Comparative assessment of the adhesion of Streptococcus mutans and Lactobacillus to pedodontic crowns made of metal and zirconium

Introduction: The microbial flora in children's oral cavities is diverse, with Streptococcus mutans (S. mutans) and Lactobacillus playing key roles in the development of dental caries and periodontal inflammation. Resin restorations, commonly used for carious lesions, may lead to secondary decay and complications over time, making dental crowns a preferred option in pediatric dentistry. Metal crowns are effective for multiple surface lesions, while zirconium crowns offer superior aesthetics and biocompatibility. However, crown placement can promote bacterial adhesion, particularly by S. Mutans on enamel and cementum, and Lactobacillus on dentin, potentially affecting long-term restoration success. Bacterial adhesion can be assessed through plaque samples to evaluate restoration durability. Aim of the study: The purpose of the study is to evaluate the microbial adhesion of S. mutans and Lactobacillus on pedodontic crown surfaces. Material and methods: 60 patients with metal and zirconium pedodontic crowns were included in the study. We analyzed the bacterial load with KariesScreenTests. Conclusion: Metal pedodontic crowns have higher microbial adhesion, with S. mutans outnumbering Lactobacillus. Zirconium crowns show lower microbial adhesion, with fewer bacteria overall. S. mutans is present in higher quantities than Lactobacillus, but still less than in metal crowns. Zirconium crowns are a better option for restoring primary teeth, as they reduce plaque buildup and bacterial growth, offering improved long-term oral health benefits. Keywords: pedodontic crowns, bacterial adhesion, KariesScreenTest.

The selection between Zirconia crowns and metal crowns for anterior teeth restorations is pivotal in prosthodontics due to their distinct properties. However, a comprehensive investigation into their effectiveness in anterior tooth restorations is warranted. This in vitro study aimed to compare the effectiveness of Zirconia crowns and metal crowns in anterior teeth restorations. A total of thirty extracted human maxillary central incisors were prepared to receive crowns and randomly allocated into two groups: group A, zirconia crowns; and group B, metal crowns. The crowns were fabricated following standardized protocols and cemented onto the prepared teeth. Various tests, including fracture resistance, marginal adaptation, and color-matching assessment, were conducted on the samples. The mean fracture resistance of Zirconia crowns (Group A) was determined to be 320 N (SD ± 25), whereas it was 280 N (SD ± 30) for metal crowns (Group B). Marginal adaptation assessment revealed a mean gap width of 50 microns (SD ± 10) for Zirconia crowns and 70 microns (SD ± 15) for metal crowns. Evaluation of color matching showed a higher percentage of acceptable matches for Zirconia crowns compared to metal crowns. Zirconia crowns exhibited superior fracture resistance, marginal adaptation, and color matching in comparison to metal crowns for anterior teeth restorations. These findings advocate for Zirconia crowns as a more effective choice for restoring anterior teeth, offering both strength and esthetic appeal.

BackgoundPreformed metal crowns (PMCs) and zirconia crowns (ZCs) are commonly used for the treatment of primary molar caries. However, there have been no reports on factors influencing parental awareness, willingness to use these treatments, and the associated discomfort after crown placement in children.This study is the first to report factors influencing preformed crowns, providing a reference for the prevention and treatment of deciduous carious teeth.MethodsParents whose children’s posterior caries were restored with preformed crowns at Shenzhen Children’s Hospital from October 2021 to October 2023 were recruited. A questionnaire gathered data on multiple variables, including basic information about the participants, their oral health behaviors, and their attitudes toward oral health.ResultsApproximately two-thirds of the surveyed parents were aware of preformed metal crowns (PMCs) (67.8%), whereas over half were hardly aware of prefabricated zirconia crowns (ZCs) (59.6%). In terms of discomfort symptoms, 105 (76.7%) and 102 (76.1%) cases were reported after PMC and ZC placement respectively; however, there was no statistically significant difference between the two groups (P > 0.05). Among the surveyed parents, 19 (8.7%) expressed that they could not accept the PMC color, whereas all could accept the ZC color, and the difference was statistically significant (P < 0.05). A total of 217 parents (99.5%) could accept PMCs to protect or repair primary carious teeth; 29.8% of the parents stated that they were reluctant to use ZCs to protect or repair their children’s deciduous teeth, and the difference was significant (P < 0.05). In terms of location selection, the majority of surveyed parents chose comprehensive hospitals (58.7%) and stomatological hospitals (41.3%). In terms of institution selection, priority was given to the doctor’s qualifications (90.4%). Pearson correlation analysis revealed that “acceptance of the PMC color”, “oral health awareness”, and “parental willingness to use PMCs” were positively correlated (P < 0.05) and that “non-nuclear family status” was negatively related to “parental willingness to use PMCs” (P < 0.05). The logistic multiple regression analysis revealed that oral health awareness and restoration awareness significantly affected the duration of discomfort symptoms after PMC placement (P < 0.15). Children with higher annual family incomes, families with fewer children, lower consumption of desserts, better oral health awareness, and teeth brushing under the assistance of their parents showed a dramatic decline in untimely PMC repair (P < 0.15); children who brushed their teeth less and whose parents had a poorer perception of restoration methods showed an increase in untimely PMC repair (P < 0.15).ConclusionsThis discrepancy is reflected in the cognition and willingness to use PMCs and ZCs. PMCs are more accepted due to cost, whereas ZCs are preferred for aesthetics. The factors affecting PMC restoration are oral health awareness, manner of restoration, family income, number of children, consumption of desserts, and toothbrushing frequency.

Early childhood caries is a multifactorial disease process affecting children below 71 months of age and continues to be a global health problem. Stainless steel crowns (SSCs) are widely used and are very popular in pediatric dentistry due to its superiority and durability when compared with multisurface amalgam restorations. However, one of the major disadvantages with these crowns is the poor esthetics. Parents often request for a more esthetic alternative to the SSC. Zirconia crowns are one of the tooth-colored full crown restorations currently available for use in primary teeth. These are available as both preformed and custom-made crowns and show excellent esthetics. However, these require extensive tooth preparation with a subgingival finish lines, which would cause gingival trauma and bleeding during the preparation. The present study uses intraoral scanners for making the custom-made zirconia crowns, which will avoid the conventional impressions. Currently, there are no studies available in pediatric dentistry regarding CAD-CAM crowns. Hence, there is a need for the study. The aim of this study is to clinically evaluate the performance of preformed SSCs and custom-made zirconia crowns in primary molars. To elicit parental and patient satisfaction with respect to preformed SSCs and custom made zirconia crowns and to radiographically compare the interproximal bone height for 1 year. The patients were selected with purposive sampling. The tooth of interest was prepared according to the crown it would receive. The upper and the lower arch of the tooth receiving custom-made zirconia crown was scanned using an intraoral scanner. The crowns were cemented using Type 1 glass ionomer cement (GIC) (SSC) and resin modified GIC (custom-made zirconia crown). After the crown placement, the patient and the parent's satisfaction was scaled regarding the time taken, comfort, cost of crown, appearance of crown, etc., using a 5-point Likert scale. A baseline radiograph was taken after crown placement. The patient was recalled every 3 months till 1 year for evaluation (loss of retention, loss of proximal contact, gingival inflammation, opposing tooth wear, and marginal integrity). At the end of 1 year, radiographs were taken to check the interproximal bone. After 1 year evaluation of custom-made zirconia crowns and preformed SSCs in primary molars, it was shown that both SSC and zirconia crowns showed good gingival scores but zirconia crown was better than SSC in improving the gingival health. SSCs showed better results with respect to the opposing tooth wear and marginal adaptability. Parents as well as patients preferred a tooth-colored crown as a treatment option. Custom-made zirconia crowns are comparable to the preformed SSCs and they show better gingival scores and excellent color match.

ABSTRACTBackgroundSurface roughness plays a crucial role in microbial adhesion and retention on dental crowns, contributing to secondary infections and the development of periodontal diseases through bacterial plaque accumulation. In treating pulpitis of primary teeth via pulpectomy, dental crowns are often used as full-coverage restorative solutions. Among the most widely utilized crowns are stainless steel and zirconia crowns. However, zirconia crowns present drawbacks, such as excessive tooth reduction and increased wear on opposing teeth, while stainless steel crowns (SSCs) pose esthetic limitations. A new alternative, Edelweiss crowns, made from laser-sintered barium and vitrified composite, is gaining attention. These crowns offer esthetic appeal, biocompatibility, reduced tooth reduction, high flexural strength, and minimal abrasivity against opposing natural teeth.AimThis study aimed to assess the microbial adherence and surface roughness of primary esthetic crown (Edelweiss crowns) following simulated toothbrushing.Materials and methodsAbout 10 pediatric posterior Edelweiss crowns were subjected to surface roughness analysis using a stylus profilometer. The crowns underwent 10,000 brushing cycles in a toothbrush simulator (ZM3.8 SD-Mechatronik). Surface roughness measurements were recorded before and after brushing. To evaluate microbial adhesion, the crowns were incubated with Streptococcus mutans suspension, and colony-forming units (CFUs) were quantified pre- and postbrushing simulation. The data were analyzed statistically using Statistical Package for the Social Sciences (SPSS) software (version 29).ResultsThe average surface roughness (Ra) values pre- and postbrushing were 10.517 and 7.541 µm, respectively. The average CFU of S. mutans on the crowns decreased from 1 × 108 CFU/mL prebrushing to 3 × 107 CFU/mL postbrushing.ConclusionEdelweiss crowns demonstrated a reduction in both surface roughness and microbial adhesion after simulated brushing, suggesting that they may help reduce the risk of gingival infections in pediatric patients while providing durable full coronal restorative outcomes.Clinical significanceEdelweiss crowns represent a valuable alternative to traditional crowns in pediatric dentistry in terms of surface roughness and microbial adhesion.How to cite this articleShabnam TI, Pooja VR. Evaluation of Surface Roughness and Microbial Adhesion of Primary Esthetic Crowns: An In Vitro Study. Int J Clin Pediatr Dent 2025;18(6):683–687.

Introduction: Root canal-treated teeth are often restored using crowns to maintain function and protect against damage. The choice of crown material, such as stainless steel or zirconia, may influence microbial colonization and potentially affect restoration longevity. Bacteria commonly found in the oral environment, such as Streptococcus mutans and Lactobacillus spp., may adhere to crown surfaces and form biofilms. Differences in surface properties such as roughness and hydrophilicity may affect bacterial adhesion and biofilm formation. This study aimed to quantify and compare the microbial loads of S. mutans and Lactobacillus spp. on stainless steel and zirconia crowns in RCT-treated teeth and to characterize the species diversity within biofilms formed on these surfaces.Materials and methods: This prospective, non-randomized, clinical study enrolled 20 patients requiring crowns on root canal-treated lower first molars using a split-mouth design. The patients received stainless steel (3M ESPE AG, Seefeld, Germany) and zirconia (VITA Zahnfabrik, Bad Säckingen, Germany) crowns based on clinical indications and preferences. Oral prophylaxis was performed using ultrasonic scalers (E.M.S. Electro Medical Systems S.A., Nyon, Switzerland), and crowns were placed within 14 days of RCT by using an endodontic system (Dentsply Sirona Inc., Charlotte, North Carolina, United States). Impressions were made with light body polyvinyl siloxane putty (Elite HD+; Zhermack SpA, Badia Polesine, Italy), and marginal fit was verified clinically. Microbial samples were collected at baseline, one month, and six months using sterile paper points, and the gingival and plaque indices were recorded. Quantitative polymerase chain reaction (qPCR) using a LightCycler 480 System (Roche Diagnostics Corporation, Indianapolis, Indiana, United States) was used to quantify S. mutans and Lactobacillus spp. Data were statistically analyzed.Results: Both crown types showed significant increases in plaque index, probing depth, S. mutans, and Lactobacillus spp. over time (p = 0.001). Stainless steel crowns exhibited significantly greater increases in all parameters than zirconia crowns (p < 0.05), with the largest difference in Lactobacillus spp. colonization.Conclusion: Zirconia crowns demonstrated lower microbial colonization than stainless steel crowns, suggesting greater biocompatibility for root canal-treated teeth. These findings support zirconia as the preferred material for minimizing microbial-related complications in restorative dentistry.

Microbial adhesion to oral splints may lead to oral diseases such as candidiasis, periodontitis or caries. The present in vitro study aimed to assess the effect of novel computer-aided design/computer-aided manufacturing (CAD/CAM) and conventional manufacturing on Candida albicans and Streptococcus mutans adhesion to oral splint resins. Standardized specimens of four 3D-printed, two milled, one thermoformed and one pressed splint resin were assessed for surface roughness by widefield confocal microscopy and for surface free energy by contact angle measurements. Specimens were incubated with C. albicans or S. mutans for two hours; a luminometric ATP assay was performed for the quantification of fungal and bacterial adhesion. Both one-way ANOVA with Tukey post hoc testing and Pearson correlation analysis were performed (p < 0.05) in order to relate manufacturing methods, surface roughness and surface free energy to microbial adhesion. Three-dimensional printing and milling were associated with increased adhesion of C. albicans compared to conventional thermoforming and pressing, while the S. mutans adhesion was not affected. Surface roughness and surface free energy showed no significant correlation with microbial adhesion. Increased fungal adhesion to oral splints manufactured by 3D printing or milling may be relevant for medically compromised patients with an enhanced risk for developing candidiasis.

Microbial biofilms on biomaterial implant surfaces or devices are troublesome, since biofilm organisms are protected by matrix of exopolymeric substances, impenetrable for most antibiotics and immune cells.It is established that bacterial adhesion to surface is required for colonization and subsequent biofilm formation.The adherent state is important for bacterial survival and development of infection.Therefore, prevention of bacterial adhesion and biofilm growth on implant surfaces should ultimately prevent the occurrence of infection.Egg white was considered to play an important role in resistance against bacteria for developing embryo mainly during early incubation.Utilization of egg white as a coating to prevent bacterial adhesion and biofilm growth on biomaterials implants is novel.Here, we studied the effect of Hen egg white as a coating to surface, on bacterial (Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli) adhesion and biofilm growth.We report that a significant reduction in bacterial adhesion was observed for S.aureus on egg white coated surface compared to control (no egg white coating).Whereas P. aeruginosa and E. coli, do not show any significant difference compared to control.When bacteria were allowed to grow in the presence of egg white, a significant reduction in growth was observed on all bacteria compared to control.Thus Hen egg white potentially used as biological coating on implants for prevention of bacterial adhesion and biofilm formation.

Microbial adhesion of streptococcus mutans on additively manufactured and milled zirconia.

Background: Pediatric dental caries is a prevalent issue, necessitating effective restorative solutions. Zirconia crowns have emerged as a promising option due to their superior mechanical properties and aesthetics compared to traditional materials. Understanding the biochemical considerations and management approaches associated with zirconia crowns is essential for optimizing their use in pediatric dentistry. Methods: This comprehensive review analyzes recent literature on zirconia crowns, focusing on their composition, mechanical properties, translucency, preparation techniques, and bonding characteristics. A systematic search was conducted across databases such as PubMed, Scopus, and Embase, retrieving studies from 2000 to 2023 that detail advancements in zirconia materials and their clinical applications. Results: The review highlights that monolithic zirconia crowns offer exceptional strength, aesthetics, and biocompatibility, making them suitable for pediatric patients. Advances in zirconia formulations have enhanced translucency and reduced the need for extensive tooth reduction. However, challenges remain in achieving optimal bonding strength due to zirconia's low surface energy. Surface treatments and the use of adhesive cements containing phosphate monomers have shown promise in improving adhesion. Conclusion: Zirconia crowns represent a significant advancement in pediatric restorative dentistry, combining durability and aesthetic appeal. Ongoing research is needed to refine bonding techniques and improve clinical outcomes. The integration of zirconia crowns into pediatric dental practice requires a thorough understanding of their properties and the implementation of effective management strategies

BACKGROUND Several auxiliary features have been proposed to achieve sustainable retention for short-prepared dental crowns; however, achieving retention is challenging. This study aimed to assess the impact of increased total occlusal convergence and auxiliary preparation factors like box and groove on the retention form of short tooth preparations. MATERIAL AND METHODS Eighty resin machine-milled dies with a height of 3 mm and a deep chamfer margin of 1 mm were prepared to mimic the short-prepared molar. Initially, 2 teeth were prepared following the guidelines, and the total occlusal convergence was kept at 10° and 20°, respectively. Auxiliary features such as the proximal box and buccal groove were prepared on separate 20° dies. Eighty dies were prepared with 10 samples each for 10°, 20°, 20° with proximal box and 20° with buccal groove for zirconia (n=40) and metal crowns (n=40). Cementation was done with glass ionomer luting cement, and a pull-off test was conducted. Data were analyzed using one-way analysis of variance and post hoc fisher least significant difference test (P<0.05). RESULTS The highest mean was observed in the proximal box group with the metal crown (14.59), and the lowest in the group with 20° zirconia crowns (9.12). Within groups, the highest retentive values were found for the 20° taper with proximal box preparation; the lowest was for the 20° taper group. CONCLUSIONS Within the study limitations, it could be concluded that incorporating a proximal box or buccal groove in short tooth preparations with an increased total occlusal convergence improved retentive values.

Prefabricated metal crowns (PMCs) have been widely used in pediatric dentistry due to their great success in various clinical situations. However, it is important to know the local effects, such as changes in pH in the oral environment. To evaluate the pH variations before and after placement of PMCs. A quasi-experimental study (before and after) was performed with 32 pediatric patients who needed rehabilitation with PMCs at a pediatric dentistry clinic in a public university. Measurements were made using a pH potentiometer before PMC placement, one week after, and one month after placement. ANOVA and Pearson correlation were performed in SPSS. The average age of the participants was 5.9 ± 1.6 years, and 53.1% were female. The average pH before, one week after, and one month after crown placement was 7.46 ± 0.37, 7.00 ± 0.32, and 7.1 ± 0.19, respectively. Significant differences (p< 0.05) were observed between the three pH measurements. We found differences when comparing the basal pH values to those at one week (p= 0.001) and one month (p= 0.002). Although there were statistically significant differences in the pH change values before and after the placement of crowns, these differences may not have a clinical impact.

With recent increases in demand for the esthetic aspects of orthodontic treatments, the use of ceramic brackets has gained more popularity. Dental demineralization is a frequent, undesired effect of microbial biofilm adhesion to orthodontic appliances. The crystalline structure of ceramics results in different material properties, and its possible effect on microbial adhesion was investigated in this study. This research was conducted experimentally and in vitro. Samples consisted of 40 monocrystalline and 40 polycrystalline brackets, further divided into two groups incubated with either Streptococcus mutans alone or S. mutans with Candida albicans. The culture medium was Tryptic Soy Broth with 20% sucrose. All samples were incubated at 37°C for 48 h. Macroscopic detachment of the formed biofilm would be the basis for adhesion scoring. The Mann-Whitney test was used to analyze the adhesion scores. In this study, a significance level of P < 0.05 was considered. The mean for adhesion score in S. mutans group was 1.85 ± 0.67 for the monocrystalline group and 2.35 ± 0.59 for the polycrystalline group (27% difference, P = 0.035). The adhesion score in S. mutans and C. albicans group was lower in the monocrystalline group (1.6 vs. 2.0) but was not statistically significant (P = 0.108). This study showed that monocrystalline ceramic brackets had less overall microbial biofilm adhesion compared to polycrystalline ceramic brackets, especially when incubated with S. mutans alone. This observation might be explained primarily by lower surface roughness in monocrystalline ceramics.

Objective: The objective of this work is to analyze the use of zirconia crowns in primary teeth, their advantages, evolution and acceptance within pediatric dentistry. Methods: An integrative review was carried out using the SciELO, PubMed and Google Scholar databases, with the objective of analyzing the use of zirconia crowns in primary teeth, including 13 articles, following the inclusion and exclusion criteria previously determined. Results: The literature shows that zirconia crowns provide a well-polished surface and less bacterial adhesion, allowing to prevent plaque accumulation and pigmentation, reducing gingival inflammation associated with rehabilitated primary teeth. Zirconia crowns have superior mechanical properties related to other types of ceramics, which gives durability and resistance to fracture and wear, in addition to a natural aesthetic to the rehabilitated tooth. Conclusion: It is concluded, therefore, that pediatric dentistry has benefited a lot from this restorative revolution that uses the use of zirconia crowns in children.

To compare the flexural properties and the adhesion of Lactobacillus salivarius (LS), Streptococcus mutans (SM), and Candida albicans (CA) on heat-polymerized (CV), CAD-CAM milled (CAD), or 3D-printed (3D) Poly (methylmethacrylate) (PMMA). Ultimate Flexural Strength (UFS), Flexural Strain (FS) (%) at Flexural Strength, and Flexural Modulus (FM) of specimens (65.0×10.0×3.3 mm) from each PMMA group (n=6) were calculated by using the 3-point bending test. The surface roughness profiles (R) were measured before and after polishing with a contact profilometer. LS, SM, and CA adhesion on PMMA specimens (n=18) (10 mm in diameter, 3 mm in height) was assessed after 90 minutes and 16 hours by using scanning electron microscopy. The Kruskal-Wallis test with post hoc analysis was performed to compare the groups (alpha=0.05). Mean UFS values were 80.79±7.64 MPa for CV, 110.23±5.03 MPa for CAD, and 87.34±6.39 MPa for 3D. Mean FS values were 4.37±1.04% for CV, 4.71±0.62% for CAD, and 6.19±0.13 % for 3D. Mean FM values were 2542±301 MPa for CV, 3435±346 MPa for CAD, and 2371±197 MPa for 3D. CAD had the lowest average R value (0.29±0.16 µm) before polishing, and bacterial adhesion after 90 minutes of incubation. R value and microbial adhesion were not different amongst groups after polishing and 16 hours of incubation, respectively. The CAD group displayed the best flexural properties, except for FS, the lowest roughness before polishing and bacterial adhesion after 90 minutes of incubation. All tested PMMAs had similar surface roughness after polishing, and microbial adhesion after 16 hours of incubation.