Search Results (251)

Teeth may retain forensic value after chemical exposure, yet the effects of commercially available corrosive agents remain insufficiently characterized. This study evaluated short-term alteration patterns in human teeth exposed to household acidic and alkaline products available on the Romanian market. Five extracted mandibular third molars were analyzed, including four experimental teeth and one control. Each experimental tooth was fully immersed for 48 h in a different agent: hydrochloric acid descaler, sodium hypochlorite bleach, mixed hydrochloric/sulfuric acid descaler, or sodium hydroxide. Morphometric changes, mass, and pH were monitored serially, while stereomicroscopy, SEM-EDX, and hard tissue ground sections were used for structural and compositional assessment. Acid-exposed teeth showed the greatest damage, with major mass loss in the hydrochloric acid and mixed-acid samples, enamel loss, and marked microstructural disruption. The mixed-acid specimen exhibited the most severe collapse and near-complete calcium/phosphorus depletion. Sodium hypochlorite produced mainly superficial and root-level alterations with relative preservation of gross morphology, whereas sodium hydroxide caused minimal dimensional change and a calcium-rich adherent surface deposit. These findings show that household corrosives produce distinct, forensically recognizable dental alteration patterns within 48 h and support an integrated pattern-recognition approach in suspected chemical concealment scenarios. Full article

Radon-222, a naturally occurring radioactive gas, is the second leading cause of lung cancer globally, after tobacco use. When inhaled, its decay products, especially polonium-218 and polonium-214, emit high-energy alpha particles that induce dense DNA damage in the bronchial epithelium. Because ambient radon measurements often vary significantly over time and across locations, they provide limited insight into individual exposure levels. This suggests the urgent need for biological markers that can accurately indicate internal dose and early signs of lung cancer development. This review offers an extensive overview of biomarkers associated with radon exposure, from internal dosimetry to early biological responses. It covers internal dose markers (e.g., radon progeny in air and ²¹⁰Po/²¹⁰Pb in bones and teeth), molecular and cytogenetic indicators of effective dose (such as chromosomal aberrations, γ-H2AX foci, and DNA adducts), and early effect markers (including somatic mutations, epigenetic changes, miRNA profiles, and autoantibody signatures). The review highlights translocations detected via FISH, discussing those that are stable over time versus those that are transient. It also evaluates the reliability and practicality of these biomarkers in occupational and residential settings, noting how smoking complicates causal inference due to overlapping mutation pathways. Finally, it suggests that integrating multi-omics technologies could improve the precision of biomarker panels. Full article

Background/Objectives: Genetic identification of human skeletal remains plays a pivotal role in forensic investigations when other traditional or primary methods are not appropriate. Decomposition, storage and environmental conditions often leave the skeletal structure as the only basis for identification. This review synthesizes current methodologies and technological advances in damaged DNA extraction and analysis, emphasizing the forensic relevance of skeletal remains for genetic identification. Methods: A comprehensive literature analysis highlights the basis of genetic identification; sampling that considers intrinsic and extrinsic factors influencing the DNA yield and its quality; pre-treatment methods; extraction protocols that are suitable for its sensitivity; genetic marker panels that allow for human identification; and statistical evaluation and analysis of the results. The last chapter demonstrates the real-world impact of genetic identification on historical cases, underscoring its broader significance in legal, humanitarian, and socio-historical contexts, supporting a critical evaluation of best practices, methodological robustness, and ethical considerations within the field. Results: Teeth, femur and the petrous portion of temporal bone are the main samples used for genetic analysis. STR profiling and mitochondrial DNA are the gold standard markers for skeletal human identification. Minimally destructive protocols that enhance a high DNA yield are chosen, with silica-based methods being highlighted in the extraction protocols. Next-Generation Sequencing techniques have also improved analytical outcomes, by enabling high-throughput data generation, increased coverage depth, nucleotide-level sequence data, and high-level multiplexing of genetic targets. Conclusions: This review provides a comprehensive framework for researchers and practitioners seeking to optimize genetic identification workflows in forensic sciences and bioarcheology. These methodological advances have significantly increased identification success rates, especially in cases involving degraded or limited skeletal remains. Reviews such as this one help us to identify methodological gaps, ethical concerns, and future research directions, thereby establishing best practices when working with highly degraded skeletal material, supporting more reliable, standardized, and legally defensible applications of genetic identification in forensic, archeological, and humanitarian contexts. Full article

Dental developmental anomalies are well documented in clinical veterinary medicine but remain rarely reported in archeological dogs. This study presents a radiologically confirmed case of an unerupted left maxillary canine associated with the absence of an alveolus for the left maxillary first molar and incisors in a dog skull from early medieval Wolin. This study aimed to determine whether the observed absence of teeth resulted from congenital agenesis, developmental arrest, ante-mortem loss, or post-depositional processes. Radiographic examination revealed a fully formed but unerupted canine, while the M¹ region exhibited a smooth bony surface without reactive remodeling, periapical radiolucencies, or signs of ante-mortem tooth loss. Differential diagnosis did not support canine agenesis, ante-mortem loss, or taphonomic damage as primary explanations. The findings most strongly support a congenital or very early developmental origin of the observed alterations. The estimated age of the individual (7–10 years) and the absence of secondary pathological changes suggest that these anomalies did not significantly impair masticatory function. Owing to the single-case nature of the material, broader population-level inferences cannot be made. This case underscores the methodological importance of radiographic imaging in archeological dental research and suggests that alveolar absence should not be automatically equated with impaired survival or poor health in this individual. Full article

Objectives: Due to extra-axial forces, post and core (PC) treatment has the worst survival probability in abutment teeth for telescopic crown-retained dentures (TCDs). The reason for this is a mismatch regarding the mechanical properties between PC material and dentin or a poor accuracy of fit of PC, resulting in tooth fracture or decementation. However, the inclusion of severely damaged endodontically treated teeth needing PC is often mandatory in order to achieve a stable situation for TCD. Thus, an advancement of PC treatment for TCD is of high clinical interest. Recently it has become possible to fabricate customized PC with favourable mechanical properties by using CAD/CAM technology. Methods: Thus, the aim of this investigation was to compare the performance of these PC types (CAD/CAM PC) to customized cast PC (CPC) and prefabricated fibre-reinforced PC (PFPC) in a TCD set-up using a chewing simulator. Results: The investigation group with CAD/CAM PC showed neither tooth fracture nor decementation, in contrast to the CPC and PFPC groups, in which both types of failure were recorded. Thus, CAD/CAM PC showed significantly better performance than CPC and PFPC. Conclusions: Within the limitations, CAD/CAM PCs are therefore recommendable for PC treatment with TCD. Full article

In computer-aided design/computer-aided manufacturing (CAD/CAM) restorations for severely damaged teeth, the cavity floor or proximal margins may be elevated with composite resin to improve adhesion. This in vitro study investigated how different surface pretreatment methods affect the shear bond strength (SBS) of hybrid CAD/CAM materials to dentin or composite surfaces, simulating clinical situations of composite elevation. Hybrid CAD/CAM samples were bonded to dentin or composite substrates following different surface pretreatment protocols and cemented using a dual-cure adhesive resin cement. The samples were thermocycled and subjected to shear bond strength testing, and failure modes were analyzed. The SBS in the sandblasting (SB)+Dentin group and hydrofluoric acid (HF)+Dentin was significantly higher than that in the SB+Composite and HF+Composite groups (p < 0.05). Untreated+composite and untreated+dentin groups showed significantly lower SBS (p < 0.05). Failure mode analysis revealed a predominance of cohesive failures in the SB+Dentin group, while adhesive failures were more frequently observed in most of the other groups. SB-treated and HF-etched hybrid CAD/CAM materials showed more favorable bonding behavior to dentin than to composite, highlighting that bonding to the elevated composite layer may be less effective than bonding directly to prepared dentin. Full article

The paper presents results of a degradation analysis of polyamide 12 reinforced with carbon fibers used for additive manufacturing of cycloidal gear. Both FEM simulation and a fatigue test indicated the ability of the material to withstand loads during the work of cycloidal transmission. However, a run-to-failure (RTF) test revealed critical failure after 10⁵ cycles, with displacement and damage of the material in the area close to bearing instead of expected areas of teeth being in friction with pins. Acceleration analysis with time synchronous averaging (TSA) confirmed rapid degradation of the material’s strength at the end of the RTF test. It was found that the PA12 cycloidal gear damage was a result of fatigue accelerated by the temperature increase under the cyclic loads that took place during the RTF test. In particular, displacement of 0.2 mm did not appear in the specimens tested at 27 °C even after 10⁵ cycles, while at 140 °C this value was reached almost immediately. At 70 °C and 90 °C, plastic deformation of 0.2 mm was reached after 30,000 and 5000 cycles, respectively. The finding can be used in a predictive maintenance system of such cycloidal transmission with 3D-printed polymer gears. Full article

Phthalimidoperoxycaproic acid (PAP) emerges as a promising alternative non-peroxide bleaching agent to hydrogen peroxide (HP), offering similar efficacy with potentially less enamel damage. This in vitro study aimed to evaluate and compare the effects of 37.5% HP, 35% carbamide peroxide (CP), and PAP on dental color, enamel surface microhardness, and morphological integrity. Fifty-seven extracted human maxillary incisors were randomly assigned to three groups (n = 18). Thirteen teeth per group were used for color evaluation, four for microhardness, and one for surface morphology analysis. Each group received three whitening sessions (three applications per session) according to the manufacturers’ instructions. Color was assessed before and one week after each session using a spectrophotometer. Lightness increased by 7.19 units (HP), 7.11 (PAP), and 4.43 (CP). ΔWI_D was 4.48 (HP), 4.16 (CP), and 8.82 (PAP). All agents produced an “excellent” bleaching effect (ΔE₀₀ index); only PAP achieved “excellent” values with the ΔWI_D index at the end of the study. PAP produced fewer morphological changes on the enamel surface and less reduction in microhardness compared to the untreated control than the other agents evaluated. PAP emerges as an effective alternative for dental bleaching, offering significant color improvement while ensuring minimal alterations to enamel morphology. Full article

Zirconia is a material that mimics human teeth and has been extensively studied and applied. This study investigated the surface modifications of dental zirconia induced by two UV-C wavelengths (222 and 254 nm). A total of 72 zirconia specimens were prepared and divided into groups for irradiation at varying distances (1, 6, 12 cm) and durations (40, 120, 480 and 1440 min), with three specimens retained as untreated controls. Surface changes were assessed by measuring colour difference (ΔE) and water contact angle, and by analyzing surface morphology and elemental composition using SEM and EDX, and XRD was employed to determine the crystalline structure. The results showed that both wavelengths induced clinically perceptible colour changes (ΔE > 2.0), with the most pronounced effect at 6 cm for 222 nm and 1 cm for 254 nm. WCA decreased significantly with irradiation time, showing a linear correlation with log(time), and 222 nm irradiation yielded lower WCA than 254 nm. While SEM revealed no morphological changes, both UV treatments significantly increased the Zr/O ratio compared to the control. XRD tests confirmed that UV-C irradiation does not damage the zirconium oxide crystal structure. It is concluded that both UV-C wavelengths can alter the colour and enhance the wettability of zirconia; these modifications are particularly relevant for dental restorative applications, specifically in the fabrication of anterior tooth crowns, where achieving a natural tooth-like appearance is desired. Full article

Objectives: This study aimed to determine whether surface wear, identified through the superimposition of intraoral scans (IOS), can predict subsurface damage progression detected by optical coherence tomography (OCT) during fatigue testing of computer-aided design/computer-aided manufacturing (CAD/CAM) composite crowns. Methods: Monolithic CAD/CAM composite crowns (Brilliant Crios; $n=8$) were adhesively luted to standardized prepared human teeth and artificially aged by cyclic loading in a mouth-motion simulator (50–500 N, 2 Hz, 37 °C). Under phantom-head condition, IOS (surface wear) and handheld swept-source (SS)-OCT (subsurface damage) were performed before loading and after every 250,000 cycles. OCT crack depth/width were normalized to local thickness and cusp-tip distance; correspondence between IOS- and OCT-derived metrics at each timepoint was assessed with Spearman’s rank correlation coefficient ($\rho$) to test whether surface wear can predict subsurface damage under the given conditions. Results: All specimens survived without catastrophic failure, and both modalities revealed progressive damage from the earliest observation interval. OCT consistently showed higher defect percentages and larger dispersion (e.g., mean vertical defects (25.47 ± 4.97)% OCT vs. (4.36 ± 0.91)% IOS at T1 and (66.79 ± 19.53)% OCT vs. (7.78 ± 3.19)% IOS at T5). Across all timepoints, no statistically significant associations between IOS and OCT were observed (p = 0.146 to 0.955). Conclusions: Within the limitations of this exploratory, single-material in vitro study, restricted to a CAD/CAM composite (Brilliant Crios), surface-based monitoring alone did not reliably reflect subsurface damage progression. Clinically, this suggests that surface wear assessment may underestimate subsurface fatigue damage. Intraoral OCT may provide complementary, non-invasive information alongside routine IOS for individualized monitoring, but its added value needs to be confirmed in larger studies and other CAD/CAM composite materials and additional restorative material classes. Full article

Reconstructing original cusp dimensions in worn molars represents a fundamental challenge across dentistry, anthropology, and paleontology, as dental wear obscures critical morphological information. In this proof-of-concept study, we present a standardized machine learning pipeline for predicting original cusp height, specifically the horn tips of the enamel–dentine junction (EDJ), in worn lower molars using three-dimensional morphometric data from micro-computed tomography (micro-CT). We analyzed 40 permanent lower first (M1) and second (M2) molars from four hominin groups, systematically evaluated across three wear stages: original, moderately worn (worn1), and severely worn (worn2). Morphometric variables including height, area, and volume were quantified for each cusp, with Random Forest and multiple linear regression models developed individually and combined through ensemble methods. To mimic realistic reconstruction scenarios while preserving a known ground truth, models were trained on unworn specimens (original EDJ morphology) and tested on other teeth after digitally simulated wear (worn1 and worn2). Predictive performance was evaluated using root mean square error (RMSE) and coefficient of determination (R²). Our results demonstrate that under moderate wear (worn1), the ensemble models achieved normalized RMSE values between 11% and 17%. Absolute errors typically below 0.25 mm for most cusps, with R² values up to ~0.69. Performance deteriorated under severe wear (worn2), particularly for morphologically variable cusps such as the hypoconid and entoconid, but generally remained within sub-millimetric error ranges for several structures. Random Forests and linear models showed complementary strengths, and the ensemble generally offered the most stable performance across cusps and wear states. To enhance transparency and accessibility, we provide a comprehensive, user-friendly software pipeline including pre-trained models, automated prediction scripts, standardized data templates, and detailed documentation. This implementation allows researchers without advanced machine learning expertise to explore EDJ-based reconstruction from standard morphometric measurements in new datasets, while explicitly acknowledging the limitations imposed by our modest and taxonomically unbalanced sample. More broadly, the framework represents an initial step toward predicting complete crown morphology, including enamel thickness, in worn or damaged teeth. As such, it offers a validated methodological foundation for future developments in cusp and crown reconstruction in both clinical and evolutionary dental research. Full article

Background: Congenital Insensitivity to Pain and Anhidrosis (CIPA) is a rare autosomal recessive disorder characterized by congenital analgesia, anhidrosis, and multisystem involvement affecting the musculoskeletal, cutaneous, oral, and para-oral structures. This case report describes the oral phenotype and multidisciplinary clinical management of a child with CIPA. Case Description: A 9-year-old boy presented with poor oral hygiene, multiple severely damaged teeth, masticatory difficulty, limited mouth opening, impaired bolus control, and para-oral traumatic injuries. Medical and orthopedic history indicated recurrent painless fractures, self-inflicted injuries, cutaneous scarring, and recurrent hyperpyrexia. Oral self-injury associated with CIPA was suspected and supported by the Nociception Assessment Test and Minor’s Iodine–Starch Test. Although the clinical findings were suggestive of CIPA, the diagnosis remained presumptive due to the absence of confirmatory molecular or histopathological testing. Management: A wearable wireless continuous temperature-monitoring device was prescribed to assist in tracking hyperpyrexia associated with CIPA (RHA-CIPA). A conservative, staged, multidisciplinary treatment was planned rather than full-mouth extraction, emphasizing prevention of dental sepsis and mitigation of future self-injury. Dental procedures were performed under local anesthesia to manage discomfort related to tactile hyperesthesia. To reduce nocturnal biting and oral trauma, a hard acrylic occlusal protector was fabricated using an intraoral scanner and a 3D-printed cast. The patient was followed for 12 months. Outcomes: At the 12-month follow-up, clinical improvement was observed, with particularly notable gains in cheek elasticity and soft tissue resilience. Conclusions: This case highlights the considerable challenges involved in the interdisciplinary management of children with CIPA, including oral self-injury prevention, limited mouth opening, and the necessity of close coordination with medical specialties. These findings are descriptive observations of a single case and do not establish efficacy or generalizability of any intervention. Full article

As a commonly used dental restorative material, light-cured composite resin exhibits mechanical properties that closely match those of natural tooth structure. In the process of biting, the filling material falls off severely due to fretting between the filling material and the fixed interface of the teeth, which shortens the life of the filling material. This study aimed to investigate the mechanisms and contributing factors of this phenomenon. In particular, this study investigated the friction and wear mechanisms at the tangential fretting interface between light-cured composite resin and the tooth substrate under varying fretting amplitudes, normal loads, and lubrication conditions. In artificial saliva, the friction coefficient increased with the fretting amplitude and decreased with the increase in the normal load. The result showed that when the fretting amplitude was large or the normal load was small, the fretting was always in the complete slip regime. When the fretting amplitude was small or the normal load was large, the fretting changed from the complete slip zone to the partial slip regime. The minimum friction coefficient in milk was 0.117, and the maximum friction coefficient in artificial saliva was 0.567. Coke and milk have little effect on the fixation of filling materials. Abrasive wear was the predominant mechanism, with small amplitudes or high loads leading to adhesive wear. The composite resin exhibited the least wear in cola and milk, while soda water and artificial saliva caused significantly greater damage. Full article

A common cause of teeth malocclusion and feeding disorders in guinea pigs is macrodontia and odontogenic abscesses. If the maxillary second or third molar teeth are affected, surgical access to them has so far been achieved through enucleation or orbital evisceration due to their location at the base of the orbit. The study aims to demonstrate a transorbital surgical approach to the apices of the maxillary molar teeth (M2 and M3) in guinea pigs, allowing preservation of the eye. Twenty six apicoectomies of maxillary M2 and M3 were performed. The surgical approach involved a skin incision above the zygomatic arch, followed by soft tissue dissection, incision of the orbital ligament, and gentle dorsolateral displacement of the eyeball. Blunt dissection between the lacrimal and zygomatic glands provided direct access to the affected tooth apices, which were removed using a dental bur. After the procedure, the soft tissues and the eye were repositioned and the skin was sutured. All animals recovered uneventfully. The described method may be applied in cases where it is necessary to perform maxillary second and/or last molar tooth apicoectomy while avoiding damage to the eyeball. Care must be taken to protect the corneal surface of the affected eye. Full article

Drilling methods have been increasingly employed for shaft excavation in coal mines in western China. However, the rock fragmentation performance of milled-tooth roller cutters remains inadequate under Jurassic strata conditions. To address this issue, a numerical orthogonal simulation study based on the Finite-Discrete Element Method (FDEM) was conducted. Cutter tooth edge geometry, cutter diameter, cone angle, and penetration depth were considered as four factors at three levels. The effects of these factors on average force, specific energy, damage factor, and proportion of shear cracks were investigated. The efficiency coefficient method was then applied to identify the optimal cutter, and the 8^# roller cutter was determined to be the most effective. The results indicated that cutter tooth edge geometry had the most significant influence on average force and specific energy, whereas penetration depth primarily affected the damage factor and proportion of shear cracks. Compared with the prototype cutter, the 8^# cutter, characterized by a 370 mm large cone-end diameter, a 3° cone angle, and V-edged teeth, exhibited superior rock fragmentation efficiency, achieving a maximum improvement of 31%. These results provide a theoretical basis for the structural optimization of cutters used in shaft drilling in coal mines in western China. Full article