Abstracts of the April 2006 Issue

Dentin bridge formation after white mineral trioxide aggregate

(white MTA) pulpotomies in primary molars

Myriam Maroto, dmd, phd, Elena Barbería, md, phd, dds, Vicente Vera, md, phd, lds

& Franklin García-Godoy, dds, ms

Abstract: Purpose: To evaluate, clinically and radiographically, the dentin bridge formation potential of white mineral trioxide aggregate (white MTA) when used in pulpotomy treatments in primary molars. Methods: A total of 23 primary molars received a pulpotomy treatment using white MTA followed by stainless steel crown restoration and controlled 6 months after treatment. Results: Clinical and radiographic success was 100% as none of the molars showed any clinical or radiographic pathological signs. Reparative dentin deposition was found in some of the cases: stenosis was present in 69.2% of the pulp canals from mandibular molars and formation of dentin bridges was seen in 11.5% of the pulp canals from mandibular molars 6 months after treatment with white MTA. (Am J Dent 2006;19:75-79).

Clinical significance: White mineral trioxide aggregate (white MTA) may be considered as an adequate pulp dressing material in pulpotomy treatment of primary molars but it produced less radiographic dentin bridges than the use of grey mineral trioxide aggregate (grey MTA).

Address: Dr. Myriam Maroto, Department of Prevention, Pediatric Dentistry and Orthodontics, Faculty of Dentistry, Complutense University of Madrid, Avda. Complutense s/n, 28040 Madrid, Spain. E-mail: myriammaroto@yahoo.com

The effect of different fluoridation methods on the red wine staining potential on intensively bleached enamel in vitro

Matthias Ley, dr med dent, Thomas Wagner, dds & Mozhgan Bizhang, dr med dent

Abstract: Purpose: To study the effect in vitro of different fluoridation methods after intensive bleaching on the color of enamel slabs during a severe staining challenge with red wine. Methods: 75 specimens were equally divided among five groups. Group 1 (no bleaching, no wine) served as control. Groups 2, 3 and 4 underwent bleaching with 35 % H₂O₂ for 10 minutes followed by home-bleaching for 8 hours/day with 10% carbamide peroxide on 14 consecutive days. Groups 2 and 3 were fluoridated for 1 hour with either Elmex gelée or Duraphat, respectively whereas Group 4 remained without fluoridation. Group 5 (no bleaching, no fluoride, wine) served as control for the influence of red wine on the color of untreated enamel. Color determination was accomplished using the CIE-Lab System. Results: Nine successive cycles of wine saliva treatment (10 minutes wine, 23 hours 50 minutes saliva) for Groups 2-5 revealed the highest changes of a-values (∆a= 4.17) (towards red) for the Duraphat-treated group (bleaching, Duraphat, wine) with significantly higher ∆a-values compared with Group 4 (bleaching, no fluoride, wine) (∆a= 2.97). After final cleaning no differences were found between the three bleached groups (Groups 2, 3 and 4) for ∆L, ∆a, ∆b and ∆E, respectively. Exposure to red wine led to an increase in a-values (∆a= 0.44) of the intrinsic tooth color in Group 5 (no bleaching, no fluoride, wine) that was significantly different from baseline. (Am J Dent 2006;19: 80-84).

Clinical significance: Fluoridation was not beneficial towards the prevention of extrinsic stains after bleaching.

Address: Dr. Matthias Ley, Lichtenbergstr. 42, 71642 Ludwigsburg, Germany. E-mail: m.ley@web.de

Clinical and histological evaluation of white ProRoot MTA in direct pulp capping

Claudio E. Iwamoto, dds, ms, Erika Adachi, dds, ms, Cornelis H. Pameijer, dmd, mscd, dsc, phd,

Douglas Barnes, dds, ms, Elaine E. Romberg, phd & Steven Jefferies, dds, ms

Abstract: Purpose: To evaluate the clinical, radiographical and histological findings in human third molars in which mechanical pulp exposures were capped with white ProRoot mineral trioxide aggregate (WMTA). Methods: Forty-eight human third molars, caries-free or with incipient caries, scheduled to be extracted, were used and randomly divided into two groups: Group A: (n= 24) received WMTA and control Group B: (n= 24) received chemical set calcium hydroxide (Dycal). The teeth were isolated with rubber dam and Class I cavities prepared. Pulp exposure was performed using a sterile diamond bur and confirmed by frank bleeding. A sterile cotton pellet dipped in saline solution was placed over the exposure for 60 seconds. The preparation was then lightly rinsed with water and gently air-dried. WMTA or CH was placed over the exposure site followed by a small amount of a light-cured compomer. After etching with 35% phosphoric acid gel for 15 seconds, rinsing and blot drying, Prime and Bond NT adhesive was applied and light-cured. The cavity was then restored with a resin composite and light-cured. Evaluations were performed by phone after 7 days and clinically at 30 ± 5 and 136 ± 24 days, using standardized tests and radiographs. The teeth were extracted after 136 ± 24 days; the roots were cut ± 4-5 mm from the apex to allow for rapid fixation in 10% neutral buffered formalin. They were then processed for routine histological evaluation, embedded in paraffin, sectioned and stained with hematoxylin and eosin and Brown and Brenn for recognition of bacteria. Statistical analyses were performed using a Mann-Whitney U-test, a Chi-square test, a Fisher’s exact test and an ANOVA. Results: No significant differences in post-operative sensitivity were reported after 7 days between the two materials (P> 0.05). Clinical examination demonstrated no significant differences at 30 ± 5 days (P> 0.05) and at 136 ± 24 days (P> 0.05). Histological findings: 45 of 48 teeth were suitable for microscopic evaluation (22 with WMTA and 23 with CH). Twenty from the WMTA and 18 from the CH group had developed a bridge. No statistically significant differences were found for superficial and deep inflammatory cell response (P> 0.05), presence of a dentin bridge (P> 0.01), and pulp vitality (P> 0.01), between WMTA and calcium hydroxide. A statistically significant difference was found for the diameter of exposure (P≤ 0.05) between WMTA (x= 0.35 ± 0.19 mm) and CH (x= 0.25 ± 0.09 mm). Only a minimal association between clinical and histological findings could be established for either material. (Am J Dent 2006;19: 85-90).

Clinical significance: This study demonstrated clinically and histologically that white ProRoot MTA was as effective a pulp capping material as the control calcium hydroxide. Only a minimal association between clinical and histological findings for both materials was established.

Address: Dr. C.H. Pameijer, 10 Highwood, Simsbury, CT 06070 USA. E-mail: phpameijer@comcast.net

Effect of dentin adhesives used as sealers and provisional cementation on bond strength of a resin cement to dentin

Nicoletta Chieffi, dds, phd, Fernanda Sadek, dds, ms, Francesca Monticelli, dds, phd,

Cecilia Goracci, dds, phd, Simone Grandini, dds, phd, Carel Davidson, phd, Franklin R. Tay, bdsc (hons), phd & Marco Ferrari, md, dds, phd

Abstract: Purpose: To evaluate the effects of dentin adhesives employed as resin sealers and provisional cementation on the bond strengths of a resin cement to dentin. Methods: A two-step etch-and-rinse adhesive (Excite DSC – Group 1) and two-step self-etch adhesive (AdheSE – Group 2) were applied to exposed dentin surfaces prepared from human molars (N=4). Water was used instead of a resin sealer in control Groups 3 and 4. A eugenol-free provisional cement (except for Group 4) was applied to the treated surfaces. After storing in distilled water for 1 week, the provisional cement was removed and cylindrical composite blocks were luted with a resin cement (Variolink II). 0.9 x 0.9 mm sticks were produced from these luted specimens for microtensile bond testing and SEM examination. Results: One-way ANOVA revealed that neither the resin sealer nor the temporary eugenol-free cement had a negative effect on the final bond strength (P> 0.05). Mixed failures were predominantly identified from SEM. (Am J Dent 2006; 19: 91-95).

Clinical significance: The use of dentin adhesives as resin sealers before provisional cementation with a non-eugenol provisional cement does not adversely affect the retentive strength of indirect restorations bonded subsequently with an adhesive and a resin cement.

Address: Prof. Marco Ferrari, Piazza Attias 19, Livorno 57120, Italy. E-mail: ferrarimar@unisi.it

Effect of polymerization mode of adhesive and cement on shear bond strength to dentin

Mark A. Latta, dmd, ms, William P. Kelsey, III, dds & William P. Kelsey, V, bs

Abstract: Purpose: To investigate the shear bond strength to dentin when two resin adhesive systems in light-cure, dual-cure, and auto-cure modes were used with three resin cements. This was done to determine the degree of compatibility that exists when resin products with different polymerization mechanisms are used together. Methods: Three hundred non-carious human molars were divided into 30 test groups in which Prime & Bond NT and ScotchBond Multi-Purpose were used as adhesives with Calibra, Nexxus and Variolink cements to attach Rexillium III posts to flattened dentin surfaces. Debonding was achieved with an Instron testing machine and mean shear bond strengths were determined for each test group. The data were subjected to three-way ANOVA and post-hoc LSD testing to determine whether significant differences existed between the test groups. Results: Bond strengths achieved were affected by the adhesive, the cement, and the cement curing mode. In general, the auto-cure application of the three cements demonstrated reduced shear bond strengths, both with respect to the different adhesives and their curing modes as well as compared to the dual-cure technique of the same cement. Additionally, Prime & Bond NT demonstrated considerably more variability than ScotchBond Multi-Purpose when used with both dual-cure and auto-cure varieties of the three cements. The bond strengths of resin cements depend on the curing mode of the cement and the adhesive. Unlike with direct light-cured resin composites, combining adhesive systems and dual-cured resin cements from different manufacturers may be contraindicated. (Am J Dent 2006;19: 96-100).

Clinical significance: When dual-cured cements are used with adhesive systems, the adhesive activator must be employed to ensure full polymerization of the cement-adhesive combination. When visible light polymerization of the adhesive/activator mixture is not possible, some systems do not generate optimal bond strengths.

Address: Dr. William P. Kelsey, III, Creighton University School of Dentistry, 2500 California Plaza, Omaha, NE 68178 USA. E-mail: wpkelsey@Creighton.edu

Influence of temporary cements on bond strength between resin-based luting agents and dentin

Katsuhito Kanakuri, dds, Yoshikazu Kawamoto, dds, phd, Yoshiyuki Kakehashi, dds, phd

& Hideo Matsumura, dds, phd

Abstract: Purpose: To examine the influence of temporary cements on the strength of the bond formed between resin-based luting agents and dentin. Methods: An acrylic resin plate was luted to bovine dentin using one of three temporary cements; HY-Bond Temporary Cement Hard (HYB), Freegenol Temporary Pack (FTP), or Neodyne T (NDT). The control group (CON) was not treated with cement. Following the removal of the temporary cement, each dentin substrate was bonded to a silane-treated ceramic material (IPS Empress) with one of four luting agents; Super-Bond C&B (SCB), Panavia F (PAF), Nexus II (NEX), or Fuji Luting S (FLS). The specimens were immersed in water for 24 hours and the strength of the bond to shearing forces was determined. Results: The bond strengths (in MPa), with statistical categories shown in parentheses were: HYB (25.7, a), CON (23.5, a, b), FTP (19.8, b, c), and NDT (16.8, c, d) for the SCB system; FTP (13.8, d, e), CON (12.9, d, e), NDT (10.6, e, f), and HYB (7.8, f, g, h) for the PAF system; FTP (9.2, e, f, g), CON (7.9, f, g, h), HYB (7.7, f, g, h), NDT (7.1, f, g, h) for the NEX agent; and FTP (5.2, g, h, i), CON (3.7, h, i), NDT (3.0, h, i), HYB (1.6, i) for the FLS agent, (P< 0.05). (Am J Dent 2006;19: 101-105).

Clinical significance: The strength of the bond between the Super-Bond luting agent and dentin was negatively affected by the eugenol temporary cement. The bond strength of the Panavia luting agent was also reduced following temporary cementation with the HY-Bond polycarboxylate cement. However, bond strength to dentin of four luting agents was not negatively affected through the use of the FTP no-eugenol temporary cement.

Address: Dr. Hideo Matsumura, Department of Crown and Bridge Prosthodontics, Nihon University School of Dentistry, 1-8-13, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8310, Japan.

E-mail: matsumura@dent.nihon-u.ac.jp

Evaluation of stainless steel crowns cemented with glass-ionomer and resin-modified glass-ionomer luting cements

Yucel Yilmaz, dds, phd, Sera Simsek, dds, phd, Anya Dalmis, dds, phd. Taskin Gurbuz, dds, phd

& M. Elcin Kocogullari, dds

Abstract: Purpose: To evaluate in vitro and in vivo conditions of stainless steel crowns (SSC) cemented using one luting glass-ionomer cement (Aqua Meron) and one luting resin-modified glass-ionomer cement (Vitremer). Methods: In the in vitro part of this study, retentive properties of SSCs cemented using Aqua Meron and Vitremer on extracted primary first molars were tested. In addition, two specimens of each group were used to evaluate the tooth hard tissue-cement, within the cement itself, cement-SSC, and tooth hard tissue-cement-SSC under scanning electron microscope (SEM). In the in vivo part of this study, 152 SSCs were placed on the first or second primary molars of 86 children, and cemented using either Aqua Meron or Vitremer. The crowns were examined for retention. In addition, the clinical views of the crowns were recorded with an intraoral camera. Results: No significant difference was found between the mean retentive forces of Aqua Meron and Vitremer (P> 0.05). SSCs cemented with Aqua Meron and Vitremer had an average lifespan of 26.44 and 24.07 months respectively. Only one (0.66%) of 152 SSCs was lost from the Aqua Meron group during post-cementation periods. Nineteen of the 152 SSCs (12.5%) had dents or perforations (Am J Dent 2006;19: 106-110).

Clinical significance: Stainless steel crowns cemented with resin-modified glass-ionomer luting cement had similar clinical success rate with those cemented glass-ionomer luting cement.

Address: Dr. Yucel Yilmaz, Ataturk University, Dis Hekimligi Fakultesi, Pedodonti Ana Bilim Dali, Erzurum, Turkey. E-mail: yyilmaz25@atauni.edu.tr

Degradation of single bottle type self-etching primer effectuated

by the primer’s storage period

Kou Fujita, phd & Norihiro Nishiyama, phd

Abstract: Purpose: To examine the hydrolytic stability of the functional methacrylate monomer utilized in single bottle type self-etching primers, by using the ¹³C nuclear magnetic resonance (NMR) technique in order to understand why the bond strength of resin to the dentin decreased, when the primer's storage duration was prolonged. Methods: After deuterium oxide was added to the Mega Bond Primer (MB), or Unifil Bond Primer (UB), the MB or UB solutions were then stored at 37ºC for 0, 3, and 10 weeks, respectively. At the end of the storage periods, ¹³C NMR observations of the MB or UB solution were performed at 25ºC by using an EX-270 spectrometer. Results: The acidic and/or hydrophilic methacrylate monomer utilized in single bottle type self-etching primers became altered during the primer's storage period. Alteration of the functional monomer was possible since the acidic monomer, utilized in the self-etching primer, could supply sufficient amounts of hydronium ions, which were the result of the dissociation of the acidic group in the acidic monomer. The degradation of the primer, caused by the alteration of the functional monomer, would result in the degradation of the etching and/or priming efficacy on the tooth. The bond strength, as a result, would become decreased as the storage period was prolonged. (Am J Dent 2006;19:111-114).

Clinical significance: In order to attain the expected bond strength of the resin to the tooth, and avoid degradation of the single bottle type self-etching primers, they should be kept refrigerated when not in use, and equally important, the primers should be used as quickly as possible upon receipt.

Address: Dr. Kou Fujita, Department of Dental Caries Control and Aesthetic Dentistry, Nihon University School of Dentistry at Matsudo, 870-1 Sakaecho, Nishi 2, Matsudo, Chiba 271-8587, Japan.

E-mail: fujita.kou@nihon-u.ac.jp

Effect of air-particle abrasion on the retention and texture

of the maxillary complete denture

Alyaa M. Husham, bds, msc & Mohammed H.K. Al-Bazirgan, bds, mscd

Abstract: Purpose: To examine the effect of air abrasive particles on the retention of maxillary complete dentures. Methods: Twenty edentulous subjects, aged 48-72 years with a mean age of 62.2 years were selected. Subjects had questionable satisfaction regarding the retention of their existing maxillary complete dentures, and satisfactory denture bearing tissue with no visible undercuts. Existing dentures were tested for retention before and after air abrasion. Then, new maxillary complete dentures were constructed for them, and tested before and after partial air abrasion. Ten of the subjects continued with a new set of dentures, to test the effect of air abrasion of the entire fitting surface. A specially designed strain gauge force transducer and a strain indicator unit were used to measure forces that required dislodging the denture from its foundation. Retention force was measured before and after the fitting surface of the dentures was uniformly air-particle abraded with 50 µm aluminum oxide abrasive particles under 4 Kg/cm² of pressure with a quick circling motion at 10-15 mm distance for 30 seconds. Results: The results showed significant improvement in the mean retention forces of the new and the existing well-fitting maxillary complete dentures at all time intervals after air-particle abrasion of part and entire fitting surfaces, while the mean retention forces for the poorly fitting dentures showed only non-significant, slightly increased retention at all time intervals after the fitting surface was air-particle abraded. (Am J Dent 2006; 19:115-122).

Clinical significance: An additional improvement in denture retention was accomplished after the fitting surface was uniformly air-particle abraded, either partly or entirely. This might be useful for patients who complain of a lack of retention for their dentures that are otherwise well fitting and accurate, and it is always advisable to strongly emphasize the importance of oral and denture hygiene in patients wearing such a prosthesis.

Address: Dr. Alyaa Husham, Mourany Orthodontic & Dental Center, P. O. Box 19310, Al-Ain, United Arab Emirates. E-mail: alyaa_husham@yahoo.com

Fluoride release and uptake by various dental materials

after fluoride application

Katsushi Okuyama, dds, phd, Yasuhiro Murata, dds, Patricia N.R. Pereira, dds, phd,

Patricia Almeida Miguez, dds, ms, Hisanori Komatsu, dds, phd & Hidehiko Sano, dds, phd

Abstract: Purpose: To measure the amounts of fluoride released from fluoride-containing materials before and after daily topical fluoride applications. Methods: A conventional glass-ionomer: Fuji Ionomer Type II (F2); a resin-modified glass-ionomer: Fuji Ionomer Type II LC (LC); two “giomer” materials: Reactmer Paste (RP), and Beautifil (BT); a fluoride-containing resin composite: Unifil F (UF); and a non-fluoride resin composite: AP-X (AP) were used in this study. Each material was filled into a plastic mold, with inner diameter of 9 mm wide x 3 mm high. The specimens were stored in vials filled with 8 ml distilled deionized water for 24 hours at 37ºC. The specimens were then removed from the vials and the amount of fluoride released into the water, over the 24-hour period, was measured. The amount of fluoride released was measured by using specific fluoride electrode and an ion-analyzer. These procedures were repeated at Days 2, 3, 7, 14, and 21. After 21 days, all specimens were exposed to 1000 ppm F NaF solution for 5 minutes once a day. This procedure and measurement of fluoride release were continued for 14 days. After 14 days, the specimens were placed in water for 7 days and fluoride release was measured. The results were statistically analyzed using Kruskal-Wallis and Mann-Whitney U-test (P< 0.05). Results: At the 22nd day (1 day after starting fluoride exposure), there was no difference between the F2 and RP, though there were significant differences between the two GICs and the groups BT and UF. After that day, there were significant differences between GIC and the group RP, BT and UF. All materials showed a decrease in fluoride release 7 days after end of the fluoride immersion period. F2, LC, and UF showed no significant difference of fluoride release between Day 21 and 1 day after the end of the fluoride immersion period (P= 0.310: F2 and UF, 0.548: LC). On the other hand, RP and BT revealed lower fluoride release 1 day after the end of the fluoride immersion period as compared to Day 21 (P= 0.075: RP, 1.000: BT). For AP, fluoride release was not detected after the fluoride immersion period. (Am J Dent 2006;19:123-127).

Clinical significance: Topical fluoride application on materials that are able to uptake fluoride increased the amount of fluoride released from such materials.

Address: Dr. Katsushi Okuyama, Department of Restorative Dentistry, Division of Oral Health Science, Hokkaido University Graduate School of Dental Medicine, Kita 13 Nishi 7, Kita-ku, Sapporo 060-8586, Japan.

E-mail: katsu@den.hokudai.ac.jp

Coronally positioned flap with or without acellular dermal matrix graft in gingival recessions: A histometric study

Enilson A. Sallum, ms, phd, Getúlio R. Nogueira-Filho, ms, phd, Marcio Z. Casati, ms, phd, Suzana Peres Pimentel, ms, Juliana Bezerra Saldanha, ms & Francisco H. Nociti Jr., ms, phd

Abstract: Purpose: To evaluate, histometrically, the healing of gingival recession treated by coronally positioned flaps (CPF) with or without acellular dermal matrix (ADM) as a subepithelial graft. Methods: Gingival recessions were created on the upper cuspids of six dogs and were randomly assigned to: CPF+ADM (ADM group) or CPF alone (CPF group). After 4 months, the dogs were sacrificed, and the histometric measurements were performed. Results: The epithelial length was 2.28 + 0.92 mm and 2.10 + 0.46 mm for the ADM and CPF groups, respectively (P=0.74). The connective tissue adaptation was 0.05 + 0.08 mm for the ADM group and 0.06 + 0.08 mm for the CPF group (P=0.36). The new cementum was 2.35 + 1.55 mm and 2.90 + 0.96 mm in the ADM and CPF groups, respectively (P=0.53). The new bone was 0.60 + 1.36 mm for the ADM group and 0.35 + 0.82 mm for the CPF group (P=0.53). The gingival recession was -0.88 + 1.33 mm in the ADM group and -0.21 + 0.22 mm in the CPF group (P=0.21). The gingival thickness was 1.63 + 0.28 mm in the ADM group and 1.16 + 0.20 mm in the CPF group (P=0.002). (Am J Dent 2006;19: 128-132).

Clinical significance: The present study indicates no major differences in the healing pattern between CPF alone and CPF combined with ADM but a superior thickness of the gingival tissues may be obtained with the inclusion of ADM.

Address: Dr. Enilson Antônio Sallum, Department of Prosthodontics and Periodontics, Division of Periodontics, School of Dentistry at Piracicaba, Av. Limeira 901 - Caixa Postal 52, 13414-018 – Piracicaba, São Paulo, Brazil. E-mail: easallum@fop.unicamp.br