 (FokI), and rs1544410 (BsmI)], CYP27B1 (rs4646536), CYP24A1 (rs927650), GC (rs4588), and SEC23A (rs8018720) were evaluated using real-time PCR. Comparison among the groups were performed (third molar anomaly vs. control; third molar agenesis vs. control; and third molar microdontia vs. control) with an alpha of 5%. A total of 164 patients were analyzed. Forty-nine (29.9%) patients had at least one third molar anomaly. In the haplotype analysis, genetic polymorphisms in VDR and CYP27B1 were associated with third molar anomalies (p<0.05). The G allele in rs8018720 (SEC23A) was more frequent in microdontia cases. In the genotype distribution analysis, rs8018720 in SEC23A was associated with third molar microdontia in the co-dominant (p=0.034; Prevalence Ratio [PR]=5.91, 95% Confidence Interval [CI]= 1.14-30.66) and in the recessive (p=0.038; PR=5.29; 95% CI= 1.09-25.65) models. In conclusion, vitamin D-related genes could be involved in third molar anomalies.

Impact of different pretreatments and attachment materials on shear bond strength between monolithic zirconia restorations and metal brackets

To investigate the influence of different pretreatment methods, attachment materials and artificial aging on shear bond strength (SBS) between monolithic zirconia and metal brackets. Zirconia substrates were pretreated with silica coated alumina (CoJet) and (1) clearfill ceramic primer plus (CF), (2) RelyX ceramic primer (RXP), (3) Futurabond U (FU). The brackets were bonded with (1) Transbond XT Adhesive (TB), (2) BrackFix Adhesive (BF), (3) bracepaste adhesive (BP). SBS was tested after 24 h, 500 thermal cycles, 90 d at 37 °C with a universal testing machine. SBS values reached from 8.3 to 16.9 MPa. The Weibull moduli ranged between 0.37 (RXP combined with BP after 90 d) and 7.42 (CF combined with TB after 24 h). The pretreatment with FU after 90 d, independent of the attachment material, and RXP with BF resulted in the lowest SBS values 8.3–9.9 MPa, the combination of RXP or CF with TB showed the highest (13.2–16.9 MPa) independent of aging. After FU pretreatment the proportion of ARI 1 and 0 was higher, of ARI 3 lower as after CF and RXP pretreatment. All tested combinations showed sufficiently high SBS values for clinical use. Pretreatment with FU presented the lowest values after 90 days.

Ideal transverse position of mandibular first molars based on CBCT-derived alveolar bone coverage

BACKGROUND

In orthodontic treatment, transverse arch width often needs to be adjusted to correct anomalies such as posterior crossbite. Ideal transverse arch width at the first molars enabling long-term stability and periodontal health, however, requires sufficient posttreatment bony coverage buccally and orally of the tooth roots. Thus, the aim of this retrospective study was to determine the physiological alveolar bone thickness at the buccal and oral roots of the first mandibular molars in the general population using human CBCT scans assessing local and gender-specific differences.

METHODS

CBCTs of 124 random 11- to 55-year old patients (46 female, 78 male) were analysed retrospectively. Alveolar bone thickness was measured digitally at mesial and distal tooth roots of the first mandibular molars buccally and orally at different vertical positions (4 and 8mm apically of the cement-enamel-junction CEJ). For each patient, the mean of corresponding measurements from left and right molars was used for analysis.

RESULTS

All measurements were reliable, as proven by interrater- and interrater-reliability-testing. On average, bone thickness increased from the mesial to the distal tooth root, as well as in apical and oral direction. These local differences in alveolar bone thickness were all highly significant at p < 0.0001. Women showed thicker bone buccally at the distal tooth root at 8mm apically of the CEJ, as well as orally at both mesial and distal tooth roots 4mm apically of the CEJ.

CONCLUSIONS

The results of this study suggest that especially in buccal, mesial and gingival direction alveolar bone around mandibular first molars becomes thinner and hence the scope for orthodontic tooth movements is limited. Our results should aid assessing ideal transverse molar position based on alveolar bone coverage, although variations due to age may occur.

Duration of toothbrushing with fixed appliances: a randomized crossover clinical trial

OBJECTIVE

Fixed orthodontic appliances might result in dental adverse effects, if sufficient oral hygiene is not maintained. Since recommendations on toothbrushing times are lacking scientific justification in orthodontic populations, the aim of the present study was to comparatively quantify the duration of toothbrushing with a manual and a powered toothbrush in two distinct age groups.

TRIAL DESIGN

Two-centre, two-period crossover balanced randomized clinical trial with computer-generated numbers and blinding at the outcome-assessing level.

METHODS

Children and adults with fixed appliances with at least 22 aligned teeth were recruited at a university clinic and private practice in Bavaria, Germany. Plaque was disclosed with staining tablets and participants brushed their teeth with their habitual technique in front of a mirror and without interference until staining was, to their own satisfaction, completely removed. The primary outcome was duration of toothbrushing in seconds. Secondary outcomes were percentage plaque reduction and questionnaire data on dental attitudes and behaviours. Data were analysed with linear mixed models.

RESULTS

Twenty-eight participants were randomized to the first and 27 to the second toothbrush sequence. The combined effect of age and toothbrush on the duration of toothbrushing was evident (n = 52, F(1, 50.8) = 5.1, P = 0.028). Children brushed 14.5 seconds less [n = 28, 95% confidence interval (CI) = -31.3 to 2.3, P = 0.090], yet adults 13.3 seconds more (n = 24, 95% CI = -4.6 to 31.3, P = 0.143) with the manual than powered toothbrush. Brushing times ranged from 2 minutes and 45 seconds to 3 minutes and 17 seconds with plaque reduction at 76% and good dental attitudes and behaviours.

CONCLUSIONS

Both children and adults with fixed appliances might equally reach an effective plaque reduction with either manual or powered toothbrushes and their habitual brushing technique in around three minutes, if plaque is visible.

REGISTRATION

DRKS-German Clinical Trials Register ID: DRKS00012463.

FUNDING

Oral-B Procter & Gamble.

Estrogen deficiency during puberty affects the expression of microRNA30a and microRNA503 in the mandibular condyle

BACKGROUND

The aim of this study was investigated if estrogen deficiency during puberty affects the expression of miRNA30a and miRNA503 in maxillary and mandibular growth centers, and also evaluated if ERα and ERβ are correlated with miRNA30a and miRNA503 expressions.

METHODS

Samples from 12 female Wistar rats randomized into experimental group (OVX) and control group (SHAM). At an age of 45 days animals were euthanized for miRNA expression analyses. RT-qPCR was performed to determine miRNA30a and miRNA503 expression in growth sites: midpalatal suture, condyle, mandibular angle, symphysis/parasymphysis and coronoid process. The data was carried out using the parametric tests at 5% of significance level.

RESULTS

miRNA 30a and miRNA503 presented higher levels in the condylar site in SHAM group when compared with OVX (p = 0.002 and p = 0.020, respectively). In the growth centers, a statistical significant difference was observed only for miRNA30a (p = 0.004), when compared mandibular angle with condyle the in OVX group (p = 0.001). A strong positive correlation between miRNA503 and ERα in the condyle of OVX group was observed (r = 0.90; p = 0.039 and it also between miRNA503 and ERβ in the coronoid process of the OVX group (r = 0.88; p = 0.05).

CONCLUSION

The results suggested that estrogen regulates specific miRNAs in maxillary and mandibular growth centers, which may participate in posttranscriptional regulation of estrogen-regulated genes.

Exploring the Association Between Genetic Polymorphisms in Genes Involved in Craniofacial Development and Isolated Tooth Agenesis

Tooth agenesis is a common congenital anomaly in humans and is more common in oral cleft patients than in the general population. Many previous studies suggested that oral cleft and tooth agenesis share a similar genetic background. Therefore, this study explored the association between isolated tooth agenesis and genetic polymorphisms in genes that are crucial for craniofacial and tooth development. Panoramic radiographs, anamnesis, and genomic DNA from 273 patients were included. Patients were classified as tooth agenesis present, when at least one permanent tooth was congenitally missing. Patients with syndromes and oral cleft were excluded. Only unrelated patients were included. The genetic polymorphisms in BMP2 (rs235768 and rs1005464), BMP4 (rs17563), RUNX2 (rs59983488 and rs1200425), and SMAD6 (rs3934908 and rs2119261) were genotyped by real-time polymerase chain reaction. Genotype and allele distributions were compared between the tooth agenesis phenotypes and controls by Chi-square test. Haplotype and diplotype analysis were also performed, in addition to multivariate analysis (alpha of 0.05). A total of 86 tooth agenesis cases and 187 controls were evaluated. For the rs235768 in BMP2, patients carrying TT genotype have higher chance to present tooth agenesis [p < 0.001; prevalence ratio (PR) = 8.29; 95% confidence interval (CI) = 4.26–16.10]. The TT genotype in rs3934908 (SMAD6) was associated with higher chance to present third molar agenesis (p = 0.023; PR = 3.25; 95% CI = 1.17–8.99). BMP2 was also associated in haplotype and diplotype analysis with tooth agenesis. In conclusion, genetic polymorphisms in BMP2 and SMAD6 were associated with isolated tooth agenesis.

Effects of mechanical strain on periodontal ligament fibroblasts in presence of Aggregatibacter actinomycetemcomitans lysate

PURPOSE

Many adult orthodontic patients suffer from periodontitis, which is caused by oral pathogens such as the gram-negative Aggregatibacter actinomycetemcomitans (Agac). Like orthodontic tooth movement, periodontitis is associated with inflammation and alveolar bone remodelling thereby affecting orthodontic treatment. Interactions of both processes, however, are not sufficiently explored, particularly with regard to oxidative stress.

METHODS

After preincubation with Agac lysate for 24 h periodontal ligament fibroblasts (PDLF) were either stretched or compressed for further 48 h simulating orthodontic forces in vitro. We analysed the expression of genes and proteins involved in the formation of reactive oxygen species (NOX-4, ROS) and nitric oxide (NOS-2), inflammation (TNF, IL-6, PTGS-2) and bone remodelling (OPG, RANKL).

RESULTS

Agac lysate elevated the expression of NOX-4, NOS-2, inflammatory IL-6 and PTGS-2 and the bone-remodelling RANKL/OPG ratio during compressive, but not tensile mechanical strain. Agac lysate stimulated pressure-induced inflammatory signalling, whereas surprisingly ROS formation was reduced. Pressure-induced downregulation of OPG expression was inhibited by Agac lysate.

CONCLUSIONS

Agac lysate impact on the expression of genes and proteins involved in inflammation and bone remodelling as well as ROS formation, when PDLF were subjected to mechanical forces occurring during orthodontic tooth movement.

Curvature-dependent shear bond strength of different attachment materials for orthodontic lingual indirect bonding

To evaluate the shear bond strength (SBS) of different attachment materials used for lingual bonding, the influence of artificial aging and the radii of curvature of the enamel surface on SBS, 192 third molars were photographed to determine the radius of curvature of the oral surface. After phosphoric acid etching a cylindrical test piece was bonded to the oral enamel using a mold that was filled with a chemically curing (Maximum Cure, Transbond IDB Premix) or a dual-curing (Nexus NX3, RelyX Unicem2) attachment material. SBS was tested after 24 h, 500 thermal cycles or 90 days at 37 °C with a universal testing machine. Computed tomography scans were performed to determine the bonded surface and calculate SBS. Values ranged from 8.3 to 20.9 MPa. RelyX Unicem2 showed the highest SBS values at baseline, 500 thermal cycles and after 90 days (p < 0.001). Ninety days of wet storage significantly reduced SBS of Maximum Cure (p = 0.028). The radius of curvature correlated positively with SBS (r_s = 0.204, p = 0.005). The SBS of all attachment materials was sufficient for clinical use, even after artificial aging. RelyX Unicem2 showed almost twice as high SBS values as the other attachment materials.

Expression of inflammatory mediators in biofilm samples and clinical association in inflammatory bowel disease patients-a preliminary study

OBJECTIVES

Inflammatory bowel disease (IBD) has multiple impacts on soft and hard tissues in the oral cavity. The aim of this study was to analyze the expression of cytokines in biofilm samples from patients suffering from IBD and compare them to healthy patients. It was hypothesized that different cytokine expression levels and clinical associations might be drawn.

MATERIAL AND METHODS

A total of 56 biofilm samples from three different patient cohorts (group 0 = healthy, HC n = 30; group 1 = Crohn's disease, CD, n = 19; group 2 = ulcerative colitis, UC, n = 7) were examined for the expression levels of the cytokine interleukins IL-2, -6, and -10; matrix metalloproteinases 7 and 9; and surface antigens CD90/CD11a by quantitative real-time PCR and according to clinical parameters (plaque index, BOP, PD, DMFT, CAL). Relative gene expression was determined using the ∆∆CT method.

RESULTS

The mean BOP values (p = 0.001) and PD (p = 0.000) were significantly higher in the CD group compared to controls. Expression of IL-10 was significantly higher in the CD (p = 0.004) and UC groups (p = 0.022). Expression of MMP-7 was significantly higher in the CD group (p = 0.032). IBD patients treated with TNF inhibitors (p = 0.007) or other immunosuppressants (p = 0.014) showed significant overexpression of IL-10 compared to controls.

CONCLUSION

Different expression levels of IL-10 and MMP-7 were detected in plaque samples from IBD patients. As only BOP was significantly increased, we conclude that no clinical impairment of periodontal tissue occurred in IBD patients.

CLINICAL RELEVANCE

With the worldwide increasing incidence of IBD, it is important to obtain insights into the effects of the disease on the oral cavity. The study was registered (01.09.2020) at the German clinical trial registry (DRKS00022956).

CLINICAL TRIAL REGISTRATION

The study is registered at the German clinical trial registry (DRKS00022956).