Microleakage assessment of CAD-CAM Cobalt-Chrome and Zirconia abutments on a conical connection dental implant: A comparative in vitro study.

OBJECTIVE: To assess the marginal and bacterial microleakage in zirconia and CAD-CAM or cast Co-Cr implant abutments. METHODS: Sixty-four conical connection implants with their respective abutments were divided into four groups (Co-Cr (milled, laser-sintered, and cast) and Zirconia (milled)). All specimens were subjected to a chewing simulation and thermocycling. After aging process, specimens were submerged in a 0.2% methylene blue solution with Porphyromonas gingivalis (P.g) for 48 h. The marginal microleakage was measured using a 40× optical microscopy at the internal part of the implant, and when positive microleakage was observed, a DNA isolation with a polymerase chain reaction (PCR) test was used. The microbiological assessment was based on colony forming units (CFUs). RESULTS: Thirty (47%) implant-abutments presented microleakage and the PCR was performed on those specimens (1 Zirconia, 1 Co-Cr milled, 14 Co-Cr laser-sintered and 14 cast). Seven specimens (1 Co-Cr laser-sintered and six cast) presented values below the PCR detection limit (< 100 CFUs). The lowest CFUs count occurred in the Co-Cr milled group (5.17E+02 CFUs/ml) followed by zirconia (7.70E+03 CFUs/ml). The Co-Cr cast (9.39E+03 CFUs/ml) and laser-sintered (2.4E+05 CFUs/ml) groups had higher bacterial count. The CFU count comparison performed between Co-Cr cast and laser-sintered resulted in a statistically significant differences in favor of Co-CrCL (p < .05). CONCLUSIONS: The abutment material and fabrication technique affected the implant-abutment microleakage. Although the CAD-CAM abutments presented favorable results, all tested groups presented microleakage.

The cumulative effect of error in the digital workflow for complete-arch implant-supported frameworks: An in vitro study.

PURPOSE: To investigate the error accumulation and distribution through various stages of the digital workflow for complete-arch implant-supported framework fabrication. MATERIALS AND METHODS: A resin model of edentulous maxilla with 6 dental implants was scanned using an intraoral scanner for 10 times (Complete-digital group). Ten conventional gypsum casts were made and digitized by a laboratory scanner (Analogue-digital group). Five implant frameworks were designed and milled using CAD-CAM technique for each workflow. Inter-implant distances and angles of the resin model (reference) and frameworks were measured by a coordinate measuring machine, while the scans and virtual frameworks were examined by an inspection software. Effect of type of workflow and the individual stage on the accuracy of the frameworks were analysed by Two-way ANOVA. RESULTS: The expanded uncertainty of both workflows was ~150 µm and ~ 0.8°. The accuracy of the CAD stage was the highest. In the complete-digital workflow, the greatest distortion was found in the data acquisition stage, while in the analogue-digital workflow, it was found in the CAM stage. Compared with the analogue-digital group, the complete-digital group showed a significant higher precision in the first quadrant, but lower trueness in the second quadrant in data acquisition, and a significantly lower precision in the second quadrant at the CAD stage. CONCLUSIONS: Linear distortions of the complete-digital and analogue-digital workflows were clinically acceptable, while angular distortions were not. Distortions were generally derived from data acquisition and CAM stage. The CAD precision depended on the distortions derived from data acquisition. The complete-digital workflow was not as accurate as the analogue-digital in complete-arch implant rehabilitation.

Does the geometry of scan bodies affect the alignment accuracy of computer-aided design in implant digital workflow: An in vitro study?

OBJECTIVES: To compare 2 implant scan bodies with different geometry on the accuracy of the virtual alignment process in the digital workflow. MATERIALS AND METHODS: A master model of the edentulous maxilla with 6 implants and multiunit abutments (MUA) inserted was fabricated. Six dome-shaped and cuboidal scan bodies were mounted on the MUAs, respectively, and consecutively scanned by a laboratory scanner 10 times. The original scans were imported to a dental-specific CAD software and virtually aligned with the default CAD model in the implant library. Thus, 10 aligned models were created. Both the original scans and the aligned models were evaluated by an inspection software for deviation of the scan body surfaces, the centroids of scan body and MUA, the scan body center-axis, and the inter-MUA distances/angles. The two-sample T-test/Mann-Whitney U test were used to analyze the data with the level of significance set at 0.05. RESULTS: The cuboidal group showed significant greater deviations of the model surface (13.9 µm vs. 10.7 µm) and the MUA centroids (31.7 µm vs. 22.8 µm) but smaller deviation of the inter-MUA angle (0.047° vs. 0.070°) than those of the dome-shaped group (p < .05). No significant differences in the deviation of scan body centroids, center-axis, and the inter-MUA distances between the 2 groups were found. CONCLUSIONS: Virtual alignment of implant scan body affected the accuracy of the digital workflow for complete-arch implant-supported prostheses (up to ~30 µm/0.09°). Different geometries of the implant scan body could also influence the transfer accuracy in the CAD process.

PDLCs and EPCs Co-Cultured on Ta Discs: A Golden Fleece for "Compromised" Osseointegration.

Material research in tissue engineering forms a vital link between basic cell research and animal research. Periodontal ligament cells (PDLCs, P) from the tooth have an osteogenic effect, whereas endothelial progenitor cells (EPCs, E) assist in neovascularization. In the present study, the interaction of PDLCs and EPCs with Tantalum (Ta, I) discs, either alone (IP or IE group) or in 1:1 (IPE) ratio was explored. Additionally, surface analysis of Ta discs with respect to different types and cycles of sterilization and disinfection procedures was evaluated. It was observed that Ta discs could be used for a maximum of three times, after which the changes in properties of Ta discs were detrimental to cell growth, irrespective of the type of the protocol. Cell-Disc's analysis revealed that cell proliferation in the IE group at day 6 and day 10 was significantly higher (p < 0.05) than other groups. A cell viability assay revealed increased live cells in the IPE group than in the IP or IE group. Similarly, adhesion and penetration of cells in the IPE group were not only higher, but also had an increased thickness of cellular extensions. RT-PCR analysis revealed that on day 8, both osteogenic (ALP, RUNX-2, and BSP) and angiogenic genes (VEGFR-2, CD31) increased significantly in the IPE group as compared to the IP or IE groups (p < 0.05). In conclusion, Ta discs promoted cellular proliferation and increased osteogenic and angiogenic activity by augmenting RUNX-2 and VEGFR-2 activity.

Current status and research trends of lithium disilicate in dentistry: A bibliometric analysis.

STATEMENT OF PROBLEM: Lithium disilicate (LD) is a popular dental ceramic and has been a focus of dental research. Nevertheless, a quantified literature analysis focusing on the research of lithium disilicate is lacking. PURPOSE: The purpose of this bibliometric analysis was to review the progress of research into lithium disilicate in dentistry, including the identification of contributing researchers, organizations, countries or regions, journals, and the analysis of high-impact keywords and research trending. MATERIAL AND METHODS: The search was carried out within the topic field of the Web of Science (WoS) database, collecting publications related to LD from between 1996 and 2019. Metadata including the titles, abstracts, keywords, authors, affiliations, countries or regions, and references were extracted. Bibliometric indicators in terms of documents, authors, journals, and keywords were analyzed. RESULTS: Between 1996 and 2019, the dental research on LD trended upward. Scholars in the United States, Germany, Switzerland, and Brazil actively participated in the research on LD, and publications from the United States had the most citations. The Journal of Prosthetic Dentistry and Dental Materials were the major contributing journals. High-impact terms could be categorized into types of restorative material, types of prostheses, and properties or techniques of materials. Co-occurrence and relative normalized citation analysis of keywords highlighted several research interests, such as comparison studies between LD and zirconia, computer-aided design and computer-aided manufacturing (CAD-CAM) techniques, and the performance of complete coverage LD restorations. CONCLUSIONS: With the global upsurge in research on lithium disilicate, extensive collaborations and citations have been noted among authors, institutions, and countries or regions. Research hotspots include types of restorative material, types of prostheses, and properties or techniques of materials.

Implant framework misfit: A systematic review on assessment methods and clinical complications.

BACKGROUND: The fit of implant-supported prostheses is of prime importance for the long-term success of implant therapy. PURPOSE: This systematic review aimed to evaluate recent evidence on current techniques for assessing implant-framework misfit, its associated strain/stress, and whether these misfits are related to mechanical, biological, and clinical consequences. MATERIALS AND METHODS: An electronic search for publications from January 2010 to October 2020 was performed using the Pubmed, Embase, Web of Science, and Cochrane Library databases with combined keywords on implant-framework misfit assessments and related clinical complications. Inclusion and exclusion criteria were applied. After full-text analyses, data extraction was implemented on current techniques of misfit assessment and the relationship between the misfit and the induced strain/stress. RESULTS: A total of 3 in vivo and 92 in vitro studies were selected, including 47 studies on quantifying the degree of implant-framework misfit with dimensional techniques, 24 studies measuring misfit-induced strain/stress with modeling techniques, and 24 studies using both methods. The technical details, advantages, and limitations of each technique were illustrated. The correlation between the implant-framework misfit and the induced strain/stress has been revealed in vitro, while that with the biological complications and implant/prostheses failure was weak in clinical studies. CONCLUSIONS: Dimensional and modeling techniques are available to measure the implant-framework misfit. The passivity of implant-supported fixed prostheses appeared related to the induced strain/stress, but not the clinical complications. Further studies combining three-dimensional (3D) assessments using dimensional and modeling techniques was needed.

Impact of hypo-salivation on severe tooth wear: A ten-year cohort of patients received radiotherapy for nasopharyngeal carcinoma.

OBJECTIVES: This study was conducted to examine the tooth wear status of nasopharyngeal-carcinoma (NPC) patients who had received radiotherapy at least 5-year previously, and to investigate the salivary parameters that may be associated with the tooth wear. METHODS: Tooth wear status of NPC survivors were clinically assessed using the Exact Tooth Wear Index. A tooth was graded to have severe wear when more than one-third of its buccal/occlusal/lingual surface had dentine loss. At the subject-level, percentages of anterior/posterior/all teeth with severe wear were calculated. Age, number of teeth, flow-rate/buffering capacity/pH of stimulated whole (SWS) and parotid (SPS) saliva's were collected. Correlation and multiple-linear regression tests were performed at the significance level α = 0.05. RESULT: Sixty-eight participants (mean age of 60.0 ±â€¯8.9), 697 anterior and 686 posterior teeth were examined with a mean of 10-years post-radiotherapy. Severe tooth wear was found in 63 (92.6 percent) participants, 288 anterior and 83 posterior teeth. The mean percentage of anterior/posterior/all teeth with severe wear were 42.3 ±â€¯28.1, 14.5 ±â€¯19.9 and 30.0 ±â€¯21.7. Anterior teeth, particularly the incisal surface of central incisors were most affected. The mean flow-rate of SWS and SPS were 0.1 ±â€¯0.1 ml/min and 0.03 ±â€¯0.07 ml/min respectively. Thirty (44.1 percent) and 48 (70.6 percent) participants were found to have low/no buffering capacity of SWS and SPS respectively. Multiple-regression analyses revealed the SWS flow-rate was associated with the percentage of anterior teeth with severe wear (p=0.03). CONCLUSION: Anterior tooth wear is a significant dental problem among NPC survivors and was associated with hypo-salivation. CLINICAL SIGNIFICANCE: Patients with hypo-salivation should be being monitored for tooth wear particularly on the anterior teeth.

Reproducibility of laboratory scanning of multiple implants in complete edentulous arch: Effect of scan bodies.

OBJECTIVES: To evaluate the reproducibility of complete arch scanning with multiple implant scan bodies using a laboratory scanner. METHODS: A master model of edentulous maxillary arch with 6 implants was fabricated. PEEK scan bodies were inserted into the model and consecutively scanned using a dental laboratory scanner (N = 10, Group C). Another 10 scans were performed with each scan body detached and reinserted into the same site between each scan (Group CR). The last group of scanning was performed with the scan bodies detached and randomly repositioned between each scan (N = 10, Group RR). Virtual models were created and the inter-implant distances and angles were measured using an inspection software. Accuracy of the complete arch scans was calculated and compared using Two-Way ANOVA (⍺ = 0.05). RESULTS: Significant greater distance distortion was found in CR (27.6 ±â€¯18.9 µm) and RR (34.2 ±â€¯25.0 µm). No significant difference in angular distortion was found among 3 groups. The greatest distance distortion was found in the anterior and cross-arch region of the arch. The smallest angular distortion was found in the first scanned sextant, with increasing distortion along the scanning path of the arch. The distance precision was significantly reduced in group CR and RR, while the angular precision was significantly reduced in group RR only. CONCLUSION: Reproducibility of complete arch scanning was significantly affected by repositioning of the scan bodies using a laboratory scanner. Repeated and random repositioning of the scan bodies would decrease the reproducibility of the spatial position and angle of the virtual implant. The distortion appeared to be small and within the clinical tolerance. CLINICAL SIGNIFICANCE: High-precision transfer of the implant information from intra-oral environment to dental laboratory is a prerequisite for the success of implant-supported prosthesis. Although laboratory scanners seem to be accurate, their accuracy is also affected by the precision and attachment procedure of the implant scan bodies and that has always been overlooked.

Correlation of anterior overbite with root position and buccal bone thickness of maxillary anterior teeth: a CBCT study.

PURPOSE: To investigate the correlation of anterior overbite with the sagittal root position (SRP) and buccal bone thickness (BBT) of the maxillary anterior teeth. METHODS: Cone-beam computed tomography (CBCT) data of southern Chinese patients who underwent CBCT examinations between November 2016 and December 2016 were collected. The anterior overbite was the predictor variable while the SRP and the BBT at 4 mm apical to the cementoenamel junction (CEJ-4) and midpoint of the root of the maxillary anterior teeth were set as the primary and secondary outcome variables, respectively. All measurements were done by two calibrated examiners. Correlations between variables were analyzed by the Spearman's correlation coefficient. The significance level was set at P < 0.05. RESULTS: CBCT data of 146 patients (65 men and 81 women) with a mean age of 44.2 ± 13.4 years were analyzed, and of the 876 maxillary anterior teeth evaluated, 9.8% were presented with deep overbites. Most of roots of the anterior teeth (94.9%) were positioned against the buccal cortical plate, of which, in 63.8% of them the apex was not covered by bone along the long axis of the tooth. The mean BBT at CEJ-4 was 0.89 mm at the central incisor, 0.85 mm at the lateral incisor and 0.84 mm at the canine. The overbite was positively correlated with SRP Class I subtypes and the BBT at CEJ-4 (P < 0.05). CONCLUSION: Deep overbite was more frequently accompanied by bone fenestration in the anterior maxillary areas.

Adhesive and oxidative response of stem cell and pre-osteoblasts on titanium and zirconia surfaces in vitro.

AIM: The aim of the present study was to investigate the initial stem cell and pre-osteoblast cell adhesion and oxidative response on zirconia in comparison with titanium. METHODS: Human dental pulp stem cells (DPSC) and murine pre-osteoblasts (MC3T3-E1) cells were cultured on zirconia and titanium surfaces, and at 3-, 12-, and 24-hour intervals, cell viability and morphology were determined with tetrazolium based colorimetric assay, scanning electron microscopy, and immunofluorescence analysis. The in situ reactive oxygen species level of both cells on each material surface was examined after 24-hour culture. RESULTS: Both DPSC and MC3T3-E1 cells revealed comparable morphological features during 24-hour cell adhesion processes, with cells continued expanding of cell size and increasing of cell viability on titanium and zirconia surfaces during 24-hour culture. Zirconia demonstrated relatively higher mean cell viability compared to titanium within 24-hour culture, with significantly higher DPSC viability at 12 hours after seeding (P < 0.05). Relatively higher mean reactive oxygen species levels in both DPSC and MC3T3E1 were found on zirconia surfaces after 24-hour culture compared to titanium. CONCLUSIONS: From the results, zirconia as a potential dental implant substrate demonstrated equivalent or better initial cellular responses compared to titanium.

Mapping intraoral photographs on virtual teeth model.

OBJECTIVES: Tooth shade is crucial to patient satisfaction in aesthetic dentistry. Two-dimensional (2D) clinical photographs have been widely used to record patients' tooth shade for creation of beautiful smile. However, in the digital workflow, 3D virtual teeth models in open file format contain only mesh information with no colour. This paper describes the mapping of colour information from the intraoral photographs onto the virtual teeth model. METHODS: Intraoral photographs of occlusal and buccal views were taken using digital single lens reflex (SLR) camera with macro lens and ring flash. Photographs were calibrated for its colour and white balance. Virtual models were generated by scanning teeth/stone casts using an intraoral/model scanner. Intraoral photographs were mapped onto the virtual model using the image-to-geometry registration method by locating corresponding feature points in the 2D and 3D images. RESULTS: Virtual teeth models of dentate (with and without crowding) and partially dentate patients were mapped with intraoral photographs. The resultant models are open file format and can be viewed and manipulated in dental or generic CAD/CAM software. Moreover, RGB (Red Green Blue) colour information and error of registration can be retrieved. CONCLUSION: Image-to-geometry registration allows mapping of colour information in the 2D intraoral photographs on 3D virtual teeth models. The proposed method is applicable across scanning systems and the coloured model can be generated from stone casts and intraoral photographs. CLINICAL SIGNIFICANCE: Virtual teeth model with colour information facilitates shade matching and creation of beautiful smile.

A clinical technique for virtual articulator mounting with natural head position by using calibrated stereophotogrammetry.

Accurate articulator-mounted casts are essential for occlusion analysis and for fabrication of dental prostheses. Although the axis orbital plane has been commonly used as the reference horizontal plane, some clinicians prefer to register the horizontal plane with a spirit level when the patient is in the natural head position (NHP) to avoid anatomic landmark variations. This article presents a digital workflow for registering the patient's horizontal plane in NHP on a virtual articulator. An orientation reference board is used to calibrate a stereophotogrammetry device and a 3-dimensional facial photograph with the patient in NHP. The horizontal plane can then be automatically registered to the patient's virtual model and aligned to the virtual articulator at the transverse horizontal axis level. This technique showed good repeatability with positional differences of less than 1 degree and 1 mm in 5 repeated measurements in 1 patient.

Accuracy of radiographic measurements for implant planning using cone-beam and helical computer tomography.

AIM: The aim of the present study was to compare the accuracy of radiographic measurements for dental implants planning using cone-beam computed tomography (CBCT) and helical computed tomography (HCT). METHODS: Six pig ribs were wrapped by putty impression material, with radiographic markers placed. Two CBCT and an HCT were taken following the standard protocols. Twenty-five locations were selected, with vertical and horizontal dimensions measured using the default software, as well as on the processed HCT films by a digital caliper. The actual dimensions of the ribs measured by the digital caliper served as the control. Differences between radiographic dimensions and the actual dimensions were tested by two-way analysis of variance. RESULTS: No differences were found between measurements made by CBCT and HCT images using the default software (P > 0.05). However, both measurements were statistically-significantly lower than the control (P < 0.001), and the mean difference was 0.3 mm. Measurements made on HCT films were statistically-significantly greater than the control (P < 0.001), and the mean difference was 0.5 mm. CONCLUSION: The accuracy of CBCT and HCT are similar, and both are reliable tools for implant planning. It is preferable to perform the planning using default software, rather than making direct measurements on films.

A 2-part facebow for CAD-CAM dentistry.

Converting the patient's clinical information into the virtual world is a prerequisite for the computer-aided design and computer-aided manufacturing (CAD-CAM) of dental restorations. This article describes a modified facebow which facilitates the radiation-free registration of the maxillary teeth to a 3-dimensional face image for transfer to a virtual articulator. This facebow can be easily fabricated with minimal materials and adjusted to fit different patients; its error in tooth registration was demonstrated to be less than 1 mm.

Salivary Anionic Changes after Radiotherapy for Nasopharyngeal Carcinoma: A 1-Year Prospective Study.

OBJECTIVES: To investigate the salivary anionic changes of patients with nasopharyngeal carcinoma (NPC) treated by radiotherapy. MATERIAL AND METHODS: Thirty-eight patients with T1-4, N0-2, M0 NPC received conventional radiotherapy. Stimulated whole saliva was collected at baseline and 2, 6 and 12 months after radiotherapy. Salivary anions levels were measured using ion chromatography. RESULTS: A reduction in stimulated saliva flow and salivary pH was accompanied by sustained changes in anionic composition. At 2 months following radiotherapy, there was a significant increase in chloride, sulphate, lactate and formate levels while significant reductions in nitrate and thiocyanate levels were found. No further changes in these anion levels were observed at 6 and 12 months. No significant changes were found in phosphate, acetate, or propionate levels throughout the study period. CONCLUSIONS: Conventional radiotherapy has a significant and prolonged impact on certain anionic species, likely contributing to increased cariogenic properties and reduced antimicrobial capacities of saliva in NPC patients post-radiotherapy.

Comparison of mechanical properties of three machinable ceramics with an experimental fluorophlogopite glass ceramic.

STATEMENT OF PROBLEM: Fluorophlogopite glass ceramic (FGC) is a biocompatible, etchable, and millable ceramic with fluoride releasing property. However, its mechanical properties and reliability compared with other machinable ceramics remain undetermined. PURPOSE: The purpose of this in vitro study was to compare the mechanical properties of 3 commercially available millable ceramic materials, IPS e.max CAD, Vitablocs Mark II, and Vita Enamic, with an experimental FGC. MATERIAL AND METHODS: Each type of ceramic block was sectioned into beams (n=15) of standard dimensions of 2×2×15 mm. Before mechanical testing, specimens of the IPS e.max CAD group were further fired for final crystallization. Flexural strength was determined by the 3-point bend test with a universal loading machine at a cross head speed of 1 mm/min. Hardness was determined with a hardness tester with 5 Vickers hardness indentations (n=5) using a 1.96 N load and a dwell time of 15 seconds. Selected surfaces were examined by scanning electron microscopy and energy-dispersive x-ray spectroscopy. Data were analyzed by the 1-way ANOVA test and Weibull analysis (α=.05). Weibull parameters, including the Weibull modulus (m) as well as the characteristic strength at 63.2% (η) and 10.0% (B10), were obtained. RESULTS: A significant difference in flexural strength (P<.001) was found among groups, with IPS e.max CAD (341.88 ±40.25 MPa)>Vita Enamic (145.95 ±12.65 MPa)>Vitablocs Mark II (106.67 ±18.50 MPa), and FGC (117.61 ±7.62 MPa). The Weibull modulus ranged from 6.93 to 18.34, with FGC showing the highest Weibull modulus among the 4 materials. The Weibull plot revealed that IPS e.max CAD>Vita Enamic>FGC>Vitablocs Mark II for the characteristic strength at both 63.2% (η) and 10.0% (B10). Significant difference in Vickers hardness among groups (P<.001) was found with IPS e.max CAD (731.63 ±30.64 H(V))>Vitablocs Mark II (594.74 ±25.22 H(V))>Vita Enamic (372.29 ±51.23 H(V))>FGC (153.74 ±23.62 H(V)). CONCLUSIONS: The flexural strength and Vickers hardness of IPS e.max CAD were significantly higher than those of the 3 materials tested. The FGC's flexural strength was comparable with Vitablocs Mark II. The FGC's Weibull modulus was the highest, while its Vickers hardness was the lowest among the materials tested.

Proximal contact loss between implant-supported prostheses and adjacent natural teeth: a retrospective study.

OBJECTIVES: To determine the prevalence of proximal contact loss between posterior implant-supported prostheses and the adjacent anterior natural tooth and to identify potential contributing factors. MATERIALS AND METHODS: Forty-five consecutive patients, who had received either implant-supported fixed partial denture (FPD) or implant-supported single crown (SC) in the posterior region and were under regular review, were recruited. Interproximal space was assessed by the number of matrix bands that could be placed, and tooth mobility was assessed by Periotest®. A self-reported questionnaire was administered. Effects of various patient and prosthesis parameters on interproximal space were analyzed by Kruskal-Wallis test or Mann-Whitney U test. Correlations were tested by Spearman's rank correlation coefficient. Differences were considered significant if P < 0.05. RESULTS: Forty-three of 66 (65%) prostheses showed proximal contact loss. Frequent food packing was reported in 40% of the prostheses. The mean interproximal space was 167 (SD = 125) µm, and it was positively correlated with patients' age (P = 0.031) and time since prostheses delivery (P = 0.002). The interproximal space in the FPD group was significantly larger than the SC group (P = 0.008). CONCLUSION: Proximal contact loss is not uncommon in posterior implant-supported prostheses. In this study, age of the patient, prosthesis type and time since delivery of prosthesis were found to be contributing factors.

Organic anion composition of human whole saliva as determined by ion chromatography.

BACKGROUND: The majority of studies examining anionic composition in human saliva have focused on inorganic anions only, and accompanying organic anion concentration has often been overlooked in the development of artificial salivas. The purpose of this study was to examine the major organic anionic species profile of human saliva, with a view to gaining further insight into human salivary chemistry. METHODS: Unstimulated whole saliva was collected from 11 healthy volunteers over a period of 18months. Samples were subjected to ion chromatography for detection and quantification of organic and inorganic anions. RESULTS: Among organic anions, acetate was predominant (0.24±0.38mmol/l), with lactate (0.01±0.04mmol/l), propionate (0.03±0.07mmol/l), and formate (0.02±0.03mmol/l) detected at lower levels. Acetate, propionate, and formate were detected in at least 80% of the saliva samples. Positive partial correlations were found between phosphate and sulfate (r=0.510, p-value=1.545×10(-4)), and between propionate and acetate (r=0.836, p-value=7.510×10(-14)). CONCLUSION: Organic anionic species were consistently detected at low levels in saliva samples collected longitudinally over a period of 18months. These salivary components must be considered in order to understand saliva chemistry, and should not be neglected during the continuing development of artificial salivas.

Rehabilitation of molar-incisor hypomineralization (MIH) complicated with localized tooth surface loss: a case report.

Molar-incisor hypomineralization (MIH) is a developmental enamel hypomineralized condition characteristically involving the first permanent molars and sometimes also the incisors. The affected teeth are predisposed to tooth surface loss (TSL) which may not only compromise the esthetics and function but also endanger the pulp and longevity of the teeth. This report describes the management of a patient with MIH complicated with localized TSL and lack of occlusal clearance due to dentoalveolar compensation. The atypical TSL pattern involved all anterior teeth and required the placement of Dahl appliances on both arches.

Comparison of two laboratory extraction techniques for the detection of Epstein-Barr virus in the saliva of nasopharyngeal carcinoma patients.

AIM: The aim of the present study was to compare the effectiveness of DNA extraction using an extraction kit against the standard boiling technique for the detection of Epstein-Barr virus (EBV) DNA in nasopharyngeal carcinoma (NPC) patients. METHODS: Stimulated whole saliva samples from newly-diagnosed NPC patients were collected. EBV DNA was extracted by both techniques (n = 23) followed by quantitative real-time polymerase chain reaction (PCR) using the primer/probe set for BALF5. RESULTS: The results of the quantitative real-time PCR were reproducible in both groups. The two techniques were moderately correlated (r = 0.67, P < 0.05), and the degree of agreement was good. However, the mean EBV DNA level in the boiling group (3.02 ± 8.67 × 10(6) copies/µL) was significantly higher than the extraction kit group (1.15 ± 2.66 × 10(6) copies/µL) (P < 0.05). The EBV DNA level was higher in patients at an advanced overall stage (P = 0.05). CONCLUSION: The results of the present study showed that the performance of the extraction kit was not superior to the simple boiling technique for the detection of salivary EBV DNA in NPC patients using real-time PCR. The salivary EBV DNA level in patients at an advanced overall stage appeared to be higher than in patients at an early stage.