Enamel Dentin Research Articles

Effect of Casein Phosphopeptide-Amorphous Calcium Phosphate on Fracture Resistance of Reattached Tooth Fragments Using Conventional and Self-Adhesive Bioactive Flowable Composite.

Objectives The present study aimed to investigate the effect of casein phosphopeptide–amorphous calcium phosphate (CPP-ACP) complex and the type of flowable composite (conventional or self-adhesive bioactive) on the fracture resistance of fractured incisors restored through reattachment technique. Materials and Methods In this experimental in vitro study, 60 extracted bovine central mandibular incisors were randomly divided into six groups ( n = 10) according to the reattachment technique. Their incisal edges were cut off to represent an enamel–dentin fracture. The fragment edges were reattached as follows: Group 1—selective etching and bonding followed by conventional flowable composite; Group 2—selective etching and bonding followed by bioactive flowable composite; Group 3 was like Group 2 but without applying bonding; Groups 4, 5, and 6 were similar to Groups 1, 2, and 3, respectively, but both tooth fragments were pretreated with CPP-ACP-containing paste for 3 minutes. Fracture resistance was assessed by a universal testing machine. Statistical Analysis Data were analyzed by SPSS—Statistical Package for the Social Sciences—software using one-way analysis of variance and Tukey post-hoc tests (α= 0.05). Results The highest and lowest fracture resistance was recorded in Groups 5 (15.96 MPa) and Group 6 (1.95 MPa), respectively, being significantly different from the other groups. The mean fracture resistance of Groups 3 and 6 was significantly lower than the other groups ( p < 0.05). However, Groups 1, 2, and 4 showed no difference in fracture resistance. Conclusion Bioactive composite was not superior to conventional composite for fragment reattachment, but using it in self-adhesive mode reduced the fracture strength significantly. Yet, pretreatment with CPP-ACP, followed by application of adhesive, improved the fracture resistance of bioactive composite.

AGENTS USED FOR ENAMEL REMINERALISATION AND REDUCING DENTIN HYPERSENSITIVITY: A COMPREHENSIVE REVIEW

ремінералізація, гіперчутливість, десенситизація, емаль, дентинRemineralisation agents not only strengthen enamel resistance, but also can occlude dentine tubules, reducing teeth sensitivity. This article provides an overview of various available agents used for enamel remineralisation and dentin hypersensitivity treatment. Conventional fluorides are used in the form of solutions, varnishes, foam, gels, dentifrices, showing low remineralising and desensitising ability as compared to newer fluoride-content products. Deep fluoridation is an effective method for reducing dentin hypersensitivity for a long time; its remineralising potential is used for white spot lesions treatment, caries prevention, and fissure sealing. Most novel fluoride compounds showed higher remineralising and desensitising abilities as compared to conventional fluorides. Deep penetration fluoridation is an effective method for remineralisation and reducing dentin hypersensitivity in long time. Despite of the fact that calcium phosphate systems have demonstrated a benefit over conventional fluorides in remineralisation their desensitising ability was not confirmed by various studies. The use of bioactive glass in remineralisation and desensitisation is quite promising, but further researches need to be undertaken to prove its efficacy. «Curodont» and synthetic nanohydroxyapatite from biomimetic systems showed good results in the above-mentioned treatments, but more researches are required to confirm their clinical efficacy. There is no doubt that iontophoresis with calcium and fluoride substances is still the most effective method in the office remineralisation, however, its potential effect in desensitisation has to be better evaluated. Efficacy of different kinds of lasers alone or in combination with a remineralisation agent has been confirmed mostly in vitro studies, therefore, there is a lack of clinical trials to prove their benefit. In latter studies, dentin sealants and desensitisers occluded dentin tubules were superior to conventional fluorides and synthetic nanohydroxyapatites. Simultaneously, the data about calcium phosphate and deep penetration fluoridation efficacy over such desensitisers as dentin sealants and nerve sensitivity inhibitors are controversial and indicate that additional studies are required to deepen our knowledge of the insufficiently explored area of reducing dentin hypesensitivity. In spite of the new advances, the ideal treatment modality for remineralisation does not exist. Within last decades, dentistry has made significant steps towards the elusive goal of enamel remineralisation and dentin desensitisation, but more long-term сlinical controlled studies are needed to confirm and quantify these findings, as well as to identify additional factors that can potentiate these processes.

Anisotropic ultimate strength and microscopic fracture patterns during tensile testing in the dentin-enamel junction region.

The dentin-enamel junction (DEJ), which is the interface between the outer tooth enamel and the underlying dentin, has unique biomechanical properties that allow the two different materials to function together without fracture. The aim of this study was to investigate the anisotropic ultimate tensile strength of the DEJ. Twenty dumbbell-shaped samples were prepared from 10 extracted human molar teeth for tensile strength testing. The maximum tensile forces at fracture were measured in the direction parallel (10 samples) and perpendicular (10 samples) to the DEJ. The mean tensile strength of the samples was significantly higher under parallel forces (30.9±3.3 MPa) than under perpendicular forces (20.6±4.8 MPa; p<0.05). Our findings confirm the structural anisotropy of the DEJ.

Seven-year-efficacy of proximal caries infiltration – Randomized clinical trial

ObjectivesWe report efficacy of resin infiltration to arrest progression of caries lesions as compared with non-invasive measures and oral hygiene education alone after a mean observation time of seven years. Materials and methodsThis randomized split-mouth placebo-controlled clinical trial included 22 young adults having 29 pairs of interproximal non-cavitated caries lesions with radiographic extensions into inner half of enamel (E2) or outer third of dentin (D1). Lesion pairs were randomly allocated to two treatment groups: infiltration (Icon, pre-product; DMG) or mock (control) treatment. All subjects received risk-related instructions for diet, flossing and fluoridation. The primary outcome was radiographic (digital subtraction radiography) lesion progression after seven years. Secondly, Kaplan-Meier-analyses were applied to analyze time-to-failure additionally including patients followed up for less than 54 months as well. ResultsTwo lesion pairs were excluded due to invasive treatment decision by another dentist, five lesion pairs were lost to follow-up prior to 54 months but included in the survival analysis. No unwanted effects could be observed. For the primary outcome in 17 patients followed up in mean for 84 months 2/22 infiltrated lesions (9 %) compared with 10/22 control lesions (45 %) progressed (p = 0.018). The relative risk reduction for test in relation to control was 80 % (CI 95 % = 19–95 %). For the survival analysis within a mean (SD) observation time of 73 (25) months mean failure rates of 1.3 % and 7.8 % could be observed for test and controls, respectively. Hazard risk (95 % CI) for caries progression was 6.6 (2–22) for the control compared with the test lesions (p = 0.002). ConclusionsWe conclude that resin infiltration of proximal caries lesions extending radiographically around the enamel dentin junction is efficacious to reduce lesion progression after a mean observation time of seven years. Clinical significanceThis randomized clinical trial proves that caries infiltration is highly efficacious compared with non-invasive measures and oral hygiene education alone after a considerably longer observation time of 7 years than studied so far before.

ISOTOPIC PALEOECOLOGY OF A TOXODONT (MIXOTOXODON LARENSIS) FROM MICHOACAN, MEXICO

The stable carbon and oxygen isotopic ratios present in dentine and tooth enamel from one Mixotoxodon larensis specimen from Hihuitlan, Michoacan, Mexico, were analyzed. Similar to other specimens in Honduras and Panama, δ13C and δ18O values showed that this individual had a mixed diet and lived in a forested zone.

Primordial odontogenic tumor: A systematic review.

Background The primordial odontogenic tumor (POT) is a recently described benign entity with histopathological and immunohistochemical features suggesting its origin during early odontogenesis. Aim: To integrate the available data published on POT into a comprehensive analysis to better define its clinicopathological and molecular features. Material and Methods An electronic systematic review was performed up to September 2019 in multiple databases. Results A total of 13 publications were included, representing 16 reported cases and 3 molecular studies. The mean age of the affected patients was 11.6 years (range 2-19), with a slight predominance in males (56.25%). The posterior mandible was the main location (87.5%), with only two cases affecting the posterior maxilla. All cases appeared as a radiolucent lesion in close relationship to an unerupted tooth. Recurrences have not been reported to date. Microscopically, POT comprises fibromyxoid tissue with variable cellularity surrounded by a cuboidal to columnar odontogenic epithelium but without unequivocal dental hard tissue formation. A delicate fibrous capsule surrounds (at least partially) the tumor. The epithelial component shows immunohistochemical positivity for amelogenin, CK19, and CK14, and variable expression of Glut-1, Galectin-3 and Caveolin-1, Vimentin, p-53, PITX2, Bcl-2, Bax and Survivin; the mesenchymal tissue is positive for Vimentin, CD90, p-53, PITX2, Bcl-2, Bax, and Survivin, and the subepithelial region exhibits the strong expression of Syndecan-1 and CD34. The Ki-67 index is low (<5%). The negative or weak expression of dentinogenesis-associated genes could explain the inhibition of dentin and subsequent enamel formation in this neoplasm. Conclusions POT is an entity with a well-defined clinicopathological, immunohistochemical and molecular profile that must be properly diagnosed and differentiated from other odontogenic lesions and treated consequently. Key words:Primordial odontogenic tumor, systematic review.

Retrospective analysis of traumatic dental injuries in the western black sea region of Turkey.

The incidence of traumatic dental injuries is affected by social, environmental, and socioeconomic variables. For this reason, epidemiological studies are an important tool for increasing social consciousness and guiding the necessary precautions about trauma. The study aims to analyze the epidemiological and clinical data of traumatic dental injuries in patients attending Department of Pediatric Dentistry, Faculty of Dentistry, Bulent Ecevit University, from around Zonguldak, over a period of 3 years (between January 2014 and January 2017). Data obtained from trauma charts were analyzed for age, sex, the time elapsed between injury and referral to the clinic, cause of trauma, number, and type of the teeth, type of the trauma, treatment, and seasonal distribution. In all, 188 patients, including 120 boys and 68 girls with a total of 316 traumatized teeth were evaluated. Most (61.7%) of the patients were 7-12 years old (the remaining 38.3% were 1-6 years old). The main cause of injury in both genders was falling. The most common types of trauma were subluxation in primary teeth and enamel dentin fracture in permanent teeth. In the primary dentition, examination and follow-up were the most applied treatments, whereas in permanent dentition, restorative treatments were the most applied treatments. Early intervention is important for the prognosis of the injured tooth. However, except for severe injuries, the rate of referral to the clinic after trauma was low. Therefore, the level of social awareness and knowledge of trauma should be increased.

Analysis of efficiency of photodynamic teeth bleaching with the use of photosensitizer chlorine e&lt;sub&gt;6&lt;/sub&gt;

Teeth whitening is one of the most sought-after procedures in aesthetic dentistry. Discolorites that are difficult to whiten, caused by dentin changes or enamel defects, can be eliminated by oxidizing the chromogens with chemical agents that penetrate to the enamel and dentin. In recent years, the method of photodynamic bleaching (PDB) is considered to be minimally invasive. It does not use hydrogen peroxide that leads to increased sensitivity of teeth, and is relatively effective over time. A convenient solution for PDB would be to use chlorin e6 as a photosensitizer, which has a high quantum yield of singlet oxygen generation, low phototoxicity, rapid elimination, on the one hand, and photobleaching capability, on the other. This paper presents quantitative data on the study of the effectiveness of PDB with chlorine e6: color change for 100 teeth after the procedure, chlorine e6 penetration into the tooth tissues, evaluation of the interstitial efficiency of the generation of singlet oxygen and photobleaching of chlorine e6 during laser exposure. It has been statistically established that for one PDB procedure, the tooth color saturation (C) varies on average by 0.5 tones on the VITA scale, and the lightness of color (L) in some cases increases by more than 10 units.

Wpływ różnych metod modyfikacji powierzchni zębiny zębów mlecznych na adhezję materiałów światłoutwardzalnych – na podstawie piśmiennictwa

Bonding dental materials to dentinal surface, demineralised in particular, still poses a challenge for contemporary dentistry. Adhesion of filling materials to primary tooth tissue poses a greater difficulty compared to permanent teeth due to poorer enamel and intertubular dentin mineralisation and wider dentinal tubules. The bonding strength of dental materials to tooth surfaces depends on, among other things, surface development, the depth of cavity, as well as the associated degree of tissue mineralisation, the content of organic components and water, as well as the number and width of dentinal tubules. The quality of bonding of dental materials to dental tissues is also determined by the mode of substrate preparation, e.g. conventional drilling or air abrasion, and the type of adhesive system used - etch and rinse or self-etch approach. The choice of material that will ensure optimal bonding to the tooth surface under given conditions, i.e. microretention or chemical adhesion, is also important. The aim of the paper was to assess the effects of different methods for primary tooth dentinal surface modification on the adhesion of light-cured materials in experimental studies, based on literature data. The subject of adhesion of light-curing materials to the dentinal surfaces in primary teeth is current and worth further exploration. Self-etching systems are a good solution for filling carious cavities in primary teeth due to less aggressive demineralising effects on dentin compared to phosphoric acid. Demineralised surface is a difficult substrate for adhesive materials, especially in primary teeth; therefore, there is a need for procedures that will improve the retention of light-cured materials in these teeth. The use of air abrasion – mechanical development of the surface combined with chemical modification using self-etching systems may be one of solutions.

Cervical Level Biological Repair of the Access Opening after Regenerative Endodontic Procedures: Three Cases with the Same Repair Pattern

IntroductionThis article describes the regenerative endodontic procedures applied in 3 cases of maxillary incisor necrosis that resulted in continuous root development, dentinal wall thickening, and cervical level biological repair of the access openings that was verified radiographically in 2 cases and clinically in 1 case. MethodsThree maxillary central incisors in 2 different patients were rendered necrotic after having dentin enamel fracture traumatic dental injuries. All teeth were treated with single- or multiple-visit regenerative endodontic procedures. ResultsThe 5- and 9-year follow-up evaluations revealed similar continuous root development, dentin wall thickening, and hard tissue biological repair of the wide access cavities. In the 9-year follow-up case, the calcium silicate cement was removed because of unacceptable discoloration. The hard tissue biological repair was visualized under the microscope and checked for its continuity with the axial walls, its resistance to displacement, and the presence of possible gaps. The repair tissue seemed to be yellowish in appearance with some brown niches of irregular texture, did not have detectable gaps, was firmly connected with the axial dentinal walls through a demarcated white line, and resisted all displacement forces applied. The tooth was restored with bonded composite resin restoration after internal bleaching. The 10-year follow-up revealed satisfactory esthetics and uneventful soft and hard tissue healing. ConclusionsCervical-level hard tissue repair of the access opening after the application of regenerative endodontic procedures in necrotic immature maxillary incisors might reinforce the weakened tooth structure to a great extent and warrants further investigation.

Fatigue resistance of ultrathin CAD/CAM ceramic and nanoceramic composite occlusal veneers

ObjectiveThe fracture resistance of different ultrathin occlusal computer-aided design/computer-aided manufacturing (CAD/CAM) veneers was investigated under cyclic mechanical loading to restore combined enamel-dentin defects. MethodsEighty-four molars were reduced occlusally until extensive dentin exposure occurred with a remaining enamel ring. Twenty-four molars were ground flat for examination of highly standardized specimens, of which 8 were treated with uniformly flat 0.3mm IPS Empress CAD and 0.3 and 0.5mm IPS e.max CAD restorations. Sixty-four molars were anatomically prepared until dentin exposure and were restored using occlusal veneers with fissure/cusp thicknesses of 0.3/0.5mm from 3 different dental CAD/CAM materials: IPS Empress CAD, IPS e.max CAD and Lava Ultimate CAD/CAM. Teeth were etched with 37% phosphoric acid, and occlusal veneers were bonded using an adhesive luting system (Syntac Primer, Adhesive, Heliobond and Variolink II). Specimens were placed under cyclic mechanical loading in a chewing simulator (1 million cycles at 50N) and were examined for cracks after each cyclic loading sequence. The anatomical 0.3/0.5mm IPS e.max CAD specimens experienced an additional 1 million cycles at 100N. Kaplan–Meier survival curves and log-rank tests were used for data analysis. ResultsAll highly standardized and 0.3/0.5mm IPS e.max CAD specimens tolerated cyclic loading. One anatomical Lava Ultimate CAD/CAM and 10 IPS Empress CAD specimens showed cracks. SignificanceUltrathin occlusal veneers of lithium disilicate ceramic and nanoceramic composite showed remarkably high fracture strength under cyclic mechanical loading. These veneers might be a tooth substance preserving option for restoring combined dentin–enamel defects.

Remineralization of Artificial Dentin Caries Using Dentin and Enamel Matrix Proteins.

To assess the remineralizing potential of dentin matrix proteins and enamel matrix derivatives (DMPs and EMDs) after application on artificially induced dentin lesions, given the hypothesis that these materials increase the mineral uptake, binding, and mineralization. Forty-eight caries-free human premolars were used. Teeth were cut, polished, and embedded, leaving an open window on the root surface, of which one-third was covered with a flowable composite to preserve the healthy untreated dentin. Then, samples were demineralized in Buskes solution for 33 days. A micro-CT scan prior to treatment was performed. Next, the samples were randomly allocated into four groups: (A) An untreated negative control (CON), (B) application of porcine dentin matrix proteins (DMP), (C) treatment with enamel matrix derivatives (EMD, Emdogain, Straumann), and (D) amine fluoride application (AMF, Elmex fluid, GABA). All samples were placed in artificial saliva for 21 days. A second micro-CT scan was performed, after which the change in gray scaling within a defined region of interest (0.25 mm3) was analyzed. ANCOVA was applied to discover statistical differences between the different treatments. Both, treatment with AMF; (P = 0.011 versus CON) as well as with DMP (P = 0.043 versus CON) yielded a statistically significant difference compared to the control treatment. EMD treatment was not found to differ (P > 0.05). Mainly the top layer of the defects showed clear signs of remineralization, which was also evident in CON. This study was able to visually confirm the remineralization potential of demineralized dentin especially after DMP application, which, however, did not outperform AMF. Based on this, additional studies combining proteins and fluorides are now warranted and ongoing.

Hyperspectral imaging system associated with novel subtracting image processing algorithm for dental caries early detection

Early detection of caries is vital for demineralization reverse offering a less pain, as well as accurate and precise caries removal. In this study, the difference in optical properties of normal tissue and human caries lesion has been used for early diagnosis, using laser induced fluorescence spectroscopy. The human tooth sample was illuminated with visible band sources (488, 514 and 633 nm) with power 5 mW. The reflected and emitted light of tested sample was collected using hyperspectral camera in an attempt to generate multispectral images (cubic image). The variation of reflected and emitted power as function in wavelength was employed to generate characteristic spectrum of each tooth tissue. Human teeth caries tissue lesion releases its excess power by emitting fluorescence light producing chemical footprint signature; this signature is dependent on the elemental composition of tooth elements and caries state. This non-invasive, non-contact and non-ionizing imaging system with associated novel pattern recognition algorithm was employed to diagnose and classify dental (enamel and dentin), caries, and white spot lesion. It was reported that the perceived fluorescence emission is function of the illuminating wavelength. While enamel and dentin caries were distinguished and characterized at 633 nm illuminating wavelength; white spot lesion cannot be detected. The enamel caries, dentin caries, and white spot lesion were contoured and recognized at 488 nm and 514 nm wavelengths. Therefore full recognition was achieved through generated cubic image after sample irradiation at 488 nm and 514 nm. This non-invasive, non-contact, and non-ionizing imaging technique with customized image processing algorithm offered high sensitivity, high resolution, and early caries detection with optimum performance at 514 nm.

Synchrotron X-ray fluorescence mapping of Ca, Sr and Zn at the neonatal line in human deciduous teeth reflects changing perinatal physiology

ObjectivesOur first objective was to review the evidence describing the appearance and microstructure of the neonatal line in human deciduous teeth and to link this with known changes in neonatal physiology occurring at and around birth. A second objective was to explore ways to improve identification of the neonatal line by mapping the pre- and postnatal distribution of Ca, Sr and Zn in deciduous cuspal enamel and superimposing these maps onto transmitted light micrographs that included a clear true section of the neonatal line. Materials and methodsWe used synchrotron X-ray fluorescence to map elemental distributions in pre- and postnatal enamel and dentine. Two deciduous canines and 5 deciduous molars were scanned with an X-ray beam monochromatised to 17.0 keV at either 10.0, 2.5 or 1.0 μm resolution and 10 ms integration time. ResultsCalcium maps distinguished enamel and dentine but did not clearly demarcate tissues formed pre- or postnatally. Strontium maps reflected presumed pre- and postnatal maternal serum levels and what are likely to be diet-dependent regions of Sr enrichment or depletion. Prenatal Zn maps, particularly for dentine, mirror elevated levels in the fetus and in colostrum during the first few days of life. ConclusionsThe neonatal line, enamel dentine junction and surface enamel were all Zn-rich. Within the neonatal line Zn may be associated with increased crystallinity but also with caries resistance, both of which have been reported previously. Elemental mapping may improve the identification of ambiguous NNLs and so be useful in forensic and archaeological studies.

Variation of 3D outer and inner crown morphology in modern human mandibular premolars.

ObjectivesThis study explores the outer and inner crown of lower third and fourth premolars (P3, P4) by analyzing the morphological variation among diverse modern human groups.Materials and MethodsWe studied three‐dimensional models of the outer enamel surface and the enamel–dentine junction (EDJ) from μCT datasets of 77 recent humans using both an assessment of seven nonmetric traits and a standard geometric morphometric (GM) analysis. For the latter, the dental crown was represented by four landmarks (dentine horns and fossae), 20 semilandmarks along the EDJ marginal ridge, and pseudolandmarks along the crown and cervical outlines.ResultsCertain discrete traits showed significantly different regional frequencies and sexual dimorphism. The GM analyses of both P3s and P4s showed extensive overlap in shape variation of the various populations (classification accuracy 15–69%). The first principal components explained about 40% of shape variance with a correlation between 0.59 and 0.87 of the features of P3s and P4s. Shape covariation between P3s and P4s expressed concordance of high and narrow or low and broad crowns.ConclusionsDue to marked intragroup and intergroup variation in GM analyses of lower premolars, discrete traits such as the number of lingual cusps and mesiolingual groove expression provide better geographic separation of modern human populations. The greater variability of the lingual region suggests a dominance of functional constraints over geographic provenience or sex. Additional information about functionally relevant aspects of the crown surface and odontogenetic data are needed to unravel the factors underlying dental morphology in modern humans.

The Treatment of a Dental Morphological Anomaly Type Dens in Dente A challenge

Dens in dente or the amelo-dentinal invagination is met rarely and involves, almost in exclusivity, the upper lateral incisisors, usually unilateral, being an invagination in glove finger of the enamel in dentine, on the level of a tooth often dismorphic. The radiologic aspect is of candle flame, occupying the central part of an upper lateral incisor.

Comparação da resistência de união ao cisalhamento de dois diferentes sistemas adesivos: estudo in vitro

Objetivos: O presente estudo buscou avaliar a resistência de união ao cisalhamento de dois sistemas adesivos aplicados em diferentes quantidades de camadas em amostras de esmalte e dentina bovina. Métodos: Os fatores estudados foram os sistemas adesivos em dois níveis: Single Bond Universal e Single Bond 2. As amostras experimentais foram compostas por 30 fragmentos de esmalte bovino (n=5) e 30 fragmentos de dentina bovina (n=5) divididos aleatoriamente em 2 grupos experimentais de esmalte e dois grupos de dentina, sendo esses subdivididos em 3 modos de aplicação do sistema adesivo em 1, 2 ou 3 camadas. Resultados: Os adesivos Single Bond 2 e Single Bond Universal, quando aplicados em 1 ou 3 camadas em dentina ou esmalte apresentaram similaridade estatística (p= 0,8726). Já quando comparamos o sistema adesivo Single Bond 2 e Single Bond Universal em substrato dentinário a aplicação de 2 camadas do sistema adesivo implicam em aumento da resistência adesiva estatisticamente significante (p=0,000) para o grupo Single Bond Universal aplicado em dentina. Conclusão: O adesivo Single Bond Universal apresentou melhor resistência adesiva que o adesivo Single Bond 2 quando aplicados em duas camadas em substrato dentina. Para o substrato esmalte, ambos os sistemas adesivos são efetivos independente do número de camadas aplicadas.

Efficacy of diffeomorphic surface matching and 3D geometric morphometrics for taxonomic discrimination of Early Pleistocene hominin mandibular molars

Morphometric assessments of the dentition have played significant roles in hypotheses relating to taxonomic diversity among extinct hominins. In this regard, emphasis has been placed on the statistical appraisal of intraspecific variation to identify morphological criteria that convey maximum discriminatory power. Three-dimensional geometric morphometric (3D GM) approaches that utilize landmarks and semi-landmarks to quantify shape variation have enjoyed increasingly popular use over the past twenty-five years in assessments of the outer enamel surface (OES) and enamel–dentine junction (EDJ) of fossil molars. Recently developed diffeomorphic surface matching (DSM) methods that model the deformation between shapes have drastically reduced if not altogether eliminated potential methodological inconsistencies associated with the a priori identification of landmarks and delineation of semi-landmarks. As such, DSM has the potential to better capture the geometric details that describe tooth shape by accounting for both homologous and non-homologous (i.e., discrete) features, and permitting the statistical determination of geometric correspondence. We compare the discriminatory power of 3D GM and DSM in the evaluation of the OES and EDJ of mandibular permanent molars attributed to Australopithecus africanus, Paranthropus robustus and early Homo sp. from the sites of Sterkfontein and Swartkrans. For all three molars, classification and clustering scores demonstrate that DSM performs better at separating the A. africanus and P. robustus samples than does 3D GM. The EDJ provided the best results. P. robustus evinces greater morphological variability than A. africanus. The DSM assessment of the early Homo molar from Swartkrans reveals its distinctiveness from either australopith sample, and the “unknown” specimen from Sterkfontein (Stw 151) is notably more similar to Homo than to A. africanus.

Bending Fibers of Hydroxyapatite for Ordered Parallel Architecture in Bovine Tooth Enamel

The nanometer-scale bending structure in the enamel–dentin interfacial region of bovine teeth was clarified using detailed electron micrographs. We found that enamel prisms of width ∼5–10 μm in the enamel are regarded as a bundle of nanometer-scale hydroxyapatite (HA) fibers of width ∼20–30 nm that are connected to the enamel–dentin interface. The radial arrangements of HA fibers elongated in the c-axis were formed on the dentin surface at the boundary. The orientation adjustment of the HA fibers was observed through stepwise bending with a gradual change of the c direction in the ordered parallel array of the enamel prisms. Our observation suggests that the crystallographic ordering in the enamel layer originates from the growth-induced orientation of HA crystals in the interfacial region.

Classification of dental diseases using hyperspectral imaging and laser induced fluorescence.

Early diagnosis of tooth enamel demineralization, and dentin caries lesions, present a valuable solution to avoid or decrease their deleterious effect. The aim of this study was to design a simple, effective, and non-invasive technique, employing a novel laser wavelength to classify and differentiate between various tooth abnormalities in-vitro, by estimating wavelengths, showing distinctive appearance for each tooth class. This study implies a fluorescence hyperspectral imaging system employing a 395-nm laser diode source, irradiating a pre-diagnosed 12 molars and premolars teeth. The obtained reconstructed images were displayed and processed by HSAnalysis2XL, accompanied by a custom made digital, and image signal processing algorithms, revealing the exact wavelengths, characterizing the fluorescence of each tooth pre-diagnosed class. The proposed hyperspectral imaging system was able to discriminate between normal, and abnormal dental classes for the entire specimens. Furthermore, a series of wavelengths, noting each lesion individually were obtained from the spectroscopic hyperspectral output. The root calculus, white spot, dentin caries, and enamel caries have a bright visual appearance at λ3 = 702 nm, λ5 = 771 nm, and λ6 = 798 nm respectively. Consequently, these abnormalities exhibit a dark appearance at λ1 = 421 nm, λ2 = 462 nm, and λ4 = 734 nm. The wavelength selections were confirmed by the grayscale image outcomes. This study provides a set of wavelengths that can be employed by dentists to diagnose white spot, root calculus, and enamel dentin caries lesions under the irradiation of a new UV-vis laser illumination source without, any hazardous thermal or mechanical effects.