Cementum Research Articles

Evaluation of Diagnostic Efficacy of Digital Subtraction Radiography in the Diagnosis of Simulated External Root Resorption: An <i>in Vitro</i> Study

External root resorption can induce the degeneration of dental cementum and dentine and may extend towards the pulp reductive. Digital subtraction radiography can function as a useful tool in diagnosing degenerative carious lesions. This study investigated the diagnostic value of digital subtraction radiography in detecting external root resorption. This was a descriptive study conducted using the lab trial method. Artificially-induced external root resorption was created in different sizes at the coronal and apical aspects of 20 premolar teeth. Digital radiographs were obtained of each tooth under standard conditions and these radiographs were subtracted by imaging devices. The subtracted images and the digital radiographs were observed by three radiologists. Chi-square, Kappa test, and Z-test were used to analyze the data. The mean of general sensitivity of digital subtraction radiography and direct digital radiography was low in diagnosing 0.05 mm lesions (Sen = 35%), yet, the accuracy index was good for all lesions (Acc ≥ 65%). Other diagnostic parameters were also acceptable. Both types of radiography worked better in diagnosing coronal than apical lesions (P > 0.05). The interpreters (observers) showed a better performance in diagnosing external root resorption using digital subtraction radiography compared to digital radiography. Both modalities were exact and accurate in detecting 0.05 mm lesions as well as other lesions. However, the results of digital subtraction radiography were not significantly different from those of direct digital radiography.

Reindeer during the Upper Palaeolithic in Poland: Aspects of variability and paleoecology

This paper presents the results of morphometric, isotopic, and dental cementum analysis of reindeer remains from Upper Palaeolithic cave deposits in Poland. Morphometric analyses indicate the variability of population. Most of the antlers belonged to females and represented a tundra form of reindeer. Analysis of dentition also indicated adaptation to life in tundra. Dental cementum analysis of reindeer teeth from Biśnik Cave showed that death of all studied specimens occurred during cold periods. Results of stable isotopes analysis of reindeer teeth from Biśnik Cave revealed that the δ18OC values were more related to the anatomical position of the tooth than to geochronological period. Isotopic differences between tooth types indicate the importance of weaning and weather in particular seasons when tooth enamel was formed. Teeth exhibit no significant change in δ13CC values between reindeer from MIS 2 and MIS 3.

Time to shift: from scaling and root planing to root surface debridement.

Non-surgical periodontal treatment has traditionally been based on the notion that bacterial plaque (dental biofilm) penetrates and infects dental cementum. Removal of this infected cementum via scaling and root planing (SRP) was considered essential for re-establishing periodontal health. In the 1980s the concept of SRP was questioned because several in vitro studies showed that the biofilm was superficially located on the root surface and its disruption and removal could be relatively easily achieved by ultrasonic instrumentation of the root surface (known as root surface debridement (RSD). Subsequent in vivo studies corroborated the in vitro findings. There is now sufficient clinical evidence to substantiate the concept that the deliberate removal of cementum by SRP is no longer warranted or justified, and that the more gentle and conservative approach of RSD should be implemented in daily periodontal practice.

Impact of HMME-PDT on Pg of the surface of implants and cementum tablets

Objective To evaluate the bactericidal effect of diode laser on Porphyromonas gingivalis (Pg),and to explore an optimized protocol for a safe dose of photodynamic therapy (PDT) to eliminate periodontal pathogens as well as the impact on the implant surfaces,so as to provide theoretical and experimental basis for PDT in periimplantitis therapy.Methods Artificial in vitro models were formatted by culturing Pg standard strain and ITI (International Team for Implantology) implants together in CDC broth.Then artificial in vitro models were treated by different doses of hematoporphyrin monomethyl ether (HMME) and different energy density of laser (EDL) for 60 s.The cultures were counted by colony form unit (CFU),and SPSS 17.0 statistical software was used for data statistical analysis to select the best EDL and HMME dose.Finally,ITI implants were observed by scanning electron microscope (SEM) to evaluate the impact of HMME-PDT on Pg of implant surfaces.Results When EDL was 12 J/cm2 and mass concentration of HMME was 25 μg/ml,SEM observations showed that PDT could effectively kill Pg ((13.00±5.00) CFU)without damaging the implant surfaces.Conclusions PDT therapy combining 630 nm diode laser with photosensitizer HMME have good bactericidal effect on Pg,and the EDL and HMME dose is as small as the clinical applicable safe dose. Key words: Photodynamic therapy; Diode laser; , Hematoporphyrin monomethyl ether; Porphyromonas gingivalis; Peri-implantitis

Regenerative periodontal therapy.

The goal of regenerative periodontal therapy is to completely restore the tooth's supporting apparatus that has been lost due to inflammatory periodontal disease or injury. It is characterized by formation of new cementum with inserting collagen fibers, new periodontal ligament, and new alveolar bone. Indeed conventional, nonsurgical, and surgical periodontal therapy usually result in clinical improvements evidenced by probing depth reduction and clinical attachment gain, but the healing occurs predominantly through formation of a long junctional epithelium and no or only unpredictable periodontal regeneration. Therefore, there is an ongoing search for new materials and improved surgical techniques, with the aim of predictably promoting periodontal wound healing/regeneration and improving the clinical outcome. This article attempts to provide the clinician with an overview of the most important biologic events involved in periodontal wound healing/ regeneration and on the criteria on how to select the appropriate regenerative material and surgical technique in order to optimize the clinical outcomes.

Periodontal tissue in a bio-implant by periodontal ligament cells sheet and bone marrow stromal cells sheet

To fabricate the bio-implant supported by regenerated periodontal tissue utilizing periodontal ligament cells (PDLC)-bone marrow stromal cells (BMSC) sheet and natural root. Premolars of 2 beagle dogs were extracted to prepare the implanted area. Autologous tooth roots were carved into cylinders. PDLC and BMSC separated from beagle dogs were cultured into cell sheets in medium. Tooth roots were wrapped by one type of cell sheets or both to fabricate bio-implant and divided into four groups, tooth roots were wrapped by PDLC sheets and BMSC sheets successively (2 samples each dog), tooth roots were wrapped by PDLC sheets alone (2 samples each dog), tooth roots were wrapped by BMSC sheet alone (2 samples each dog), tooth roots without cell sheet (1 sample each dog). The implants were implanted into the mandibles. The mandibles were dissected 12 weeks later, sliced and stained by HE and Masson dyes for histological examination. In the PDLC cell sheet/root implants, histological examination revealed that new periodontal-like tissue including cementum, periodontium and alveolar bone was regenerated.In the BMSC implants, tooth ankylosis was observed. PDLC sheet and natural root can be used to fabricate bio-implant. PDLC sheet could promote periodontal regeneration.

Role of DNA in Forensic Identification

Forensic identification of dead and decayed had always posed a problem, as there is any evidentiary material available for forensic analysis. In such cases DNA analysis plays a role in identification of the victims. DNA plays a significant role at various points through the criminal case from the initiation of any investigation till the confirmation of a death. DNA is available in two forms namely the chromosomal DNA present in the nucleus and mitochondrial DNA present in the cytoplasm of a cell. DNA is available from numerous sources in a human body. However, when there is complete decomposition of the body, DNA from dental tissues helps in revealing the identity. DNA from dental tissues can be extracted from dental pulp, cementum and dentin. DNA analysis also forms a prime role in Bite mark analysis when traces of saliva are left behind as DNA is rich in saliva and it helps in identification. This review serves as a primer on the basics of DNA, its application in dentistry and the methods of extraction.

Stress analysis of two methods of ceramic inlay preparation by finite element

Ceramic inlays are bonded to tooth structure with resin cements. During the resin cement setting, shrinkage stress develops at the interfaces. During tooth preparation, the undercut areas formed due to the different patterns of caries progression can either be blocked out before taking impression with suitable cement such as glass ionomer cement, or before making the final restoration in the laboratory. Then, the relieved space will be filled with luting cement in clinic. The aim of this study was to compare these two methods of undercut filling in term of stress distribution in the ceramic inlay. An axisymmetric finite element analysis was performed to study the stress distribution during inlay cementing. The solid model was generated from a longitudinal section of maxillary premolar in which a class I cavity with 60 degree undercut at the preparation wall and 20 degree divergence of the vertical walls was prepared. A thermal model was used to simulate the polymerization shrinkage of the resin cement. Finite element analysis was carried out in ANSYS environment. Filling the undercut by glass ionomer cement decreased the stress concentration at the ceramic/cement interface. The dominant normal stress at the tooth cement interface in absence of glass ionomer cement was tensile with maximum of 30 Mpa. Using glass ionomer, cement developed stresses with different compressive and tensile signs. With increasing the thickness of resin cement (100 µm, 150 µm, 200 µm), the stress increased. Cements with minimum shrinkage and as thin layer as possible should be used. Filling the undercut with glass ionomer cement decreases the stress. Other experimental and clinical studies must follow this research.

Paleoecology of bears from MIS 8–MIS 3 deposits of Biśnik Cave based on stable isotopes (δ13C, δ18O) and dental cementum analyses

The deposits of Biśnik Cave yielded numerous bear remains from sediments dated to the MIS 8–MIS 3 interval. This situation allowed examination of the paleoecology of Ursus spelaeus over time, compared with two other species of bears: Ursus deningeri and Ursus arctos, also present in fossil material from Biśnik Cave. The stable isotope ratios (δ13C, δ18O) in tooth enamel were applied in combination with examination of seasonal deposition of dental cementum. The δ13C values showed the diet of each bear species stayed in the range of C3 plants. Results for U. spelaeus showed a wider range of δ13C values than for U. deningeri or U. arctos. The values are relatively negative in comparison to fossil bears from other European sites. Low δ13C values observed in bears from Biśnik Cave could be linked to a canopy effect and document a forested environment for these bears. No correlation between δ18O and δ13C values was noted. The cementum analysis revealed that season of death of all species was winter and all studied specimens died during hibernation. The highest mortality concerned mostly individuals below 4 years old and the highest individual aged was U. deningeri.

Estimación de edades mediante análisis dentales en individuos de Tayassu pecari y Pecari tajacu (Artiodactyla: Tayassuidae)

Age in mammals is usually estimated using weight and morphometric measurements of anatomical structures of growth, as well as by tooth wear. Another tooth analysis method is counting the growth layers of the root's dental cementum that alternates in light and dark bands corresponding to seasonal changes. This study estimates the ages and correlation level between the tooth wear and counting growth layers methods from a sample of 106 individuals of Tayassu pecari and 29 of Pecari tajacu from the subsistence hunting activities in the Takana indigenous communal lands “Tierra Comunitaria de Origen Takana-I” northern La Paz Department, Bolivia. The tooth wear method classified premolars and molars into seven age classes according to a previously designed peccary tooth wear key. A histological technique was also applied to count of growth layers in incisors. The tooth wear method estimated ages from 1 to 12 years old, although 12% of the samples had contradictions caused by a variation among individuals of the third molar eruption. The counting growth layer method was successfully applied to 80% of the sample, with estimated ages from 1 to 18 years old, however it was more difficult to differentiate between adjacent growth layers for older individuals. These 2 methods were significantly correlated for T. pecari (r=0.87; p<0.05) and P. tajacu (r=0.86; p<0.05), and presented very similar estimates for individuals estimated to be between 2 to 10 years in T. pecari and 1 to 4 years in P. tajacu.

Variabilité intra-individuelle de l’estimation de l’âge au décès adulte à partir des anneaux du cément dentaire

The reliability of adult age-at-death estimates based on counting the incremental lines in dental cementum is uncertain because their accuracy and precision vary from one study to another. Moreover, no previous study has addressed intra-individual variability in counts of incremental lines in cementum. We quantified this variability from a sample of 51 clinically extracted teeth of 15 individuals. Incremental lines were counted on five cross sections from the median third of each tooth root. Two age estimates were calculated per tooth, taking into account (1) the maximum number of lines counted and (2) the average value of counts. Our results show that a) age estimates based on the incisor are more accurate than those based on the canine or premolar; b) age estimates based on maximum counts are more accurate than those based on average counts; c) age estimates based on mandibular incisors are more accurate than those based on maxillary incisors. Substantial variability was observed in the number of increment lines on the same tooth. For an individual, the estimated age at death between two teeth can differ by 26 years, which produces a bias in age estimations from this parameter.

Proteomic analysis of human dental cementum and alveolar bone.

Periodontal disease is a highly prevalent disease affecting the world population, which involves breakdown of the tooth supporting tissues, the periodontal ligament, alveolar bone, and dental cementum. The lack of knowledge on specific factors that differentiate alveolar bone and dental cementum limits the development of more efficient and predictable reconstructive therapies. In order to better understand cementum development and potentially identify factors to improve therapeutic outcomes, we took the unique approach of using matched patient samples of dental cementum and alveolar bone to generate and compare a proteome list for each tissue. A potential biomarker for dental cementum was identified, superoxide dismutase 3 (SOD3), which is found in cementum and cementum-associated cells in mouse, pig, and human tissues. These findings may provide novel insights into developmental differences between alveolar bone and dental cementum, and represent the basis for improved and more predictable therapies.

Marginal leakage of amalgam and modern composite materials related to restorative techniques in class II cavity (Comparative study)

Restoration of the gingival margin of Class II cavities with composite resin continues to be problematic, especially where no enamel exists for bonding to the gingival margin. The aim of study is to evaluate the marginal leakage at enamel and cementum margin of class II MOD cavities using amalgam restoration and modern composite restorations Filtek™ P90, Filtek™ Z250 XT (Nano Hybrid Universal Restorative) and SDR bulk fill with different restoratives techniques. Materials and method: Eighty sound maxillary first premolar teeth were collected and divided into two main groups, enamel group and cementum group (40 teeth) for each group. The enamel group was prepared with standardized Class II MOD cavity with gingival margin (1 mm above C.E.J) on both box sides. While the cementum group with the gingival margin (1 mm below C.E.J) on both sides. The enamel and cementum groups were then subdivided into eight subgroups for each (five teeth) with 10 boxes for each group. Subgroups within the main group named according to materials and techniques that were used with it as following: Amalgam subgroup (Permite, SDI), SDR subgroup (DENTSPLY) with bulk technique, Filtek™ P90 subgroup (3M ESPE) with three incremental techniques (Oblique, Horizontal and Centripetal technique), and Filtek™ Z250XT subgroup (3M ESPE) with three incremental techniques (Oblique, Horizontal and Centripetal technique).After specimens were stored in distilled water at 37°C for 7 days. All specimens were subjected to thermocycling at (5° to 55 °C). Microleakage was evaluated by stereomicroscope (20 X). Data were analyzed statistically by Kruskal-Wallis test and Mann-Whitney U-test. Result: All experimental groups showed leakage at cementum more than enamel groups. SDR bulk fill subgroup showed the highest marginal leakage among all experimental groups followed by Filtek™ Z250 XT subgroup with horizontal technique at both enamel and cementum groups. Silorane and Filtek™ Z250 XT subgroups with oblique technique showed the least marginal leakage followed by centripetal technique at both enamel and cementum groups. Amalgam restoration subgroup shows lesser leakage than SDR bulk fills subgroup significantly at both enamel and cementum groups. While it show higher leakage than Silorane subgroup with oblique technique significantly at enamel margin only. Conclusion: The limiting factors for marginal leakage are technique and material dependent.

Luting of ceramic crowns with a self-adhesive cement: Effect of contamination on marginal adaptation and fracture strength

Objectives: This study evaluated the percentages of continuous margins (%CM) and fracture strength (FS) of crowns made out from blocs of leucite-reinforced ceramic (IPS Empress CAD) and luted with a representative self-adhesive cement (RelyX Unicem) under four contaminating agents: saliva, water, blood, a haemostatic solution containing aluminium chloride (pH= 0.8) and a control group with no contamination. Study Design: %CM at both tooth-cement (TC) and cement-crown (CC) interfaces were determined before and after a fatigue test consisting of 600’000 chewing loads and 1’500 temperature cycles changing from 5º C to 50º C. Load to fracture was recorded on fatigued specimens. Kruskal-Wallis test was used to compare %CM and FS between the five groups with a level of confidence of 95%. Results: At the TC interface, no significant differences in marginal adaptation before loading could be detected between groups. After loading, a significant marginal degradation was observed in the group contaminated with aluminium chloride (52 ± 22 %CM) in respect to the other groups. No significant differences in %CM could be detected between the groups contaminated with saliva, water, blood and the control. At the CC interface, no significant differences in marginal adaptation were observed between the groups. The FS on loaded specimens was around 1637N, with no significant differences between groups as well. Conclusions: An adverse interaction of the highly acidic haemostatic agent with either dentin or the self-adhesive cement could explain the specimens’ marginal degradation. The self-adhesive cement tested in this study was no sensitive to moisture contamination either with saliva, water or blood. Key words:Marginal adaptation, RelyX Unicem, contamination, all-ceramic crowns.

Treatment modalities and evaluation models for periodontitis

Periodontitis is the most common localized dental inflammatory disease related with several pathological conditions like inflammation of gums (gingivitis), degeneration of periodontal ligament, dental cementum and alveolar bone loss. In this perspective, the various preventive and treatment modalities, including oral hygiene, gingival irrigations, mechanical instrumentation, full mouth disinfection, host modulation and antimicrobial therapy, which are used either as adjunctive treatments or as stand-alone therapies in the non-surgical management of periodontal infections, have been discussed. Intra-pocket, sustained release systems have emerged as a novel paradigm for the future research. In this article, special consideration is given to different locally delivered anti-microbial and anti inflammatory medications which are either commercially available or are currently under consideration for Food and Drug Administration (FDA) approval. The various in vitro dissolution models and microbiological strain investigated to impersonate the infected and inflamed periodontal cavity and to predict the in vivo performance of treatment modalities have also been thrashed out. Animal models that have been employed to explore the pathology at the different stages of periodontitis and to evaluate its treatment modalities are enlightened in this proposed review.

Cemental tear: a case report with nonsurgical periodontal therapy

PURPOSE: To report a case of cemental tear, a rare periodontal condition characterized by total or partial separation of the dental cementum, mainly addressing issues related to its diagnosis and treatment. CASE DESCRIPTION: A 50 years-old man sought dental assistance complaining of pain located in the mandibular left second premolar that showed a 4 mm probing depth with the presence of a foreign body in the distal gingival sulcus. Radiographic examination demonstrated a slight radiopaque fragment detached from the root. The fragment was removed without a periodontal flap. Histopathological examination was performed and evidenced the presence of a cementum fragment with cementum lamellae, cementocytes, and adhered periodontal ligament fibers, confirming the diagnosis of cemental tear. CONCLUSION: After a follow-up of 2 years, the nonsurgical periodontal therapy showed satisfactory clinical and radiographic outcome. Therefore, this approach should be a suitable and predictable treatment modality for the cemental tear.

An In Vitro Evaluation of the Microleakage under Complete Metal Crowns Using Three Adhesive Luting Cements

Despite the material advancements and precise laboratory techniques, cement lines are inevitable in fixed prosthodontics which leads to increased dependence on the integrity of the cement to maintain the marginal seal. The material class of luting agent is known to influence microleakage. Studies of cement dissolution and disintegration have produced varying results. Hence, this study was done to evaluate marginal leakage under complete metal crowns using three adhesive cements, two resin cements (one self cure, one dual cure) and a glass ionomer cement. Metal crowns were prepared on sixty intact extracted premolars and were randomly divided into three groups of twenty each, with each group using a different cement for luting. All the samples were then subjected to thermocycling and were sectioned using a diamond saw. Reflected Binocular Stereomicroscope at 100× magnification was used to study the extent of microleakage at both metal cement (MC) and tooth cement (TC) interface, at two opposite margins of each sectioned specimen. Data was analyzed with a one way analysis of variance. For comparison among the groups multiple comparison Bonferroni test was done. Within group data was analysed with independent student t test. Between three groups, metal crowns cemented with multilink cement showed significantly less microleakage at both the interfaces. Glass ionomer cement recorded maximum combined microleakage amongst three cements irrespective of the interfaces. Within group, glass ionomer and multilink cement showed more microleakage at MC interfaces than at TC interface. A complex interaction between variables related to dental restoration, luting agent and tooth structure probably influence microleakage. In vitro studies must always be followed by in vivo studies before definite conclusion can be drawn.

Using gazelle dental cementum studies to explore seasonality and mobility patterns of the Early-Middle Epipalaeolithic Azraq Basin, Jordan

Determining the origins of sedentism is integral in understanding the origins of complex societies. There is great interest in Early-Middle Epipalaeolithic mobility patterns in the Near East to understand why permanent settlement occurred in the Natufian. Current theories relating to the Early-Middle Epipalaeolithic ‘Mega Sites’ of Kharaneh IV and Wadi Jilat 6 suggest that these sites may have been occupied for prolonged periods of time. A sample of gazelle teeth from Kharaneh IV and Wadi Jilat 6 were studied using cementum analysis to determine the season of death of the animals providing an insight into when these sites were occupied. Cementum analysis could be successfully applied in the region, and initial results demonstrated that gazelle were culled in two different seasons. Future work sampling mandibles from discrete temporal deposits and increasing the sample size, supplemented by using additional seasonality indicators would be beneficial in exploring further seasonality and mobility in the Azraq Basin.

Age diagnosis based on incremental lines in dental cementum: A critical reflection

Age estimation based on the counting of incremental lines in dental cementum is a method frequently used for the estimation of the age at death for humans in bioarchaeology, and increasingly, forensic anthropology. Assessment of applicability, precision, and method reproducibility continue to be the focus of research in this area, and are occasionally accompanied by significant controversy. Differences in methodological techniques for data collection (e.g. number of sections, factor of magnification for counting or interpreting "outliers") are presented. Potential influences on method reliability are discussed, especially for their applicability in forensic contexts.

Influence of bone quality on the stress distribution for three-posterior immediately loaded implants: a three-dimensional finite element analysis

To assess and compare the peri-implant stress distribution of three posterior implants under immediate loading with 4 different bone qualities using three dimensional (3D) finite element (FE) analysis. A 3D finite element model representing three implants in a portion of mandible at the 654 region was developed, and three implants received a crown each. Four types of bone qualities (B1, B2, B3 and B4) were designed for the model. Load of 100 N was applied on the occlusal surfaces of the crowns at a 45° angle to the vertical axis of the implants. Von Mises stresses in the peri-implant bone of 4 in bone quality from B1 to B4 were (13.17 ± 9.32), (12.95 ± 9.14), (15.00 ± 9.44), and (16.81 ± 10.74) MPa, and those of 5 were (15.51 ± 10.32), (14.73 ± 8.96), (16.79 ± 8.40), and (18.34 ± 8.45) MPa. Stress in bone quality B4 showed the highest value, followed by B3 bone, the lowest stress were found in B1 and B2 bone. It was significantly different (P < 0.05). However, von Mises stresses in different quality of bone around 6 [(42.45 ± 25.71), (41.66 ± 25.29), (42.70 ± 23.24), (42.06 ± 23.66) MPa] were close to each other, and were as twice or three times as those of 4 and 5, irrespective of different bone qualities. The stress distribution around implant under immediate loading was not only affected by different bone qualities, but also by the direction of loading, and the latter may have a greater impact when a severe load delivered.