Abstracts.

The International Association for Dental Research (IADR), in association with the American Association for Dental Research (AADR), Canadian Association for Dental Research (CADR), and American Dental Educators Association (ADEA) held a combined meeting and exhibition March 8-11, 2006, in Orlando, Florida. Scientists and researchers from around the world present their research findings for discussion. The IADR has given us permission to publish a selection of abstracts presented at that meeting.

CLINICAL TECHNIQUES

1289 PREDICTING DENTAL HYGIENE CLINICAL SKILLS

L.A. SPOONTS, Texas Woman's University, Denton, USA

Much of dental hygiene curriculum for clinical instruction is focused on developing fine motor skills such as hand-to-eye coordination. The objective: to determine if instrumentation competency could be predicted utilizing educational methods taught in pre-clinical courses. Method: a carving exercise in Dental Morphology was averaged and compared to instrumentation scores in a pre-clinic techniques course and then further correlated to the students' averages on instrumentation competencies in Clinic I. Twenty-one students were assigned the exercise of carving to scale a maxillary permanent central incisor, as well as, a permanent mandibular second molar. The students were given step-by-step instructions, carving wax and carving instruments to complete the assignment. The averages of these scores were compared to a clinical instrumentation mid-term OSCE examination administered in the pre-clinical techniques course and to the final instrumentation OSCE which was administered in the same course. Upon completion of Clinic I, the scores on the student's two required instrumentation competencies (IC) were averaged and correlated to the above data. A linear regression was used to correlate the data. Results: R2 = .000 when using a linear regression correlating carving to the instrumentation competency (IC). When comparing the final OSCE to IC, R2 = .014 and when comparing the mid-term OSCE to IC, R2 = .317. The latter having the strongest correlation of the three groups of data. Conclusion: The pre-clinical mid-term OSCE had the most predictive value to instrumentation skills. Further research is needed to determine possible predictors for dental hygiene clinical skills. The opportunity to identify these predictors would enhance dental hygiene teaching methodology and would provide early identification of students needing additional clinical instruction.

1299 INFLUENCE OF TRAYS AND TECHNIQUES ON ACCURACY OF PVS IMPRESSIONS

A.W. HOYOS, University of Florida, Gainesville, USA, and K. SODER-HOLM, University of Florida, Gainesville, USA

Objectives: To determine how tray rigidity and impression technique affect the accuracy of impressions made with an addition polymerizing silicone. Methods: Metallic rim-lock trays (M) and disposable plastic trays (P) were used in combination with three different impression techniques. The three techniques consisted of: 1) Heavy/light body materials in a one-step impression (HL), 2) Putty impression with 2 mm space and light body impression made in two steps (PS), and 3) Putty impression without spacer and light body impression made in two steps (PL). Ten impressions of each combination technique/tray were made of a master model. The master model included two steel abutments (44 and 47) and a steel rod placed at ridge level between the two abutments. Five marks had been placed on each steel abutment. One mark placed on the steel rod in between the two abutments served as reference point. By use of a universal measuring microscope, the x, y, z-coordinates were recorded for each of the 11 marks on the master model and the impressions. The distances between the different marks and the reference point were calculated and compared with the master model. Using a t-test and pair wise comparisons, significant differences (p<0.05) were found between 4 of the investigated groups and the master model. Results: All techniques (PL, PS and HL) used with the plastic trays had distances that were significantly different from the master model, while for the metal trays it was only the HL technique that resulted in a distance that was significantly shorter than the matching distance on the master model. Conclusions: Plastic trays produced less accurate impressions than metal trays. When metal trays were used, putty based impressions were dimensionally better than heavy /light body impressions. Consequently, tray rigidity and maximal rigidity of the bulk of the impression improved impression reliability.

SALIVA

1049 PROTECTIVE ROLE OF GREEN TEA IN SJOGREN'S SYNDROME ANIMAL MODELS

S. HSU, D.P. DICKINSON, H. QIN, J.L. BORKE, K. OGBUREKE, M. SHARAWY, A. CAMBA, R. PODOLSKY, and G.S. SCHUSTER, Medical College of Georgia, Augusta, USA

Sjogren's syndrome (SS), an autoimmune disorder involving atrophy of the salivary glands. The etiology is not completely understood, but involves autoantigen presentation leading to development of autoantibodies. It may also involve apoptosis. In contrast to the U.S., the prevalence of xerostomia is significantly lower in green tea-consuming countries such as China and Japan. Green tea polyphenols (GTPs) are major bioactive components of green tea. Objectives: to investigate in vitro and in vivo the potential role of GTPs in modulation of autoantigen expression and apoptosis. Methods: Immortalized human salivary acinar cell line NS-SV-AC cells were incubated with EGCG (epigallocat-echin-3 gallate), the most abundant GTP, prior to determination of expression changes in major autoantigens by microarray, RT-PCR and Western analysis. To investigate effects on apoptosis, cell viability changes were measured by MTT assay after the cells were exposed to tumor necrosis factor (TNF)-alpha with or without EGCG treatment. To determine whether GTPs could protect against or ameliorate SS NOD and MRL mice representing two mouse models of the disease were either fed with GTP-water or water only prior to analysis of lymphocytic infiltration in the submandibular glands. Results: EGCG inhibited the expression of major autoantigens and protected NS-SV-AC cells from TNF-alpha-induced cytotoxicity, possibly mediated by a p38 MAPK pathway. NOD and MRL mice fed with GTPs exhibited significantly reduced lymphocyte infiltration in the salivary glands. Conclusions: in vitro, GTPs provide a measure of protection against two SS disease mechanisms: autoantigen expression and apoptosis. This may explain, in part, GTP-mediated protection of salivary glands in two animal models. These findings, taken together with green tea's anti-inflammatory and anti-apoptotic properties, suggest that GTPs could serve as an important component in novel approaches to delay and reduce the severity of SS. This study was supported in part by NIH grant 5R21CA097258-02.

0624 EFFECT OF ORAL MUCOSA CLEANING ON SALIVARY BACTERIA LEVELS

M.I. WILLIAMS, J. VAZQUEZ, and J. HALUKO, Colgate Palmolive Company, Piscataway, NJ, USA

Epithelial cells desquamated from the oral mucosa can become a part of the plaque biofilm matrix as well as serve as a key source of nutrients for bacteria. The cleansing of these cells may help to improve the oral conditions of patients. Objective: This study evaluates the effect of cleansing oral mucosal surfaces with a specialized toothbrush with and without a soft-tissue cleaning implement on the back of the toothbrush head on the level of salivary bacteria. Methods: In this randomized, cross-over study, healthy adult subjects brushed their teeth for 1 min with the assigned toothbrush. Salivary samples, collected at baseline and up to 2 hours after use, were analyzed for epithelial cells using a colorimetric assay and for bacteria grown on generalized blood media. DNA was extracted from the bacteria in the collected salivary samples and analyzed by real-time PCR. Representative bacteria that are implicated in various oral conditions were chosen as markers: Prevotella melaninogenica, Prevotella intermedia, Porphyromonas gingivalis, Fusobacterium nucleatum, and Streptococcus mutans. Results: The specialized toothbrush with the cleaning implement statistically significantly (p<0.05) reduced the levels of both the salivary levels of desquamated cells and total bacteria including the DNA of bacteria implicated in the formation of halitosis, gingivitis and caries compared to the toothbrush without the cleaning implement. Conclusion: The clinical results indicate that the cleaning implement on the back of the head of a specialized toothbrush is effective in reducing the levels of desquamated epithelial cells, a key nutrient source for oral bacteria, as wells total salivary bacteria including the DNA of problematic bacteria.

MOUTHRINSES

1542 REDUCING ORAL MUTANS STREPTOCOCCI LEVELS WITH XYLITOL MOUTH RINSE

G. HILDEBRANDT, I. LEE, and J. HODGES, University of Minnesota -, Minneapolis, USA

Xylitol-sweetened chewing gum has cariostatic properties, but is not suitable for all caries-prone patients. Objectives: The purpose of this study was to compare the effect of xylitol rinse and xylitol chewing gum on mutans streptococci (MS) load on the dentition. Methods: 202 subjects were screened for MS levels in paraffin-stimulated saliva. 104 qualifying subjects (i.e., [greater than or equal to]5 log CFU/ml) were randomly assigned to one of three groups. Positive control subjects (N = 34) chewed two xylitol gum pellets [Spry[TM], Xlear Inc., Orem, UT] for at least 5 minutes three times daily (xylitol dose: 4.3g/day). Experimental group subjects (N = 36) rinsed with 20ml of an 11%-aqueous solution of xylitol twice daily for 60 seconds (dose: 4.3g/day). Negative control group subjects (N = 34) did not use either product. No attempt was made to change the subject's diet. Salivary MS levels were monitored at one and three months. Compliance was very high as measured by use-diaries and exit questionnaires. Results: Mean MS levels [log CFU/ml (SE)] at baseline were 5.6 (0.1) in positive control, 5.5 (0.1) in experimental, and 5.5 (0.1) in negative control subjects. After 3-mos, MS levels were 4.4 (0.2) in the positive control, 4.4 (0.2) in the experimental, and 4.9 (0.2) in the negative control groups. Differences between groups were not significant by ANOVA (p = 0.2), however, MS levels tended to be lower in the experimental and positive control groups. Conclusion: Both xylitol rinse and chewing gum caused a similar reduction in MS levels on the dentition. This effect might be increased by altering exposure time, concentration, etc. Larger studies will be needed to determine if xylitol rinse can reduce caries incidence in high risk populations. Supported by the Minnesota Oral Health Clinical Research Center.

2053 COMPARATIVE EFFICACY OF TWO MOUTHRINSES IN A 6-MONTH STUDY

J.J. WITT (1), R. GIBB (1), A. HAMILTON (1), N. LANG (2), A. ALBERT-KISZELY (2), B.E. PJETURSSON (2), G.E. SALVI (2), and G.R. PERSSON (2), (1) The Procter & Gamble Company, Mason, OH, USA, (2) University of Berne, Switzerland

Objective: The objective of this study was to compare the effects of a commercial CPC (cetylpyridinium chloride) mouthrinse containing 0.07% CPC (Crest[R] ProHealth Rinse) versus those provided by a commercial essential flavor oil mouthrinse (Listerine[R] Antiseptic) on dental plaque accumulation and prevention of gingivitis in an unsupervised 6 month clinical study. Methods: This was a double blind, 6-month, parallel group, positive controlled study involving 128 subjects who were balanced and randomly assigned to either positive control (essential oil) or experimental (CPC) mouthrinse treatment groups. The CPC mouthrinse passed proposed performance assays by the FDA for an OTC CPC mouthrinse. At baseline, subjects received a dental prophylaxis and began unsupervised rinsing twice daily with 20 ml. of their assigned mouthrinse for 30 seconds after brushing their teeth for 1 min. Subjects were assessed for gingivitis and ingival bleeding by the Gingival Index (GI) of Loe and Silness and plaque by the Silness and Loe Plaque Index (PI) at baseline and after 3 and 6 months of product use. Oral soft tissue health was also assessed. Microbiological samples were also taken for community profiling by the DNA-DNA checkerboard method. Results: Results show that after 3 and 6 months use there was no significant difference (p = 0.05) between the CPC and essential oil mouthrinse treatment groups for overall gingivitis status, gingival bleeding, and plaque. At 6 months the covariant (baseline)--adjusted mean GI and bleeding sites numbers for the CPC and essential oil mouthrinses were 0.52 and 0.53 and 5.5 and 6.3, respectively. Both mouth rinses were well tolerated by the subjects. Microbiological community profiles were similar for the 2 treatment group. Conclusion: This study shows that the 0.07% CPC mouthrinse can provide similar plaque and gingivitis benefits to those provided by an essential oil mouthrinse over a 6 month period.

TOOTHPASTES

0695 DENTAL PLAQUE CONTROL EFFECT OF A ZINC CITRATE DENTIFRICE 

V.M. BARNES, R. RICHTER, D. BASTIN, P. LAMBERT, and T. XU, Colgate-Palmolive Technology Center, Piscataway, NJ, USA

Effective anti-plaque dentifrices have been a long standing demand of consumers. In addition to the obvious oral benefits of dental plaque control such as caries reduction and gingivitis prevention, the link between a healthy mouth and a healthy body has further driven the demand for efficacious oral care products. Zinc ion is a well-known bacteriostatic agent and has been used in dentifrices for control of dental plaque. Objective: This research evaluated the anti-plaque efficacy of a new 2% zinc citrate fluoride dentifrice vs. a non-zinc matching placebo and a commercial fluoride dentifrice (Colgate Dental Cream--CDC) in two cross-over clinical studies. Method: Healthy human subjects meeting inclusion criteria entered two respective clinical studies. Study 1 (24 subjects) compared the zinc dentifrice to CDC (over a 24 hours period. Study 2 (19 subjects) compared the zinc dentifrice to the matching placebo over a 24 hour period. After 1 week of washout, subjects used the test product for 1 week prior to the test period. Both studies employed the Modified Gingival Margin Plaque Index (MGMPI), a clinical method measuring dental plaque formation along the gingival margin after 24-hrs post-brushing. Result: In study 1, the mean MGMPI score, representing post-treatment plaque re-growth along the gingival margin for the zinc prototype as compared to CDC was 13.87[+ or -]8.27 and 21.23[+ or -]11.08 respectively. Study 2 demonstrated mean MGMPI scores for the zinc dentifrice and a matching placebo were 14.99([+ or -]13.32) and 24.38([+ or -]7.69) respectively. In both studies, the zinc dentifrice demonstrated significant 35% and 39% inhibition of dental plaque formation than those of their respective controls, CDC or a matching placebo. Conclusion: Two clinical studies demonstrated plaque control efficacy for a new zinc citrate containing dentifrice, suggesting a new anti-plaque and possible multi-benefit dentifrice for effective oral hygiene.

0634 CLINICAL ANTIMICROBIAL EFFICACY OF THE TRICLOSAN/COPOLYMER DENTIFRICE ON ORAL MICROORGANISMS

D. FINE (1), D. FURGANG (1), K. MARKOWITZ (1), P. SREENIVASAN (2), and W. DE VIZIO (2), (1) New Jersey Dental School--UMD, Newark, USA, (2) Colgate-Palmolive Company- / Piscataway, NJ, USA

Objectives: This cross-over design clinical study compared the in vivo antimicrobial effects following regular use of the triclosan/copolymer dentifrice and a fluoride toothpaste on oral microorganisms of dental plaque, saliva and tongue. Methods: Fifteen adults (27-49 years) completed a 1-week washout with a commercial fluoride dentifrice (CFD) prior to baseline sampling of supragingival plaque, saliva and tongue. Agar plating quantified total anaerobes, hydrogen sulfide (H[.sub.2]S) producing bacteria, Veillonella and Fusobacteria. Subjects were randomly assigned CFD or the triclosan/copolymer dentifrice for twice daily use for the next week. On day 8 subjects brushed with assigned dentifrice and provided samples (plaque, saliva and tongue scrapings) at 6 and 12 hours post brushing for enumeration of study bacteria This concluded one phase of the cross-over with subjects undergoing a 1-week washout prior to assignment of the second dentifrice. Results: All baseline samples demonstrated no differences in bacterial populations prior to random assignments of test dentifrices (p>0.05). A significant reduction (88-96%) of total anaerobic bacteria of the tongue, saliva and supragingival plaque samples were observed in the triclosan/copolymer group at both the 6 and 12 hour in comparison to subjects provided CFD (p = 0.001). Subjects brushing with triclosan/copolymer demonstrated a 77-92% decrease in Fusobacteria and a 84-89% reduction of Veillonella at 6 and 12 hour post-brushing versus CFD. A significant (74-85%) decrease in H[.sub.2]S producing bacteria were observed in the triclosan/copolymer group at 6 and 12 hour post-brushing (p = 0.001). Conclusions: Brushing with triclosan/copolymer resulted in significant and sustained reductions (for 12 hours post-brushing) in several microorganisms of the dental plaque, saliva and tongue compared to a commercial fluoride dentifrice. Antimicrobial effects of triclosan/copolymer may help explain the significant reductions in supragingival plaque and associated gingivitis observed with this dentifrice in previous clinical trials. Funded by the Colgate-Palmolive Co.

WHITENING

0882 WHITENING AGENTS WITH ACP: ENAMEL CARIES FORMATION AND PROGRESSION

C. FLAITZ, University of Texas Dental Branch--Houston, USA, and J. HICKS, Baylor College of Medicine, Houston, TX, USA

Objective: This in vitro study evaluated the effect of whitening agents containing amorphous calcium phosphate (ACP) on human enamel caries formation and progression. Methods: 15 teeth with sound enamel surfaces were divided into 4 portions. Each tooth portion was assigned to a treatment group: 1) No Treatment Control; 2) Day White Excel 3--9.5% hydrogen peroxide ACP; 3) Nite White Turbo--6% hydrogen peroxide ACP; 4) Nite White--16% carbamide peroxide ACP. The teeth were treated according to the manufacturer's recommendations (Discus Dental Inc, Culver City, CA 90232), followed by synthetic saliva, on a daily basis for 14 days. Control tooth portions were exposed only to synthetic saliva. A modified ten Cate solution was used for in vitro enamel caries formation and progression. The teeth were treated prior to lesion formation, and before lesion progression 1 and lesion progression 2 periods. Longitudinal sections were taken after lesion formation, lesion progression 1 and lesion progression 2 periods for polarized light study and statistical analysis (ANOVA, DMR). Results: Mean lesion depths were: Lesion Formation Period: Control 108[+ or -]15um; Day White 93[+ or -]11um; Nite White Turbo 48[+ or -]7um (P<.05); Nite White-16% 105[+ or -]12um. Progression Period 1: Control 171[+ or -]18um; Day White 126[+ or -]13um (P<.05); Nite White Turbo 96[+ or -]9um (P<.05); Nite White-16% 132[+ or -]12um (P<.05). Progression Period 2: Control 228[+ or -]20um; Day White 165[+ or -]17um (P<.05); Nite White Turbo 129[+ or -]11um (P<.05); Nite White-16% 152[+ or -]16um (P<.05). Conclusions: Whitening agents containing calcium phosphate have a reduced susceptibility to in vitro enamel caries lesion initiation and progression.

0687 SAFETY OF OVERNIGHT WHITENING WITH A BRUSH-APPLIED PEROXIDE GEL

R.W. GERLACH (1), M.L. BARKER (1), A.A. DESAI (2), C. MAHONY (2), M.J. PRENDERGAST (2), and R.F. DATE (2), (1) The Procter & Gamble Company, Mason, OH, USA, (2) Procter & Gamble, Egham, Surrey, England, UK

Objectives: Clinical research was conducted to evaluate safety of a brush-applied peroxide-based whitening gel across a diverse population. Methods: After informed consent, 560 healthy adult subjects were screened to ascertain whitening history and current tooth sensitivity. Of these, 544 were assigned to treatment with a 19% sodium percarbonate brush-applied whitening gel (Crest[R] Night Effects[TM]) that dries to form a film. Treatment was unsupervised QD for 14 nights. Safety and tolerability were assessed from clinical examination (baseline and end-of-treatment) and interview. Adverse events were collected irrespective of causality. Results: 511 subjects completed the 14 night regimen. The study population exhibited considerable diversity. Mean (SD) age was 41.3 (13.4), ranging from 18-98. Most (74%) participants were female, and 12% of the sample reported daily tobacco usage. A total of 63 subjects (12%) had a possibly or probably-related adverse events during treatment. These were predominantly symptomatic events, particularly oral irritation (6.1% of subjects) and tooth sensitivity (5.5%). 95% confidence intervals for percent occurrence were (4.16%, 8.50%) for oral irritation and (3.67%, 7.82%) for tooth sensitivity. Only two subjects (0.4%) had both oral irritation and tooth sensitivity during treatment. Clinical examination findings were unremarkable. Adverse events were overwhelmingly (99%) mild in severity, though 1 subject reported moderate pharyngitis during the treatment. No subjects discontinued use early due to treatment-related adverse events. Conclusion: Use of a 19% sodium percarbonate brush-applied film over 14-days was well tolerated, with mild and transient oral irritation or tooth sensitivity representing the most common adverse events associated with treatment.

RESEARCH METHODOLOGY

1478 INTRA-EXAMINER RELIABILITY IN A CLINICAL TRIAL AMONG OLDER VETERANS

C. WEHLER (1), S. RICH (1), R. GARCIA (2), E. KRALL (2), and J. JONES (1), (1) Boston University School of Dental Medicine, VA Medical Center (Bedford, MA), MA, USA, (2) Boston University School of Dental Medicine, VA Medical Center (Boston, MA), MA, USA

Objective: Clinical trials must carefully monitor intermediate outcome measures. We examined the intra-examiner reliability from a randomized, controlled, clinical trial of periodontal disease and diabetes among users of VA health care. Methods: This study randomized 193 subjects. Due to exclusions and attrition over time, 165 were seen for clinical exams (mean age 59.1, 97% male). A dental hygienist examined each subject seen in this study three times over the course of one year. Every tenth subject underwent the regular exam, followed by a calibration exam, for a total of 47 calibration exams. The calibration exams consisted of measuring gingival recession (6 sites per tooth, in mm), Gingival Index (3 sites on 6 index teeth, range 0-3), mobility (greater than 1mm in any direction, yes/no), and tooth identification. Also, full mouth periodontal probing (6 sites per tooth, in mm) was completed on each subject twice at each study visit to assure maximum reliability of these data; thus, calibration results for probing depths are available on 386 individual exams. Percent agreement, kappa statistics, and correlation were calculated on both a per person basis and per surface/tooth basis. Results:

                           Per surface/tooth analysis
Variable              n    % Agree  Kappa  Correlation

Pocket depth          386  72.0     .709   .845
Recession              47  92.4     .879   .893
Mobility               32  96.0     .805   .819
Gingival index         47  85.4     .736   .852
Tooth identification   32  99.8     .996   .998

                      Per person analysis
Variable              % Agree  Kappa  Correlation

Pocket depth          86.5     .799   .942
Recession             72.3     .905   .988
Mobility              75.0     .691   .970
Gingival index        76.6     .899   .979
Tooth identification  93.8     .932   .999

Conclusions: These results suggest that a dental hygienist can attain a high level of intra-examiner reliability in a large-scale study among a population of older veterans. Supported by VA HSR & D QUERI DII 99.206, NIH K24 DE00419, Boston University, and the Department of Veterans Affairs.