Abstracts of the October 2006 Issue

Clinical performance and SEM evaluation of direct composite restorations in primary molars

Regina Maria Puppin-Rontani, dds, ms, phd, Mario Fernando de Góes, dds, ms, phd, Cleane Elizabete Voelske, dds & Franklin García-Godoy, dds, ms

Abstract: Purpose: To evaluate the clinical outcome of composite restorations performed in primary molars after 18 months and the morphology of the dentin/resin interface. Methods: 41 primary molars from children aged 4-9 years were restored with Scotchbond Multi-Purpose Plus adhesive system and Z100 resin-based composite. The restorations were evaluated at baseline, 6, 12 and 18 months using the USPHS method for direct clinical analysis. Plaster models were made at each evaluation period for indirect evaluation. For the morphologic analysis of the dentin/resin interface, seven exfoliated teeth were sectioned longitudinally in a mesio/distal direction and observed in the electro scanning electron microscope. Results: 100% (n = 40) of the restorations evaluated at 6 months were scored as Alpha for anatomical form, color matching, secondary caries, color alteration, and marginal degradation. At 12 months, 96.4% (n = 28) of the restorations received Alpha score and 3.4% Charlie score. At 18 months, all restorations evaluated (27/27) received Alpha score. 23 restorations were indirectly evaluated at 6, 12 and 18 months postoperatively. No significant wear or fractures were observed in any of the restorations. In the evaluation of the dentin/resin interface, the formation of a consistent hybrid layer was observed and the restorations were well adapted to the dentin at 18 months postoperatively. (Am J Dent 2006;19:255-261).

Clinical significance: Scotchbond Multi-Purpose Plus and Z100 restorations using the total-etch technique in primary molars revealed excellent clinical/radiographic performance in relation to the anatomical form, color alteration, marginal degradation and secondary caries. In the indirect analysis, Z100 presented high wear resistance. The scanning electron microscopic evaluation demonstrated excellent adaptation at the dentin/resin interface at 18 months of clinical service.

*: Dr. Regina M. Puppin-Rontani, Department of Pediatric Dentistry, FOP/UNICAMP, Av. Limeira, 901, Piracicaba - 13414-018 – SP, Brazil. E-*: rmpuppin@fop.unicamp.br

Clinical performance of pulpotomized primary molars restored with resin-based materials. 24-month results

Zafer C. Cehreli, dds, phd, Aysegul Cetinguc, dds, Sevi Burcak Cengiz, dds, phd & A. Nil Altay, dds, phd

Abstract: Purpose: To evaluate the clinical and radiographic success rates of pulpotomized (formocresol) primary molar teeth restored with a resin-based composite (TPH) or a polyacid-modified resin composite (Dyract AP) over a 2-year period. Methods: 100 composite and 100 compomer restorations were placed over pulpotomized teeth by two clinicians in 84 patients. Two other calibrated clinicians evaluated the restorations using the modified USPHS/Ryge criteria observing the following characteristics: marginal discoloration, marginal adaptation, wear/anatomic form, enamel loss and caries. Mann Whitney U test, Friedman test and Wilcoxon signed ranks tests were used for statistical analysis (P= 0.05). Results: At 24 months, 80 composite and 72 compomer restorations were available for evaluations. Except for baseline, compomer restorations showed significantly more marginal discoloration (P= 0.001) and marginal disintegrity (P= 0.001) than did the resin composite. Compomer restorations demonstrated a significant increase in minor enamel cracks along restoration margins over time (P= 0.001), but no chipping or loss of enamel was detected. Caries was observed only in 2.8% of compomer restorations and was restricted to restoration margins. 2% of composite and 17% of compomer restoration-treated teeth were extracted due to radiographic evidence of failure. Pathological root resorption patterns observed beneath failed compomer restorations were strongly suggestive of coronal microleakage. (Am J Dent 2006;19: 262-266).

Clinical significance: Provided that natural exfoliation of the tooth is expected within 2 years, the clinical and radiographic data obtained herein support the restoration of pulpotomized molars with the tested resin-based composite system (TPH). The use of the tested compomer (Dyract AP) in conjunction with the single-bottle adhesive cannot be recommended.

*: Dr. Zafer C. Cehreli, Gazi M. Kemal Bulvari, 61/11, 06570 Maltepe, Ankara, Turkey.

E-*: zcehreli@yahoo.com

Treating open carious lesions in anxious children with ozone.

A prospective controlled clinical study

Jan Eric Dähnhardt, Dr med dent, THOMAS JAEGGI, Dr med dent & Adrian Lussi, dipl chem, Dr med dent

Abstract: Purpose: To determine whether the treatment of dental caries with ozone was possible in apprehensive children and to ascertain whether ozone reverses caries in open single-surface lesions. Further, the influence of ozone on laser fluorescence was investigated. Methods: 82 lesions in 28 children with at least two open single-surface lesions were assessed. The children were anxious and were judged by the referring dentist as non-treatable. For each test lesion, which was treated with ozone, a control lesion was left without ozone treatment. Hardness and laser fluorescence values were assessed and the changes for hardness and laser fluorescence values in the test lesion were compared with the values in the control lesion after 2, 4, 6, and 8 months. Results: 94 percent of the children were treatable and 93% lost their dental anxiety. The hardness values improved significantly in the ozone-treated test lesions after 4, 6, and 8 months (P< 0.05) compared with baseline while the control lesions had no significant change in hardness at any recall interval. Comparing the differences between test and control teeth over time, the laser fluorescence values improved, however the improvement was not statistically significant (P> 0.05). The use of ozone resulted in an average reduction of 13% of the laser fluorescence values immediately after the ozone treatment. (Am J Dent 2006;19: 267-270).

Clinical significance: Ozone reversed caries in open single-surface lesions when used on uncooperative and anxious children. The painless approach with multiple visits made most of the children treatable. Laser fluorescence values should be measured before ozone application.

*: Dr. Jan Eric Dähnhardt, Klinik für Zahnerhaltung, Präventiv- und Kinderzahnmedizin, Freiburgstrasse 7, 3010 Bern, Universität Bern, Switzerland. E-*: daehnhardt@zmk.unibe.ch

Effect of surface treatments on the bond strength of brackets bonded with a compomer

Ascensión Vicente, dds, phd, Raúl Navarro, Ana Mena & Luis A. Bravo, md, dds, ms, phd

Abstract: Purpose: To evaluate the effectiveness of the compomer Dyract AP for bonding brackets when conditioning the enamel with phosphoric acid and a non-rinsing conditioner (NRC), in comparison with a control group in which the resin orthodontic adhesive system Transbond XT was used. Methods: The brackets were bonded to extracted premolars which were divided into three groups: (1) Acid/Transbond XT, (2) NRC/Dyract AP and (3) Acid/Dyract AP. Shear bond strength was measured with a universal testing machine. The crosshead speed was 1mm/minute. The adhesive remnant on the tooth after debonding was determined using image analysis equipment. Results: The bond strength of Acid/Transbond XT was significantly higher than bond strengths of Acid/Dyract AP and NRC/Dyract AP (P< 0.017). No significant differences were observed between Acid/Dyract AP and NRC/Dyract APBond strength values (P> 0.017). Acid/Transbond XT left significantly more adhesive on the tooth than Acid/Dyract AP and NRC/Dyract AP, whereas NRC/Dyract AP left significantly less adhesive than Acid/Dyract AP (P< 0.05). (Am J Dent 2006;19: 271-274).

Clinical significance: Although the bond strength values of the compomer, regardless of the enamel pre-treatment, were significantly lower than resin values, they were above the minimum values reported to achieve a clinically effective adhesion in orthodontics. NRC is a good alternative to acid-etching as it provides a bond strength which is similar to the strength provided by acid-etching and it also left less adhesive on the tooth after debonding.

*: Dr. Ascensión Vicente, Unit of Orthodontics, Dental Clinic, University of Murcia, Hospital Morales Meseguer, 2ª planta, C/Marqués de los Vélez, s/n. 30008 Murcia, Spain. E-: ascenvi@um.es

Evaluation of the fluoride release from orthodontic band cements

Senem Selvİ Kuvvetlİ, dds, phd, Elİf Bahar Tuna, dds, phd, Şule Kavaloğlu Çıldır, dds, mSc, phd,

Nüket Sandallı, dds, phd & Koray Gençay, dds, phd

Abstract: Purpose: To compare the fluoride levels released from a polyacid-modified resin composite (Ultra BandLok), a resin-modified glass-ionomer cement (Multicure) and a conventional glass-ionomer cement (Meron). Methods: Fluoride concentration in the deionized water was measured at 1, 2, 3, 7, 14 and 28 days. Fluoride measurement was undertaken using a fluoride ion selective electrode connected to an ion-analyzer. Friedman test was used in the repeated measurements of multiple groups. Kruskal-Wallis test was used to compare the groups. Dunn’s multiple comparison test was applied for the comparison of subgroups. Results: The fluoride release pattern of the three materials was similar. The highest level of fluoride was obtained at the 24-hour measurement from all samples. According to comparisons among materials, Ultra BandLok released significantly less fluoride than Multicure and Meron (P 0.01) at all the measurement times. In addition, the differences between the fluoride concentrations released from Multicure and Meron materials at all measurement days were not significant (P> 0.05). (Am J Dent 2006;19:275-278).

Clinical significance: Resin-modified and conventional glass-ionomer cements released similar amounts of fluoride throughout the study. These cements may have potential caries preventive activity under the bands of fixed space maintainers.

*: Dr. Senem S. Kuvvetli, Yeditepe University Faculty of Dentistry, Bağdat Cd. No. 238, 34730 Göztepe, Istanbul, Turkey. E-: sskuvvetli@yahoo.com.tr

Bond strength and failure patterns of adhesive restorations in primary teeth aged in the oral environment

Luciano Casagrande, dds, ms, Vinícius de Hipólito, dds, ms, Mário Fernando de Góes, dds, ms, phd, Juliana Sarmento Barata, dds, ms, phd, Fernando Borba de Araújo, dds, ms, phd & Franklin Garcia-Godoy, dds, ms

Abstract: Purpose: To evaluate the bond strength and micromorphology of the fracture pattern of adhesive composite restorations in primary teeth after long-term clinical function. Methods: Subjects (8-10 years-old) with deep carious lesions in primary molars had their teeth restored with resin composite (Z250). The teeth were randomly divided into two groups, according to the adhesive system used: (1) Scotchbond Multi-Purpose (SMP); and (2) Clearfil SE Bond (CSE). After the clinical and radiographic follow-up period (15-17 months), the teeth were exfoliated and the adhesive restorations were subjected to microtensile bond test. Results: Student’s t-test revealed a statistical difference (P= 0.001) between the two adhesive systems tested (SMP = 16.8 ± 2.62 MPa; CSE = 27.3 ± 2.28 MPa). The micro-morphology evaluation of the failure zone revealed a weak area in the demineralized dentin (SMP) and at the top of the hybrid layer (CSE). (Am J Dent 2006;19:279-282).

Clinical significance: The demineralized zone in bonded dentin substrates had a negative effect on the adhesive restorations over time.

*: Dr. Luciano Casagrande, Felipe de Oliveira, 566, Apt. 802, Porto Alegre, RS 90630-000, Brazil.

E-: lucianocasagrande@hotmail.com

Influence of opalescence and fluorescence properties on the light transmittance of resin composite as a function of wavelength

Yong-Keun Lee, dds, phd & John M. Powers, phd

Abstract: Purpose: To determine the influence of opalescence and fluorescence properties on the light transmittance of resin composites as a function of wavelength (410-750 nm). Methods: Spectral distribution of seven resin composites of A2 shade was measured according to the CIELAB color scale relative to the standard illuminant D65 in the reflectance and transmittance modes. Opalescence spectrum (OPS) was calculated as the subtraction spectrum (i.e., the spectrum measured in the transmittance mode subtracted at each wavelength from the spectrum measured in the reflectance mode). UV component of the illuminant was included and excluded to calculate the fluorescence spectrum (FLR and FLT in the reflectance and transmittance mode, respectively). Contrast ratio (CR) was calculated as the ratio of reflectance over a black background and over a white background. The total transmittance spectral distribution (TSD) value was used as the parameter to indicate masking ability of the resin composites over background color. Multiple regression analyses were performed among TSD and other optical parameters at the significance level of 0.05. Results: In all the resin composites and wavelength range, correlation between CR and TSD was very high (r = -0.99). Correlations between each parameters varied by the wavelength range of fluorescence (410-500 nm) and no-fluorescence (510-750 nm). Correlation between OPS and TSD varied by the wavelength range (r = -0.86 to -0.94, P< 0.05). Fluorescence of resin composites increased the TSD values. Based on this in vitro study, the influence of opalescence and fluorescence of resin composite varied by the wavelength. (Am J Dent 2006;19:283-288).

Clinical significance: The opalescence of resin composite caused a decrease and the fluorescence caused an increase in the light transmittance. The influence of opalescence and fluorescence on the masking ability was affected by the wavelength range of fluorescence emission or no-emission. Practical contributions of these properties on masking effect should be studied further.

*: Dr. Yong-Keun Lee, Department of Dental Biomaterials Science and Dental Research Institute, College of Dentistry, Seoul National University, 28 Yeongeon-dong, Jongro-gu, Seoul, Korea. E-: ykleedm@snu.ac.kr

Clinical evaluation of self-etch adhesives in Class V non-carious lesions

Ali I. Abdalla, phd & Franklin García-Godoy, dds, ms

Abstract: Purpose: To evaluate the clinical performance of two self-etching and one total-etch adhesives in Class V non-carious cervical lesions (NCCL). Methods: Two self-etching primers, Clearfil SE Bond and Hybrid Bond, and one total etch adhesive, Admira Bond, were placed in 195 NCCL. Restorations were evaluated at baseline, 1 and 2 years using the USPHS criteria. Results: No restoration was lost after 1 and 2 years for all materials. There was no significant difference between the baseline and 2-year results for Admira Bond and Clearfil SE Bond restorations. In contrast, Hybrid Bond restorations showed significant deterioration in marginal adaptation and cavosurface marginal discoloration after 2 years. Also, there was no significant difference between Admira Bond and Clearfil SE Bond at each recall period. (Am J Dent 2006;19:289-292).

Clinical significance: Total-etch adhesive (Admira Bond) and two-step self-etch adhesive (Clearfil SE Bond) showed excellent clinical performance when placed in non-carious Class V lesions after 2 years. In contrast, one step self-etch adhesive (Hybrid Bond) showed significant deterioration on the marginal adaptation and marginal discoloration.

*: Dr Ali I. Abdalla, Department of Restorative Dentistry, Faculty of Dentistry, University of Tanta, Tanta, Egypt. E-: aliebraheem01@yahoo.com

Clinical evaluation of a polyacid-modified resin composite (Dyract) in Class III cavities: 5-year results

Mustafa Demirci, dds, phd, Handan Ersev, dds, phd, Hande Şar Sancakli, dds & Mert Topçubaşi, dds, phd

Abstract: Purpose: This study evaluated the 5-year clinical performance of Dyract polyacid-modified resin composite material in Class III cavities. Methods: 62 Class III cavities in 30 patients were restored with Dyract. Two experienced, calibrated examiners evaluated the restorations clinically at baseline and at 1-, 2-, 3-, 4-, and 5-year recalls, according to the modified Ryge criteria. Results: After 5 years, a total of six restorations had failed and the cumulative failure rate was 94.6%. By the 5-year recall, one restoration was replaced due to pulpitis and five were replaced due to secondary caries. After 5 years, marginal discoloration was statistically significant (P= 0.0002). (Am J Dent 2006;19:293-296).

Clinical significance: The durability of Dyract in Class III cavities was very high after 5 years.

*: Dr. Mustafa Demirci, Faculty of Dentistry, Department of Conservative Dentistry, Istanbul University, Çapa, Istanbul-34390, Turkey. E-: demirci.md@superonline.com

Pulpal response to a newly developed MMA based resin cement for bonding tooth-colored indirect restorations

Yuichi Seki, dds, Yasushi Shimada, dds, phd, Richard M. Foxton, bds, mfds, rcs ed, phd

& Junji Tagami, dds, phd

Abstract: Purpose: To evaluate the pulpal responses to a newly-developed MMA-based self-etch resin cement, when used as a luting agent for indirect resin composite restoration, and to compare the results with those obtained from a total-etch luting agent, glass-ionomer cement, and amalgam restoration. Methods: 120 cervical cavities were prepared in monkey teeth and divided into four equal groups according to the restorative materials used: (1) the cavities were restored with resin composite inlays using a self-etch resin cement as a luting agent (M-Bond); (2) the cavities were also restored with resin composite inlays but using a total-etch resin cement as a luting agent (Super-Bond C&B); (3) the cavities were directly restored with glass-ionomer cement (Fuji II); or (4) the cavities were directly restored with amalgam (Dispersalloy). The restored teeth were extracted at 3, 30, or 90 days after restoration, then fixed in 10% neutral buffered formalin. The specimens were prepared using routine histopathological procedures. Five µm-thick sections were stained with hematoxylin and eosin or Brown & Brenn gram stain for bacterial observations. Histological responses in the pulpal tissue and bacterial penetration were observed under a light microscope and evaluated using standard scores. The results were statistically analyzed using the Kruskal-Wallis test (P< 0.05) Results: At all time intervals, no significant differences of pulpal inflammatory responses between M-Bond and Super-Bond C&B were observed (P> 0.05). Both resin cements showed no serious pulpal responses, such as necrosis or abscess formation. In general, both MMA-based resin cements showed similar pulpal responses to those of glass-ionomer cement except for congestion of pulpal blood vessels at 3 days after restoration in which glass-ionomer cement exhibited a lower level than that of the MMA-based resin cements. For the group restored with amalgam, at 3 days after restoration, severe odontoblastic disorders and blood vessel congestions with a large infiltration of inflammatory cells were detected. At 30 and 90 days after restoration, slightly inflammatory irritations were observed irrespective of the materials used. Reparative dentin formation and bacterial penetration were found mostly in the group restored with amalgam (Am J Dent 2006;19: 297-302).

Clinical significance: The newly developed MMA-based resin cement showed acceptable biocompatibility to the pulp when used as an adhesive luting agent for composite resin inlays in preparations with a mean RDT between 0.53 and 0.7 mm.

*: Dr. Yuichi Seki, Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.

E-: sekiope@tmd.ac.jp

Post-irradiation hardening of dual-cured and light-cured resin cements through machinable ceramics

Keiichi Yoshida, dds, phd & Mitsuru Atsuta, dds, phd

Abstract: Purpose: To evaluate the surface hardness (Knoop Hardness Number) of the thin layer in three light-cured and dual-cured resin cements irradiated through or not through 2.0 mm thick machinable ceramics. Methods: A piece of adhesive polyethylene tape with a circular hole was positioned on the surface of the ceramic plate to control the cement layer (approximately 50 µm). The cement paste was placed on the ceramic surface within the circle. The ceramic plate with resin cement paste was placed on a clear micro cover glass over a zirconia ceramic block to obtain a flat surface, and the material was polymerized using a visible-light-curing unit. The surface hardness was recorded at a series of time intervals up to 5 days, starting from the end of a light-irradiation period. Results: The hardness steadily increased with post-irradiation time and tended towards a maximum, usually reached after 1 or 2 days. In all cases, the increase in hardness was relatively rapid over the first 30 minutes and continued at a lower rate thereafter. The dual-cured resin cement for each material showed a significantly higher hardness value than the light-cured resin cement irradiated either through or not through ceramics at all post-irradiation times. The resin cements cured through ceramic for each material were significantly less hard compared with those cured not through ceramics at all post-irradiation times. (Am J Dent 2006;19: 303-307).

Clinical significance: For dual-cured resin cement, light-curing activation alone was not adequate to achieve sufficient hardening. Machinable ceramic thickness of 2 mm hindered maximum hardening of dual-cured resin cements.

*: Dr. Keiichi Yoshida, Division of Applied Prosthodontics, Nagasaki University, Graduate School of Biomedical Sciences, 1-7-1, Sakamoto, Nagasaki 852-8588, Japan. E-: keiichi@ nagasaki-u.ac.jp

Effect of polymers used in saliva substitutes on demineralized bovine enamel and dentin

Hendrik Meyer-Lueckel, Dr med dent, Peter Tschoppe, Dr med dent, Werner Hopfenmuller, dr rer nat, dr med, Wolfgang-Ruediger Stenzel, dr rer nat & Andrej M. Kielbassa, prof Dr med dent

Abstract: Purpose: To evaluate the effects of porcine mucin- and carboxymethylcellulose-based (CMC) solutions on the inhibition of demineralization of pre-demineralized bovine enamel and dentin in vitro. Additionally the sugar substitutes sorbit or xylit were added to the various solutions. Methods: 54 enamel and dentin samples were prepared from 14 freshly extracted permanent bovine central incisors. The samples were demineralized (pH 5.0 for enamel and pH 5.5 for dentin; 14 days) and subsequently exposed to either mucin- or CMC-based solutions combined with xylit and sorbit at pH 5.5. After in vitro exposure, the specimens were cut perpendicular to the enamel/dentin surface and the sections were ground (4000 grit) to a uniform thickness (100 µm). Mineral loss and lesion depths were evaluated from microradiographs with a dedicated software package (TMR 2.0.27.2). Results: For both dental hard tissues, storage in the mucin-containing solutions resulted in significantly higher lesion depths (LD), but lower mineral loss values (Z) compared to the CMC-containing solutions (P< 0.05; 2-way ANOVA). For the dentin specimens, significant differences in Z were observed between sorbit and xylit (P< 0.05; 2-way ANOVA). The mineral loss and lesion depths of the enamel specimens did not differ significantly after storage in the various solutions (P> 0.05; Bonferroni post hoc test). For the dentin specimens stored in the solution containing mucin/xylit the mineral loss was significantly decreased compared to the other mucin groups as well as to the CMC/xylit solution (P< 0.05; Bonferroni post hoc test). (Am J Dent 2006;19:308-312).

Clinical significance: Within the limitations of an in vitro study, it was concluded that neither mucin nor CMC, as commonly used bases of saliva substitutes, were capable of inhibiting further demineralization in the absence of caries-protective ions.

*: Dr. Peter Tschoppe, Department of Operative Dentistry and Periodontology, University School of Dental Medicine, Campus Benjamin Franklin, Charité, Universitätsmedizin Berlin, Aßmannshauser Strasse 4-6, D-14197 Berlin. E-: peter.tschoppe@charite.de

Effect of bleaching agents on enamel permeability

Renato Jonas Schiavoni, dds, Cecilia Pedroso Turssi, dds, phd, Antonio Luiz Rodrigues Jr, dds, phd,

Monica Campos Serra, dds, phd, Jesus Djalma Pécora, dds, phd & Izabel Cristina Fröner, dds, phd

Abstract: Purpose: To evaluate enamel permeability after external bleaching procedures. Methods: The coronal portion of 75 human canines were covered with an acid resistant varnish, except for a 7.1 mm² circular area on the labial surface and, according to a randomized complete block design, specimens were allocated to bleaching treatments using carbamide peroxide-containing agents (CP): 10%, 16% or 37%; or a 35% hydrogen peroxide product (HP). The control group was exposed to artificial saliva. The bleaching agents were applied following the manufacturer's recom-mendations over 21 days. In between bleaching exposures, specimens were stored in artificial saliva. Samples were then prepared according to a histochemical coloring method based on copper sulfate and dithiooxamide solutions. Digital images captured in an optical microscope were used to measure the percentage of copper ion penetration over the total enamel thickness on three sections taken from the exposed area. Results: Analysis of Deviance showed a significant difference for the permeability values among groups (P = 0.046). Likelihood ratio test revealed that the use of the CP10% and HP35% agents caused significantly greater enamel permeability than did the control treatment. No significant differences in percentage of copper ion penetration were found among CP10%, CP16%, CP37% and HP35%. This in vitro study demonstrated that depending on the external bleaching procedure, enamel permeability may be increased. (Am J Dent 2006;19: 313-316).

Clinical significance: Depending on the bleaching agent, enamel permeability may be increased and factors other than the active agent concentration may account for its occurrence.

*: Dr. Izabel Fröner, Faculty of Dentistry of Ribeirão Preto – USP, Av. do Café, s/nº - Monte Alegre, CEP: 14040-904 Ribeirão Preto, SP, Brazil. E-: froner@forp.usp.br