Valeria V. Gordan

Correlations of oral bacterial arginine and urea catabolism with caries experience

BACKGROUND/AIM Alkali generation by oral bacteria plays a key role in plaque pH homeostasis and may be a major impediment to the development of dental caries. To determine if the capacity of oral samples to produce ammonia from arginine or urea was related to caries experience, the arginine deiminase system (ADS) and urease activity in saliva and dental plaque samples were measured in 45 adult subjects. METHODS The subjects were divided into three groups according to caries status; 13 caries-free (CF) individuals (decayed, missing, and filled teeth = 0); 21 caries-active (CA) individuals (decayed teeth >or= 4); and 11 caries-experienced (CE) individuals (decayed teeth = 0; missing and filled teeth > 0). Real-time polymerase chain reaction was used to quantify the proportion of certain acid- or alkali-producing organisms in the samples. RESULTS The amount of ammonia generated from the test substrates by plaque samples was generally higher than that produced by salivary samples in all groups. Significantly higher levels of salivary ADS activity and plaque urease activity were observed in CF subjects compared to CA subjects (P = 0.0004 and P = 0.014, respectively). The proportions of Streptococcus mutans from saliva and dental plaque of CA subjects were significantly higher than those from the CF group (P = 0.0153 and P = 0.0009, respectively). In the CA group, there was an inverse relationship between urease activity and the levels of S. mutans (P < 0.0001). CONCLUSION This study supports the theory that increased caries risk is associated with reduced alkali-generating capacity of the bacteria colonizing the oral cavity; providing compelling evidence to further our understanding of oral alkali-generation in health and disease.

Increasing the Longevity of Restorations by Minimal Intervention: A Two-year Clinical Trial

UNLABELLED This investigation assessed the effectiveness of alternative treatments for the replacement of amalgam and resin-based composite restorations. Sixty-six patients (age 18 to 80 years, mean = 26.6) with 271 (amalgam [n = 193] and resin-based composite [n = 78]) defective restorations were randomly assigned to one of five different treatment groups: A) Repair (n = 27); B) Sealing of margins (n = 48); C) Refurbishing (n = 73); D) Replacement (n = 42) and E) Untreated (n = 81). USPHS/Ryge criteria were used to determine the quality of the restorations. Two calibrated examiners (Cohens Kappa 0.74) assessed the restorations independently at the beginning of the study (baseline) and at two years after treatment using seven parameters from the USPHS/Ryge criteria (Marginal Adaptation, Anatomic Form, Roughness, Marginal Stain, Occlusal Contact, Secondary Caries and Luster). RESULTS Two-hundred and fifty-six restorations (178 amalgam and 78 resin-based composite) were examined at the two-year recall exam. The sealing of marginal defects showed significant improvements in marginal adaptation (p < 0.05). Refurbishing of the defective restorations significantly improved anatomic form (p < 0.0001), luster (p < 0.016), marginal adaptation (p < 0.003) and roughness (p < 0.0001). The repair significantly improved anatomic form (p < 0.002) and marginal stain (p < 0.002). Replacement showed significant improvements for all parameters (p < 0.05). The Untreated group showed significant deterioration on marginal adaptation (p < 0.013). CONCLUSIONS The two-year recall examination showed that sealant, repair and refurbishing treatments improved the clinical properties of defective amalgam and resin-based composite restorations by increasing the longevity of the restorations with minimal intervention.

Clinical evaluation of replacement of class V resin based composite restorations.

OBJECTIVES The purpose of this clinical study was to evaluate any increase in size of Class V resin based composite restorations that required replacement. Emphasis was placed on measurements of the loss of tooth structure in areas distant from the site of failure. METHODS 14 Class V restorations scheduled for replacement were recorded with pre-operative impressions and intra-oral photographs. Restorations were then removed and cavity preparations were completed. A second impression and photograph were taken and stone casts were prepared for each impression. The perimeter and area of each restoration and cavity preparation were measured with a video-based imaging system (Dage 725 CCD camera) equipped with a macro lens, at a fixed magnification of x 10-15. The initial measurements of the restoration image were compared to the measurements of the new cavity preparation, in both instances excluding the site of failure. Intra-class correlation coefficient (ICR) and paired t-test were used for statistical analysis. RESULTS A significant difference between the pre and post-operative measurements for both area (P=0.0125) and perimeter (P=0.003) was found. CONCLUSION The study showed that replacement of Class V resin based composite restorations resulted in increased size of the cavity preparation in areas distant from the site of failure.

2-year Clinical Evaluation of Alternative Treatments to Replacement of Defective Amalgam Restorations

OBJECTIVE To investigate the effectiveness of alternative treatments for replacing defective amalgam restorations through a prospective longitudinal cohort clinical study. METHODS Forty-five patients aged 21 through 77 (mean=56) years with 113 defective amalgam restorations, which were independently diagnosed during treatment planning, participated in the study. These patients were assigned to 5 treatment groups: repair (n=20), sealing of defective margins (n=23), refurbishing (n=23), replacement (n=23) and no-treatment (n=24). The replacement and no-treatment groups served as comparison groups and received random assignment. Two clinicians examined the restorations (n=113) prior to and after the assigned treatment and at subsequent recalls, using a modified Ryge Criteria that included marginal adaptation, anatomy, contact, post-operative sensitivity and secondary caries. RESULTS At 1- and 2-year recalls, 79 (70%) and 74 (65%) restorations were examined. Kruskal-Wallis Test showed significant differences for marginal adaptation and anatomic form for both 1- and 2- year recall exams (p<.05). The repair and replacement groups had significant differences when compared to the no-treatment group. CONCLUSIONS Defective restorations that have a Bravo rating for clinical characteristics other than marginal integrity and anatomical form do not need to be immediately replaced.

Survival rate of sealed, refurbished and repaired defective restorations: 4-year follow-up

The most common treatment in general dental practice is the replacement of restorations affected by secondary caries or marginal deficiencies. Alternative treatments to replacement of defective restorations, such as marginal sealing, refurbishment and repair, have demonstrated improvement of their clinical properties with minimal intervention. The aim of this clinical study was to estimate the median survival time (MST) of marginal sealing, repair and refurbishment of amalgam and resin-based composite restorations with localized defects as a treatment to increase the restoration longevity. A cohort of 66 patients, with 271 class I and II restorations clinically diagnosed with localized defects was longitudinally assessed. Each restoration was assigned to one of the following 5 groups: Marginal Sealing (n=48), Refurbishment (n=73), Repair (n=27), Replacement (n=42), and Untreated (n=81). Two calibrated examiners assessed the restorations at baseline and annually during 4 years, using the modified Ryge criteria: marginal adaptation, anatomic form, roughness, secondary caries and luster. Fifty-two patients with 208 restorations were assessed after 4 years; the distribution of restorations in the groups was as follows: Marginal Sealing (n=36), Refurbishment (n=63), Repair (n=21), Replacement (n=28) and Untreated (n=60). Kaplan Meier test indicated that the Sealed margins group showed the lowest MST while the Repair group showed the highest MST for restorations examined after 4 years of follow up. Defective amalgam and resin-based composite restorations treated by sealing of marginal gaps, refurbishment of anatomic form, luster or roughness, and repair of secondary caries lesions, had their longevity increased.

Research in general dental practice

Spurred by an initiative by the National Institute of Dental and Craniofacial Research in the USA, this article presents the need for a change in clinical dental research towards practice-based research. It outlines the shortcomings of past and present-day research in dentistry, with emphasis on the lack of clinical relevance of much of the research performed. The slow transfer of sound research findings to clinical practice is also a major problem. The article reviews some problems related to restorative dentistry and how they have adversely affected general dental practice. Practice-based research places emphasis on the problems experienced by clinicians in the routine care of patients. Clinicians should be linked together in research networks. The problems they face in dental practice and the clinical experience they have will form the basis for studies by the network. Experienced clinical researchers will provide guidance and statistical support for the studies initiated by the clinicians. □ Clinical experience, clinical networks, clinical research

Comparison of the apical seal obtained by a dual-cure resin based cement or an epoxy resin sealer with or without the use of an acidic primer.

This study compared the apical leakage of roots obturated with gutta-percha using either a dual-cure resin based cement (Panavia F) or an epoxy-resin sealer (Thermaseal plus) with or without the application of an acidic primer (ED Primer). Eighty-six single rooted canine teeth were decoronated, cleaned, and shaped by using hand and rotary instruments, randomly divided into four groups, and obturated as follows: group A (n = 20): ED Primer applied followed by thermoplastized obturation with gutta-percha and Thermaseal Plus sealer; group B (n = 20): thermoplastized obturation with gutta-percha and Thermaseal Plus; group C (n = 20): ED primer applied followed by thermoplastized obturation with gutta-percha and Panavia F; group D (n = 20): thermoplastized obturation with gutta-percha and Panavia F. Both a negative control (n = 3; entire root coated with wax) and a positive control (n = 3; obturated with only a fitted master cone) were included in the study. Groups A, B, C, D, and the controls were immersed in molten sticky wax, leaving the apical 2-mm exposed, and quickly chilled. All teeth were immersed in 1% methylene blue dye solution for 10 days, rinsed, and sectioned longitudinally. Apical dye penetration was measured stereomicroscopically at 10-fold magnification. The analysis of variance and Duncan Multiple Range were used for result analysis. The specimens obturated with gutta-percha and an epoxy-resin sealer (with or without an acidic primer) demonstrated significantly less linear dye penetration than specimens obturated with gutta-percha and the dual-cure, resin-based cement (with or without an acidic primer).

Restorative material and other tooth-specific variables associated with the decision to repair or replace defective restorations: findings from The Dental PBRN.

OBJECTIVES Using data from dentists participating in The Dental Practice-Based Research Network (DPBRN), the study had 2 main objectives: (1) to identify and quantify the types of restorative materials in the existing failed restorations; and (2) to identify and quantify the materials used to repair or replace those failed restorations. METHODS This cross-sectional study used a consecutive patient/restoration recruitment design. Practitioner-investigators recorded data on consecutive restorations in permanent teeth that needed repair or replacement. Data included the primary reason for repair or replacement, tooth surface(s) involved, restorative materials used, and patient demographics. RESULTS Data for 9875 restorations were collected from 7502 patients in 197 practices for which 75% of restorations were replaced and 25% repaired. Most of the restorations that were either repaired or replaced were amalgam (56%) for which most (56%) of the material used was direct tooth-coloured. The restorative material was 5 times more likely to be changed when the original restoration was amalgam (OR=5.2, p<.001). The likelihood of changing an amalgam restoration differed as a function of the tooth type (OR=3.0, p<.001), arch (OR=6.6, p<.001); and number of surfaces in the original restoration (OR=12.2, p<.001). CONCLUSION The probability of changing from amalgam to another restorative material differed with several characteristics of the original restoration. The change was most likely to take place when (1) the treatment was a replacement; (2) the tooth was not a molar; (3) the tooth was in the maxillary arch; and (4) the original restoration involved a single surface.

Restorative Treatment Thresholds for Proximal Caries in Dental PBRN

This study was conducted to assess caries treatment thresholds among Japanese dentists and to identify characteristics associated with their decision to intervene surgically in proximal caries lesions within the enamel. Participants (n = 189) were shown radiographic images depicting interproximal caries and asked to indicate the lesion depth at which they would surgically intervene in both high- and low-caries-risk scenarios. Differences in treatment thresholds were then assessed via chi-square tests, and associations between the decision to intervene and dentist, practice, and patient characteristics were analyzed via logistic regression. The proportion of dentists who indicated surgical intervention into enamel was significantly higher in the high-caries-risk scenario (73.8%, N = 138) than in the low-caries-risk scenario (46.5%, N = 87) (p < 0.001). In multivariate analyses for a high-caries-risk scenario, gender of dentist, city population, type of practice, conducting caries-risk assessment, and administering diet counseling were significant factors associated with surgical enamel intervention. However, for a low-caries-risk scenario, city population, type of practice, and use of a dental explorer were the factors significantly associated with surgical enamel intervention. These findings demonstrate that restorative treatment thresholds for interproximal primary caries differ by caries risk. Most participants would restore lesions within the enamel for high-caries-risk individuals (Clinicaltrials.gov registration number NCT01680848).

Rubber Dam Use During Routine Operative Dentistry Procedures: Findings From The Dental PBRN

Rubber dam use during operative dentistry procedures has been quantified based on questionnaires completed by dentists. However, based on the knowledge of the authors of the current study, there are no reports based on use during actual clinical procedures other than in dental materials studies and none based on routine care. The objectives of the current study were to: 1) quantify how commonly the rubber dam is used during operative dentistry procedures; 2) test the hypothesis that certain dentist, restoration and patient-level factors are associated with its use. A total of 229 dentist practitioner-investigators in The Dental Practice-Based Research Network (DPBRN) participated. DPBRN comprises five regions of the USA: Alabama/Mississippi, Florida/Georgia, Minnesota, Permanente Dental Associates and Scandinavia. Practitioner-investigators collected data on 9,890 consecutive restorations done in previously unrestored tooth surfaces from 5,810 patients. Most dentists (63%) did not use a rubber dam for any restoration in this study. A rubber dam was used for only 12% of restorations, 83% of which were used in one DPBRN region. With regions accounted for, no other dentist characteristics were significant. A multi-level multiple logistic regression of rubber dam use was done with restoration and patient-level variables modeled simultaneously. In this multi-variable context, these restoration-level characteristics were statistically significant: tooth-arch type, restoration classification and reason for placing the restoration. These patient-level characteristics were statistically significant: ethnicity, dental insurance and age. These results, obtained from actual clinical procedures rather than questionnaires, document a low prevalence of usage of the rubber dam during operative dentistry procedures. Usage varied with certain dentist, restoration and patient-level characteristics.