Abstracts of the October 2008 Issue

The cracked tooth conundrum: Terminology, classification, diagnosis, and management  

William  Kahler, mscdent, dclindent, fracds  

Abstract: Purpose: To provide an overview of the clinical features, diagnosis, classification and management of cracked teeth which may be a diagnostic challenge in clinical practice. Results: Cracks may initiate from coronal tooth structure or from within the root and affect healthy or root treated teeth. There are many terminologies and classifications in the literature for cracked teeth that can be as confusing as the array of clinical symptoms which are associated with this condition. The term “cracked tooth syndrome” is misleading as there are a range of symptoms that do not form a distinct and reliable pattern. Symptoms will vary with teeth that have healthy pulps, for teeth with inflamed or necrotic pulps, and for teeth that have been root treated. The American Association of Endodontists have classified five specific variations of cracked teeth; craze line, fractured cusp, cracked tooth, split tooth, and vertical root fracture. The importance of differentiating dentin, pulpal and periodontal pain for diagnosis and treatment for these specific entities will be elaborated. A decision flow chart indicating the treatment options available is presented. (Am J Dent 2008;21:275-282).

*: Dr. William Kahler, University of Queensland, Dental School, 200 Turbot St., Brisbane, 4000  Australia. E-*: w.kahler@uq.edu.au

Association of salivary Streptococcus mutans levels determined by rapid detection system using monoclonal antibodies with prevalence of root surface caries  

Kazunori  Ikebe, dds, phd,  Satoshi  Imazato, dds, phd,  Naomi  Izutani, dds, Ken-ichi  Matsuda, dds, phd, Shigeyuki  Ebisu, dds, phd,  Takashi  Nokubi, dds, phd  &  Angus  W.  Walls, dds, phd

Abstract: Purpose: To examine the hypothesis that salivary Streptococcus mutans levels determined by a rapid detection system using monoclonal antibodies are associated with prevalence of root surface caries in a selected population of older adults. Methods: Oral examinations were performed in 241 elderly people aged over 60 years with at least 10 teeth, and root surface caries were recorded. Populations of S. mutans in saliva were classified into three groups (Low: < 1 x 10⁵ CFU/mL; Moderate: ≤ 1 x 10⁵ CFU/mL, < 1 x 10⁶ CFU/mL; High: ≤ 1 x 10⁶ CFU/mL) using the analyzing kit with species-specific monoclonal antibodies. Stimulated whole saliva was collected; the flow rate and pH value were determined. Results: About 38% of subjects had at least one decayed lesion (inactive, active, or secondary lesions). Subjects were grouped according to levels of S. mutans into Low (51.5%), Moderate (39.4%), and High (9.1%). Significant associations were observed between inactive, secondary, or total decayed lesions and salivary S. mutans levels by Kruskal-Wallis test (P< 0.05). Multiple ordinary regression analyses demonstrated that numbers of inactive, secondary, and total decayed lesions were significantly associated with S. mutans levels (P< 0.05) independent of age, gender, frequency of brushing, salivary flow rate, or pH value of saliva. (Am J Dent 2008;21:283-287).

*: Dr. Satoshi Imazato, Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, 1-8, Yamadaoka, Suita , Osaka 565-0871, Japan . E-*: imazato@dent.osaka-u.ac.jp  

Polishing performance of multiple-use silicone rubber-based polishing instruments with and without disinfection/sterilization  

Siegward  Dietmar  Heintze, dmd  &  Monika  Forjanic  

Abstract: Purpose: To evaluate the effect of the multiple-use of a three-step rubber-based polishing system on the polishing performance with and without a disinfection/sterilization protocol with prolonged disinfection (overnight). Methods: The three-step polishing system Astropol was applied under standardized contact pressure of 2 N on 320 grit pre-roughened flat composite specimens of Tetric EvoCeram for 10 seconds (F and P disc) and 30 seconds (HP disc) respectively. After each polishing step, the surface gloss and roughness were measured with a glossmeter and an optical sensor (FRT MicroProf), respectively. Material loss of the composite specimens and polishing instruments were measured after each step with a high precision digital scale. For all four variables (surface gloss, surface roughness, composite loss, loss of rubber material) the mean percentage of change compared to the reference was calculated. Results: Already after the first use, the instruments which were used without disinfection or sterilization demonstrated a statistically significantly reduced polishing performance in all polishing steps compared to the reference (new polishing system) (t-test, P< 0.05). In addition, this loss in performance further increased with the second and third re-use. Especially the third component (Astropol HP) was affected by performance loss. By contrast, the multiple-use of the instruments which were subjected to prolonged disinfection did not result in a reduced polishing performance. For the P disc, a statistically significant improvement of the polishing performance could be observed throughout almost all multiple-use sessions (ANOVA, P< 0.05). The improved polishing performance was, however, accompanied by an increased loss of the silicone rubber material of the P and F polishing discs; the HP discs were not affected by this loss. Furthermore, particles of the rubber material also adhered to the composite. The polishing performance of the discs which were only subjected to the sterilization process was not statistically significantly different to the polishing performance of the control group in terms of surface roughness; but the surface gloss was worse than that of the control group. No loss of rubber material or adherence to the composite was observed in this group. (Am J Dent 2008;21:288-294).  

*: Dr. Siegward D. Heintze, Ivoclar Vivadent AG, In Vitro Research, Bendererstrasse 2, FL-9494 Schaan, Liechtenstein.  E-*: siegward.heintze@ivoclarvivadent.com

Effect of different 1% chlorhexidine varnish regimens on mutans streptococci levels in saliva and dental biofilm  

Luciana  Gazaniga  Maia  Ribeiro, md,  Lina Naomi Hashizume, phd  &  Marisa  Maltz, dr odont  

Abstract: Purpose: To evaluate in a randomized controlled study the effect of different 1% chlorhexidine (CHX) varnish regimens on levels of mutans streptococci (MS) in saliva and dental biofilm. Methods: Subjects with MS £10⁵ CFU/ml saliva, 11-16 years old, were allocated into four groups: Group A (n = 14): one 1% CHX varnish application; Group B (n = 14): 1% CHX varnish was applied once daily on 3 consecutive days; Group C (n = 15): 1% CHX varnish was applied three times with an interval of 4 days between each application; and Group D (n = 12): placebo varnish was applied once daily on 3 consecutive days. Saliva and dental biofilm samples were collected at baseline and 1, 4, and 8 weeks after the final varnish application. Results: After 1 week, a slight reduction in salivary levels of MS in Groups A, B, and C (-0.70, -0.90, and -0.41 log₁₀ CFU/ml saliva, respectively) was observed, significant only in Groups A and B (P< 0.05). No difference in salivary levels of MS was observed between the experimental groups in the different experimental periods. After 1 week in the dental biofilm a significant increase in total bacterial counts was observed in all experimental groups while a significant decrease in the levels of MS was observed only in Group A. (Am J Dent 2008;21:295-299).

*: Prof. Marisa Maltz, Faculty of Dentistry, Federal University of Rio Grande do Sul, Rua Ramiro     Barcelos, 2492, Bom Fim, Porto Alegre, Rio Grande do Sul, Brazil.  E-*: mmaltz@ufrgs.br

 

Potential effect of sodium bicarbonate-containing dentifrice in controlling enamel erosion in situ 

Danielle  Cristine  Furtado  Messias, dds, ms,  Mônica  Campos  Serra, dds, ms phd &  Cecilia  Pedroso  Turssi, dds, ms, phd  

Abstract: Purpose: To assess, by a crossover 2 x 2 in situ study, the speculated protective role of a sodium bicarbonate-containing toothpaste in controlling erosive lesions. Methods: Bovine enamel slabs were sterilized, and submitted to baseline Knoop microhardness measurements. After a 3-day lead-in period, 14 volunteers wore palatal acrylic appliances containing six enamel slabs (three on each side), for 4 consecutive days. On the first day, appliances with contained specimens were placed in the oral cavity to allow salivary pellicle formation. On the subsequent days, half of the enamel slabs were immersed extraorally in a lemonade-like soft drink for 90 seconds, twice daily. On both of these occasions, the appliance was dipped in toothpaste slurry of either a sodium bicarbonate-containing toothpaste or a regular counterpart for 60 seconds. Following a 3-day washout period, a new set of enamel slabs were mounted and the volunteers started the second period using the alternate dentifrice. Results: ANOVA (α = 0.05) showed no statistically significant difference between enamel treated with regular and sodium bicarbonate-based dentifrices, regardless of whether specimens were eroded or not (P= 0.8430). Acid-challenged specimens revealed lower microhardness values than uneroded samples. (Am J Dent 2008;21:300-302).

*: Dr. Cecilia Pedroso Turssi, Laboratory of Dental Materials Research, University of Uberaba – UNIUBE, Av. Nenê Sabino, 1801/Sala 2H-207, CEP 38055-500, Uberaba – MG , Brazil.  E-*:cturssi@yahoo.com

Self-limiting caries therapy with proteolytic agents  

Aya Abdulla Rashid Ahmed, dmd,  Franklin  García-Godoy, dds, ms  &  Karl-Heinz Kunzelmann, dmd, phd

Abstract: Purpose: To determine the extent to which artificial carious dentin can be removed by agents that do not seem to attack sound dentin such as pepsin, trypsin, collagenase and NaOCl, and to evaluate the effect of the enzyme pepsin and a new enzymatic solution SFC-V (pepsin in mild acidic buffer) as a self-limiting caries therapy in deep dentin carious lesions using our new model for artificial dentin caries. Methods: Artificial dentin caries was used to investigate different proteolytic agents which have the potential to remove carious tissue. 408 slices of coronal dentin were subjected to a demineralization regime which produces dentin caries very similar to natural lesions: acetic acid (pH 5) or lactic acid (pH 4) were used (7 days). Subsequently, sodium hypochlorite, collagenase, trypsin and pepsin were dissolved each in a suitable buffer and the demineralized dentin was treated for 10 minutes or 24 hours with these solutions. To differentiate the influence of the acidic buffer in case of pepsin, a second experiment was performed. 192 slices were exposed to lactic acid for 1 week. Subsequently the demineralized dentin surfaces were treated with either the enzyme pepsin in its acidic buffer, the acidic buffer alone, and in addition a neutral buffer as a control. In addition a fourth group was added where a new enzyme-based solution SFC-V was used. This second experiment differentiated further the influence of “diffusion enhanced by agitation” versus “diffusion” alone. The application time of the solutions was 3 minutes with and without agitation using a stiff nylon brush. To obtain information on the morphology of the pre- and post-treatment dentin surfaces, high resolution FE-SEM was used. Descriptive statistics were used based on cross tabulation of the morphological criteria. Results: Lactic acid produced demineralized dentin covered with a surface layer removable by proteolytic enzymes while acetic acid produced only demineralized dentin. The amount of tissue removed with the current proteolytic agents ranked as follows: trypsin<pepsin<collagenase<NaOCl. The neutral and the acidic buffers did not affect the surface precipitates while the enzyme pepsin and the solution SFC-V were effective in removing the degraded organic matrix. (Am J Dent 2008;21:303-312).

*: Prof. Dr. Karl-Heinz Kunzelmann, Department of Operative Dentistry and Periodontology, Ludwig Maximilians University, Goethestraße 70, D-80336 Munich, Germany.  E-*: karl-heinz@kunzelmann.de

Reduction in bacterial contamination of toothbrushes using the Violight ultraviolet light activated toothbrush sanitizer  

Robert Boylan, phd, Yihong Li, dds, dr ph, Lidia Simeonova, dds, Gene Sherwin, dds, Judith Kreismann, rdh, Ronald G. Craig, dmd, phd, Jonathan A. Ship, dmd  &  Jane A. McCutcheon, dds, phd  

Abstract: Purpose: This two armed, self-controlled, investigator blinded, clinical study tested the efficacy of an ultraviolet (UV) light toothbrush holder (Violight) to decrease toothbrush bacterial contamination. Methods: 25 subjects were randomly assigned to control or experimental groups and received two toothbrushes for home use on either even or odd days. The control group rinsed both toothbrushes after use in cold tap water with no mechanical manipulation. The experimental group rinsed one toothbrush in cold running water while storing the other toothbrush in the Violight toothbrush holder after use. The toothbrushes were returned after 2 weeks use in sealed plastic bags and were analyzed for the number of colony forming units (CFU) of S. mutans, S. salivarius, lactobacilli, E. coli, and other coliforms, and total bacterial counts by culture. An additional analysis of the total bacterial profile was performed using denaturing gradient gel electrophoresis (DGGE). Results: The Violight toothbrush holder reduced total CFU by an average of 86% (ANCOVA, P= 0.037). In addition, a tendency was noted for a reduction in total bacterial population as detected by DGGE. (Am J Dent 2008;21:313-317).

*: Dr. Jane McCutcheon, Department of Basic Sciences and Craniofacial Biology, New York University College of Dentistry, Mail Code 9436, 345 East 24th Street, New York, New York 10010-4086, USA. E-*: jam2@nyu.edu

 

Early dental plaque formation on toothbrushed titanium implant surfaces  

Evandro  Scligliano  Amarante, phd, msd, dds ,  Leandro  Chambrone, dds , Roberto  Fraga  Moreira  Lotufo, phd, msd, dds   &  Luiz  A.  Lima, LD, phd, msd, dds  

Abstract: Purpose: To evaluate the qualitative and quantitative differences on dental plaque formation on two different roughness titanium implant surfaces, i.e. machined and titanium plasma sprayed, as well as the amount of plaque removal by regular toothbrushing after 72-hour plaque accumulation. Methods: Eight systemically healthy subjects were recruited from the patient pool of a private dental practice. All patients underwent oral hygiene instruction and full mouth pro-phylaxis. Subsequently, maxillary casts from all patients were obtained and removable 0.7 mm-thick acetate stents without occlusal contact points were fabricated to support four titanium specimens of 4x2x2 mm divided into two groups (machined and plasma sprayed). Subjects were instructed to wear the stents for 72 hours, full time, removing them only during regular oral hygiene. Subsequently, the appliances were immediately repositioned and then the test side was brushed for 20 seconds. At the end of the 72-hour period, the stents were removed and prepared for microbiological analy-sis. Results: Both machined and plasma sprayed brushed surfaces presented statistically significant fewer bacteria than non-brushed surfaces. Similarly, regarding surface roughness, machined surfaces presented a total number of bacteria sig-nificantly smaller than those presented by plasma sprayed surfaces (P< 0.05). Statistically, the non-brushed machined turned surfaces presented a greater amount of Streptoccocus sp. when compared to the brushed machined surfaces. It was concluded that rough surfaces accumulated more dental plaque than polished surfaces. Both brushed surfaces presented less plaque accumulation, however, implant brushing was more effective on machined surfaces. (Am J Dent 2008;21:318-322).  

 *: Dr. Luiz A. Lima, Division of Periodontics, Department of Stomatology, Faculty of Dentistry, University of São Paulo, R. Prof. Lineu Prestes, 2227 Cidade Universitaria, 05508-000 São Paulo, SP, Brazil. E-*: lapalima@usp.br  

Bonding of autopolymerizing denture base resin to cast Type IV gold alloy  

Hiroshi  Shimizu, dds, phd, Yuzo  Tachii, dds  &  Yutaka  Takahashi, dds, phd  

Abstract: Purpose: To evaluate the shear bond strengths of an autopolymerizing denture base resin to cast Type IV gold alloy using four metal conditioners. Methods: Type IV gold alloy discs were cast. The disc surfaces were sandblasted with 50 µm alumina particles and primed with four metal conditioners (Metaltite; Alloy Primer; Metal Primer II; and V-Primer). An autopolymerizing denture base resin was applied on an area of the discs defined by a hole punched in a piece of sticky tape and by a Teflon ring. All the specimens were immersed in 37°C distilled water for 24 hours. Half of the specimens were thermocycled up to 20,000 cycles in water between 4°C and 60°C with a dwell time of 1 minute at each temperature. The shear bond strengths were determined at a crosshead speed of 1.0 mm/minute. The data was analyzed using a 2-way ANOVA (P< 0.05). Results: The shear bond strengths of the autopolymerizing denture base resin to cast Type IV gold alloy specimens primed with the four metal conditioners (P< 0.05) were significantly enhanced. However, the bond strength was reduced for all thermocycled groups (P< 0.01). Metaltite exhibited the greatest pre- and post-thermocycling bond strength (27.5 and 22.4 MPa) compared to the other groups (P< 0.05). (Am J Dent 2008;21:323-326).  

*: Dr. Hiroshi Shimizu, Division of Removable Prosthodontics, Department of Oral Rehabilitation, Fukuoka Dental College, 2-15-1, Tamura, Sawaraku, Fukuoka 814-0193, Japan. E-*: simizuh1@college.fdcnet.ac.jp

Clinical evaluation of a self-etch adhesive in non-carious cervical lesions

Ali I. Abdalla,  phd  &   Hussein Y. El Sayed,  phd   

Abstract: Purpose: To evaluate the clinical performance of a self-etching adhesive in Class V non-carious lesions with and without acid etching procedures. Methods: A total of 125 Class V non-carious cervical lesions (NCCL) with incisal or occlusal margins in enamel and gingival margins in dentin/cementum were selected and restored with Clearfil SE Bond self-etch adhesive and Clearfil APX resin composite. All cavities were restored using two techniques; after etching the whole cavity for 20 seconds and without acid etching (control). The restorations were evaluated at baseline, 1- and 2-year using modified USPHS criteria. Results: No loss of restorations was recorded after 1 and 2 years for the two restorative techniques. There was no significant difference between the baseline and 2-year results for any of the tested technique. However, restorations made after acid etching showed less marginal discoloration at the enamel margins. (Am J Dent 2008; 21:327-330).

*: Dr. Ali I. Abdalla, Department of Restorative Dentistry, Faculty of Dentistry, University of Tanta, Tanta, Egypt. E-*: ali_abdalla79@yahoo.com

A finite element analysis of ceramic restorations in endodontically treated premolars  

Liang Lin  Seow, bds, msc, fds rcs, phd,  Chooi Gait Toh, bds (hons), msc, fds rcs, drd rcs, Alex Siu-Lun Fok, beng, phd, ceng  &  Nairn  H. F.  Wilson, phd, msc, bds, fds rcs, drd rcs

Abstract: Purpose: To investigate the level and distribution of stresses in endodontically treated maxillary premolar teeth restored using various cavity designs of bonded all-ceramic restorations. The hypothesis tested was that the various all-ceramic approaches, including incorporating a pulp chamber extension in the restoration, had no influence on the stresses in the restored tooth unit. Methods: Finite element packages Patran and Abaqus were used for the stress analysis. The cavity designs investigated include: (1) inlay (I); (2) inlay with palatal cusp coverage (IPC); (3) onlay (O); (4) inlay with pulp chamber extension (IPE); (5) inlay with palatal cusp coverage and pulp chamber extension (IPCPE); and (6) onlay with pulp chamber extension (OPE). Results: In each case, tensile stresses were found to be concentrated subjacent to the occlusal fossa. Peak tensile stress and peak shear stress values along the tooth/restoration interface for IPC, O IPCPE and OPE cavity designs were found to be associated with the axiogingival line angle. Overall, the order of the various forms of restoration investigated in terms of the maximum principal stress (from greatest to lowest) was as follows: IPE> IPCPE> OPE> I> IPC> O. (Am J Dent 2008;21:331-336).

*: Dr. Liang Lin Seow, School of Dentistry , International Medical University , 126, Jalan 19/155B, Bukit Jalil, Kuala Lumpur , Malaysia . E-*: llseow@gmail.com