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Excessive gingival display (EGD) is defined as more than 2 mm of gingiva display above the maxillary incisors at maximum smile. Various skeletal, dental, and soft tissue etiological factors for EGD have been suggested. This study assessed the effectiveness and stability of surgical (SX) and nonsurgical (NSX) interventions for correction of EGD through a systematic review and meta-analysis following PRISMA 2020 guidelines. An electronic search of Ovid MEDLINE, EMBASE, CENTRAL, Scopus, Web of Science, and LILACS was conducted (2010–2023). Results were expressed as mean change in gingival display using the random-effects model at 1, 3, 6, and 12-month follow-up. At 1 month, SX and NSX treatments yielded a comparable mean reduction of 3.50 mm (2.13–4.86) and 3.43 mm (2.67–4.19) in gingival display, respectively. However, by 6 months, NSX treatments showed a reduction of 0.51 mm compared to 2.86 mm with SX treatments. SX outcomes remained stable past 6 months, while NSX outcomes partially relapsed at 6 months and returned to baseline levels at 12 months. Notably, NSX treatments were more effective in cases with mild initial EGD, while SX treatments showed a better outcome in severe cases. To draw more robust conclusions regarding the treatment outcomes, future primary studies of greater rigor are required. [ABSTRACT FROM AUTHOR]

Despite reductions in bacterial infection and enhanced success rate, the widespread use of systemic antibiotic prophylaxis in implant dentistry is controversial. This use has contributed to the growing problem of antimicrobial resistance, along with creating significant health and economic burdens. The basic mechanisms that cause implant infection can be targeted by new prevention and treatment methods which can also lead to the reduction of systemic antibiotic exposure and its associated adverse effects. This review aims to summarize advanced biomaterial strategies applied to implant components based on anti-pathogenic mechanisms and immune balance mechanisms. It emphasizes that modifying the dental implant surface and regulating the early immune response are promising strategies, which may further prevent or slow the development of peri-implant infection, and subsequent failure. [ABSTRACT FROM AUTHOR]

Until recently, it was widely accepted that bacteria participate in caries pathogenesis mainly through carbohydrate fermentation and acid production, which promote the dissolution of tooth components. Neutrophils, on the other hand, were considered white blood cells with no role in caries pathogenesis. Nevertheless, current literature suggests that both bacteria and neutrophils, among other factors, possess direct degradative activity towards both dentinal collagen type-1 and/or methacrylate resin-based restoratives and adhesives, the most common dental restoratives. Neutrophils are abundant leukocytes in the gingival sulcus, where they can readily reach adjacent tooth roots or gingival and cervical restorations and execute their degradative activity. In this review, we present the latest literature evidence for bacterial, dentinal, salivary, and neutrophil degradative action that may induce primary caries, secondary caries, and restoration failure. [ABSTRACT FROM AUTHOR]

Tooth decay, or dental caries, is a widespread and costly disease that is reversible when detected early in its formation. Current dental caries diagnostic methods including X-ray imaging and intraoral examination lack the sensitivity and specificity required to routinely detect caries early in its formation. Thermophotonic imaging presents itself as a highly sensitive and non-ionizing solution, making it suitable for the frequent monitoring of caries progression. Here, we utilized a treatment protocol to produce bacteria-induced caries lesions. The lesions were imaged using two related three-dimensional photothermal imaging modalities: truncated correlation photothermal coherence tomography (TC-PCT) and its enhanced modification eTC-PCT. In addition, micro-computed tomography (μ-CT) and visual inspection by a clinical dentist were used to validate and quantify the severities of the lesions. The observational findings demonstrate the high sensitivity and depth profiling capabilities of the thermophotonic modalities, showcasing their potential use as a non-ionizing clinical tool for the early detection of dental caries. [ABSTRACT FROM AUTHOR]

Here, we explored the role of S. mutans's whole cell and discrete fractions in the degradation of type I collagen and dentinal collagen. Type I collagen gels and human demineralized dentin slabs (DS) were incubated in media alone or with one of the following: overnight (O/N) or newly inoculated (NEW) cultures of S. mutans UA159; intracellular proteins, supernatant or bacterial membranes of O/N cultures. Media from all groups were analyzed for protease-mediated release of the collagen-specific imino acid hydroxyproline. Images of type I collagen and DS were analyzed, respectively. Type I collagen degradation was highest for the supernatant (p < 0.05) fractions, followed by intracellular components and O/N cultures. Collagen degradation for DS samples was highest for O/N samples, followed by supernatant, and intracellular components (p < 0.05). There was lower detectable degradation for both type I collagen and DS from NEW culture samples (p < 0.05), and there was no type I collagen or DS degradation detected for bacterial membrane samples. Structural changes to type I collagen gel and dentinal collagen were observed, respectively, following incubation with S. mutans cultures (O/N and NEW), intracellular components, and supernatant. This study demonstrates that intracellular and extracellular proteolytic activities from S. mutans enable this cariogenic bacterium to degrade type I and dentinal collagen in a growth-phase dependent manner, potentially contributing to the progression of dental caries. [ABSTRACT FROM AUTHOR]

The ability to detect dental caries at early stages lies at the heart of minimal intervention dentistry, enabling the curing or arresting of carious lesions before they advance to the cavity stage. Enhanced truncated-correlation photothermal coherence tomography (eTC-PCT) using mid-wave infrared (MWIR) cameras has recently been shown to offer tomographic visualization of early caries. The tomographic slicing ability of such systems, however, is believed to be limited by direct radiative thermal emission through the translucent dental enamel in the 3-5 µm MWIR spectral range. Such radiative emissions can dominate the delayed conductive thermal contributions needed for tomographic reconstruction of internal dental defects. It has been hypothesized that long-wave infrared (LWIR) eTC-PCT systems may offer better tomographic performance by taking advantage of the intrinsic attenuation of direct radiative emission by dental enamel in the LWIR spectral range, enabling more effective delayed conductive thermal contributions from subsurface caries. More than an order of magnitude lower cost of the system is another key attribute of LWIR eTC-PCT which can open the door for downstream translation of the technology to clinics. In this report, we offer a systematic comparison of the performance/effectiveness of caries detection with LWIR and MWIR eTC-PCT systems for detecting natural caries, bacterial caries, and artificially demineralized enamel surfaces. Our results suggest that the low-cost LWIR based eTC-PCT system provides 3D visualization and 2D slice-by-slice images of early caries and internal micro-cracks similar to those obtained from the more expensive MWIR-based eTC-PCT system, albeit with ∼1.3dB lower signal-to-noise ratio. [ABSTRACT FROM AUTHOR]

Purpose: To assess the three-dimensional (3D) accuracy and clinical acceptability of implant definitive casts fabricated using a digital impression approach and to compare the results with those of a conventional impression method in a partially edentulous condition. Materials and Methods: A mandibular reference model was fabricated with implants in the first premolar and molar positions to simulate a patient with bilateral posterior edentulism. Ten implant-level impressions per method were made using either an intraoral scanner with scanning abutments for the digital approach or an open-tray technique and polyvinylsiloxane material for the conventional approach. 3D analysis and comparison of implant location on resultant definitive casts were performed using laser scanner and quality control software. The inter-implant distances and interimplant angulations for each implant pair were measured for the reference model and for each definitive cast (n = 20 per group); these measurements were compared to calculate the magnitude of error in 3D for each definitive cast. The influence of implant angulation on definitive cast accuracy was evaluated for both digital and conventional approaches. Statistical analysis was performed using t test (α = .05) for implant position and angulation. Clinical qualitative assessment of accuracy was done via the assessment of the passivity of a master verification stent for each implant pair, and significance was analyzed using chi-square test (α = .05). Results: A 3D error of implant positioning was observed for the two impression techniques vs the reference model, with mean ± standard deviation (SD) error of 116 ± 94 μm and 56 ± 29 μm for the digital and conventional approaches, respectively (P = .01). In contrast, the inter-implant angulation errors were not significantly different between the two techniques (P = .83). Implant angulation did not have a significant influence on definitive cast accuracy within either technique (P = .64). The verification stent demonstrated acceptable passive fit for 11 out of 20 casts and 18 out of 20 casts for the digital and conventional methods, respectively (P = .01). Conclusion: Definitive casts fabricated using the digital impression approach were less accurate than those fabricated from the conventional impression approach for this simulated clinical scenario. A significant number of definitive casts generated by the digital technique did not meet clinically acceptable accuracy for the fabrication of a multiple implant-supported restoration. [ABSTRACT FROM AUTHOR]

Biomaterial–dentin interfaces undergo degradation over time, allowing salivary, tissue fluid, and bacterial movement between the root filling or restoration and dentin. This study aims to investigate the effect of aging in simulated human salivary/bacterial/blood esterases (SHSE) on proliferation and viability of Enterococcus faecalis biofilm within the dentin interface with four materials used to fill/restore the endodontic space. Root canals of human anterior teeth were prepared and filled with gutta-percha and one of the following: self-cured resin composite (BisfilTM 2B, Bisco, Schaumburg, IL, USA) with either self-etch (SE) (EasyBond) or total-etch (TE) (ScotchbondTM, 3M, Saint Paul, MN, USA) methacrylate-based adhesives, epoxy-resin sealer (AH Plus®, Dentsply Sirona, York, PA, USA), or bioceramic sealer (EndoSequence® BC Sealer™, Brasseler USA, Savannah, GA, USA). Specimens were aged in SHSE or phosphate-buffered saline (PBS) for up to 360 days, followed by cultivation of steady-state E. faecalis biofilm. Depth and viability of interfacial bacterial biofilm proliferation were assessed by confocal laser scanning microscopy and live/dead staining. Data were analyzed using three-way ANOVA and Scheffe's post hoc analyses. Initial depths of biofilm proliferation were similar among material groups (p > 0.05). All groups showed significantly deeper biofilm proliferation with increased aging period (p < 0.05). SHSE aging increased interfacial biofilm depth for TE, SE and BC (p < 0.05) but not AH. For unaged interfaces, BC exhibited the lowest ratio of live bacteria, followed by AH, TE, and SE (p < 0.05). Interfacial bacterial biofilm proliferation and viability were dependent on the biomaterial, aging media, and period. [ABSTRACT FROM AUTHOR]

Purpose:To compare the in vitro 3-dimensional (3D) accuracy of fit of laser-scanned Computer Numeric Controlled (CNC)--milled implant titanium frameworks to that of conventional cast frameworks. Materials and Methods: Nine cast frameworks were fabricated on the mandibular master casts of 9 patients with 5 implants each following the well-established conventional fabrication technique. The frameworks were then laser scanned, and 9 CNC-milled titanium frameworks matching the outline of the conventional frameworks were fabricated. The accuracy of fit of both framework types was measured using a contact-type coordinate measuring machine and a computer program developed specifically for this purpose. Statistical analysis was done by a series of paired ttests. Results:The laser-scanned CNC-milled frameworks showed significantly less distortion along the x-axis (transversal, dx) compared with the conventional frameworks (means: 33.7µm and 49.2 µm, respectively) ( P= .011). The titanium frameworks also demonstrated significantly less distortion on the horizontal plane compared with the conventional frameworks (means: 56 µm and 85 µm, respectively) ( P= .012). The dy (sagittal) and dz (vertical) axes and total 3D distortion (√ dx² + dy² + dz²) showed less distortion overall in the laser-scanned CNC-milled frameworks, but this was not statistically significant (mean: 22.3 vs 35.6 µm, 13.3 vs 59.2 µm, 51 vs 114.1 µm, respectively, for y, z, and 3D distortion). Conclusion:Within the limitations of this study, fabrication of an implant-prosthodontic framework using the CNC milling technique yields a more accurate fit than the currently used cast technique. In vivo studies are needed to investigate the clinical significance of this recorded difference. [ABSTRACT FROM AUTHOR]

Purpose: To compare the clinical outcomes of immediate versus conventional delayed loading of four dental implants in edentulous mandibles with fixed prostheses. Materials and methods: A blinded, two-arm, parallel group, randomised controlled trial was conducted. A total of 42 patients were included, and each received four Brånemark System implants with a TiUnite surface. The patients were randomly assigned to two study arms: 1) immediateloading arm (IL), in which the mandibular denture was converted into an interim implant-supported fixed prosthesis (ISFP) on the day of surgery, with a permanent ISFP being inserted at least 3 months postsurgery; 2) conventional-loading arm (CL), in which the mandibular removable prosthesis was relieved at the implant site and relined with a soft tissue conditioner. Only implants with a minimum insertion torque of = 35 Ncm were included in the IL group. Implants were loaded 4 to 6 months postsurgery. Independent, blind investigators assessed the patients at 2, 6 and 12 months and at 10 years. The outcome measures were prosthesis and implant success rates, type and frequency of complications and changes in peri-implant marginal bone levels. Results: A total of 20 patients were allocated to the IL group and 22 to the CL group. However, one patient from the IL arm was excluded and three patients were reallocated to the CL arm. Two implants in one patient and one in another patient could not be placed with a = 35 Ncm insertion torque, and a third patient developed severe sudden gag reflex and thus it was not possible to load the implants immediately. At a later stage, one of the patients who failed the initial stability test dropped out of the study. Therefore, initially, 24 patients were conventionally loaded and 16 patients were immediately loaded. At the 10-year follow-up, six patients dropped out from the IL arm and two from the CL arm. Also, at the 10-year-follow-up, the CL and IL study arms consisted of 22 and 10 participants, respectively, using the per-protocol (PP) analysis. Six implants failed in two patients of the CL arm (two implants in one patient and four implants in another patient), and three implants failed in three patients in the IL arm (PP analysis), respectively. The patient-level implant failure rate was 10% (intention-to-treat [ITT] analysis) and 14% (PP analysis) in the CL arm, and 25% (ITT) and 20% (PP) in the IL arm. The difference was not statistically significant (95% CI from -0.18 to 0.39, P = 0.65). The failure rate at the implant level was 8% (ITT) and 8% (PP) in the CL arm, and 6% (ITT) and 5% (PP) in the IL arm. The difference was not statistically significant (95% CI from -0.06 to 0.14, P = 0.44). Ten years after loading, patients in the IL arm lost an average of 0.55 ± 0.64 mm of peri-implant bone versus 0.41 ± 0.40 mm of peri-implant bone loss observed in the CL arm. The 10-year bone loss in both arms was statistically significant compared with the baseline (P < 0.001). However, there was no statistically significant difference between the two arms for peri-implant bone level changes (the difference between the arms was 0.14 mm ± 0.50 mm; 95% CI --0.23 to 0.52; P = 0.43). One prosthesis failed due to the loss of all four implants in one patient of the CL arm. Eight patients from the IL arm were affected by 13 complications (such as pain from fractures and inflammation) versus seven patients (10 complications) from the CL arm. The complication rate was 67% in the IL arm and 35% in the CL arm. The difference in complication proportions between the two arms was not statistically significant (difference in proportions = 0.32; 95% CI = --0.08 to 0.61; P = 0.14). All complications were managed successfully. Conclusions: Long-term data of immediate loading of four dental implants with a mandibular fixed prosthesis revealed comparable clinical outcomes to conventional loading. Therefore, immediate loading should be considered in the treatment of edentulous patients. [ABSTRACT FROM AUTHOR]

Triethylene glycol dimethacrylate (TEGDMA) is a diluent monomer used pervasively in dental composite resins. Through hydrolytic degradation of the composites in the oral cavity it yields a hydrophilic biodegradation product, triethylene glycol (TEG), which has been shown to promote the growth of Streptococcus mutans, a dominant cariogenic bacterium. Previously it was shown that TEG up-regulated gtfB, an important gene contributing to polysaccharide synthesis function in biofilms. However, molecular mechanisms related to TEG’s effect on bacterial function remained poorly understood. In the present study, S. mutans UA159 was incubated with clinically relevant concentrations of TEG at pH 5.5 and 7.0. Quantitative real-time PCR, proteomics analysis, and glucosyltransferase enzyme (GTF) activity measurements were employed to identify the bacterial phenotypic response to TEG. A S. mutans vicK isogenic mutant (SMΔvicK1) and its associated complemented strain (SMΔvicK1C), an important regulatory gene for biofilm-associated genes, were used to determine if this signaling pathway was involved in modulation of the S. mutans virulence-associated genes. Extracted proteins from S. mutans biofilms grown in the presence and absence of TEG were subjected to mass spectrometry for protein identification, characterization and quantification. TEG up-regulated gtfB/C, gbpB, comC, comD and comE more significantly in biofilms at cariogenic pH (5.5) and defined concentrations. Differential response of the vicK knock-out (SMΔvicK1) and complemented strains (SMΔvicK1C) implicated this signalling pathway in TEG-modulated cellular responses. TEG resulted in increased GTF enzyme activity, responsible for synthesizing insoluble glucans involved in the formation of cariogenic biofilms. As well, TEG increased protein abundance related to biofilm formation, carbohydrate transport, acid tolerance, and stress-response. Proteomics data was consistent with gene expression findings for the selected genes. These findings demonstrate a mechanistic pathway by which TEG derived from commercial resin materials in the oral cavity promote S. mutans pathogenicity, which is typically associated with secondary caries. [ABSTRACT FROM AUTHOR]

Human molars were subjected to demineralization in acid gel followed by incubation in remineralization solutions without or with fluoride (1 or 1000 ppm). Photothermal radiometry (PTR) and modulated luminescence (LUM) frequency scans were performed prior to and during de/remineralization treatments. Transverse Micro-Radiography (TMR) analysis followed at treatment conclusion to determine mineral loss and lesion depth. The remineralization process illustrated a complex interplay between surface and subsurface mineral deposition, confining the thermal-wave centroid toward the dominating layer. Experimental amplitudes and phases were fitted to a coupled diffuse-photon-density-wave and thermal-wave theoretical model used to quantitatively evaluate evolving changes in thermal and optical properties of de/remineralized enamel lesions. Additional information obtained from the LUM data corroborated the remineralization kinetics affecting the PTR signals. The results pointed to enhanced effectiveness of subsurface lesion remineralization in the presence of fluoride. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Human Salivary Derived Esterases (HSDE) are part of the salivary group of enzymes which show strong degradative activity toward the breakdown of one of the most common monomers used in dental composites and adhesives, 2,2‐[4(2‐hydroxy 3‐methacryloxypropoxy)‐phenyl] propane (Bis‐GMA), to form the degradation product 2,2‐bis [4 (2,3‐hydroxy‐propoxy)phenyl] propane (Bis‐HPPP). This study was aimed to evaluate the effects of HSDE on the biodegradation and fracture toughness of the adhesive resin‐dentin interface. Adhesive resin (Scotchbond Multi Purposes), resin composite (Z250) and mini short‐rod specimens, were either not incubated; or incubated in phosphate‐buffered saline (PBS) or HSDE media for up to 180 days (37°C, pH 7.0). The amount of Bis‐HPPP was analyzed by high performance liquid chromatography and mini‐SR specimens were tested for fracture toughness using universal testing machine following 30, 90, or 180‐day incubation periods. Significantly higher amounts of Bis‐HPPP were produced in HSDE than in PBS incubated specimens (p < 0.05). Non‐incubated mini‐SR specimens had the higher fracture‐toughness values, while specimens incubated for 180‐days in HSDE had the lowest fracture toughness (p < 0.05). This study suggests that biodegradation is an on‐going clinically relevant process that progressively compromises the integrity of the critical resin restoration‐adhesive interface, as well as the resin‐composite component with time. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. [ABSTRACT FROM AUTHOR]

The article discusses the result of a study which investigated neck parameters and self-limiting bone remodeling in dental implants. It suggests ways to reduce self-limiting post-uncovering bone remodeling which includes elimination of the implant-abutment interface and the addition of micromechanical features such as microthreads. The findings also suggests dental surgeons must exercise caution and care in utilizing research data of implant applications which are based on animal studies.

This article presents a study on the use of bioactive agents on dental implant surfaces to improve osseointegration. Bioactive agents that have been studied include bisphosphonate pamidronate, bone morphogenic proteins (BMP), and hydroxyapatite. A summary of the findings of studies on bioactive agents, particularly BMP, is also presented. Although BMP shows the most potential benefits, the authors conclude that further investigation on the application of any bioactive agent to dental implant surfaces is warranted.

The article presents a study to determine which design geometry of osseointegrated dental implants is superior to others in terms of osseointegration. Osseointegration was discovered by Dr. Per-Ingvar Branemark in 1965 when he inserted a metal cylinder in a rabbit's thigh which fused with the bone after several months. A table summarizing the findings on different design geometry is also presented. The authors conclude that no reliable data is available to determine which dental implant design is superior to others.

Purpose: All-ceramic crowns are subject to fracture during function, especially in the posterior area. The use of yttrium-stabilized zirconium-oxide ceramic as a substructure for all-ceramic crowns to improve fracture resistance is unproven. The aim of this study was to compare fracture strength and fatigue resistance of new zirconium-oxide and feldspathic all-ceramic crowns made with computer-aided design/computer-aided manufacturing (CAD/CAM). Materials and Methods: An ivorine molar was prepared to receive an all-ceramic crown. Using epoxy resin, 40 replication dies were made of the prepared tooth. Twenty feldspathic all-ceramic crowns (Vita Mark II) (VMII) and 20 zirconium-oxide crown copings (In-Ceram YZ) (YZ) were made using CAD/CAM technique (CEREC-3D). The YZ copings were sintered and veneered manually with a fine-particle ceramic (VM9). All crowns were cemented to their respective dies using resin cement (Panavia F 2.0). Ten crowns in each group were subjected to compressive fatigue loading in a universal testing machine (instron). The other ten crowns from each group were loaded to fracture at a crosshead speed of 1 mm/min. Data were statistically analyzed using independent t-test and Fisher's exact test at α= 0.05. Results: There was a significant difference between the survival rates of the two materials during the fatigue test ( p < 0.001). All VMII crowns survived without any crack formation, while all YZ crowns fractured (40%) or developed cracks (60%). All the YZ crown fractures occurred within the veneering layer during the fatigue test. There was no significant difference in mean fracture load between the two materials ( p= 0.268). Mean fracture loads (standard deviation) in N were: 1459 (492) for YZ crowns and 1272 (109) for VMII crowns. Conclusions: The performance of VMII crowns was superior to YZ crowns in the fatigue test. The premature fractures and cracks of the YZ crowns were attributed to weakness in the YZ veneer layer or in the core/veneer bond. [ABSTRACT FROM AUTHOR]

Despite their popularity, resin composite restorations fail earlier and at higher rates than comparable amalgam restorations. One of the reasons for these rates of failure are the properties of current dental bonding agents. Modern bonding agents are vulnerable to gradual chemical and mechanical degradation from a number of avenues such as daily use in chewing, catalytic hydrolysis facilitated by salivary or bacterial enzymes, and thermal fluctuations. These stressors have been found to work synergistically, all contributing to the deterioration and eventual failure of the hybrid layer. Due to the expense and difficulty in conducting in vivo experiments, in vitro protocols meant to accurately simulate the oral environment's stressors are important in the development of bonding agents and materials that are more resistant to these processes of degradation. This narrative review serves to summarize the currently employed methods of aging dental materials and critically appraise them in the context of our knowledge of the oral environment's parameters. [ABSTRACT FROM AUTHOR]

In recent years, due to a better understanding of the caries pathology and advances in dental materials, the utilization of non-invasive and minimally invasive techniques that delay/obviate the need for traditional restorations has started gaining momentum. This literature review focuses on some of these approaches, including fluoride varnish, silver diamine fluoride, resin sealants, resin infiltration, chemomechanical caries removal and atraumatic restorative treatment, in the context of their chemistries, indications for use, clinical efficacy, factors determining efficacy and limitations. Additionally, we discuss strategies currently being explored to enhance the antimicrobial properties of these treatment modalities to expand the scope of their application. [ABSTRACT FROM AUTHOR]

The use of resin composites and adhesives in dental restorations is ubiquitous. However, the longevity of resin composites is less than that of comparable restorative materials, mainly because of higher fracture rates and greater prevalence of secondary caries. Dental resin composites and adhesives contain ester links, which are vulnerable to biochemical hydrolysis by esterase activity from human saliva and bacteria. In this article, we review biodegradation processes that occur in the oral cavity and their contribution to the premature failure of resin composites. Biodegradation causes deterioration of resin composite bulk and the composite-tooth interface and releases by-products, such as methacrylic acid, triethylene glycol and bishydroxy-propoxy-phenyl-propane. These by-products have been shown to affect cariogenic bacterial growth and virulence. A compromised restoration-tooth interface allows saliva and oral bacteria to infiltrate the spaces between the tooth and the composite, exacerbating the effects of biodegradation, undermining the restoration and leading to recurrent caries, hypersensitivity and pulpal inflammation. It is important to consider the biochemical stability of these materials to advance their chemistry beyond the current formulations and conceive more biochemically stable and better-performing dental resin composites and adhesives. [ABSTRACT FROM AUTHOR]

Bacteriocins are ribosomally synthesized proteinaceous antibacterial peptides. They selectively interfere with the growth of other bacteria. The production and secretion of bacteriocins confer a distinct ecological advantage to the producer in competing against other bacteria that are present in the same ecological niche. Streptococcus mutans, a significant contributor to the development of dental caries, is one of the most prolific producers of bacteriocins, known as mutacins in S. mutans. In this study, we characterized the locus encoding mutacin B-Ny266, a lantibiotic with a broad spectrum of activity. The chromosomal locus is composed of six predicted operon structures encoding proteins involved in regulation, antimicrobial activity, biosynthesis, modification, transport, and immunity. Mutacin B-Ny266 was purified from semisolid cultures, and two inhibitory peptides, LanA and LanA', were detected. Both peptides were highly modified. Such modifications include dehydration of serine and threonine and the formation of a C-terminal aminovinyl-cysteine (AviCys) ring. While LanA peptide alone is absolutely required for antimicrobial activity, the presence of LanA' enhanced the activity of LanA, suggesting that B-Ny266 may function as a two-peptide lantibiotic. The activation of lanAA' expression is most likely controlled by the conserved two-component system NsrRS, which is activated by LanA peptide but not by LanA'. The chromosomal locus encoding mutacin B-Ny266 was not universally conserved in all sequenced S. mutans genomes. Intriguingly, the genes encoding LanAA' peptides were restricted to the most invasive serotypes of S. mutans. [ABSTRACT FROM AUTHOR]