Human Teeth Research Articles

Comparative evaluation of accuracy of three different electronic apex locators in the presence of various endodonticirrigants: An in vitro study

AIM AND OBJECTIVES. To evaluate and compare the accuracy of Root ZX, Raypex6, and I Root and electronic apex locators in the presence of NaOCl (3%), Citric acid (10%), MTAD and Green tea extract as endodontic irrigants.MATERIAL AND METHOD. Sixty single rooted human permanent teeth were used for the study. Access cavities were prepared and the teeth were decoronated. Teeth were divided as follows: Group I-Root ZX apex locator (n=20), IA – NaOCl 3% endodontic irrigant (n=5), IB – Citric Acid 10% endodontic irrigant (n=5), IC – MTAD endodontic irrigant (n=5), ID- Green Tea extract endodontic irrigant (n=5). Group II: Raypex 6 apex locator (n=20). IIA – NaOCl 3% endodontic irrigant (n=5), IIB – Citric acid 10% endodontic irrigant (n=5). IIC – MTAD endodontic irrigant (n = 5), IID – Green tea extract endodontic irrigant (n=5). Group III-i-ROOT apex locator (n=20). IIIA – NaOCl 3% endodontic irrigant (n=5), IIIB – Citric Acid 10% endodontic irrigant (n=5), IIIC – MTAD endodonticirrigant (n=5), IIID – Green tea extract endodontic irrigant (n=5). The actual working length was determined using a 15 K file and the working model was prepared using Alginate in a rectangular box. The teeth were embedded into the working model and the electronic measurements were made with each electronic apex locator. The data was collected, analyzed and subjected to statistical analysis.RESULTS. No significant difference was found when Raypex 6 apex locator was used along with all the endodontic irrigants except green tea extract. Root ZXshowed statistically significant difference with green tea extract and MTAD. I-root showed statistically significant difference with all the irrigants except green tea extract.CONCLUSION. Citric acid 10% was consistently accurate when assessed with all the three apex locators, whereas Green tea extract demonstrated the least accurate readings with all apex locators.

Radiculomegaly as a key clinical feature in oculo-facio-cardio-dental (OFCD) syndrome: a case report with a novel truncating variant in BCOR gene.

Radiculomegaly is a rare dental anomaly characterised by the enlargement of the root canals of teeth. It is usually associated with oculo-facio-cardio-dental (OFCD) syndrome due to truncating variants in BCL-6 transcriptional corepressor (BCOR) (MIM*300485). We present the case of a 21-year-old female patient who was referred to genetics for a polymalformative syndrome including bilateral glaucoma and dental anomalies, especially radiculomegaly. Some others dysmorphic features were right superior lip notch, ogival palate, long philtrum, difficulty in pronation, café-au-lait spots, II-III toe bilateral syndactyly, and macrocephaly. Cone-beam CT confirmed radiculomegaly. The genetic analysis identified a heterozygous pathogenic variant NM_001123385.1:c.2093del (p.Pro698Glnfs*17) in the BCOR gene. After genetic diagnosis of OFCD syndrome, cardiac CT-scan revealed a large asymptomatic atrial septal defect that was subsequently surgically closed. Reviews of the literature have previously highlighted the prevalence of radiculomegaly in OFCD syndrome with a positive predictive value of 88.23% and a sensitivity of 75.94%. This case report highlights the importance of radiculomegaly as a clinical sign of OFCD syndrome, emphasising the rarity of non-syndromic radiculomegaly and the benefits of its diagnosis in clinical management, especially in cardiac screening.

LMVSegRNN and Poseidon3D: Addressing Challenging Teeth Segmentation Cases in 3D Dental Surface Orthodontic Scans.

The segmentation of teeth in 3D dental scans is difficult due to variations in teeth shapes, misalignments, occlusions, or the present dental appliances. Existing methods consistently adhere to geometric representations, omitting the perceptual aspects of the inputs. In addition, current works often lack evaluation on anatomically complex cases due to the unavailability of such datasets. We present a projection-based approach towards accurate teeth segmentation that operates in a detect-and-segment manner locally on each tooth in a multi-view fashion. Information is spatially correlated via recurrent units. We show that a projection-based framework can precisely segment teeth in cases with anatomical anomalies with negligible information loss. It outperforms point-based, edge-based, and Graph Cut-based geometric approaches, achieving an average weighted IoU score of 0.97122±0.038 and a Hausdorff distance at 95 percentile of 0.49012±0.571 mm. We also release Poseidon's Teeth 3D (Poseidon3D), a novel dataset of real orthodontic cases with various dental anomalies like teeth crowding and missing teeth.

Effect of double adhesive layer application on micro-tensile dentin bond strength of a universal adhesive

IntroductionAchieving optimal dentin bond strength is crucial for the long-term success of adhesive restorations. This study aims to evaluate the impact of double adhesive layer application, with and without light curing between applications, on the micro-tensile dentin bond strength (µ-TBS) of a universal adhesive, in comparison to the conventional single-layer application.MethodsIntact human molars were divided into three groups (n = 15) according to the adhesive application technique using a universal self-etch adhesive (Tetric N-Bond Universal, Ivoclar) as follows: (1) according to the manufacturer's instructions, (2) double-layer application without light curing between layers, and (3) double-layer application with light curing between layers. Samples were immediately tested for µ-TBS, with failure types recorded as adhesive, cohesive, or mixed. Representative samples were observed by scanning electron microscopy. Data were analyzed using multiple-way ANOVA (α = 0.05).ResultsThe double adhesive layer with and without light curing between layers showed similar μ-TBS to that of the control group (p > 0.05).DiscussionFrom a clinical perspective, these findings suggest that the accurate application of a single layer of a universal adhesive can be as effective as more complex techniques. Additionally, the use of universal bonding agents may have contributed to the outcomes observed in this study. In conclusion, double adhesive layer application and light curing between adhesive layers did not increase the µ-TBS with the universal adhesive agent explored.

Orthodontic treatment of patients with cleft lip and palate from birth through maturity

Cleft lip and palate (CLP) is one of the most common congenital anomalies, requiring lifelong care by a team of craniofacial specialists. A key member of that team is the craniofacial orthodontist, who provides treatment for these patients throughout the lifetime. This care actually begins prenatally, when families first meet with a craniofacial team. The family is provided with resources to prepare for their child's arrival and counseled about future treatment. Presurgical infant orthopedics (PSIO) will usually begin within a week of birth and continues for 3–5 months. PSIO helps approximate the lip and alveolar segments and reshapes the nostrils to facilitate primary surgical repairs. This is followed by a phase of monitoring growth and dental development throughout childhood, as patients with CLP are at increased risk for dental anomalies. Once the maxillary canine roots are one-third developed, the patient will be prepared for secondary alveolar bone grafting. This may include expansion, alignment, and/or maxillary protraction via facemask therapy. A short phase of maxillary dental alignment might follow if functional or esthetic concerns arise. Comprehensive orthodontic treatment is then performed at skeletal maturity, and coordinated with orthognathic surgery when indicated. The orthodontist and surgeon will collaborate closely in planning and managing the surgical correction. It is crucial that each stage of orthodontics is followed by an appropriate retention protocol. Finally, surgical and esthetic finishing procedures take place after surgical orthodontics is complete. This may include surgery to address lip, nose, speech, and breathing concerns, as well as definitive dental restorations.

Antimicrobial evaluation of root canal irrigants of natural sources with and without gamma radiation activation (in vitro study)

ABSTRACT Aims: The present study aimed to evaluate the antibacterial effectiveness of newly formulated root canal irrigants derived from natural sources. In particular, this study investigated how these irrigants’ antimicrobial properties were affected by gamma radiation activation. Materials and Methods: Fifty-three single-rooted extracted human teeth with straight canals were selected, fully prepared, and sterilized. The roots were then infected with Escherichia coli, Enterococcus faecalis, and Candida albicans for 21 days at 37°C. Based on the irrigating solution utilized, the roots were divided into seven groups: Group I: chitosan irrigant, Group II: chitosan irrigant gamma irradiated, Group III: curcumin irrigant, Group IV: curcumin irrigant gamma irradiated, Group V: sodium hypochlorite (NaOCl) 5% irrigant, Group VI: positive control (infected roots without treatment), and Group VII: negative control (uncontaminated roots). After cleaning and shaping, microbiological sampling was performed. The samples were then transferred to sterile centrifuge tubes containing 1 mL of saline to determine the microbial growth. Colony-forming unit counts were employed for assessing the antimicrobial action. Statistical analysis was conducted to compare the percentage reduction in the microbial count from the initial count. Results: Group V and Group IV showed significantly higher values in microbial reduction than Group III and Group I. In addition, the results showed that Group II and Group III have significantly higher values than Group I. Conclusion: Natural irrigating solutions exposed to gamma radiation exhibited promising antimicrobial activity that is comparable to that of NaOCl and may be used as effective antimicrobial agents in endodontic treatment.

Fluoride-incorporated apatite coating on resin-based composite via laser-assisted rapid pseudo-biomineralization

A thin-layer of fluoride-incorporated hydroxyapatite (FAp) is useful as an acid-resistant antibacterial mineralized coating to protect a tooth surface. Recently, we achieved rapid and area-specific FAp coating on the surfaces of human tooth substrates via precoating with a light-absorbing agent, indocyanine green, followed by laser irradiation in a fluoride-containing supersaturated calcium phosphate solution. In the present study, this FAp coating technique was applied to a substrate of resin-based composite (RBC), an artificial material with no biomineral component. Similar to the case of tooth substrates, a mineralized layer consisting of needle-like FAp crystals was formed on the RBC surface after laser irradiation for 3 min. The needle-like crystals increased in size with increasing laser power. In the absence of fluoride ions in the supersaturated solution, a layer consisting of plate-like octacalcium phosphate crystals was formed on the RBC surface. The present FAp coating technique was finally applied to an RBC-restored tooth substrate. Cross-sectional analyses revealed that the boundary region between the tooth and RBC was coated and sealed with a mineralized layer. The present FAp coating technique is potentially a new tool to seal the tooth–RBC boundary and reduce the risk of secondary caries associated with RBC restorations.

Fixed Prosthodontic Rehabilitation of a Patient with Cleidocranial Dysplasia: A Case Report

Introduction Cleidocranial Dysplasia (CCD) is a rare congenital disease characterized by skeletal and dental anomalies. Clinical findings of CCD patients include low facial height, pseudoprognathism, unerupted teeth, an excessive deep bite, chewing difficulties, and unsatisfied dentofacial appearance. These patients’ dental treatments present a substantial challenge. Case Representation This case report describes the prosthodontic treatment of a 29-year-old male CCD patient using porcelain-fused-to-metal restorations. The avoidance of a surgical procedure serves to minimize the potential for complications and expedites the attainment of outcomes with greater celerity. Throughout the follow-up period of 1 year, the patient maintained good periodontal health. The restoration of masticatory function and enhancement of facial esthetics were successfully achieved and the patient expressed a high degree of satisfaction with the outcome of the treatment. Conclusion The use of fixed prostheses in CCD patients is a treatment modality that resolves many of the issues caused by the surgical approach.

In Vitro Models Used in Cariology Mineralisation Research-A Review of the Literature.

Dental caries remains a significant global health problem. One of the fundamental mechanisms underlying the development and progression of dental caries is the dynamic process of demineralisation/remineralisation. In vitro models have played a critical role in advancing our understanding of this process and identifying potential interventions to prevent or arrest dental caries. This literature review aims to provide a structured oversight of in vitro mineralisation models which have been used to study the tooth demineralisation/remineralisation process. Publications from 2019 to 2023 were screened to identify articles reporting the use of in vitro models to study the demineralisation/remineralisation of tooth caries. The included studies were methodologically assessed for their information on (i) substrate, (ii) lesion formation, and (iii) mineralisation models. The most reported substrates used in the studies were human teeth along with bovine incisors. Acetic/lactic buffers were the most common solutions to induce caries lesions. pH cycling was the most frequently used mineralisation model for simulating the daily change within the oral environment. This review discussed the advantages and limitations of various approaches. Standardisation of in vitro mineralisation models is crucial for enabling effective comparison between studies and advancing caries research.

Evaluation of the Root Canal Centering Ratio and Canal Transportation Associated With Three Rotary File Systems Using Cone Beam Computed Tomography (CBCT) Analysis.

Aim The aim of the present study was to evaluate the in vitro comparative assessment of root canal centering ratio and canal transportation associated with ProTaper Universal (PTU) (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Next (PTN) (Dentsply Maillefer, Ballaigues, Switzerland), and ProTaper Gold (PTG) (Dentsply Tulsa Dental Specialties, Tulsa, OK, USA) rotary file systems, with or without glide-path preparation, using cone beam computed tomography (CBCT) analysis. Materials and methods A total of 120 mesial roots of extracted human mandibular first molar teeth were collected and randomly divided into three groups (n = 40) depending on the type of rotary file system used for mesiobuccal root canal instrumentation: Group 1: PTU, Group 2: PTN, and Group 3: PTGrotary file systems. Each group was further divided into two Sub-groups (a and b) with 20 specimens, depending on whether glide-path preparation was performed using the ProGlider (PG) file (Dentsply Maillefer, Ballaigues, Switzerland). Before the root canal instrumentation, mesiobuccal root canals of all specimens were first scanned using the NewTom Go CBCT machine (Cefla S.C., Imola, Italy), and all root canals were then instrumented according to their groups and sub-groups. All rotary files were used according to their manufacturer's guidelines. Post-instrumentation, CBCT images of all specimens were taken with the same exposure parameters as those used in pre-instrumentation CBCT imaging. The distance between the external root surface and the internal canal wall was measured in both bucco-lingual and mesio-distal planes at 3 mm, 5 mm, and 7 mm levels of the mesiobuccal root canal of all specimens, comparing the pre-instrumentation and post-instrumentation CBCT scans for the evaluation of canal centering ratio and canal transportation using NewTom NNT software (Cefla S.C., Imola, Italy). Data were analyzed using one-way analysis of variance (ANOVA), multiple pairwise Tukey post-hoc tests, and Student's t-tests; a p-value ≤ 0.05 was considered statistically significant. Results Canal centering ratio was significant bucco-lingually and mesio-distally at 3 mm and 5 mm levels between Groups 1a, 1b, and 3a, 3b (p < 0.05). However, at 7 mm bucco-lingually, a significant difference was observed between groups 3a and 3b, and mesio-distally between Groups 2a and 2b (p < 0.05). Canal transportation was significantly bucco-lingually at 3 mm, 5 mm, and 7 mm levels between Groups 3a and 3b (p < 0.05). However, mesio-distally, no statistically significant difference (p > 0.05) was seen between the groups at all three levels of the root canal. Conclusion The use of the PG/PTN rotary file system showed the maximum canal centering ratio at all three levels of the root canal compared to the PTU and PTG rotary file systems, whether used with or without a glide-path. The PG/PTN rotary file system showed the least canal transportation at the 3 mm level, while at the 5 mm and 7 mm levels, the PG/PTU rotary file system showed the least canal transportation.

Abrasive challenge effects on enamel and dentin from irradiated human teeth: an in vitro study.

This study aimed to evaluate the effects of radiotherapy (RT) and chemoradiotherapy (CRT) on the wear and surface roughness of in vitro irradiated human enamel and dentin subjected to abrasive challenge. Enamel and dentin specimens (n = 42) were prepared from teeth donated by healthy patients and those with head and neck cancer who had received radiotherapy (RT) or chemoradiotherapy (CRT). The specimens were categorized into three groups: control, RT, and CRT (n = 14 per group for both enamel and dentin). These samples were subjected to an in vitro abrasive experiment using a brushing machine, followed by wear and surface roughness assessments with a confocal laser scanning microscope conducted before and after the abrasive challenge, considering both exposed and non-exposed areas. Statistical analysis used Shapiro-Wilk tests for normality, Wilcoxon tests for comparing two means, and Kruskal-Wallis tests. A significance level of 5% was adopted. In enamel specimens, wear profile values ​​of CRT and RT groups were not different from the control (p > 0.05). The RT group presents lower step values than the CRT and control groups (p < 0.001). No significant difference in final surface roughness was observed in all groups (p > 0.05). In dentin specimens, no significant difference in wear profile and step was observed in all groups (p > 0.05). However, CRT and RT groups present higher values in final surface roughness (p < 0.001). The exposure to ionizing radiation (associated or not to chemotherapy) influenced the surface roughness of dentin and the wear (step) of enamel after the in vitro abrasive challenge.Trial registration: Ethical procedures were approved by the FORP/USP Research Ethics Committee (CAAE: 61308416.4.0000.5419), and Hospital do Câncer de Barretos/Fundação Pio XII (CAAE: 61308416.4.3001.5437).

NEDD4L affects stability of the CHEK2/TP53 axis through ubiquitination modification to enhance osteogenic differentiation of periodontal ligament stem cells

ABSTRACT Background Checkpoint kinase 2 (CHEK2) and its regulated tumor protein p53 (TP53) have been correlated with osteogenic differentiation of osteoblast-like cells. Based on bioinformatics predictions, this study aims to investigate the effect of the CHEK2/TP53 axis on osteogenic differentiation of periodontal ligament stem cells (PDLSCs) and to explore the regulatory mechanism. Methods PDLSCs were isolated from human impacted wisdom teeth, and they were cultured in normal medium (NM) or osteogenic medium (OM). Protein levels of CHEK2 and TP53 were examined using western blot analysis. Osteogenic differentiation ability of PDLSCs was analyzed by measuring marker proteins (RUNX2, OCN, and OSX), ALP activity, and ALP staining. Molecular interaction between NEDD4 like E3 ubiquitin protein ligase (NEDD4L) and CHEK2 was examined by ubiquitination and co-immunoprecipitation assays. Gain- and loss-of function assays of NEDD4L, CHEK2, and TP53 were performed to analyze their function in osteogenic differentiation of PDLSCs. A rat model of mandibular bone defect was generated for in vivo validation. Results NEDD4L was upregulated, while CHEK2 and TP53 were downregulated in PDLSCs cultured in OM. CHEK2 protected TP53 from degradation, while NEDD4L reduced CHEK2 protein level by ubiquitination modification. NEDD4L silencing reduced osteogenic differentiation ability of PDLSCs both in vitro and in vivo, which was restored by CHEK2 silencing. By contrast, CHEK2 overexpression blocked the osteogenic differentiation of PDLSCs in vitro. Conclusion This study demonstrates that NEDD4L affects protein stability of the CHEK2/TP53 axis through ubiquitination modification, thus increasing osteogenic differentiation of PDLSCs.

Synergistic bactericidal activity of chlorhexidine loaded on positively charged ionic liquid-protected silver nanoparticles as a root canal disinfectant against Enterococcus faecalis: An ex vivo study

The advancement of nanotechnology and the development of nanocomplexes offer promising solutions to address the limitations in biofilm management within endodontics. Current cleaning and disinfection methods often fail to completely eliminate bacterial biofilms from the complex anatomical structures of root canals, making the invention of new disinfectants or disinfection methods highly relevant. Previously, chlorhexidine-loaded positively charged ionic liquid-protected silver nanoparticles (CHX@AgNPs⁺) were introduced as an innovative root canal irrigation solution, demonstrating significant antibacterial efficacy against Enterococcus faecalis in vitro. This study aimed to further evaluate the antibiofilm activity of CHX@AgNPs⁺ in the root canals of extracted human teeth contaminated with E. faecalis biofilm. Fifty single-rooted human teeth with mature apices were randomly assigned to five experimental groups based on the irrigants used: CHX@AgNPs⁺, AgNPs⁺, 2.5 % NaOCl, 2 % CHX, and normal saline (n = 10 per group). The root canals were contaminated with E. faecalis, and biofilm formation was confirmed. Initial sampling (S1) was performed, followed by mechanical preparation of the root canals using ProTaper F3 files and irrigation with the respective test solutions. Post-instrumentation sampling (S2) was then conducted. The results demonstrated that CHX@AgNPs⁺ exhibited antibiofilm properties comparable to 2.5 % NaOCl, with no significant difference between them. Additionally, CHX@AgNPs⁺ significantly enhanced antimicrobial efficacy compared to CHX alone (P < 0.05), highlighting its potential as an effective root canal disinfectant.

Do Tunisian children with unilateral cleft lip and palate differ from normal individuals in dental maturity? A pilot study.

Cleft lip and palate (CLP) is the most common congenital malformation of the head and neck. Children with CLP often exhibit dental anomalies. To evaluate the dental age (DA) of unilateral CLP in Tunisian children. This was a cross-sectional study carried out in the department of pediatric dentistry at the University Hospital La Rabta, Tunis. Patients aged between 5 and 14 years, with no other congenital anomalies or syndromes in the craniofacial region other than CLP, were included. The patients' chronological ages were first calculated in years and months. DA was assessed in panoramic radiographs using Demirjian's method. The score of each stage is allocated, and the sum of the scores provides an evaluation of the subject's dental maturity. Fifty-three patients were included in the present study. No difference was observed between the two groups regarding the dental age. A strong and positive correlation between the DA and the chronological age in the two groups was observed (r=0.826). Estimated regression showed that chronological age alone explained 57,4% (r2=0.574) of the dental age variation in the study group and 64.5% (r2=0.645) in the control group. For dental management, CLP children should have the same approach in orthodontics and pediatric dentistry as individuals without clefts, with a focus on the individualization of diagnosis and treatment planning.

Integrating Phosphate Enhances Biomineralization Effect of Methacrylate Cement in Vital Pulp Treatment with Improved Human Dental Pulp Stem Cells Stimulation.

Vital pulp treatment (VPT) is crucial for preserving the health and function of the tooth in cases where the pulp tissue remains vital despite exposure. Various materials are introduced for this purpose. However, challenges such as low strength, high solubility, and tooth discoloration persist. Methylmethacrylate-based cement (MC) offers excellent sealing ability, feasibility, and mechanical properties, making it a promising alternative for VPT. Phosphate-based glass (PBG) has the potential to promote hard tissue regeneration by releasing key inducers, phosphorus (P) and calcium (Ca), for reparative odontogenesis. This study investigates PBG-integrated MC (PIMC) by characterizing its properties, assessing human dental pulp stem cell activity related to initial inflammatory adaptation and odontogenic differentiation, and evaluating hard tissue formation using an in vivo dog pulpotomy model. Results indicate that a 5% PBG-integrated MC (5PIMC) maintains the physicochemical properties of MC. Furthermore, 5PIMC demonstrates cytocompatibility, excellent expression of osteo/odontogenic markers, and resistance to inflammatory markers, significantly outperforming MC. Enhanced hard tissue formation is observed in the dental pulp of mongrel dog teeth treated with 5PIMC. These findings suggest that 5PIMC could be an optimal and suitable material for reparative odontogenesis through VPT.

Tri-Lineage Differentiation Potential of Stem Cells from Human Exfoliated Deciduous Teeth - An In-Vitro Study

ABSTRACT Background: The use of SHED might bring advantages for tissue engineering over the use of stem cells from adult human teeth as SHEDs were reported to have higher proliferation rate and increase cell population doublings as compared with stem cells from permanent teeth. Objective: The study’s objective was to assess the growth kinetics and tri-lineage differentiation capacity of stem cells derived from human exfoliated deciduous teeth. Material and Method: After being propagated through multiple sequential subcultures, adherent fibroblastic cells in the pulp tissue culture from human exfoliation teeth were evaluated to assess their tripotent differentiation potential into bone, cartilage, and adipose cell lineages. Result: The stem cells derived from dental pulp had a comparatively high ability for proliferation and successfully differentiated into chondrocytes and osteocytes while less significant for adipocytes. Conclusion: Stem cells from Human Exfoliated Deciduous teeth are mesenchymal stem cells which are multipotent and can serve as a promising incentive for therapeutic and future research purposes.

Microleakage Assessment of Repaired Pit and Fissure Sealants Using Different Surface Treatment – An In vitro Study

ABSTRACT Aim: In this in vitro study, the microleakage evaluation of repaired pit and fissure sealants with various surface treatments was compared. Study Design: The study included 120 extracted human third molars. The teeth were divided into two groups of 60 each. Group 1 was sealed with Clinpro™ unfilled sealant, while group 2 was sealed with Grandioseal nanofilled sealants. After curing, half of the polymerized sealant were removed. Both groups were divided further into two subgroups of 30 teeth each, with repair techniques using either Adper Easy One or Futura Bond. Three sections were obtained from each tooth resulting 6 surfaces per tooth to be examined and the sections of all four groups were scored for microleakage. Results: Conventional acid etching was found to be superior to self-etch adhesive technique. Conclusion: Microleakage was found to be greater with Grandio seal compared to Clinpro.

Familial hypodontia in bronze age Northwest China (1046–771BC)

ObjectiveThis research aimed to report hypodontia cases in a Middle Bronze Age high-tier cemetery in China and test the possible hereditary behind hypodontia by performing kinship tests on those individuals. DesignIn this study, dental anomalies were observed on a human skeletal sample (n = 45) uncovered from Yaoheyuan, China. Ancient DNA analysis was subsequently employed on a subsample of the Yaoheyuan individuals (n = 15), including individuals observed hypodontia and individuals randomly sampled from the cemetery for preliminary investigation on the cemetery demography. Kinship estimation tests (READ, TKGWV2, KIN, and F3 test) were subsequently employed. ResultsThe Yaoheyuan elite population had a prevalence (n = 7, 15 %) of tooth agenesis in either the maxilla or mandible, with one to two teeth missing. All missing teeth were incisors, except for one individual missing maxillary second molar. Preliminary ancient DNA results indicate that several kinship groups existed among interred individuals, including those with hypodontia, indicating the hereditary origin of these cases. ConclusionsThe prevalence of hypodontia observed on site is high compared to that in both modern East Asian populations and archaeological samples in the Chinese population. The preliminary kinship analysis suggests a case of familial hypodontia. Ancient DNA analysis should be thoroughly conducted in future studies to understand the genetic markers contributing to those hypodontia cases among the Yaoheyuan individuals.

Effects of Time-Elapsed Bleaching on the Surface and Mechanical Properties of Dentin Substrate Using Hydrogen Peroxide-Free Nanohydroxyapatite Gel.

There is a critical need to address concerns surrounding the potential impact of bleaching gels specifically on the tooth substrate. Therefore, this laboratory investigation aimed to assess the impact of a hydrogen peroxide (HP)-free bleaching (HiSmileTM) in comparison to an HP-based bleaching (Opalescence RegularTM) on the surface and mechanical characteristics of tooth substrate. Sixty sound human premolar teeth were sectioned to produce dentin fragments and divided into two primary groups based on the bleaching agent used. Each group was subdivided into three subgroups (n = 10) per distinct bleaching regimens: (T1) fragments underwent a 7-day immersion in distilled water at 37°C without any bleaching treatment, (T2) fragments underwent a 7-day immersion in distilled water at 37°C, with the application of bleaching gel occurring on the seventh day for 10minutes, and (T3) fragments underwent a bleaching regimen for seven consecutive days, each session lasting for 10minutes. The initial and final evaluations of surface roughness, nano-hardness, and elastic modulus were performed. Following the bleaching regimens of T3, a composite stub was fabricated on the dentin fragments for the shear bond strength (SBS) test. Statistical testing was accomplished using the analysis of variance (P < 0.05). HP-based bleaching gel showed significant differences between measurement intervals in surface roughness, elastic modulus, and SBS parameters (P < 0.05). In contrast, HP-free bleaching gel showed insignificant differences within the group (P > 0.05). The SBS between dentin-composite was significantly affected with the use of HP-based bleaching gel, while HP-free bleaching gel showed insignificant difference between measurement intervals. The qualitative validation of the treatment's impact was further demonstrated using the scanning electron microscopy. The findings suggest that the bonding stability of composite restorations to dentin may be compromised after bleaching with an HP-based gel, whereas immediate bonding procedures can be safely conducted following the application of an HP-free bleaching gel.

Inherited dental anomalies – part 2: dentine defects

Inherited dental anomalies – part 2: dentine defects