Do Implant Coatings Affect Healing of Placed Implants? An Umbrella Review.

PURPOSE: To analyze the available evidence and assess the effect of different implant coatings on healing outcomes. MATERIALS AND METHODS: Using the PICOS strategy, a structured question was formed. A protocol was agreed upon and registered with PROSPERO (no. CRD42022321926). The MEDLINE, Embase, Cochrane Database of Systematic Reviews, Scopus, Web of Science, Pubmed, and ScienceDirect databases were searched using a structured strategy. Study selection was independently carried out in duplicate, first by title and abstract, then by full-text assessment. Quality and risk of bias were independently assessed in duplicate using AMSTAR 2 and ROBIS. Data extraction was independently undertaken in duplicate using a predefined extraction form. RESULTS: The search yielded 11 systematic reviews for inclusion. The most commonly assessed coatings were based on calcium phosphate-including hydroxyapatite (HA), brushite, and bioabsorbable nano-HA-followed by bisphosphonate, then bioactive glass coatings. Included reviews most frequently assessed marginal bone loss (MBL), bone-to-implant contact (BIC), and survival/success rates. There was considerable heterogeneity and small sample sizes. The quality assessment suggested low confidence in the reviews and high risk of bias. CONCLUSIONS: The included reviews provide weak evidence that implant coatings improve osseointegration and reduce MBL following implant placement. There was weak evidence for progressive complications for calcium phosphate coatings. Further research and long-term multicenter controlled clinical trials with improved standardization and control of bias are required to better understand the effects of coating implants.

Do metal artifact reduction algorithms influence the detection of implant-related injuries to the inferior alveolar canal in CBCT images?

BACKGROUND: The routine application of dental implants for replacing missing teeth has revolutionized restorative and prosthetic dentistry. However, cone beam computed tomography (CBCT) evaluations of structures adjacent to the implants are limited by metal artifacts. There are several methods for reducing metal artifacts, but this remains a challenging task. This study aimed to examine the effectiveness of metal artifact reduction (MAR) algorithms in identifying injuries of implants to the inferior alveolar canal in CBCT images. METHOD: In this in vitro study, mono-cortical bone windows were created and the inferior alveolar canal was revealed. Using 36 implants, pilot drill and penetration damage of the implant tip into the canal was simulated and compared to the control implants with distance from the canal. CBCT images were evaluated by four experienced observers with and without the MAR algorithm and compared to direct vision as the gold standard. The values of accuracy, sensitivity, and specificity were obtained and compared by receiver operating characteristic (ROC) curve (α = 0.05). RESULT: The area under the ROC curve values for detection of pilot drill injuries varied between 0.840-0.917 and 0.639-0.854 in the active and inactive MAR conditions, respectively. The increase in ROC area was only significant for one of the observers (P = 0.010). For diagnosing penetrative injuries, the area under the ROC curve values was between 0.990-1.000 and 0.722-1.000 in the active and inactive MAR conditions, respectively. The improvement of ROC curve values in active MAR mode was only significant for one of the observers (P = 0.006). CONCLUSION: Activation of MAR improved the diagnostic values of CBCT images in detecting both types of implant-related injuries to the inferior alveolar canal. However, for most observers, this increase was not statistically significant.

Soft tissue simulant materials in X-ray-based imaging in dentomaxillofacial radiology: a scoping review.

INTRODUCTION: In in-vitro dental radiographic research, simulation of soft tissue is required to replicate the clinical condition as close as possible. This study aimed to find out which soft tissue simulation material have been studied to use in dentomaxillofacial radiology and showed similarity in radiodensity to the soft tissues of the maxillofacial region. METHODS: In this scoping review, Web of Science, Embase, Scopus, Google scholar and PubMed databases were searched on April 9, 2023, considering the following PICOS: Population: soft tissue simulants, Intervention: X-ray-based imaging, Comparison: -, Outcome: properties of the soft tissue simulants, Study design: in-vitro studies. Screening, study selection, and data extraction were performed by two independent researchers. A third team member was consulted in the case of disagreement. Quality assessment of the included studies was made using Quality Assessment Tool For In-Vitro Studies (QUIN Tool). RESULTS: Of the initial 1172 articles retrieved in the database search, 13 studies were included in the review. Seven studies had a low risk of bias. In 8 studies, computed tomography (CT) or cone beam computed tomography (CBCT), in 4 studies intraoral radiography, and in 2 studies panoramic radiography was used (one study has used CT/CBCT and panoramic radiography). The studies varied in the radiographic modality, acquisition parameters, selected outcomes, and gold standard. In the majority of the studies (n = 10, 77%), acrylic resin derivatives were used in the soft tissue simulant formula alone or as a major component. Wax was used in the simulant material in 8 studies (62%). In addition, in 3 studies (23%) ice/water was used as the main simulant. CONCLUSION: Ballistic gelatin, expanded 2-cm thick polystyrene with or without 1-cm utility wax, and 0.5 cm of acrylic resin were shown to have a radiographic density similar to soft tissue in standardized studies employing CBCT scanning. For intraoral radiographs, using self-polymerizing acrylic resin, utility wax, and wood, as well as a polymethylmethacrylate box filled with water in thicknesses ranging from 4 to 45 mm, provides suitable radiographic contrast. However, for 4 and 8 mm of wax and 4 mm of water, the radiographic contrast is not appropriate. In addition, 13-17 mm wax and 14.5 mm acrylic resin showed acceptable soft tissue densities in intraoral radiography. Further studies using different imaging modalities with standardized conditions and objective metrics are required to confirm the most appropriate soft tissue simulant material for in-vitro dental radiographic research.

Use of artificial intelligence software in dental education: A study on assisted proximal caries assessment in bitewing radiographs.

INTRODUCTION: Teaching of dental caries diagnostics is an essential part of dental education. Diagnosing proximal caries is a challenging task, and automated systems applying artificial intelligence (AI) have been introduced to assist in this respect. Thus, the implementation of AI for teaching purposes may be considered. The aim of this study was to assess the impact of an AI software on students' ability to detect enamel-only proximal caries in bitewing radiographs (BWs) and to assess whether proximal tooth overlap interferes with caries detection. MATERIALS AND METHODS: The study included 74 dental students randomly allocated to either a test or control group. At two sessions, both groups assessed proximal enamel caries in BWs. At the first session, the test group registered caries in 25 BWs using AI software (AssistDent®) and the control group without using AI. One month later, both groups detected caries in another 25 BWs in a clinical setup without using the software. The student's registrations were compared with a reference standard. Positive agreement (caries) and negative agreement (no caries) were calculated, and t-tests were applied to assess whether the test and control groups performed differently. Moreover, t-tests were applied to test whether proximal overlap interfered with caries registration. RESULTS: At the first and second sessions, 56 and 52 tooth surfaces, respectively, were detected with enamel-only caries according to the reference standard. At session 1, no significant difference between the control (48%) and the test (42%) group was found for positive agreement (p = .08), whereas the negative agreement was higher for the test group (86% vs. 80%; p = .02). At session 2, there was no significant difference between the groups. The test group improved for positive agreement from session 1 to session 2 (p < .001), while the control group improved for negative agreement (p < .001). Thirty-eight per cent of the tooth surfaces overlapped, and the mean positive agreement and negative agreement were significantly lower for overlapping surfaces than non-overlapping surfaces (p < .001) in both groups. CONCLUSION: Training with the AI software did not impact on dental students' ability to detect proximal enamel caries in bitewing radiographs although the positive agreement improved over time. It was revealed that proximal tooth overlap interfered with caries detection.

3D printed denture base material: The effect of incorporating TiO2 nanoparticles and artificial ageing on the physical and mechanical properties.

OBJECTIVES: To evaluate the physical and mechanical properties of three-dimensional (3D) printed denture base resin incorporating TiO2 nanoparticles (NPs), subjected to a physical ageing process. METHODS: Acrylic denture base samples were prepared by a Stereolithography (SLA) 3D printing technique reinforced with different concentrations (0.10, 0.25, 0.50, and 0.75) of silanated TiO2 NPs. The resulting nanocomposite materials were characterized in terms of degree of conversion (DC), and sorption/solubility flexural strength, impact strength, Vickers hardness and Martens hardness and compared with unmodified resin and conventional heat-cured (HC) material. The nanocomposites were reassessed after subjecting them to ageing in artificial saliva. A fractured surface was studied under a scanning electron microscope (SEM). RESULTS: The addition of TiO2 NPs into 3D-printed resin significantly improved flexural strength/modulus, impact strength, Vickers hardness, and DC, while also slightly enhancing Martens hardness compared to the unmodified resin. Sorption values did not show any improvements, while solubility was reduced significantly. The addition of 0.10 wt% NPs provided the highest performance amongst the other concentrations, and 0.75 wt% NPs showed the lowest. Although ageing degraded the materials' performance to a certain extent, the trends remained the same. SEM images showed a homogenous distribution of the NPs at lower concentrations (0.10 and 0.25 wt%) but revealed agglomeration of the NPs with the higher concentrations (0.50 and 0.75 wt%). SIGNIFICANCE: The outcomes of this study suggested that the incorporation of TiO2 NPs (0.10 wt%) into 3D-printed denture base material showed superior performance compared to the unmodified 3D-printed resin even after ageing in artificial saliva. The nanocomposite has the potential to extend service life of denture bases in future clinical use.

3D-printed nanocomposite denture base resin: The effect of incorporating TiO2 nanoparticles on the growth of Candida albicans.

PURPOSE: To develop a biocompatible denture base resin/TiO2 nanocomposite material with antifungal characteristics that is suitable for 3D-printing denture bases. MATERIALS AND METHODS: TiO2 nanoparticles (NPs) with a 0.10, 0.25, 0.50, and 0.75 weight percent (wt.%) were incorporated into a commercially available 3D-printed resin material. The resulting nanocomposite material was analyzed using Lactate dehydrogenase (LDH) and AlamarBlue (AB) assays for biocompatibility testing with human gingival fibroblasts (HGF). The composite material was also tested for its antifungal efficacy against Candida albicans. Fourier transform infrared (FTIR) and Energy Dispersive X-ray Spectroscopy (EDX) mapping were conducted to assess the surface coating and the dispersion of the NPs. RESULTS: LDH and AB assays confirmed the biocompatibility of the material showing cell proliferation at a rate of nearly 100% at day 10, with a cytotoxicity of less than 13% of the cells at day 10. The concentrations of 0.10, 0.25, and 0.50 wt.% caused a significant reduction (p < 0.05) in the number of candida cells attached to the surface of the specimens (p < 0.05), while 0.75 wt.% did not show any significant difference compared to the control (no TiO2 NPs) (p > 0.05). FTIR and EDX analysis confirmed the presence of TiO2 NPs within the nanocomposite material with a homogenous dispersion for 0.10 and 0.25 wt.% groups and an aggregation of the NPs within the material at higher concentrations. CONCLUSION: The addition of TiO2 NPs into 3D-printed denture base resin proved to have an antifungal effect against Candida albicans. The resultant nanocomposite material was a biocompatible material with HGFs and was successfully used for 3D printing.

Current challenges for 3D printing complete dentures: experiences from a multi-centre clinical trial.

Aims To develop an optimal clinical and laboratory protocol for the fabrication of 3D printing dentures.Design A prospective feasibility study across three UK dental schools.Material and methods Each patient received one conventional and one 3D-printed denture. Both dentures were constructed using the same impression, jaw registration and wax trial denture. Variables investigated included methods of digitisation of the impression and optional use of a 3D-printed baseplate for jaw registration.Results Clinicians strongly preferred 3D-printed baseplates. Patients felt that conventional and printed dentures were similar in retention and stability. More patients favoured conventional dentures over 3D-printed dentures in terms of comfort.Discussion It is feasible to combine conventional clinical work with digital techniques to produce 3D-printed dentures. 3D-printed baseplates offer a cost-effective alternative to conventional bases at the jaw registration stage. Challenges were faced in tooth positioning and managing occlusion, particularly where roots required adjustment.Conclusion 3D printing is suitable for producing baseplates for jaw registration blocks and wax trial insertions. It is feasible to produce 3D-printed dentures using conventional clinical techniques for impressions, jaw registration and wax trial insertion. The workflow used in this study for 3D-printed dentures is not superior to conventional dentures. Further work is required.

A historical review of 'phossy jaw'.

The aim of this article is to stimulate interest and discussion on the pathogenesis of 'phossy jaw'. Historical evidence from newspapers and articles of the time is presented, as other scientific evidence is largely absent. It has stimulated considerable interest in present-day media due to the struggles of nineteenth century reformers to improve working conditions against an apathetic government and weak enforcement of regulation. Those afflicted were often young women who suffered severe pain, loss of segments of jaw, and disfigurement.

Distinct microbiome profiles in convergent wisdom tooth impactions.

AIMS: Long-term retention of impacted third molars (wisdom teeth) is associated with plaque stagnation and the development of caries on the adjacent surface of the neighboring second molar. While caries and tooth loss are common outcomes of impaction, there is currently insufficient evidence to support the pre-emptive removal of asymptomatic wisdom teeth. Emerging evidence suggests that convergently growing impactions are associated with caries. We have therefore investigated the composition of dental plaque on the distal surface of the mandibular second molar at various impaction angles. METHODS AND RESULTS: We have compared the microbiome of these surfaces at four impaction angulations using short-read sequencing of the bacterial 16S rRNA gene: two convergent (horizontal and mesial) and two divergent (distal and vertical) angulations, and in cases where the wisdom tooth is missing. Horizontal angulations exhibited lower microbial diversity than mesial impactions. Amplicon Sequence Variants (ASVs) associated with Veillonella were significantly more abundant at impactions with angulations toward the midline. Using machine learning, a random forest classifier trained to distinguish microbiome profiles was used to predict the native angulations for a subset of samples, with samples from the two convergent impactions estimated with the greatest accuracy. CONCLUSIONS: Differences in microbial diversity were apparent between caries-associated convergent (horizontal and mesial) impacted wisdom teeth, as well as greater abundances of Veillonella ASVs at horizontal impactions.

Assessing the physical and mechanical properties of 3D printed acrylic material for denture base application.

OBJECTIVE: Three-dimensional (3D) printing is increasingly being utilised in the dental field because of its time-saving potential and cost effectiveness. It enables dental practitioners to eliminate several fabrication steps, achieve higher precision, and attain consistency in complex prosthetic models. The properties of 3D-printed resin materials can be affected by many factors, including the printing orientation (PO) and insufficient post-curing time (CT). This study aimed to investigate the effect of PO and CT on the mechanical and physical properties of a 3D-printed denture base resin (NextDent). METHODS: 3D-printed specimens were fabricated in 0°, 45°, and 90° POs, followed by three CTs (20, 30, and 50 min). The microhardness was tested using a Vickers hardness test, while the flexural property was evaluated using a three-point bending test. Sorption and solubility were measured after the specimens had been stored in an artificial saliva for 42 days, and the degree of conversion during polymerisation was analysed using Fourier Transform Infra-red (FTIR) spectroscopy. RESULTS: The flexural strength of the material significantly increased (p < 0.05) when the printing orientation was changed from 0° to 90°. A similar increase was observed in the hardness, degree of conversion, and water sorption results. In general, no significant difference (p > 0.05) in any of the tested properties was found when the post-curing times were increased from 20 to 50 min. SIGNIFICANCE: The highest physical and mechanical properties of the 3D-printed denture base resin can be obtained by printing vertically (90° angle to the platform base). The minimal post-curing time to achieve ideal results is 30 min, as further curing will have no significant effect on the properties of the material.

Endocrowns Clinical Performance and Patient Satisfaction: A Randomized Clinical Trial of Three Monolithic Ceramic Restorations.

PURPOSE: The purpose of this randomized, double-blind, clinical trial was to assess the survival of endocrowns made from three different monolithic ceramic materials, and to evaluate patient satisfaction. MATERIALS AND METHODS: Fifty-three patients (sixty root canal treated molar teeth) were enrolled. Teeth were prepared to a flat butt-joint margin and randomly divided between three material groups: lithium disilicate-reinforced glass-ceramic, monolithic zirconia and polymer infiltrated hybrid ceramic. Predefined cementation protocols were used. Clinical assessment using modified United States Public Health Service (USPHS) criteria was carried out after two years by two independent clinicians blinded to the material used. Radiographic examination was conducted to check for the presence of caries, excess cement, and periapical infection. Statistical analysis was performed using the Kruskal Wallis and Wilcoxon signed-rank tests as well as the Kaplan-Meier survival estimate. RESULTS: Forty-eight patients were available for assessment after 2 years (recall rate 90.6%). The overall Kaplan-Meier survival estimate among all groups was 90.9% with no statistically significant difference between the groups (p = 0.17). Three zirconia endocrowns debonded after 9, 10 and 13 months (82.4% survival rate), while 2 hybrid ceramic endocrowns chipped/fractured (89.5% survival rate). Lithium disilicate endocrowns had a 100% survival rate. The Kruskal Wallis test revealed no statistically significant difference between the groups in the USPHS criteria ratings and the radiographic assessment (P>0.05). Patient satisfaction ranged from 82.3% in the zirconia group to 100% in both the lithium disilicate and hybrid ceramic groups. CONCLUSIONS: Endocrowns provide a predictable option for the restoration of endodontically treated molar teeth in the short term. Lithium disilicate-reinforced ceramic had fewer complications and required less intervention compared with zirconia and hybrid ceramics. Long-term follow-up is required to substantiate these study results.

The ADEPT study: a comparative study of dentists' ability to detect enamel-only proximal caries in bitewing radiographs with and without the use of AssistDent artificial intelligence software.

Introduction Reversal of enamel-only proximal caries by non-invasive treatments is important in preventive dentistry. However, detecting such caries using bitewing radiography is difficult and the subtle patterns are often missed by dental practitioners.Aims To investigate whether the ability of dentists to detect enamel-only proximal caries is enhanced by the use of AssistDent artificial intelligence (AI) software.Materials and methods In the ADEPT (AssistDent Enamel-only Proximal caries assessmenT) study, 23 dentists were randomly divided into a control arm, without AI assistance, and an experimental arm, in which AI assistance provided on-screen prompts indicating potential enamel-only proximal caries. All participants analysed a set of 24 bitewings in which an expert panel had previously identified 65 enamel-only carious lesions and 241 healthy proximal surfaces.Results The control group found 44.3% of the caries, whereas the experimental group found 75.8%. The experimental group incorrectly identified caries in 14.6% of the healthy surfaces compared to 3.7% in the control group. The increase in sensitivity of 71% and decrease in specificity of 11% are statistically significant (p <0.01).Conclusions AssistDent AI software significantly improves dentists' ability to detect enamel-only proximal caries and could be considered as a tool to support preventive dentistry in general practice.

Methodological Quality of Systematic Reviews Relating to Performance of All-Ceramic Implant Abutments, Frameworks, and Restorations.

PURPOSE: To assess the methodological quality of published systematic reviews relating to all ceramic implant frameworks, abutments and restorations. MATERIALS AND METHODS: Published systematic reviews relating to all ceramic implant restorations for single tooth and multiple teeth replacements were retrieved to assess their methodological qualities. Sixteen systematic reviews were included for methodological quality assessment by two independent assessors using AMSTAR-2 critical appraisal tool. Inter-rater agreement was assessed using the weighted Cohen's Kappa statistic. RESULTS: Most systematic reviews included randomized clinical trials and nonrandomized studies of intervention. The majority of included systematic reviews (15 out of 16) scored critically low on quality with more than one critical flaw when assessed using the AMSTAR-2 tool. Most systematic reviews assessed lacked analysis of the effects of the risk of bias and heterogeneity of the included studies. The inter-rater agreement of the independent assessors was substantial (0.63). CONCLUSIONS: Confidence in the evidence presented in these systematic reviews was undermined by their tendency to overlook the effect of risk of bias and heterogeneity in evidence synthesis.

A systematic review of second molar distal surface caries incidence in the context of third molar absence and emergence.

Objective The aim of this systematic review was to gain a greater insight into the incidence rates of distal surface caries (DSC) on second permanent molars.Data sources A literature search using the Cochrane Library, Lilacs, Embase and Medline via Ovid retrieved English and non-English language articles from inception to June 2016. The electronic searches were supplemented with reference searching and citation tracking. Reviewers independently and in duplicate performed data extraction and completed structured quality assessments using a validated risk of bias tool for observational studies and categorised the summary scores.Data selection The search yielded 81 records and, after application of inclusion and exclusion criteria, two incidence studies were included in this systematic review.Data extraction The DSC incidence was reported in one study as relative risk (RR = 2.53; 95% CI, 1.55 to 4.14) adjacent to erupted, (RR = 0.83; 95% CI, 0.11 to 6.04) soft tissue impacted and (RR = 1.44; 95% CI, 0.55 to 3.72) bony impacted third molars in comparison to when the third molar was absent with a 25-year follow-up. The second study reported a DSC incidence of 100 surface-years (1% of all sites) with an 18-month follow-up period.Conclusions Both cohort studies indicated that DSC incidence was higher when third molars were erupted in the intermediate term, but greater over the long term for an ageing male population. However, further high-quality research is required to improve the accuracy of these findings.

Osteoporosis risk assessment in primary dental care-The attitudes of Swedish dentists, patients and medical specialists.

OBJECTIVE: To explore and identify the attitudes of dentists, patients and medical specialists regarding implementation of osteoporosis risk assessment into Swedish primary dental care. BACKGROUND: Osteoporosis is a major health problem leading to fragility fractures. As shown in academic-based research, dental radiological examination can be used for osteoporosis risk assessment. A substantial number of patients undergo radiographic examinations in primary dental care each year, but little is known about implementation of osteoporosis risk assessment in this setting. MATERIALS AND METHODS: A qualitative research approach using focus group discussions and manifest content analysis was applied. Five focus groups with dentists and representatives from patient support groups and a single individual interview with one medical specialist were included in the sample. RESULTS: From the manifest content analysis, three categories emerged: (a) barriers to change in practice, (b) benefits to change in practice, and (c) needs and requirements prior to change in practice. Most participants felt that there was insufficient knowledge of osteoporosis as well as a heavy existing workload. A concern was expressed about medical practitioners' willingness to take on responsibility for patients referred by dentists. Representatives from patient support groups highlighted a lack of knowledge about osteoporosis among both the general public and the medical professionals. Clear guidelines and improved communication channels between stakeholders would have to be established to ensure a smooth treatment path for patients. CONCLUSION: Despite interest in osteoporosis risk assessment in primary dental care, there are political, workflow and educational barriers that must be overcome for successful implementation.

Micron-scale crack propagation in laser-irradiated enamel and dentine studied with nano-CT.

OBJECTIVES: The aim of this study was to see the effect of Er:YAG laser irradiation in dentine and compare this with its effect in enamel. The mechanism of crack propagation in dentine was emphasised and its clinical implications were discussed. MATERIALS AND METHODS: Coronal sections of sound enamel and dentine were machined to 50-µm thickness using a FEI-Helios Plasma (FIB). The specimen was irradiated for 30 s with 2.94-µm Er:YAG laser radiation in a moist environment, using a sapphire dental probe tip, with the tip positioned 2 mm away from the sample surface. One of the sections was analysed as a control and not irradiated. Samples were analysed using the Zeiss Xradia 810 Ultra, which allows high spatial resolution, nanoscale 3D imaging using X-ray computed tomography (CT). RESULTS: Dentine: In the peritubular dentine, micro-cracks ran parallel to the tubules whereas in the inter-tubular region, the cracks ran orthogonal to the dentinal tubules. These cracks extended to a mean depth of approximately 10 µm below the surface. On the dentine surface, there was preferential ablation of the less mineralised intertubular dentine, and this resulted in an irregular topography associated with tubules. Enamel: The irradiated enamel surface showed a characteristic 'rough' morphology suggesting some preferential ablation along certain microstructure directions. There appears to be very little subsurface damage, with the prismatic structure remaining intact. CONCLUSIONS: A possible mechanism is that laser radiation is transmitted down the dentinal tubules causing micro-cracks to form in the dentinal tubule walls that tend to be limited to this region. CLINICAL RELEVANCE: Crack might be a source of fracture as it represents a weak point and subsequently might lead to a failure in restorative dentistry.

Effect of the Er: YAG laser on the shear bond strength of conventional glass ionomer and Biodentine™ to dentine.

OBJECTIVES: The purpose of this study was to determine if Er: YAG laser etching improves the shear bond strength (SBS) of Biodentin™ and GC Fuji IX® to dentine. MATERIALS AND METHODS: Forty human dentine specimens were standardized and embedded in stone. The specimens were randomized into four groups (n = 10). Twenty samples were treated with the Er: YAG laser radiation and 10 of these restored with GC Fuji IX® and 10 with Biodentine™. The remaining 20 specimens acted as controls (no laser treatment); 10 were restored with GC Fuji IX® and 10 with Biodentin™. All samples were then stored in an incubator at 37.5°C and 100% humidity for 7 days. The SBS was determined using a Zwick universal testing machine. A two-way analysis of variance test was used to evaluate the statistical difference in SBS between the groups. An independent sample t-test was used to determine the statistical significance of differences between control and lased groups within the same material. RESULTS: A highly statistically significant difference in SBS was found with the laser treatment (P = 0.0001) and material (i.e., Biodentin™ or Fuji IX® (P = 0.0001). The GC Fuji IX® group recorded the highest mean SBS required to dislodge the material from the laser-treated dentine surface (1.77 ± 0.22 Mega-Pascal [MPa]). The mean SBS of Biodentin™ to dentine following the laser radiation (1.12 ± 0.16 MPa) was significantly greater compared to the nonlased dentine (0.53 ± 0.09). Pearson Chi-square test indicated a nonsignificant relation between shear strength and mode of failure (P = 0.467). CONCLUSION: Laser etching of the dentine surfaces yielded a significant increase in the bond strength for both GC Fuji IX® and Biodentin™. The SBS of Biodentin™ to dentine is greater than with conventional glass ionomer (Fuji IX®).

Effect of 2.94 µm Er: YAG laser on the chemical composition of hard tissues.

The aim was to investigate the effect of the Er-YAG laser radiation on morphology and chemical composition of enamel, dentin, and bone. The specimens of the three groups were irradiated with a very long pulse mode (VLP) of 2.94 µm Er-YAG laser with 100 mJ pulse energy and energy density of 8.42 J/ c m 2 for 30 s, at a repetition rate of 15 Hz. The organic and inorganic content of the samples were investigated by Fourier Transforms Infrared spectroscopy (FTIR). The morphological characteristics were investigated with scanning electron microscopy (SEM) and elemental analysis (calcium and phosphorus) with energy-dispersive X-ray spectroscopy (EDX). FTIR data were analyzed with a One-Way ANCOVA test and EDX data with the independent sample t-test. Following the laser radiation, FTIR showed a significant decrease in the organic content of all tissues. The weight percentage (wt %) calcium content of dentin and bone increased significantly following irradiation with a p-value of .002 for both tissues, but the wt % of phosphorus content was not influenced significantly. The morphological alterations expressed signs of fusion in all the samples.

Prediction of implant loss and marginal bone loss by analysis of dental panoramic radiographs.

PURPOSE: One of the major factors governing implant success is the quantity and density of the host bone. The aim of this work was to determine whether mandibular bone texture and cortical width measurements on plain radiographs could be associated with implant failure and/or marginal bone loss. MATERIALS AND METHODS: A statistical model was built to predict implant failure; it incorporated several radiographic features of cortical and cancellous bone texture, cortical width, and patient smoking habits. Cortical width measurements and texture measurements of cortical and cancellous bone were made on the panoramic radiographs of 460 subjects. These were used to predict implant failure and marginal bone loss after 5 years. Receiver operating characteristic (ROC) curve analysis and area under the curve (AUC) were used to determine the diagnostic accuracy of the variables in predicting implant failure and marginal bone loss. Additionally, for 91 of 460 subjects with periapical radiographs, marginal bone levels around implants were measured over a 5-year period. RESULTS: Of the 460 patients assessed for implant failure, 29 had failed implants (93.7% success rate). The ROC curve built from this model had a sensitivity of 62.1% and specificity of 67.5%. The AUC from the model was 0.690 (95% confidence interval [CI] 0.597 to 0.783). A model was also built to predict marginal bone loss. The ROC curve had 78.6% sensitivity and 74.6% specificity (AUC = 0.880, 95% CI = 0.810 to 0.953). Mandibular cortical width was not a significant predictor of either implant failure or bone loss. CONCLUSION: In a retrospective analysis 5 years after implant placement, features of cancellous and cortical bone of the mandible were significant in predicting implant failure and marginal bone loss in a sample of 460 patients.

The Effect of Cyclic Loading on the Compressive Strength of Core Build-Up Materials.

PURPOSE: To evaluate the effect of cyclic loading on compressive strength of core build-up materials. MATERIALS AND METHODS: Four dual-cured composites (Core.X Flow, Grandio Core, Bright Flow Core, Spee-Dee) and one light-cured reinforced resin-modified glass ionomer (Fuji II LC) were tested. One hundred cylindrical specimens (4 mm × 6 mm) were prepared. Each material had two groups (ten specimens to be tested under static loading and ten specimens to be tested after cyclic loading). The specimens were stored wet, and after 30 days, one group of each material was cyclically loaded (for 250,000 cycles with a frequency of 1.6 Hz under stress load of 68.6 N) in a chewing simulator CS-4.2. Then specimens were subjected to static compressive loading until failure in a universal testing machine. RESULTS: Mean compressive strength values before cycling ranged from 144 MPa (15.8) for Fuji II LC to 277 MPa (23.2) for Grandio Core. Independent t-test showed no statistically significant difference (p > 0.05) in the compressive strength of each material before and after cycling (p = 0.7 Grandio Core, p = 0.3 Core. X Flow, p = 0.6 Bright Flow Core, p = 0.2 Spee-Dee, p = 0.6 Fuji II LC); however, there was a statistically significant difference between the materials when comparing before and after cycling. CONCLUSIONS: All tested materials showed no reduction in the compressive strength after cycling. Therefore, the tested materials can survive 1 year in service without a reduction in compressive strength.