Article Options
Categories


Search


Advanced Search



This service is provided on D[e]nt Publishing standard Terms and Conditions. Please read our Privacy Policy. To enquire about a licence to reproduce material from endodonticsjournal.com and/or JofER, click here.
This website is published by D[e]nt Publishing Ltd, Phoenix AZ, US.
D[e]nt Publishing is part of the specialist publishing group Oral Science & Business Media Inc.

Creative Commons License


Recent Articles RSS:
Subscribe to recent articles RSS
or Subscribe to Email.

Blog RSS:
Subscribe to blog RSS
or Subscribe to Email.


Azerbaycan Saytlari

 »  Home  »  Endodontic Articles 11  »  Micro-tensile bond strengths of bonding agents to pulpal floor dentine
Micro-tensile bond strengths of bonding agents to pulpal floor dentine
Discussion - References.



Discussion.
Composite resin is recommended as a core build-up material in root filled teeth when adequate tooth structure remains. The advantage of Bonding properties coupled with a composite core buildup can achieve satisfactory form for resistance and retention (Morgano & Brackett 1999) as well as adequate mechanical properties (Levartovsky et al.1996). In the case of FluoroCore, fluoride release may be of value in preventing demineralization of adjacent tooth structure (Triolo et al.1991).
The micromechanical retention to tooth structure occurs when resin completely infiltrates dentinal surfaces and creates a hybrid or resin-reinforced dentine layer (Nakabayashi et al.1982). The one-bottle adhesive systems have been introduced to simplify the Bonding procedures and decrease the time needed for application. Whilst these materials have been evaluated for Bonding to the cut surface of coronal dentine, the intact pulpal floor dentine may behave differently as a Bonding substrate. The micro-tensile bond strength to superficial occlusal dentine of predominantly third molars was 36.0 _8.1MPa for Clearl Liner Bond 2 V and 29.9 _ 6.1MPa for Prime and Bond NT/NRC (Tanumiharja et al.2000) whichwas similar to the results of Schreiner et al. (1998).The bond strengths of two systems to pulpal floor dentine in this study were 22.49 _7.08 MPa for Clearl SE Bond and 15.58 _4.24 MPa for Prime and Bond NT which were lower than coronal dentine, as previously reported (Schreiner et al. 1998, Tanumiharja et al.2000).Thus, the Bonding mechanisms may be affected by the dentine location and changes in the properties in different parts of a tooth structure. This result is in accordance with a previous report by Belli et al. (2001).
The SEM study demonstrated the presence of numerous calcospherites on the surface of pulpal floor dentine (Fig.1). When acid etching was applied to the pulpal floor dentine, the superficial dentine was demineralized to expose the collagen fibers of the dentinal matrix (Fig. 2). The penetration of primer and adhesive resin in the conditioned dentine surface is to provide micromechanical interlocking between the dentine collagen and resin (Nakabayashi et al. 1982, Van Meerbeek et al. 1992). However, the use of strong phosphoric acid (Fig. 2) could remove inorganic material more aggressively than the acidic primer (Fig. 3), especially since the surface was not covered by a smear layer initially. This finding leads to the different characteristics of conditioned dentine surfaces, which may also affect the different bond strengths of the two systems (Wakabayashi et al.1994, Vargas et al.1997).
Accessory canals, which have been reported to occur frequently on the pulpal floor of molars (Vertucci & Anthony1986), may also assist in mechanical retention. In this study, we observed only one accessory canal in the pulpal floor of eight teeth. Accessory canals may not occur frequently enough to influence bond strength. However, the tubule density of dentine at pulpal floor area was less than in coronal dentine and this factor may influence bonding. Hence, the net influence of pulpal floor features on bond strength is difficult to predict.
The mean micro-tensile bond strength of the self-etching- priming system (Clearl SE Bond) was significantly greater than that of the one-bottle system (Prime &Bond NT) (P < 0.05) in this study. The acid conditioning of primer in Clearl SE Bond appeared sufficient to demineralize the dentine and envelop the collagen fibres and hydroxyapatite crystals. The use of strong 34%phosphoric acid with Prime & Bond NT, according to the manufacturer’s instructions, may be excessive in the absence of a smear layer and smear plugs, possibly causing ‘over etching’ and subsequent collapse of the collagen network. This situation may inhibit the penetration of adhesive resin and result in a weak hybrid layer (Phrukkanon et al.1999).
From this study, the SEM observation of debonded specimens from the Prime & Bond NT system mostly showed partial cohesive failure within Bonding resin/ composite, whereas those of the Clearl SE Bond system mostly showed partial cohesive failure within dentine. This finding may demonstrate that either the self-etching- priming system had a good Bonding to pulpal floor dentine or was more compatible with composite resin than the one-bottle system. The pretreatment of the pulp chamber with NaOCl, as occurs in routine biomechanical preparation, merits further study. One report mentioned that without pretreatment with NaOCl, irregular shapes of broken resin tags were observed (Belli et al.2001).
Bonding restorative material to the floor of the pulp chamber and the remaining tooth structure should eliminate any gaps and thus would promote a better quality of coronal seal (Davalou et al.1999). Good adhesion between the restorative materials and dentine is a crucial factor in increasing the opportunity for good marginal sealing, reduced microleakage, and longer life of the restoration (Nakabayashi & Pashley 1998). Thus, the use of composite resin and a dentine Bonding system has become widely accepted for restorative treatment of nonvital teeth.

References.

Belli S, Zhang Y, Pereira PNR, Ozer F, Pashley DH (2001) Regional   bond strengths of adhesive resin to pulp chamber dentin. Journal of Endodontics   27, 527-32.
Berkovitz BK, Holland GR, Moxham BJ (1992) A Color Atlas and Texbook of Oral   Anatomy, Histology and Embryology, 2nd edn. London, UK: Wolfe Publishing, pp.130-45.
Bouillaguet S, Gysi P, Wataha J et al. (2001) Bond strength of composite to   dentin using conventional, one-step, and selfetching adhesive systems. Journal   of Dentistry 29, 55-61.
Davalou S, Gutmann JL, Nunn MH (1999) Assessment of apical and coronal root   canal seals using contemporary endodontic obturation and restorative materials   and techniques. International Endodontic Journal 32, 388-96.
Gutmann JL (1978) Prevalence, location, and patency of accessory canals in the   furcation region of permanent molars. Journal of Periodontology 49, 21-6.
Hernandez R, Bader S, Boston D, Trope M (1994) Resistance to fracture of endodontically   treated premolars restored with new restoration dentin bonding systems. International   Endodontic Journal 27, 281-4.
Leinfelder K (1993) Current developments in dentine bonding system: major progress   found in today's products. Oral Health 8, 7-8.
Levartovsky S, Goldstein GR, Georgescu M (1996) Shear bond strength of several   new core materials. Journal of Prosthetic Dentistry 75, 154-8.
Morgano SM, Brackett SE (1999) Foundation restorations in fixed prosthodontics:   current knowledge and future needs. Journal of Prosthetic Dentistry 82, 643-57.
Nakabayashi N, Kojima K, Masuhara E (1982) The promotion of adhesion by the   infiltration of monomers into tooth substrates. Journal of Biomedical Material   Research16, 265-73.
Nakabayashi N, Pashley DH(1998) Hybridization of Dental Hard Tissues, 1st edn.   Tokyo, Japan: Quintessence Publishing, pp. 82-3.
Phrukkanon S, Burrow MF, Tyas MJ (1999) The effect of dentine location and tubule   orientation on the bond strengths between resin and dentine. Journal of Dentistry   27, 265-74.
Ray HA, Trope M (1995) Periapical status of endodontically treated teeth in   relation to the technical quality of the root filling and the coronal restoration.   International Endodontic Journal 28, 12-8.
Sano H, Shono T, Sonoda H et al. (1994) Relationship between surface area for   adhesion and tensile bond strengths - evaluation of a micro-tensile bond test.   DentalMaterials10, 236-40.
Saunders WP, Saunders EM(1994) Coronal leakage as a cause of failure in root   canal therapy: a review. Endodontics and Dental Traumatology 10, 105-8.
Schreiner RF, Chappell RP, Glaros AG, Eick JD (1998) Microtensile testing of   dentin adhesives. Dental Materials 14, 194-201.
Swartz DB, Skidmore AE, Griffin JA(1983) Twenty years of endodontic success   and failure. Journal of Endodontics 9, 198-202.
Tanumiharja M, Burrow MF, Tyas MJ (2000)Micro-tensile bond strengths of seven   dentin adhesive systems. Dental Materials 16, 180-7.
Triolo PT, Wefel JS, Jensen ME (1991) Fluoride-releasing core materials and   artificial caries. American Journal of Dentistry 4, 207-10.
VanMeerbeek B, Inokoshi S, BraemM, Lambrechts P, Vanherle G (1992) Morphological   aspects of the resin-dentin interdiffusion zone with different dentin adhesive   systems. Journal of Dental Research 71, 1530-40.
Vargas MA, Cobb DS, Armstrong SR (1997) Resin-dentin shear bond strength and   interfacial ultrastructure with and without a hybrid layer. Operative Dentistry   22, 159-66.
Vertucci FJ, Anthony R (1986) A scanning electron microscopic investigation   of accessory foramina in the furcation and pulp chamber floor of molar teeth.   Oral Surgery, OralMedicine, Oral Pathology 58, 589-99.
Wakabayashi Y, Kondou Y, Suzuki K, Yatani H, Yamashita A (1994) Effect of dissolution   of collagen on adhesion to dentin. International Journal of Prosthodontics 7,   302-6.