How teeth can be used to estimate sexual dimorphism? A scoping review.

INTRODUCTION: Teeth are biological structures with a high degree of hardness, density, calcification, and capacity to adapt to extrinsic factors at physical, biological, and physiological levels. Subsequently, they resist for a longer period in deteriorating environmental conditions. With dental analysis, it is possible to acquire biographical data about a person. The aim of this scoping review was to identify publications using human teeth tissues to estimate sexual dimorphism. METHODS: The scoping review was carried out in the following databases: Jstor, Scielo, Science Direct, PubMed, and Scopus, using ten search strategies in English and guaranteeing completeness and reproducibility of the phases stipulated in the PRISMA guide. RESULTS: 143 studies on sexual dimorphism based on dental tissue traits were included, of which 40.6% (n = 58) were done in Asia and 27.2% (n = 39) in America. 80% of the studies (equivalent to 114 articles) focused their observations and measurements on the dental crown; 4.2% in enamel, dentin, and pulp together; 3.5% in dental pulp; 2.1% in the entire tooth; 2.8% in enamel, root, and the enamel-cementum junction, and only 0.7% in dentin and pulp. In addition, 92.3% of the studies used metric methods, while only 4.9% and 2.8% used biochemical and non-metric method respectively. CONCLUSION: For sexual dimorphism establishment, enamel has been the most analyzed dental tissue in permanent canines and molars mainly. Likewise, the most widely and accurately used methods for this purpose are the metrics, with the odontometry as the most implemented (intraoral or by using dental plaster models, digital scanning or software) with prediction percentages ranging from 51% to 95.9%. In contrast to biochemical methods, that can achieve the highest precision (up to 100%), the non-metric methods, to a less extent, reported prediction percentages of 58%.

Investigation of mechanical properties, remineralization, antibacterial effect, and cellular toxicity of composite orthodontic adhesive combined with silver-containing nanostructured bioactive glass.

BACKGROUND: The formation of white spots, which represent early carious lesions, is a major issue with fixed orthodontics. The addition of remineralizing agents to orthodontic adhesives may prevent the formation of white spots. The aim of this study was to produce a composite orthodontic adhesive combined with nano-bioactive glass-silver (nBG@Ag) for bracket bonding to enamel and to investigate its cytotoxicity, antimicrobial activity, remineralization capability, and bond strength. METHODS: nBG@Ag was synthesized using the sol-gel method, and characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy with an attenuated total reflectance attachment (ATR-FTIR). The cytotoxicity test (MTT) and antimicrobial activity of adhesives containing 1%, 3%, and 5% (wt/wt) nBG@Ag were evaluated, and the shear bond strength of the adhesives was measured using a universal testing machine. Remineralization was assessed through microhardness testing with a Vickers microhardness tester and scanning electron microscopy (SEM). Statistical analyses were conducted using the Shapiro-Wilk test, Levene test, one-way ANOVA, Robust-Welch test, Tukey HSD method, and two-way ANOVA. RESULTS: The biocompatibility of the adhesives was found to be high, as confirmed by the lack of significant differences in the cytotoxicity between the sample and control groups. Discs made from composites containing nBG@Ag exhibited a significant reduction in the growth of Streptococcus mutans (p < 0.05), and the antibacterial activity increased with higher percentages of nBG@Ag. The shear bond strength of the adhesives decreased significantly (p < 0.001) after the addition of nanoparticles, but it remained above the recommended value. The addition of nBG@Ag showed improvement in the microhardness of the teeth, although the differences in microhardness between the study groups were not statistically significant. The formation of hydroxyapatite deposits on the tooth surface was confirmed through SEM and energy-dispersive X-ray spectroscopy (EDX). CONCLUSION: Adding nBG@Ag to orthodontic adhesives can be an effective approach to enhance antimicrobial activity and reduce enamel demineralization around the orthodontic brackets, without compromising biocompatibility and bond strength.

North and South in Medieval Iberia: A historical and environmental estimate through isotopic analyses.

The Middle Ages in the Iberian Peninsula is a period of special interest for studying the relationship of climate change with historical and socioeconomic processes. Between the 8th and 15th centuries AD, the Peninsula was characterized not only by complex political, cultural, and social transitions but also by major variations in the climate. The objective of this study was to examine differences in diet and mobility between distinct populations of the Peninsula and explore the possible relationship of diet, mobility, and culture with environmental variables and geographical settings. For this purpose, we obtained stable isotopic ratios of carbon and oxygen (δ13C and δ18O) from the enamel apatite of first upper incisors from 145 individuals at eight archeological sites that represent both Christian and Islamic communities and both rural and urban social settings. Results revealed a dietary difference between Christian and Islamic populations, observing a greater contribution of C4 plants, possibly sorghum, in the diet of the latter, especially in a rural setting. The disparity in oxygen isotopic ratios between populations from the North and South of the Peninsula is consistent with modern climatic differences between these regions. In this line, intraregional variability in oxygen isotopic ratios may hint at diachronic occupation phases under varying climatic conditions. The few isotopic outliers in our sample suggest overall low mobility levels.

Multi-isotope reconstruction of Late Pleistocene large-herbivore biogeography and mobility patterns in Central Europe.

Interpretations of Late Pleistocene hominin adaptative capacities by archaeologists have focused heavily on their exploitation of certain prey and documented contemporary behaviours for these species. However, we cannot assume that animal prey-taxa ecology and ethology were the same in the past as in the present, or were constant over archaeological timescales. Sequential isotope analysis of herbivore teeth has emerged as a particularly powerful method of directly reconstructing diet, ecology and mobility patterns on sub-annual scales. Here, we apply 87Sr/86Sr isotope analysis, in combination with δ18O and δ13C isotope analysis, to sequentially sampled tooth enamel of prevalent herbivore species that populated Europe during the Last Glacial Period, including Rangifer tarandus, Equus sp. and Mammuthus primigenius. Our samples come from two open-air archaeological sites in Central Germany, Königsaue and Breitenbach, associated with Middle Palaeolithic and early Upper Palaeolithic cultures, respectively. We identify potential inter- and intra-species differences in range size and movement through time, contextualised through insights into diet and the wider environment. However, homogeneous bioavailable 87Sr/86Sr across large parts of the study region prevented the identification of specific migration routes. Finally, we discuss the possible influence of large-herbivore behaviour on hominin hunting decisions at the two sites.

Effect of treatment with phosphate, casein phosphopeptide and fluoride on the remineralization: in vitro study.

This study aimed to evaluate in vitro the effect protocols and anticaries agents containing casein amorphous calcium fluoride phosphopeptide-phosphate (CPP-ACPF, MI Paste Plus), sodium trimetaphosphate (TMP) and fluoride (F), in remineralization of caries lesions. Bovine enamel blocks with initial caries lesions were divided into groups (n = 12): 1) Toothpaste without F-TMP-MI Plus (Placebo); 2) Toothpaste 1100 ppm F (1100F), 3) 1100F + MI Paste Plus (1100F-MI Paste Plus), 4) Toothpaste with 1100F + Neutral gel with 4,500 ppm F + 5%TMP (1100F + Gel TMP) and 5) Toothpaste with 1100F + Neutral gel with 9,000 ppm F (1100F + Gel F). For the 4 and 5 groups the gel was applied only once for 1 minute, initially to the study. For the 3 group, after treatment with 1100F, MI Paste Plus was applied 2x/day for 3 minute. After pH cycling, the percentage of surface hardness recovery (%SHR); integrated loss of subsurface hardness (ΔKHN); profile and depth of the subsuperficial lesion (PLM); concentrations of F, calcium (Ca) and phosphorus (P) in enamel was determined. The data were analyzed by ANOVA (1-criterion) and Student-Newman-Keuls test (p < 0.001). Treatment with 1100F alone led to ~ 28% higher remineralization when compared to treatment with 1100F associated with MI Paste Plus (p < 0.001). The 1100F and 1100F + Gel F groups showed similar values for %SHR (p = 0.150). 1100F + Gel TMP treatment also remineralized the enamel surface by ~ 30% and 20% when compared to the 1100F + Gel F and 1100F groups (p < 0.001). The lower lesion depth (ΔKHN) was observed for the 1100F + Gel TMP group (p < 0.001), where it was 54% and 44% lower in comparison to the 1100F and 1100F + Gel F groups (p < 0.001). Polarized light microscopy photomicrographs showed subsurface lesions in all groups, but these lesions were present to a lower extent in the 1100F + Gel TMP group (p < 0.001). Treatment with 1100F + Gel TMP promoted an increase in the concentration of Ca in the enamel by ~ 57% and ~ 26% when compared to the 1100F and 1100F + MI Paste Plus groups (p < 0.001), respectively. There were no significant differences between the 1100F, 1100F + MI Paste Plus and 1100F + Gel F groups (p > 0.001). Similar values of P in the enamel were observed in the 1100F, 1100F + MI Paste Plus and 1100F + Gel F groups (p > 0.001), except for the 1100F + Gel TMP group, which presented a high concentration (p < 0.001). We conclude that the 1100F+TMP gel treatment/protocol led to a significant increased remineralization when compared to the other treatments/protocols and may be a promising strategy for patients with early caries lesions.

Paedodontic preformed crowns in primary teeth and relative degree of dental wear.

AIM: Prosthetic rehabilitation of deciduous teeth in paediatric age using pre-formed crowns has been considered one of the best methods of dental restoration since their introduction. Their main advantages are related to durability, longevity and a low rate of recurrent cavities. Since stainless steel crowns do not coincide with aesthetic needs of parents and patients, preformed paedodontic crowns made of zirconia and nano-hybrid composite was introduced. The aim of the study is to evaluate the degree of wear on the enamel and on themselves of the different paedodontic crowns. MATERIALS: Nine bovine teeth and nine paedodontic crowns for deciduous molars were selected for the study, three of which in zirconia, three in nano-hybrid composite and three in stainless steel. Wear test was carried out on the Rtech™ Instruments tribometer applying a force of 50 N. After that, both the bovine teeth and the paedodontic crowns were observed using a stereo microscope (Zeiss Stemi C-500) and a scanning electron microscope (SEM, Cambridge Stereoscan 440). The areas of wear were calculated with a software [ImageJ, version 1x, Wayne Rasband, Maryland, USA]. CONCLUSION: Pre-formed paediatric crowns in zirconia, nano-hybrid composite and stainless steel are a valid aid for the restoration of deciduous teeth and do not compromise the physiological wear characteristic of the phases of the dental exchange. The stainless steel crown is preferable for the restorations in the posterior sectors as its behaviour is the most similar to that of a natural tooth. Zirconia and nano-hybrid composite crowns showed an inversely proportional behaviour between their wear volume and that of the opposing tooth.

Does surface priming increase the bond strength of orthodontic brackets? An experimental study.

OBJECTIVE: To evaluate the effects of metal primer II (MP II) on the shear bond strength (SBS) of orthodontic brackets bonded to teeth and bis-acryl composite provisional material (Bis-Acryl). MATERIAL AND METHODS: Twenty extracted human premolars specimens and 20 premolar shaped Bis-Acryl specimens were obtained and randomly divided into two surface groups. The first group consisted of human premolars (T) bonded to brackets in the conventional way while in the second (T-MP) MP II was applied on the bracket base before bonding. Similarly, one group of provisional material (PM) was prepared according to conventional treatment and another with the application of MP-II metal bonder (PM-MP). In all cases Ortho-brackets (Victory Series, 3 M) were bonded employing Transbond XT resin cement. Then the brackets were debonded under shear and the results were statistically analyzed by two-way analysis of variance and Holm Sidak at α = .05. The debonded surfaces of all specimens were examined by light microscopy and the Adhesive Remnant Index (ARI) was recorded. RESULTS: The SBS results exhibited significant differences er (p < .001). For both the T and TM the application of MP-II increased the SBS compared to respective control groups (p < .001). The T-C group was found inferior compared to PM-C (p < .001) and the same is true for the comparison between T-MP and PM-MP (p < .001). ARI indexes demonstrated that the tooth groups were characterized by a predominantly adhesive failure at the resin-dentin interface. In contrast, the control group for provisional crowns (PM-C) showed a predominantly cohesive failure mode, which moved to predominantly adhesive after the application of MP II. CONCLUSION: The application of MP II enhances the SBS on both, human enamel and provisional crown materials.

Surface deterioration of resin composites and enamel after toothbrush simulation with new and used toothbrushes.

PURPOSE: To investigate the effect of toothbrushing with new and used toothbrushes on the surface of resin composites and dental enamel. METHODS: The extracted human incisors were selected after vestibular enamel surfaces (ES) were examined. Disc-shaped specimens of direct composite (DC) and indirect composite (IC) were fabricated. Computer-aided design-computer-aided manufacturing (CAD-CAM) composite blocks (CC) were sliced in 2 mm thickness (n= 8). The surface roughness, gloss, and color were measured. The measurements were performed before and after 3 months of toothbrushing simulation (TBS) for 2,500 circular cycles. The wear index was calculated by using the ImageJ program. The specimens were subjected to an additional 2,500 cycles and the same measurements were repeated. RESULTS: No significant increase in surface roughness values was observed in DC, IC, and CC groups after 3 and 6 months of TBS except in the ES group. The highest change in surface gloss was observed in the DC group. Although the wear index of toothbrushes increased over time, only the increase in the IC group was statistically significant (P= 0.033). CLINICAL SIGNIFICANCE: Changes in surface roughness, gloss, and discoloration of the dental enamel and restorations and wear of toothbrush bristles were increased over time.

Effect of fluoride or chitosan toothpaste and at-home bleaching in enamel roughness, tooth color, and staining susceptibility.

PURPOSE: To evaluate how fluoride- or chitosan-based toothpaste used during at-home bleaching affects enamel roughness, tooth color, and staining susceptibility. METHODS: Bovine enamel blocks were submitted to a 14-day cycling regime considering a factorial design (bleaching agent x toothpaste, 2 x 3), with n=10: (1) bleaching with 16% carbamide peroxide (CP) or 6% hydrogen peroxide (HP), and (2) daily exposure of a fluoride (1,450 ppm F-NaF) toothpaste (FT), chitosan-based toothpaste (CBT), or distilled water (control). Then, 24 hours after the last day of bleaching procedure the samples were exposed to a coffee solution. Color (ΔEab, ΔE00, L*, a*, b*) and roughness (Ra, µm) analyses were performed to compare the samples initially (baseline), after bleaching, and after coffee staining. The results were evaluated by linear models for repeated measures (L*, a*, b*, and Ra), 2-way ANOVA (ΔEab, ΔE00) and Tukey's test (α= 0.05). RESULTS: After the at-home bleaching procedure (toothpaste vs. time, P< 0.0001), the toothpaste groups presented a statistically lower Ra than the control (CBT 0.05). After coffee exposure, CBT presented lower ΔEab and ΔE00 values in the HP groups (toothpaste, P< 0.0001), and lower b* and a* values in the CP groups (toothpaste vs. time, P= 0.004). CLINICAL SIGNIFICANCE: Fluoride or chitosan delivered by toothpaste can reduce surface alterations of the enamel during at-home bleaching, without affecting bleaching efficacy.

Enamel remineralisation prospect of Moringa Oleifera hydrogel, eggshell hydrogel versus sodium fluoride varnish on artificially demineralised primary teeth: in vitro study.

PURPOSE: The purpose of the present in vitro study is to investigate and compare the remineralising potential of Moringa Oleifera extract, eggshell, and sodium fluoride varnish on microhardness of artificially demineralised enamel of primary teeth with biomimetic minimally invasive approach following the world paradigm shift towards natural products in paediatric dentistry. MATERIAL AND METHODS: Sample size included 44 primary molars. The mineral content and surface microhardness of all specimens were initially assessed using energy dispersive x-ray examination (EDX) and Vickers microhardness. The specimens were artificially demineralised for 96 h at a temperature of 37°C and then reassessed directly after demineralisation. The demineralised enamel specimens were randomly divided into four groups according to the remineralisation regimen utilised. Group 1: Artificial saliva (control); Group 2: Sodium fluoride varnish; Group 3: Eggshell hydrogel; and Group 4: Moringa Oleifera hydrogel. The specimens were stored for 8 days and then subsequently evaluated using EDX and microhardness assessment by Vickers microhardness test and scanning electron microscope (SEM).  Results: Regarding the microhardness test, there was a significant difference between the Moringa Oleifera group and Eggshell group compared to fluoride varnish (p < 0.05). Regarding EDX analysis, there was a statistically significant difference (p < 0.05) between Moringa Oleifera group and Eggshell group compared to fluoride varnish as the highest values were for Moringa Oleifera and Eggshell. On the other hand, there was no statistically significant difference (p > 0.05) between Moringa Oleifera and Eggshell in both the measurements. CONCLUSION: Moringa Oleifera and Eggshell might be considered as a biomimetic natural material capable of guiding enamel tissue remineralisation in early carious lesion of primary teeth. CLINICAL RELEVANCE: This research demonstrated the capability for early enamel caries to be remineralised using novel materials with a naturally counterpart implicated in biomineralisation as proved to be more effective than traditionally used fluoride varnish in primary teeth.

Enamel Matrix Derivative, 58S5 Bioactive Glass, and Fluoride Varnish for Enamel Remineralization: A Multi-analysis Approach.

PURPOSE: This study aimed to evaluate the enamel remineralization efficacy of enamel matrix derivative (EMD), experimental bioactive glass (BAG), and fluoride varnish in vitro. METHODS AND MATERIALS: Artificial initial caries lesions were developed on fifty human enamel specimens using demineralization solution (pH 4.5, 37°C, 96 hours). Specimens were randomly assigned to five groups (n=10): I-5% NaF varnish (Enamelast), II-experimental 58S5 BAG+37% phosphoric acid (PA), III-EMD (Emdogain) + Ethylenediaminetetraacetic Acid (EDTA), IV-EMD+37% PA, V-Control (untreated). All remineralization agents were applied with pH cycling for seven days. The specimens were scanned by spectral domain optical coherence tomography (SD-OCT) at baseline, at demineralization, and after pH cycling. Lesion depths were measured using image analysis software (ImageJ). Lesions were evaluated using surface microhardness (SMH) and two fluorescence methods (FluoreCam and DIAGNOdent Pen [DDPen]). The data were statistically analyzed by Kruskal Wallis, Friedman, and Wilcoxon tests (α=0.05). RESULTS: According to SD-OCT results, fluoride varnish was found to be the most effective agent in reducing lesion depth (p=0.005). All agents increased the SMH values after pH cycling. No significant difference was found among fluoride varnish, BAG, and EMD+PA groups. These SMH values were significantly higher than EMD+EDTA and control groups (p<0.001). All groups showed lower DDPen scores compared with the control group (p<0.001), however, no significant difference was found among the remineralization agents. In FluoreCam assessment, size and intensity values of all treated groups showed improvement. However, there was no significant difference between the treatment groups in terms of FluoreCam size measurements (p=0.186). CONCLUSION: 58S5 BAG and EMD+PA have remineralization capacity as effective as fluoride varnish. EMD+PA showed better SMH and lesion intensity results than EMD+EDTA.

Interplay Between Minerals in Bottled Water and Fluoride Toothpaste and Caries Lesion Remineralization.

OBJECTIVES: he aim of this in vitro study was to evaluate the effects of some bottled waters on fluoride toothpaste efficacy in enhancing caries lesion remineralization. METHODS: Early caries lesions were created in bovine enamel specimens and stratified into treatment groups based on Vickers surface microhardness (VHN). The present study followed a two (fluoride and fluoride-free toothpaste) by five (four bottled waters and tap water) factorial design. The treatment groups were bottled water with the following attributes: (a) 309.9 ppm Ca/1.20 ppm F; (b) 118.4 ppm Ca/0.16 ppm F; (c) 1.00 ppm Ca/1.01 ppm F; and (d) 0.1 ppm Ca/0.04 ppm F and tap water (48.7 ppm Ca/0.7 ppm F). The five water groups were paired either with 1100 ppm fluoride or fluoride-free toothpaste, yielding 10 groups. Specimens were pH-cycled for 10 days with the daily regimen comprised of twice daily toothpaste slurry, with four exposures to water in between. VHN was measured again and the difference was calculated (ΔVHN). Data were analyzed using two-way ANOVA at a 5% significance level. RESULTS: The two-way interaction between water and toothpaste was significant (p<0.001). All groups except fluoride-free toothpaste/bottled water with 0.1 ppm Ca/0.04 ppm F (p=0.411) had significant increases in VHN after pH cycling (p≤0.023). Fluoridated toothpaste resulted in a higher rate of remineralization compared to fluoride-free toothpaste (all p<0.001). Bottled water with 1.20 ppm F/309.9 ppm Ca exhibited the greatest extent of remineralization within fluoride toothpaste groups (p<0.001) and higher remineralization than lower fluoride water in fluoride-free toothpaste groups (p≤0.006). Within the fluoridated toothpaste group, tap water exhibited significantly less remineralization than all bottled waters (all p<0.001). CONCLUSION: Within the limitation of this study, bottled water with higher fluoride and calcium concentrations might improve fluoridated toothpaste efficacy by enhancing remineralization of early enamel caries-like lesions.

Inhibition of incipient caries lesion progression by different fluoridated varnishes.

The aim of this in vitro study was to evaluate the potential of different fluoridated varnishes to inhibit the progression of incipient caries lesions after cariogenic challenge. Seventy-five enamel specimens of bovine teeth were prepared and selected based on the initial surface microhardness (SMH). The specimens were first subjected to artificial demineralization (in buffer solution) after which SMH was re-analyzed (SM1). They were then randomly assigned to five experimental groups: 1- CONTROL (pH cycling), 2 - MI VAR (MI Varnish with RECALDENTTM - CPP-ACP), 3 - PROFL (Profluorid®), 4 - CLIN (ClinproTM White Varnish with TCP), and 5 - DUR (Duraphat®) (n=15). The varnishes were applied in a thin layer and the specimens were then subjected to pH cycling for eight days. The SMH and cross-sectional microhardness (CSMH) were then analyzed (SM2). The fluoride and calcium ion concentrations in the solution were analyzed by the indirect method and atomic absorption spectrophotometry, respectively. Data were statistically analyzed by Student's t-test, ANOVA/Tukey-Kramer, or Kruskall-Wallis/Dunn tests for individual comparisons (p˂0.05). All varnishes led to significantly higher surface and subsurface remineralization compared with the control group but did not differ from each other. The varnishes with the highest fluoride release were: PROFL and CLIN, followed by MI VAR and DUR. The varnishes with significantly higher release of calcium were: DUR, CLIN, and PROFL. In conclusion, all commercial fluoridated varnishes tested have good potential to inhibit the progression of demineralization, regardless of the ion release mechanisms.

In Vitro Biofilm Removal From Human Enamel Using a Philips® Sonicare® Power Flosser.

The objective of this in vitro study was to quantify the removal of dental biofilm from human enamel surfaces after treatment with the Philips® Sonicare® Power Flosser. Dental biofilms were grown from pooled human saliva on human enamel disks for 4 days, according to an established academic model.* The biofilms (n = 6) were treated with the Philips Sonicare Power Flosser for 3 seconds using the Quad Stream nozzle. To quantify the number of bacteria before treatment, the biofilm volume was measured using optical coherence tomography (OCT) and the bacterial cell density was determined from untreated control samples (n = 6) using confocal laser scanning microscopy (CLSM). After treatment the number of remaining bacteria were counted using CLSM. Additionally, scanning electron microscope (SEM) images were recorded. While before treatment 0.2-mm thick dense biofilms were present, after treatment only scattered groups of bacteria remained (Figure 1 through Figure 4). Quantitative analysis showed 99.96% removal for the Quad Stream nozzle. The Philips Sonicare Power Flosser oral irrigator with Quad Stream nozzle removed over 99.9% of the bacteria in this established laboratory model of dental biofilm.

Effect of phosphate group on remineralization of early enamel caries regulated by amelogenin peptide.

OBJECTIVE: To show the effect of the phosphate group on the remineralization process of early enamel caries mediated by amelogenin peptide. METHODS: Freshly extracted, completed, and crack-free bovine teeth were used to create artificial early enamel caries, which were randomly divided into four groups: Group A: fluorination remineralized solution treatment group; Group B: pure remineralized solution treatment group. Group C: 100 g/ml recombinant Amelogenin peptide remineralized solution treatment group (with single phosphate group on N-terminus); Group D: 100 g/ml non-phosphorylated recombinant Amelogenin peptide remineralized solution treatment group (without single phosphate group on N-terminus). For 12 days, fresh remineralized solutions were replaced daily. Transverse microradiography (TMR) was used after remineralization to determine mineral loss and demineralization depth before and after each sample's remineralization. Each sample's depth of remineralization and mineral acquisition were then determined. RESULTS: The recombinant amelogenin peptide group significantly outperformed the non-phosphorylated amelogenin peptide group in terms of mineral acquisition and mineralization depth (P<0.05). CONCLUSIONS: The recombinant Amelogenin's solitary phosphate group at the N-terminus helps recombinant Amelogenin to encourage the remineralization process of early enamel caries.

A novel mutation in GPR68 causes hypomaturation amelogenesis imperfecta.

OBJECTIVES: To identify the genetic cause of a Chinese family with hypomaturation amelogenesis imperfecta (AI) and to characterize the structure of GPR68 mutated enamel in order to develop a deeper understanding of the role of the GPR68 protein during the intricate process of amelogenesis. DESIGN: One Chinese family with generalized hypomaturation AI was recruited. Two of the third molars from the proband were subjected to scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Whole exome sequencing (WES) was performed, and the identified mutation was confirmed by Sanger sequencing. Bioinformatics studies were further conducted to analyze the potential deleterious effects of the mutation. RESULTS: The proband presented with a hypomaturation AI phenotype, characterized by fragile and discolored enamel surface. The AI enamel showed prismatic structure, which was sporadically obscured by areas of amorphous material and porous structure. EDX analysis showed the proband's enamel demonstrated a significant decrease in calcium and phosphorus content and a significant increase in oxygen compared with normal enamel. A novel homozygous mutation of G protein-coupled receptor 68 (GPR68) (c .149 T > A, p.Ile50Asn) was identified in the proband. Bioinformatics analysis indicated that the mutation site displayed a high level of evolutionary conservation among species, and the mutation might impact the stability and conformation of the protein. CONCLUSION: The novel homozygous GPR68 mutation resulted in hypomaturation AI. We first described the effect of GPR68 mutation on enamel structure. Our results provide new genetic evidence that mutations involved in GPR68 contribute to hypomaturation AI.

Differences in childhood stress between Neanderthals and early modern humans as reflected by dental enamel growth disruptions.

Neanderthals' lives were historically portrayed as highly stressful, shaped by constant pressures to survive in harsh ecological conditions, thus potentially contributing to their extinction. Recent work has challenged this interpretation, leaving the issue of stress among Paleolithic populations highly contested and warranting in-depth examination. Here, we analyze the frequency of dental enamel hypoplasia, a growth disruption indicator of early life stress, in the largest sample of Neanderthal and Upper Paleolithic dentitions investigated to date for these features. To track potential species-specific patterns in the ontogenetic distribution of childhood stress, we present the first comprehensive Bayesian modelling of the likelihood of occurrence of individual and matched enamel growth disruptions throughout ontogeny. Our findings support similar overall stress levels in both groups but reveal species-specific patterns in its ontogenetic distribution. While Neanderthal children faced increasing likelihoods of growth disruptions starting with the weaning process and culminating in intensity post-weaning, growth disruptions in Upper Paleolithic children were found to be limited around the period of weaning and substantially dropping after its expected completion. These results might, at least in part, reflect differences in childcare or other behavioral strategies between the two taxa, including those that were advantageous for modern humans' long-term survival.

Efficacy of the Probiotic L. brevis in Counteracting the Demineralizing Process of the Tooth Enamel Surface: Results from an In Vitro Study.

BACKGROUND: Enamel plays an essential role in protecting the underlying layers of the human tooth; therefore, preserving it is vital. This experimental study aimed to evaluate the potential ability of L. brevis to counteract the action of a demineralizing agent on dental enamel morphology and mineral composition in vitro. METHODS: The sample consisted of 12 healthy human posterior teeth. The coronal portion of each tooth was subdivided into two equal parts longitudinally. The specimens were randomly divided into four groups: artificial saliva, L. brevis suspension, demineralizing agent (DA), and DA plus L. brevis. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to evaluate the surface micromorphology and the mineral content, respectively. The statistical analysis was conducted using a one-way ANOVA, followed by Tukey's post hoc test. RESULTS: SEM analysis did not highlight significant changes in the enamel microstructure of L. brevis-treated specimens compared to the control. DA-induced damage to the enamel structure was drastically reduced when the specimens were contextually exposed to the probiotic. The treatment with DA substantially reduced the weight % of crucial enamel minerals, i.e., Ca and P. Notably, the probiotic was able to reverse the demineralization process, bringing Ca and P weight % back to basal levels, including the Ca/P ratio. CONCLUSIONS: The findings indicate that L. brevis is able to efficiently protect the dental enamel surface from the damage caused by DA and increase the enamel resistance to demineralization. Overall, L. brevis confirms its efficacy in preventing or counteracting the action of carious lesions through a novel mechanism that protects the tooth surface under a chemical challenge that mimics the caries process.

The effect of freezing on the fracture pattern of adhesive on debonding: an in-vitro study.

The purpose of this study was to quantitatively evaluate adhesive remnants on the enamel surface following bracket debonding using a freezing element. Thirty-six sound premolars were used in this study. In each case, a bracket was bonded onto each tooth with conventional light-cured composite resin and de-bonded after one week. Freezing of the underlying composite through the bracket was performed immediately before debonding with a portable cryosurgical system (-55 °C). Specimens were divided into three groups according to the duration of freezing: a control group without freezing was used as a reference and two interventional groups with different durations of freezing (15 or 40 s). Brackets were removed by using debonding pliers to squeeze the wings of the bracket in an occluso-gingival manner. Adhesive remnants on the tooth were then quantitatively evaluated by stereo-microscopy. Pearson's Chi-squared test was used to investigate the relationship between the proportion of remaining resin and the group of teeth. In the control group, 100% of the composite remained on the enamel surface of all specimens. Significantly less adhesive remnants were found in the intervention groups (p = 0.001 for the 15 s group and p = 0.043 for the 40 s group). There was no significant difference between the two interventions (p = 0.165) in terms of the proportion of remaining adhesive remnants. Freezing of the bracket and the underlying adhesive resin prior to bracket debonding may favorably alter the behavioral pattern of composite fracture, thus reducing the extent of adhesive remnants on the enamel. Increasing the freezing time from 15 to 40 s did not exert significant effects on adhesive remnants following debonding. Further research now needs to investigate the effect of freezing on the mechanical properties of the adhesive remnants and its in-vivo effect on pulp vitality over both short- and long-terms.

Comparative evaluation of probiotic solutions on surface roughness and microhardness of different restorative materials and enamel.

This research study aimed to investigate the impact of probiotic mouthwash and kefir on the surface characteristics, specifically surface roughness and microhardness, of different restorative materials, as well as permanent and deciduous tooth enamels. Thirty disc-shaped specimens were prepared from composite resin (G-ænial Posterior (GP)), polyacid-modified composite resin (compomer) (Dyract-XP (DXP)), and resin-modified glass ionomer cement (Ionoseal (IS)). Additionally, thirty specimens of enamel were obtained from permanent teeth (PT) and thirty from deciduous teeth (DT) by embedding buccal and lingual sections, acquired through vertical sectioning of 15 permanent and 15 deciduous human tooth crowns in the mesiodistal orientation within acrylic resin blocks. The specimens were then categorized into three distinct groups and immersed for 14 days in one of the following solutions: distilled water, kefir or probiotic mouthwash. The mean surface roughness values of all specimens were assessed using an atomic force microscope, while the mean surface microhardness was measured using a Vickers hardness measuring instrument. The results revealed a statistically significant difference in mean surface roughness among the various restorative materials (p < 0.001). Among the restorative materials, the IS material exhibited notably higher mean surface roughness values than other restorative materials and tooth enamel, while no significant differences were observed between the PT and DT groups. Importantly, the main effect of the solutions under investigation was not statistically significant (p = 0.208). No significant difference was found between the surface roughness values of specimens subjected to the different solutions. When evaluating the effects of materials and solutions on microhardness, the main effects of material and solution variables and the influence of material-solution interactions were statistically significant (p < 0.001). Taken together, these results indicate that consistent use of kefir or probiotic mouthwashes may impact the surface properties of various restorative materials and tooth enamel.