Biocompatibility and mineralization potential of new calcium silicate cements.

Background/purpose: As calcium silicate cements (CSCs) have been successfully used in various types of vital pulp therapy, many new CSC products have been developed. The aim of this study was to evaluate the biocompatibilities and mineralization potential of new CSC. The experimental materials were NeoMTA Plus and EndoSequence Root Repair Material-Fast Set Putty (ERRM-FS) which were compared to ProRoot MTA. Materials and methods: In vitro, the effects of the new CSC on stem cells were evaluated. Each CSC was prepared for cell viability testing, alkaline phosphatase (ALP) assay, and calcium ion release assay. In vivo, the exposed pulp model was used for the partial pulpotomy procedure. Thirty-six teeth were treated with three materials: ProRoot MTA, NeoMTA Plus, or ERRM-FS. After four weeks, the teeth were extracted and processed for histologic analysis. Dentin bridge formation, pulp inflammation, and odontoblastic cell layer were evaluated and the area of newly formed calcific barrier of each group was measured. Results: Three CSCs demonstrated similar cell viability on stem cells and the levels of ALP and calcium release were not significantly different between tested materials. ProRoot MTA and ERRM-FS showed better tissue healing process than NeoMTA Plus after partial pulpotomy, in terms of quality of calcific barrier and pulp inflammation. The outcomes from measuring newly formed calcific area demonstrated no significant differences between the materials. Conclusion: NeoMTA Plus and ERRM-FS displayed similar biocompatibilities and mineralization potential compared to ProRoot MTA. Therefore, these new CSCs can be used as desirable alternatives to ProRoot MTA.

Establishment of quantitative indicators for an efficient treatment on masticatory muscle pain.

BACKGROUND: Although several studies have investigated effective treatments for masticatory muscle pain (MMP), no unified conclusion has been drawn regarding the effectiveness of these treatments. OBJECTIVES: This study aimed to define quantitative indicators for predicting the outcome of MMP treatment. MATERIALS AND METHODS: In total, patients aged 20-70 years were recruited and divided into the MMP (n = 24) and control (n = 36) groups, based on the presence of MMP according to the Diagnostic Criteria for Temporomandibular Disorders. At pretreatment, the MMP group was assessed using quantitative indicators such as subjective pain levels, pain duration, graded chronic pain scale (GCPS), and perceived stress scale (PSS). Salivary alpha-amylase (sAA) and interleukin-6 (IL-6) levels were analyzed. The masticatory muscle palpation score and the range of mouth opening were measured. At posttreatment, subjective pain levels, mouth opening, and treatment/medication duration were examined. The PSS and sAA levels were assessed in the control group. RESULTS: sAA levels in the MMP group were significantly higher than those in the control group (p < .05). The masseter muscle palpation score (MPS) showed a positive correlation with IL-6 levels (ρ = 0.503, p < .05) and a negative correlation with nonsteroidal anti-inflammatory drug (NSAID) treatment period (ρ = -0.462, p < .05). The temporalis muscle palpation score (TPS) was positively correlated with pain duration and GCPS grade (ρ = 0.483, p < .05, and ρ = 0.445, p < .05, respectively). CONCLUSIONS: Treatment with NSAIDs was effective in the MMP group with high MPS and IL-6 levels, but not in the MMP group with high TPS, pain duration, and GCPS grade.

Chemical and Physical Properties of Contemporary Pulp Capping Materials.

Purpose: The purpose of this study was to compare the chemical and physical properties of eight contemporary direct pulp capping materials. Methods: Materials included: calcium hydroxide-based (Dycal®, Lime-LiteTM, and Ultra-BlendTM plus), bioceramic-based (MTA Angelus®, Biodentine®, TheraCal LC®, Ceramir® Protect LC), and resin ionomer-based materials (Bio-Cap®). Calcium release and pH changes were measured after one, seven, 28, and 90 days in 36.8 degrees Celsius of deionized water. Water sorption and solubility were calculated with weight loss after 90 days. Results: Biodentine® (965.5 ppm) and MTA Angelus® (921.2 ppm) released significantly more cumulative calcium ions (P<0.05), followed by Ceramir® Protect LC (450.8 ppm) and Dycal® (268.1 ppm); Lime-LiteTM had the least amount of calcium ions. After 90 days, Biodentine® and MTA Angelus® showed significantly higher pH (P<0.05), while Bio-Cap® and Lime-LiteTM had limited effects in raising the pH to alkaline. Dycal® presented the most weight loss (26 percent, P<0.05) after 90 days. Conclusions: Biodentine® and MTA Angelus® demonstrated more favorable in vitro characteristics for clinical pulp capping purposes, while Lime-LiteTM had no effect in releasing calcium ions and limited influence in raising pH value.

Evaluation of children's pain expression and behavior using audio visual distraction.

OBJECTIVES: Dental anxiety distresses children and their families with consequent poor oral health and costly pediatric dental services. Children's behaviors could be modified using a distraction technique for improved dental treatment. The study evaluates the effects of an audio-visual distraction on children's behaviors and pain expressions during dental treatment. MATERIAL AND METHODS: One hundred healthy children, between 4 and 6 years of age, were randomly assigned to one of two groups: audio visual distraction (AVD, N = 61) group and control (CTR, N = 39) group. The pre and post pain expression was collected using a faces pain rating scale from the participated children. Children's behavior was evaluated using the Frankl behavior rating scale by the assigned dentist. Data was analyzed using chi-squared tests and analysis of variance. RESULTS: The AVD group demonstrated more "definitely positive" behavior (91.8%) compared to the CTR group (35.9%) based on the Frankl scale evaluation from pre- and post-treatment (p < 0.0001). The pain rating scale did not demonstrate a significant difference in post-treatment pain scales (p = 0.2073) or changes in pain (p = 0.1532) between the AVD group and CTR group. CONCLUSIONS: The AVD is an effective distraction tool for young children during dental treatment regardless of child's subjective pain expression.

In Vivo Evaluation of Decellularized Human Tooth Scaffold for Dental Tissue Regeneration.

Conventional root canal treatment may result in loss of tooth vitality, which can lead to unfavorable treatment outcomes. Notably, a ceased tooth development of immature permanent teeth with open apices, regeneration of periodontal ligaments (PDL), and pulp is highly expected healing process. For regeneration, the scaffold is one of the critical components that carry biological benefits. Therefore, this study evaluated a decellularized human tooth as a scaffold for the PDL and pulp tissue regeneration. A tooth scaffold was fabricated using an effective decellularization method as reported in previous studies. PDL stem cells (PDLSCs) and dental pulp stem cells (DPSCs) obtained from human permanent teeth were inoculated onto decellularized scaffolds, then cultured to transplant into immunosuppressed mouse. After 9 weeks, PDLSCs and DPSCs that were inoculated onto decellularized tooth scaffolds and cultured in an in vivo demonstrated successful differentiation. In PDLSCs, a regeneration of the cementum/PDL complex could be expected. In DPSCs, the expression of genes related to revascularization and the hard tissue regeneration showed the possibility of pulp regeneration. This study suggested that the potential possible application of decellularized human tooth could be a scaffold in regeneration PDL and pulp tissue along with PDLSCs and DPSCs, respectively, as a novel treatment method.

Doxycycline-Loaded Nitric Oxide-Releasing Nanomatrix Gel in Replanted Rat Molar on Pulp Regeneration.

The aim of the present study was to evaluate the effect of doxycycline-loaded NO-releasing nanomatrix gel on pulp regeneration in replantation of avulsed rat teeth. A total of 28 maxillary first molars extracted from rats were replanted. The rats were divided into two groups based on the use of root surface treatment: doxycycline-loaded NO-releasing nanomatrix group and no treatment. Eight weeks after replantation, the rats were sacrificed, and the teeth were evaluated using histomorphometric analysis. On histomorphometric analysis, the NO-releasing nanomatrix group demonstrated a significantly lower grade of pulp inflammation (1.00 ± 1.11, mean ± standard deviation) compared to the no treatment group (2.21 ± 1.25, p = 0.014). NO-releasing nanomatrix group showed a significantly higher grade of pulp regeneration (2.57 ± 0.85, p = 0.012) and significantly lower grade of pulp inflammation (1.00 ± 0.68, p = 0.025) compared to the no treatment group. In conclusion, NO-releasing nanomatrix gel improved pulp regeneration of replanted teeth, though the sample size of this study was rather small. Within the limits of this study, NO-releasing nanomatrix gel can provide more favorable pulpal regeneration despite replantation.

Pulp-Dentin Tissue Healing Response: A Discussion of Current Biomedical Approaches.

Dental pulp tissue exposed to mechanical trauma or cariogenic process results in root canal and/or periapical infections, and conventionally treated with root canal procedures. The more recent regenerative endodontic procedure intends to achieve effective root canal disinfection and adequate pulp-dentin tissue regeneration; however, numerous limitations are reported. Because tooth is composed of vital soft pulp enclosed by the mineralized hard tissue in a highly organized structure, complete pulp-dentin tissue regeneration has been challenging to achieve. In consideration of the limitations and unique dental anatomy, it is important to understand the healing and repair processes through inflammatory-proliferative-remodeling phase transformations of pulp-dentin tissue. Upon cause by infectious and mechanical stimuli, the innate defense mechanism is initiated by resident pulp cells including immune cells through chemical signaling. After the expansion of infection and damage to resident pulp-dentin cells, consequent chemical signaling induces pluripotent mesenchymal stem cells (MSCs) to migrate to the injury site to perform the tissue regeneration process. Additionally, innovative biomaterials are necessary to facilitate the immune response and pulp-dentin tissue regeneration roles of MSCs. This review highlights current approaches of pulp-dentin tissue healing process and suggests potential biomedical perspective of the pulp-dentin tissue regeneration.

Candida Infection Associated with Salivary Gland-A Narrative Review.

Candida species are common global opportunistic pathogens that could repeatedly and chronically cause oral mucosa infection and create an inflammatory environment, leading to organ dysfunction. Oral Candida infections may cause temporary or permanent damage to salivary glands, resulting in the destruction of acinar cells and the formation of scar tissue. Restricted function of the salivary glands leads to discomfort and diseases of the oral mucosa, such as dry mouth and associated infection. This narrative review attempts to summarize the anatomy and function of salivary glands, the associations between Candida and saliva, the effects of Candida infection on salivary glands, and the treatment strategies. Overall, clinicians should proactively manage Candida infections by educating patients on oral hygiene management for vulnerable populations, conducting frequent checks for a timely diagnosis, and providing an effective treatment plan.

Evaluation of the periodontal and pulpal healing of replanted rat molars with doxycycline root conditioning.

PURPOSE: This study aimed to evaluate periodontal and pulpal healing in replanted rat teeth, preserved under different storage conditions, with or without root conditioning using doxycycline. METHODS: A total of 40 maxillary first molars extracted from 20 Sprague-Dawley rats were stored for different durations under different conditions (5 minutes in dry storage and 60 minutes in Hank's balanced salt solution [HBSS]) and subsequently replanted. The rats were divided into 2 groups based on the use of root surface treatment: the doxycycline group (root surface treated with doxycycline) and the control group (no doxycycline treatment). Eight weeks after replantation, the animals were sacrificed, and the teeth were evaluated using micro-computed tomography (micro-CT) and histomorphometric analysis. RESULTS: In the micro-CT analysis, the doxycycline group showed the same rate of occurrence of periapical radiolucency as was observed in the control group, but a lower degree of root resorption in teeth replanted after 60 minutes of storage in HBSS (P<0.05). In the histomorphometric analysis, the doxycycline group exhibited no improvement in either pulpal or periodontal healing of the replanted tooth after 5 minutes of dry storage, but showed a lower grade of surface root resorption (1.37±0.77) and inflammatory resorption in the teeth stored for 60 minutes in HBSS (1.33±0.71). CONCLUSIONS: In conclusion, doxycycline improved the periodontal healing of replanted teeth stored for 60 minutes in HBSS, whereas doxycycline did not improve periodontal healing of replanted tooth after 5 minutes of dry storage. Within the limits of this study, doxycycline showed more favorable periodontal healing despite delayed replantation.

Effects of the nitric oxide releasing biomimetic nanomatrix gel on pulp-dentin regeneration: Pilot study.

Successful disinfection alongside complete endodontic tissue regeneration and revascularization are the most desired clinical outcomes of regenerative endodontics. Despite reported clinical successes, significant limitations to the current regenerative endodontic procedure (REP) have been elucidated. To improve the current REP, an antibiotics and nitric oxide (NO) releasing biomimetic nanomatrix gel was developed. The study evaluates antibacterial effects of an antibiotics and NO releasing biomimetic nanomatrix gel on multispecies endodontic bacteria. Antibiotics, ciprofloxacin (CF) and metronidazole (MN) were mixed and encapsulated within the NO releasing biomimetic nanomatrix gel. The gel was synthesized and self-assembled from peptide amphiphiles containing various functional groups. Antibacterial effects of the antibiotics and NO releasing biomimetic nanomatrix gel were evaluated using bacterial viability assays involving endodontic microorganisms including clinical samples. Pulp-dentin regeneration was evaluated via animal-model experiments. The antibiotics and NO releasing biomimetic nanomatrix gel demonstrated a concentration dependent antibacterial effect. In addition, NO alone demonstrated a concentration dependent antibacterial effect on endodontic microorganism. An in vivo analysis demonstrated the antibiotics and NO releasing biomimetic nanomatrix gel promoted tooth revascularization with maturation of root canals. An optimal concentration of and NO releasing nanomatrix gel is suggested for its potential as a root treatment material for REP and an appropriate protocol for human trials. Further investigation is required to obtain a larger sample size and decide upon ideal growth factor incorporation.

Angiogenic and Osteogenic Synergy of Human Mesenchymal Stem Cells and Human Umbilical Vein Endothelial Cells Cocultured on a Nanomatrix.

To date, bone tissue regeneration strategies lack an approach that effectively provides an osteogenic and angiogenic environment conducive to bone growth. In the current study, we evaluated the osteogenic and angiogenic response of human mesenchymal stem cells (hMSCs) and green fluorescent protein-expressing human umbilical vein endothelial cells (GFP-HUVECs) cocultured on a self-assembled, peptide amphiphile nanomatrix functionalized with the cell adhesive ligand RGDS (PA-RGDS). Analysis of alkaline phosphatase activity, von Kossa staining, Alizarin Red quantification, and osteogenic gene expression, indicates a significant synergistic effect between the PA-RGDS nanomatrix and coculture that promoted hMSC osteogenesis. In addition, coculturing on PA-RGDS resulted in enhanced HUVEC network formation and upregulated vascular endothelial growth factor gene and protein expression. Though PA-RGDS and coculturing hMSCs with HUVECs were each previously reported to individually enhance hMSC osteogenesis, this study is the first to demonstrate a synergistic promotion of HUVEC angiogenesis and hMSC osteogenesis by integrating coculturing with the PA-RGDS nanomatrix. We believe that using the combination of hMSC/HUVEC coculture and PA-RGDS substrate is an efficient method for promoting osteogenesis and angiogenesis, which has immense potential as an efficacious, engineered platform for bone tissue regeneration.

Orthodontic Treatment in Conjunction with Twin-bock Treatment and Growth Hormone Therapy in Silver Russell Syndrome.

Silver-Russell syndrome (SRS) is a very rare genetic disorder characterized by intrauterine growth retardation, short stature, and typical craniofacial abnormalities including micrognathia. While growth hormone (GH) therapy in children with SRS significantly improves somatic growth, functional orthopedic treatment can also be effective in adolescents with mandibular deficiency. We report the effects of Phase 1 functional orthopedic treatment of a twin-block appliance in conjunction with GH administration in a 9-year-old boy with GH deficiency and SRS, and the result of the subsequent Phase 2 orthodontic treatment.

Association Between Early Childhood Caries and Colonization with Streptococcus mutans Genotypes From Mothers.

PURPOSE: The purpose of this study was to evaluate Streptococcus mutans genotypes (GT) between mother and child (M-C) in a high caries risk cohort to explore the association with early childhood caries (ECC). METHODS: Sixty-nine infants (each approximately one year old) had periodic oral examinations (dmfs) and microbial samples collected from dental plaque, saliva, and other oral surfaces. Their mothers had an examination and plaque collected. S mutans isolates were genotyped using repetitive extragenic palindromic-PCR (rep-PCR). Statistical analyses were conducted for associations of S mutans in M-C dyads with caries outcomes. RESULTS: Twenty-seven S mutans genotypes (GT) from 3,414 isolates were identified. M-C were categorized as GT match (n equals 40) or no-match (n equals 29). When modeling the severity of ECC at 36 months (approximately four years old), the estimated dmfs in the match group was 2.61 times that of the no-match group (P=.014). CONCLUSIONS: Colonization of children with Streptococcus mutans genotypes that matched with mothers was shown to be highly associated with early childhood caries. Although the data suggest vertical transmission of S mutans in 40 of 69 children that shared GT with their mother, it is possible that other individuals transmitted the S mutans. Nonetheless, these findings support the importance of the mother's oral microbial status as a contributing influence to their children's oral health.

Genetic Diversity and Evidence for Transmission of Streptococcus mutans by DiversiLab rep-PCR.

This two-part study investigated the genetic diversity and transmission of Streptococcus mutans using the DiversiLab repetitive extragenic palindromic PCR (rep-PCR) approach. For children with S. mutans and participating household members, analysis for evidence of unrelated child-to-child as well as intra-familial transmission was evaluated based on commonality of genotypes. A total of 169 index children and 425 household family members from Uniontown, Alabama were evaluated for genetic diversity using rep-PCR. Thirty-four unique rep-PCR genotypes were observed for 13,906 S. mutans isolates. For transmission, 117 child and household isolates were evaluated for shared genotype (by child and by genotype cases, multiple matches possible for each child). Overall, children had 1-9 genotypes and those with multiple genotypes were 2.3 times more likely to have caries experience (decayed, missing and filled teeth/surfaces>0). Only 28% of children shared all genotypes within the household, while 72% had at least 1 genotype not shared with anyone in the household. Children had genotype(s) not shared with any household members in 157 cases. In 158 cases children and household members shared a genotype in which 55% (87/158 cases) were shared with more than one family member. Children most frequently shared genotypes with their mothers (54%; 85/158), siblings (46%; 72/158) and cousins (23%; 37/158). A reference library for S. mutans for epidemiological surveillance using the DiversiLab rep-PCR approach is detailed. The genetic diversity of S. mutans in this population demonstrated frequent commonality of genotypes. Evidence for both child-to-child and intra-familial transmission of S. mutans was observed by rep-PCR.

Biomimetic microenvironments for regenerative endodontics.

Regenerative endodontics has been proposed to replace damaged and underdeveloped tooth structures with normal pulp-dentin tissue by providing a natural extracellular matrix (ECM) mimicking environment; stem cells, signaling molecules, and scaffolds. In addition, clinical success of the regenerative endodontic treatments can be evidenced by absence of signs and symptoms; no bony pathology, a disinfected pulp, and the maturation of root dentin in length and thickness. In spite of the various approaches of regenerative endodontics, there are several major challenges that remain to be improved: a) the endodontic root canal is a strong harbor of the endodontic bacterial biofilm and the fundamental etiologic factors of recurrent endodontic diseases, (b) tooth discolorations are caused by antibiotics and filling materials, (c) cervical root fractures are caused by endodontic medicaments, (d) pulp tissue is not vascularized nor innervated, and (e) the dentin matrix is not developed with adequate root thickness and length. Generally, current clinical protocols and recent studies have shown a limited success of the pulp-dentin tissue regeneration. Throughout the various approaches, the construction of biomimetic microenvironments of pulp-dentin tissue is a key concept of the tissue engineering based regenerative endodontics. The biomimetic microenvironments are composed of a synthetic nano-scaled polymeric fiber structure that mimics native pulp ECM and functions as a scaffold of the pulp-dentin tissue complex. They will provide a framework of the pulp ECM, can deliver selective bioactive molecules, and may recruit pluripotent stem cells from the vicinity of the pulp apex. The polymeric nanofibers are produced by methods of self-assembly, electrospinning, and phase separation. In order to be applied to biomedical use, the polymeric nanofibers require biocompatibility, stability, and biodegradability. Therefore, this review focuses on the development and application of the biomimetic microenvironments of pulp-dentin tissue among the current regenerative endodontics.

Assessment of clonality and serotypes of Streptococcus mutans among children by multilocus sequence typing.

Studies using multilocus sequence typing (MLST) have demonstrated that Streptococcus mutans isolates are genetically diverse. Our laboratory previously demonstrated clonality of S. mutans using MLST but could not discount the possibility of sampling bias. In this study, the clonality of randomly selected S. mutans plaque isolates from African-American children was examined using MLST. Serotype and the presence of collagen-binding proteins (CBPs) encoded by cnm/cbm were also assessed. One-hundred S. mutans isolates were randomly selected for MLST analysis. Sequence analysis was performed and phylogenetic trees were generated using start2 and mega. Thirty-four sequence types were identified, of which 27 were unique to this population. Seventy-five per cent of the isolates clustered into 16 clonal groups. The serotypes observed were c (n = 84), e (n = 3), and k (n = 11). The prevalence of S. mutans isolates of serotype k was notably high, at 17.5%. All isolates were cnm/cbm negative. The clonality of S. mutans demonstrated in this study illustrates the importance of localized population studies and are consistent with transmission. The prevalence of serotype k, a recently proposed systemic pathogen, observed in this study, is higher than reported in most populations and is the first report of S. mutans serotype k in a United States population.

Assessment of two multilocus sequence typing (MLST) schemes available for Streptococcus mutans.

OBJECTIVE: Two multilocus sequencing typing (MLST) schemes are currently available for Streptococcus mutans. The first, introduced by Nakano et al. in 2007, consists of 8 conserved housekeeping genes. The second, introduced in 2010 by Do et al., includes 6 housekeeping genes and 2 putative virulence genes. The purpose of the current study was to compare the two MLST schemes for use in validating repetitive extragenic palindromic polymerase chain reaction (rep-PCR) genotypes. DESIGN: Thirty-three S. mutans isolates, representing the 11 most commonly occurring rep-PCR genotype groups, were selected for MLST. MLST was performed with SYBR Green™ PCR with published primers for both MLST schemes. Amplicons were purified, sequenced, and data checked against the www.PubMLST.org database for allelic and sequence type (ST) assignment. Discriminatory power, congruence, and convenience criteria were evaluated. Concatenated sequences for each scheme were analyzed using MEGA to generate phylogenetic trees using minimum evolution with bootstrap. RESULTS: No significant difference in discriminatory power was observed between the two MLST schemes for S. mutans. Clonal clusters were consistent for both schemes. Overall, MLST demonstrated marginally greater discriminatory power than rep-PCR; however all methods were found to be congruent. New alleles and ST are reported for each scheme and added to the PubMLST database. CONCLUSIONS: Clonality, supported by both methods and rep-PCR, indicates S. mutans genotypes are shared between unrelated subjects. Both Nakano and Do schemes demonstrates similar genotype discrimination for S. mutans isolates suggesting each are well designed and may be used to verify rep-PCR genotypes.

Evaluation of ciprofloxacin and metronidazole encapsulated biomimetic nanomatrix gel on Enterococcus faecalis and Treponema denticola.

BACKGROUND: A triple antibiotic mixture (ciprofloxacin; CF, metronidazole; MN, and minocycline; MC) has been used for dental root canal medicaments in pulp regeneration therapy. However, tooth discolorations, cervical root fractures, and inadequate pulp-dentin formation have been reported due to the triple antibiotic regimen. Therefore, an antibiotic encapsulated biomimetic nanomatrix gel was developed to minimize the clinical limitations and maximize a natural healing process in root canal infections. In this study, minimal bacterial concentrations (MBC) of the selected antibiotics (CF and MN) were tested in 14 representative endodontic bacterial species. Then MBC of each CF and MN were separately encapsulated within the injectable self-assembled biomimetic nanomatrix gel to evaluate antibacterial level on Enterococcus faecalis and Treponema denticola. RESULTS: Antibiotic concentrations lower than 0.2 µg/mL of CF and MN demonstrated antibacterial activity on the 14 endodontic species. Furthermore, 6 different concentrations of CF and MN separately encapsulated with the injectable self-assembled biomimetic nanomatrix gel demonstrated antibacterial activity on Enterococcus faecalis and Treponema denticola at the lowest tested concentration of 0.0625 µg/mL. CONCLUSIONS: These results suggest that each CF and MN encapsulated within the injectable self-assembled biomimetic nanomatrix gel demonstrated antibacterial effects, which could be effective for the root canal disinfection while eliminating MC. In the long term, the antibiotic encapsulated injectable self-assembled biomimetic nanomatrix gel can provide a multifunctional antibiotic delivery method with potential root regeneration. Further studies are currently underway to evaluate the effects of combined CF and MN encapsulated within the injectable self-assembled biomimetic nanomatrix gel on clinical samples.

Mutans streptococci enumeration and genotype selection using different bacitracin-containing media.

The primary etiological agents associated with dental caries include the mutans streptococci (MS) comprised of Streptococcus mutans and Streptococcus sobrinus. The effective cultivation and isolation of MS are necessary for the study of MS, including their proper clinical assessment in the epidemiological study of dental caries. Several selective media have been developed for the isolation, enumeration, and characterization of MS. However, inhibition of MS may occur, reducing counts and perhaps limiting selection of some strains. The purpose of this study was to compare five culture media containing bacitracin recommended for the isolation of MS. Five commonly used bacitracin-containing media (MSB, MSKB, GTSB, TYS20B, and TYCSB) used for MS isolation were quantitatively evaluated. Standard plate counts were performed in duplicate for 2 prototype MS strains (S. mutans UA159 and S. sobrinus 6715) and for MS isolates from clinical saliva samples obtained from 16 children (approximate age 5years) to determine total plate counts, and total S. mutans counts. Selected isolates (n=249) from all five media for 5 saliva samples were further confirmed as S. mutans with real-time PCR then subsequently evaluated qualitatively with rep-PCR for genotype determination. All media resulted in variable enumeration with no significant difference in MS counts. MS prototype strains grew well on all five media; clinical isolates demonstrated more variability in counts but no overall significant differences were found. MSB demonstrated comparable ability to grow S. mutans but allowed for more non-S. mutans growth. All 5 media identified a consistent predominant genotype by rep-PCR. Recovery of minor genotypes was not inhibited by media type.

Characteristics of Streptococcus mutans genotypes and dental caries in children.

This longitudinal cohort study evaluated the diversity, commonality, and stability of Streptococcus mutans genotypes associated with dental caries history. Sixty-seven 5- and 6-yr-old children, considered as being at high caries risk, had plaque collected from baseline through 36 months for S. mutans isolation and genotyping using repetitive extragenic palindromic-PCR (4,392 total isolates). Decayed, missing, or filled surfaces (dmfs (primary teeth)/DMFS (secondary teeth)) for each child were recorded at baseline. At baseline, 18 distinct genotypes were found among 911 S. mutans isolates from 67 children (diversity), and 13 genotypes were shared by at least two children (commonality). The number of genotypes per individual was positively associated with the proportion of decayed surfaces (p-ds) at baseline. Twenty-four of the 39 children who were available at follow-up visits maintained a predominant genotype for the follow-up periods (stability) and this was negatively associated with the p-ds. The observed diversity, commonality, and stability of S. mutans genotypes represent a pattern of dental caries epidemiology in this high-caries-risk community, which suggests that fewer decayed surfaces are significantly associated with lower diversity and higher stability of S. mutans genotypes.