Recurrent Decay Research Articles

Bevels And Flares for Different Restorations: A Narrative Review

The connection between the tooth and the restoration is the weakest link in any of the restoration. The success and longevity of a restoration greatly depend on the design and preparation of the marginal peripheries, which are the edges where the restoration meets the natural tooth structure.When the margins of the restoration closely adapt to the cavosurface finish line of the tooth preparation, it creates a favorable relationship between the restoration and the tooth structure. This close adaptation helps to improve the survival of the restoration in the oral environment.A well-fitting margin provides several benefits. It helps prevent microleakage, Microleakage can lead to recurrent decay, sensitivity, and even failure of the restoration. By closely adapting the margins, the risk of microleakage is minimized.A precise margin adaptation helps in creating a strong bond between the restoration material and the tooth structure. This bond enhances the structural integrity of the restoration and provides better retention, preventing its dislodgement or fracture.

Clinical evaluation of bulk-fill and universal nanocomposites in class II cavities: Five-year results of a randomized clinical split-mouth trial

AimEvaluating the clinical survival and quality parameters of class-II restorations using 3M™ FiltekTM Bulk Fill Posterior Restorative compared to 3M™ FiltekTM Supreme XTE Universal Restorative over a period of five years. Materials and methodsA longitudinal, randomized, prospective split-mouth study with 60 patients (29 female, 31 male; mean age 44 y; range 20-77 y) and a total of 120 load-bearing class II restorations (TEST: n=60 Filtek Bulk Fill Posterior Restorative; CONTROL: n=60 Filtek Supreme XTE Universal Restorative) was conducted. Clinical evaluation was performed by blinded evaluators according to FDI criteria. Kaplan-Meier method was used for survival analysis and an intergroup comparison (Mann-Whitney-U-Test) was carried out. A basic significance level of 0.05 was corrected by the Bonferroni method to account for multiple testing (significance after correction: p<0.00067). ResultsThe mean overall survival of restorations was 92% after 56.98±1.51 months in the TEST group (95 CI= 54.02;59.94) and 92% after 57.25±1.46 months (95 CI= 54.39; 60.12) in the CONTROL group (log-rank p=0.995). In total, four failures occurred in both TEST and CONTROL group during the observation period (mean annual failure rate: 1.6%). The most common reasons for failure were chipping-fractures, debonding, cracked-tooth-syndrome and recurrent decay. With regard to the FDI criteria, no significant differences between TEST and CONTROL material occurred for any of the evaluated variables. In the TEST group two restorations had to be repaired and two had to be replaced, in the CONTROL group four restorations had to be replaced. ConclusionBoth materials showed acceptable clinical performance and survival during the 5-year observation period. Clinical SignificanceThe use of a nanofilled bulk-fill composite proved to be an aesthetically, functionally and biologically satisfactory alternative in posterior dentition.

Factors relating to failure rates of dental procedures in children following comprehensive dental treatments under general anesthesia: A 2-year retrospective study.

This study assessed the demographic, treatment, and patient characteristics relating to 2-year postoperative failure and success rate of 2 to 12-years-old healthy children that underwent various dental procedures during comprehensive dental treatment under general anesthesia (GA). A retrospective study was conducted after the completion of a 2-year postoperative follow-up examination. The hospital records of all the children were reviewed by an experienced examiner. In the follow-up appointment, the clinical and radiographic evaluations of the treatments, oral hygiene, and oral hygiene practices were recorded. A P value of <0.05 was set as statistically significant. Around 221 healthy children were included in the study, with a mean (SD) age of 4.92 (1.37). The most common type of failure detected 2 years postoperatively were recurrent decay (mean = 2.68, SD = 2.50), followed by stainless steel crown (SSC) open margin (mean = 0.69, SD = 1.02). Children with good oral hygiene involved the highest number of successful procedures (mean = 5.28, SD = 1.99) (P = 0.032). Children with poor oral hygiene was the factor that involved the highest number of procedure failures (mean = 8.28, SD = 3.38) (P < 0.001). The Pearson correlation coefficient showed that the younger the mean age of children during treatment under GA, the higher the rate of dental procedure failure (r = -0.202, n = 221, P < 0.01). The failure rate of dental procedures performed during treatment under GA was highest among younger children and children with poor oral hygiene at the time of treatment. SSC crown restoration was the most common type of dental procedure received, and recurrent decay and SSC open margin were the most common types of failure detected.

A randomized clinical split-mouth trial of a bulk-fill and a nanohybrid composite restorative in class II cavities: Three-year results

ObjectivesThe aim of this randomized controlled clinical trial was to evaluate the clinical survival and quality parameters of class-II restorations using a bulk-fill composite resin compared to a conventional nanohybrid composite resin in a split-mouth design. MethodsOne hundred and twenty direct restorations were placed in stress bearing class II cavities (n = 60 test group: Filtek™ Bulk Fill Posterior and n = 60 control group: Filtek™ Supreme XTE) in adult permanent teeth. Survival and clinical quality were evaluated at baseline and after 3 years using modified World Dental Federation (FDI) criteria. Participants and clinical evaluators were blinded relating to the group assignment of the restorations. ResultsSeventeen restorations (14.2%) were lost to follow-up, leading to 51 restorations available for survival analysis in the test group and 52 restorations in the control group. Seven restorations showed unfavorable events and were classified as failure. Four bulk-fill restorations failed due to tooth infracture (n = 1), chipping fractures (n = 2) and recurrent decay (n = 1), whereas three conventional nanohybrid composite restorations failed due to adhesive failure (n = 1), tooth infracture (n = 1) and chipping as well as recurrent decay (n = 1). The mean annual failure rate was 2.4% and 1.8%, respectively. The difference between test and control group was not significant (p = 0.7). Data on the detailed assessment of FDI criteria were available for n = 48 and n = 49 restorations, respectively. No significant differences between the two groups could be found regarding the assessment of esthetic, functional and biological properties. SignificanceBoth materials showed similar clinical performance and survival. The use of bulk-fill composite proved to be an esthetically, functionally and biologically satisfactory alternative in the posterior dentition during the 3-year follow-up.

Reconfigurable Dual Peptide Tethered Polymer System Offers a Synergistic Solution for Next Generation Dental Adhesives.

Resin-based composite materials have been widely used in restorative dental materials due to their aesthetic, mechanical, and physical properties. However, they still encounter clinical shortcomings mainly due to recurrent decay that develops at the composite-tooth interface. The low-viscosity adhesive that bonds the composite to the tooth is intended to seal this interface, but the adhesive seal is inherently defective and readily damaged by acids, enzymes, and oral fluids. Bacteria infiltrate the resulting gaps at the composite-tooth interface and bacterial by-products demineralize the tooth and erode the adhesive. These activities lead to wider and deeper gaps that provide an ideal environment for bacteria to proliferate. This complex degradation process mediated by several biological and environmental factors damages the tooth, destroys the adhesive seal, and ultimately, leads to failure of the composite restoration. This paper describes a co-tethered dual peptide-polymer system to address composite-tooth interface vulnerability. The adhesive system incorporates an antimicrobial peptide to inhibit bacterial attack and a hydroxyapatite-binding peptide to promote remineralization of damaged tooth structure. A designer spacer sequence was incorporated into each peptide sequence to not only provide a conjugation site for methacrylate (MA) monomer but also to retain active peptide conformations and enhance the display of the peptides in the material. The resulting MA-antimicrobial peptides and MA-remineralization peptides were copolymerized into dental adhesives formulations. The results on the adhesive system composed of co-tethered peptides demonstrated both strong metabolic inhibition of S. mutans and localized calcium phosphate remineralization. Overall, the result offers a reconfigurable and tunable peptide-polymer hybrid system as next-generation adhesives to address composite-tooth interface vulnerability.

Microbial population shift and metabolic characterization of silver diamine fluoride treatment failure on dental caries.

The objective of this pilot study was to describe the microbial profiles present in the plaque and saliva of children who continued to develop new carious lesions following treatment with silver diamine fluoride ("nonresponders") compared to caries active, caries-free, and children immediately receiving SDF treatment for untreated caries in order to identify potential microbial differences that may relate to a re-incidence of caries. Saliva and plaque samples from infected and contralateral sites were obtained from twenty children who were either caries free, had active carious lesions, were caries active and received SDF treatment immediately before sampling, or had previously received SDF treatment and developed new caries. In total, 8,057,899 Illumina-generated sequence reads from 60 samples were obtained. Reads were processed using the Quantitative Insights Into Microbial Ecology pipeline. Group differences were assessed using Analysis of Variance Models and Tukey Honest Significant Differences. To identify significant taxa between treatment groups, Linear discriminant analysis Effect Size (LefSe) and Analysis of Differential Abundance Taking Sample Variation Into Account were used. Differential abundant analysis indicated that members of the Lachnospiraceae family were significantly enriched in non-responders and the genus Tannerella and species Granulicatella adiances were also highly abundant in this group. LefSe analysis between non-responders and SDF-treated groups revealed that genera Leptotrichia and Granulicatella were enriched in non-responders. We observed the highest abundance of phosphotransferase system and lowest abundance of lipopolysaccharide synthesis in non-responders. The microbiome in dental biofilms is responsible for initiation and progression of dental caries. SDF has been shown to be effective in arresting the progression carious lesions, in part due to its antimicrobial properties. Findings suggest that the differential abundance of select microbiota and specific pathway functioning in individuals that present with recurrent decay after SDF treatment may contribute to a potential failure of silver diamine fluoride to arrest dental caries. However, the short duration of sample collection following SDF application and the small sample size emphasize the need for further data and additional analysis.

Quantification and characterization of nanometer-sized particles released from dental composite products using a multimodal approach

Dental composites are widely used by dentists as restorative material to restore tooth fractures and dental caries or decay. Dental composites often contain advanced nanomaterials. After restoring a tooth, the dentist may use a high-speed handpiece to contour the surface of the composite through the process of drilling, utilizing various dental burs depending on the situation. Additionally, dentists must often remove existing composite restorations for numerous reasons (e.g., recurrent decay or need for a crown). If appropriate controls, such as water aerosol in conjunction with the grinding process and/or local exhaust ventilation, are inadequately utilized, both the dentist and patient may inhale airborne particles released in the drilling process. This study aimed to identify the potential exposure from dental procedures that utilize advanced nanocomposites and to characterize the particles released from commonly used dental composites. To identify the characteristics and elemental composition of the released particles, a uniquely designed nanoparticle sampler, a Sioutas cascade impactor, and real-time instruments were utilized. Both microscopic and size-fractionated concentration analyses confirmed the release of nanometer-sized particles consisting of various metal components that are potentially concerning for human exposure. These results elucidate the potential nanoparticle exposure that may occur during dental practice with advanced materials, based on simulated restoration grinding situations.

COMPARISON OF PHOTOTHERMAL RADIOMETRY AND MODULATED LUMINESCENCE, INTRAORAL RADIOGRAPHY, AND CONE BEAM COMPUTED TOMOGRAPHY FOR DETECTION OF NATURAL CARIES UNDER RESTORATIONS

<h3>Background</h3> Intraoral radiographs (IR) are commonly used to evaluate for caries but require approximately 30% to 40% mineral loss before detection, thereby necessitating techniques with a high sensitivity index for early detection. Photothermal radiometry and modulated luminescence (PTR/LUM) offers a potentially more sensitive and safe method for detecting recurrent caries; however, there are no published studies comparing its use in detection of recurrent caries under composite restorations relative to IR and cone beam computed tomography (CBCT). <h3>Objective(s)</h3> The aim of this in vitro study was to compare the sensitivity, specificity, and receiver operating characteristic area under the curve (ROC AUC) of a caries diagnostic system based on PTR/LUM to digital IR and CBCT in detecting simulated recurrent decay under restorations. <h3>Study Design</h3> The study used 54 teeth with Class II composite restorations on 70 proximal surfaces; 35 had caries lesions remaining, and 35 were sound. The gingival floor of the restored surfaces was assessed for presence or absence of caries under composite restorations using each of the 3 modalities. Statistical calculations and analysis were performed using the R statistical computing environment. Sensitivity and specificity were calculated for each device, for each rater and image combination, and ROC analysis was performed. <h3>Results</h3> Average sensitivity across the 6 experienced dentists was 0.40 for both IR and CBCT. However, the sensitivity for the PTR/LUM was 0.89. Specificity of PTR/LUM and IR was 0.80, whereas the CBCT method was 0.70. The intrarater agreement varied for different observers with the use of IR and CBCT, ranging between moderate and substantial with only 1 observer having poor intrarater agreement for both methods. PTR/LUM showed only moderate agreement. <h3>Discussion/Conclusions</h3> PTR/LUM, which involves nonionizing radiation, can serve as a sensitive adjunct in early caries detection and monitoring.

Threats to adhesive/dentin interfacial integrity and next generation bio-enabled multifunctional adhesives.

Nearly 100 million of the 170 million composite and amalgam restorations placed annually in the United States are replacements for failed restorations. The primary reason both composite and amalgam restorations fail is recurrent decay, for which composite restorations experience a 2.0-3.5-fold increase compared to amalgam. Recurrent decay is a pernicious problem-the standard treatment is replacement of defective composites with larger restorations that will also fail, initiating a cycle of ever-larger restorations that can lead to root canals, and eventually, to tooth loss. Unlike amalgam, composite lacks the inherent capability to seal discrepancies at the restorative material/tooth interface. The low-viscosity adhesive that bonds the composite to the tooth is intended to seal the interface, but the adhesive degrades, which can breach the composite/tooth margin. Bacteria and bacterial by-products such as acids and enzymes infiltrate the marginal gaps and the composite's inability to increase the interfacial pH facilitates cariogenic and aciduric bacterial outgrowth. Together, these characteristics encourage recurrent decay, pulpal damage, and composite failure. This review article examines key biological and physicochemical interactions involved in the failure of composite restorations and discusses innovative strategies to mitigate the negative effects of pathogens at the adhesive/dentin interface. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2466-2475, 2019.

New silyl-functionalized BisGMA provides autonomous strengthening without leaching for dental adhesives

Resin-based composite has overtaken dental amalgam as the most popular material for direct restorative dentistry. In spite of this popularity the clinical lifetime of composite restorations is threatened by recurrent decay. Degradation of the adhesive leads to gaps at the composite/tooth interface–bacteria, bacterial by-products and fluids infiltrate the gaps leading to recurrent decay and composite restoration failure. The durability of resin-dentin bonds is a major problem. We address this problem by synthesizing silyl-functionalized BisGMA (e.g., silyl-BisGMA), formulating dental adhesives with the new monomer and determining the physicochemical properties and leaching characteristics of the silyl-BisGMA adhesives. Silyl-BisGMA was synthesized by stoichiometric amounts of BisGMA and 3-isocyanatopropyl trimethoxysilane (IPTMS). The control adhesive was a mixture based on HEMA/BisGMA (45/55, w/w). In the experimental formulations, BisGMA was partially or completely replaced by silyl-BisGMA. Water miscibility, polymerization behavior (Fourier transform infrared spectroscopy, FTIR), thermal property (modulated differential scanning calorimetry, MDSC), mechanical properties in dry and wet conditions (dynamic mechanical analysis, DMA), and leached species (HPLC) were investigated. Data from all tests were submitted to appropriate statistical analysis (α = 0.05). Silyl-BisGMA-containing adhesives exhibited comparable water miscibility, lower viscosities, and significantly improved degree of conversion of CC bond as compared to the control. After 4 weeks aqueous aging, the glass transition temperature and rubbery moduli of the experimental copolymers were significantly greater than the control (p < 0.05). HPLC results indicated a substantial reduction of leached HEMA (up to 99 wt%) and BisGMA (up to 90 wt%). By introducing silyl-functional group, the new BisGMA derivative exhibited potential as a monomer that can lead to dental adhesives with improved mechanical properties and reduced leaching under conditions relevant to the oral environment. Statement of SignificanceThe low-viscosity adhesive that bonds the composite to the tooth (enamel and dentin) is intended to seal and stabilize the composite/tooth interface, but it degrades leading to a breach at the composite/tooth margin. As the most popular crosslinking monomer in adhesives, Bisphenol A-glycerolate dimethacrylate (BisGMA) has limitations, e.g. susceptible to hydrolysis and concomitant property degradation. A methoxysilyl-functionalized BisGMA derivative (silyl-BisGMA) was introduced in this work to respond to these limitations. Our results indicated that by introducing silyl-BisGMA, higher crosslinked networks were obtained without sacrificing the homogeneity, and the leached amount of HEMA was reduced up to 99%. This novel resin offers potential benefits including prolonging the functional lifetime of dental resin materials.

Fabrication of hybrid crosslinked network with buffering capabilities and autonomous strengthening characteristics for dental adhesives.

The interfacial gaps between the restorative composite biomaterial and the tooth structure contributes to recurrent decay and failure of the composite restoration. The inability of the material to increase the pH at the composite/tooth interface facilitates the outgrowth of more cariogenic and aciduric bacteria. This paper reports a novel, synthetic resin that provides buffering capability and autonomous strengthening characteristics. In this work, two amino functional silanes were synthesized and the effect of alkoxy substitutions on the photoacid-induced sol-gel reaction was investigated. We evaluated the neutralization capability (monitoring the pH of lactic acid solution) and the autonomous strengthening property (monitoring the mechanical properties of the hybrid copolymers under wet conditions and quantitatively analyzing the leachable species by HPLC). The novel resin investigated in this study offers the potential benefits of reducing the risk of recurrent decay and prolonging the functional lifetime of dental adhesives.

Abordagem dos Cirurgiões Dentistas em Relação a Fotopolimerização de Resinas Compostas

Aparelhos e métodos para a polimerização das resinas compostas vêm buscando melhorar as propriedades das restaurações. Este trabalho objetivou avaliar o conhecimento dos cirurgiões dentistas perante o uso de aparelhos fotopolimerizadores. A obtenção dos dados foi feita por meio de um questionário aplicado para 34 cirurgiões dentistas do curso de especialização em Dentística Restauradora da Pós-Graduação da IMED no ano de 2015 e 2016. Os resultados mostraram que dos 34 cirurgiões dentistas entrevistados 35,30% utilizavam fotopolimerizador da marca Gnatus, 23,53% RadiCall, e 20,58% Schuster. Quanto ao ano 35,3% possuiam fotopolimerizador do ano de 2015, 17,64% de 2010, e 11,77% de 2014. Quanto ao tipo de lâmpada utilizada 91,14% utilizavam Led, 5,38% halógena, e 2,94% led e halógena. Em relação as consequências da contração de polimerização 23,52% dos cirurgiões-dentistas relacionaram a sensibilidade pós-operatória, infiltração marginal, cárie recorrente e trinca de esmalte como consequências, já 20,58% consideraram a infiltração marginal a única consequência e 23,52% apenas a sensibilidade pós-operatória. Do total da amostra 29,4% disseram que para diminuir o estresse da contração de polimerização utilizavam outras técnicas de fotopolimerização, 17,64% do tipo ramp, 20,58% do tipo step. Pode-se observar que 70,56% dos entrevistados relataram que em menos da metade dos seus casos ocorreram incidência de sensibilidade após o tratamento restaurador, 20,58% nunca observaram sensibilidade pós operatória, e 8,82% apenas na metade dos casos. Foi possível observar os tipos e marcas dos aparelhos mais utilizados pelos profissionais, e notou-se ainda uma falta de conhecimento dos profissionais sobre quais são as consequências da contração de polimerização.

Probing the neutralization behavior of zwitterionic monomer-containing dental adhesive

ObjectiveTo investigate the polymerization kinetics, neutralization behavior, and mechanical properties of amine-functionalized dental adhesive cured in the presence of zwitterionic monomer, methacryloyloxyethyl phosphorylcholine (MPC). MethodsThe control adhesive was a mixture based on HEMA/BisGMA/2-N-morpholinoethyl methacrylate (MEMA) (40/30/30, w/w/w). The control and experimental formulations containing MPC were characterized with regard to water miscibility of liquid resins, photopolymerization kinetics, water sorption and solubility, dynamic mechanical properties and leachables from the polymers (aged in ethanol). The neutralization behavior of the adhesives was determined by monitoring the pH of lactic acid (LA) solution. ResultsThe water miscibility decreased with increasing MPC amount. The water sorption of experimental copolymer specimen was greater than the control. The addition of 8wt% water led to improved photo-polymerization efficiency for experimental formulations at MPC of 2.5 and 5wt%, and significant reduction in the cumulative amounts of leached HEMA, BisGMA, and MEMA, i.e. 90, 60 and 50% reduction, respectively. The neutralization rate of MPC-containing adhesive was faster than control. The optimal MPC concentration in the formulations was 5wt%. SignificanceIncompatibility between MEMA and MPC led to a decrease in water miscibility of the liquid resins. Water (at 8wt%) in the MPC-containing formulations (2.5–5wt% MPC) led to higher DC, faster RPmax and significant reduction in leached HEMA, BisGMA, and MEMA. The neutralization rate was enhanced with the addition of MPC in the amine-containing formulation. Promoting the neutralization capability of dentin adhesives could play an important role in reducing recurrent decay at the composite/tooth interface.

Engineered Peptide Repairs Defective Adhesive-Dentin Interface.

Failure of dental composite restorations is primarily due to recurrent decay at the tooth-composite interface. At this interface, the adhesive and its bond with dentin is the barrier between the restored tooth and the oral environment. In vivo degradation of the bond formed at the adhesive/dentin (a/d) interface follows a cascade of events leading to weakening of the composite restoration. Here, a peptide-based approach is developed to mineralize deficient dentin matrices at the a/d interface. Peptides that have an inherent capacity to self-assemble on dentin and to induce calcium-phosphate remineralization are anchored at the interface. Distribution of adhesive, collagen, and mineral is analyzed using micro-Raman spectroscopy and fluorescence microscopy. The analysis demonstrates remineralization of the deficient dentin matrices achieved throughout the interface with homogeneous distribution of mineral. The peptide-based remineralization demonstrated here can be an enabling technology to design integrated biomaterial-tissue interfaces.

Can we trust visual methods alone for detecting caries in teeth?

Data sourcesElectronic Databases searched in PubMed, Embase and Scopus. Unpublished literature was traced through OpenSIGLE, annals of IADR/AADR (International and American Associations for Dental Research) and ORCA (European Organisation for Caries Research) from 2003-2014. Studies were limited to English.Study selectionStudies involving visual inspection for detection of primary coronal caries lesions in primary or permanent human teeth were considered. All papers needed to include a clearly defined reference standard and the reporting of absolute numbers of true positives, false positives, true negatives and false negatives or a presentation of sufficient data to calculate these figures. Reference methods considered appropriate were histologic evaluation, operative intervention, direct visual inspection after temporary tooth separation and radiography. For studies with the same data set only the most complete study was included. Articles that reported caries detection using artificial caries, root caries or recurrent decay adjacent to restorations were excluded.Data extraction and synthesisStudy selection for inclusion was performed independently by two reviewers and disagreements were resolved by discussion with a third reviewer. Data were collected by two reviewers on structured tables. Discrepancies were resolved by consensus. A meta-analysis was performed. The following information was extracted; reference standard method, setting (clinical or laboratory), type of teeth (primary or permanent), surface evaluated (smooth, proximal or occlusal), sample size, examiner's experience. Also recorded were visual scoring systems. Studies that did not report any criteria were classified as 'with no criteria'. If authors used criteria with no reference to previously published studies they were classified as 'own criteria'. The PRISMA guideline was followed to report the review and the QUADAS-2 checklist (Quality assessment of studies of diagnostic performance included in systematic reviews) was used to assess the risk of bias of the included studies.ResultsData were used to calculate the pooled sensitivity, specificity, diagnostic odds ratio and summary receiver operating characteristics curve. Heterogeneity of the studies was also assessed. A total of 102 manuscripts and one abstract were included. The analysis demonstrated that the visual method had good accuracy for detecting carious lesions. Clinically obtained specificity was higher. Also observed was moderate to high heterogeneity and evidence of publication bias. Studies employing well known visual scoring systems were significantly more accurate than those that used their own criteria. The results were grouped and differentiate the type of dentition (permanent or primary), type of lesion (initial or advanced), proximal or occlusal surface and clinical settings from laboratory settings.The pooled specificity calculated was high in most of the groups and ranged from 0.573 to 0.992 mostly > 0.90; the lowest was in the occlusal initial caries lesions in primary teeth.The sensitivity ranged from 0.274 to 0.77; the lowest from clinical studies in proximal surfaces in permanent teeth, the highest from three studies evaluating the occlusal initial caries lesions in permanent teeth. Most of the pooled sensitivities were around a low level.ConclusionsVisual caries detection method has good overall performance. Although the studies together had high heterogeneity and risk of bias, the use of detailed and validated indices seems to improve the accuracy of the method.

A 2-year Retrospective Clinical study of Enamic Crowns Performed in a Private Practice Setting.

To evaluate the clinical performance and survival of Enamic crowns placed in a prosthodontic dental practice. Thirty-five patients and 45 crowns were included in the study. At 1-year recall appointments, the restorations were examined for survival. At the 2-year recall appointment, all restorations were clinically evaluated by an independent evaluator for CDA clinical criteria. Kaplan-Meier method and a log-rank test were used to compare the survival of the restorations placed with resin and resin-modified glass ionomer (RMGI) cements. Out of the 45 crowns that were followed, 2 were lost to follow-up by 1 year and 7 were lost to follow-up by 2 years. Severe complications were observed in 2 teeth by the 2-year follow-up and were recorded as failures due to recurrent decay, and an internal crack in the abutment tooth. There was no difference between the survival probability for crowns cemented with resin cement (96.8%) and with RMGI cements (92.9%) (p = 0.42), however, 1 out of the 14 crowns cemented with RMGI cement debonded. The crowns were evaluated according the CDA criteria with over 90% alfa scores for all categories aside from surface texture (86% alfa). The estimated 2-year survival of Enamic crowns is >90%. Based on the preliminary 2-year results achieved in a clinical practice, Enamic is a suitable material for full-coverage single-unit crowns. Further studies are necessary to evaluate the long term success. (J Esthet Restor Dent 28:231-237, 2016).

Algebraic Statistics of Poincaré Recurrences in a DNA Molecule.

The statistics of Poincaré recurrences is studied for the base-pair breathing dynamics of an all-atom DNA molecule in a realistic aqueous environment with thousands of degrees of freedom. It is found that at least over five decades in time the decay of recurrences is described by an algebraic law with the Poincaré exponent close to β=1.2. This value is directly related to the correlation decay exponent ν=β-1, which is close to ν≈0.15 observed in the time resolved Stokes shift experiments. By applying the virial theorem we analyze the chaotic dynamics in polynomial potentials and demonstrate analytically that an exponent β=1.2 is obtained assuming the dominance of dipole-dipole interactions in the relevant DNA dynamics. Molecular dynamics simulations also reveal the presence of strong low frequency noise with the exponent η=1.6. We trace parallels with the chaotic dynamics of symplectic maps with a few degrees of freedom characterized by the Poincaré exponent β~1.5.

Linear measurements of finish line length associated with various preparation designs using CAD/CAM technology

Abstract Purpose The aim of this study was to measure the length of finish lines associated with various commonly used preparation designs using high technology CAD/CAM. Materials and methods A total of 80 extracted human permanent teeth (including 4 distinct morphologies) were divided into 8 groups according to the type of preparation design (all-ceramic crown, ceramic onlay, or ceramic veneer) and tooth type (upper first molar, lower first premolar, upper central incisor and lower central incisor). The length of the finish line for each specimen was measured after performing tooth preparation using Dental Wings 7Series 3D Scanners. The measured lengths associated with the various preparation designs were analyzed. Results The length of the finish line was significantly different between complete- and partial-coverage tooth preparations, in which the partial coverage had a longer finish line than the complete coverage. Conclusion The complete-coverage preparations evaluated in this study exhibited significantly shorter finish lines compared to the partial-coverage preparations. Clinical significant The risk of recurrent caries has been directly related to the marginal integrity of any restoration. However, the relationship between the length of the finish line and recurrent decay may also be significant. Therefore, obtaining baseline information regarding the differences in finish line length of various preparation designs is important.

In vitro near-infrared imaging of natural secondary caries.

Secondary caries stands as the leading reason for the failure of composite restorations and dentists spend more time replacing existing restorations than placing new ones. Current clinical strategies, and even modern visible light methods designed to detect decay, lack the sensitivity to distinguish incipient lesions, are confounded by staining on the surface and within the tooth, or are limited to detecting decay on the tooth surface. Near-IR (NIR) imaging methods, such as NIR reflectance and transillumination imaging, and optical coherence tomography are promising strategies for imaging secondary caries. Wavelengths longer than 1300-nm avoid interference from stain and exploit the greater transparency of sound enamel and dental composites, to provide increased contrast with demineralized tissues and improved imaging depth. The purpose of this study was to determine whether NIR transillumination (λ=1300-nm) and NIR cross-polarized reflectance (λ=1500-1700-nm) images can serve as reliable indicators of demineralization surrounding composite restorations. Twelve composite margins (n=12) consisting of class I, II & V restorations were chosen from ten extracted teeth. The samples were imaged in vitro using NIR transillumination and reflectance, polarization sensitive optical coherence tomography (PS-OCT) and a high-magnification digital visible light microscope. Samples were serially sectioned into 200-μm slices for histological analysis using polarized light microscopy (PLM) and transverse microradiography (TMR). The results presented demonstrate the utility of NIR light for detecting recurrent decay and suggest that NIR images could be a reliable screening tool used in conjunction with PS-OCT for the detection and diagnosis of secondary caries.

Antimicrobial properties of conventional restorative filling materials and advances in antimicrobial properties of composite resins and glass ionomer cements—A literature review

ObjectivesIt has been reported that complete caries removal from cavities during restoration of teeth is difficult. Furthermore with the tissue saving approach it is expected that more of the saved affected tissue will possibly harbor more residual bacteria. Antimicrobial restorative filling materials would be ideal to prevent the spread of caries after completion of tooth restoration, thus preventing recurrent decay and eventually restoration failure. This paper reviews the literature on the antimicrobial properties of dental restorative filling materials. MethodsPubmed searches on the antibacterial properties of restorative materials were carried out. Keywords were chosen to assess antibacterial properties of conventional filling materials. Methods of introducing antimicrobial agents in restorative materials were also reviewed together with the methodology used to assess antimicrobial activity. Results174 articles from 1983 till 2014 were included. SignificanceAdhesive materials have decreased antimicrobial activity when compared to amalgams and zinc oxides. Several techniques have been employed in order to increase the antimicrobial activity of restorative materials. Although antimicrobial activity of restorative materials is important, the introduction of antimicrobial agents/techniques should not be at the expense of other material properties. Environmental changes within a material may affect the bacterial response to the antimicrobial. Bacterial adhesion to the restorative materials should be assessed. Long term assessment of antimicrobial activity is important and is clinically relevant. The use of antimicrobial dental materials is important unless such characteristics are gained to the detriment of other material properties.