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Authors : Dr. Gunjan Gupta , Dr Varun Goyal , Dr. Anshul Mel.

Abstract

The aesthetic and functional rehabilitation of patients with multiple missing teeth can be performed with several techniques and materials. Ceramic restorations provide reliable masticatory function and good aesthetics. However, fracture can occur in some cases due to their brittle behaviour. In some cases, the replacement of an extensive prosthesis is a problem due to the high treatment cost and hence the fractured ceramics are repaired using composites. This paper introduces the use of nanohybrid composite with fluoride release and recharge ability which can reduce the incidence of caries in people having repaired ceramic fixed prosthesis.

Introduction

Metal-ceramic restorations have been used for 40 years. During this time improvements have been achieved in the physical properties and composition of alloys, porcelain, and investments, in the methods of handling the materials, and in design.1-2 Dental restorations containing ceramics should be designed in such way as to overcome their weakness. When a fracture occurs in a metal ceramic restoration, there is a loss of esthetics as well as loss of contour of the ceramic restorations. It is on these occasions that repair materials are required for restoring the shape and contour of the existing restoration. Hence these metal ceramic systems are repaired intraorally using composites. Composite resins have been the material of choice for their esthetic appearance and ease of manipulation. These composites are an adhesive system provide with various bonding technology to improve the bonding of composites to fractured ceramic restoration. Intraoral repair of fractured ceramic traditionally relied on the surface roughening of the fracture site followed by application of silane coupling agent to enhance the resin to bond with porcelain. The surface roughening of the fractured site on the porcelain is done with a coarse diamond, sandblasting with aluminium oxide and etching with hydrofluoric acid or acidulated phosphate gel to facilitate micromechanical retention.3 In the present study a Light-Cure Fluoride Releasing composite material was used.

Materials and methods

A nanohybrid composite (Beautifil II) with fluoride release and recharge was used to prepare the samples. Beautifil II is an universal nano-hybrid composite incorporating S-PRG (surface pre-reacted glass ionomer) technology that contains a stable phase of glass-ionomer for aesthetic and long-lasting restorations that release and recharge fluoride. Beautifil II responds to the concentration of fluoride in the mouth while maintaining the strength and stability of a composite resin. When the concentration of fluoride is less in mouth, it releases fluoride and protect the teeth from caries but as the concentration of fluoride increases in mouth, it takes up the fluoride and gets recharged. (fig 1)

A total of 30 samples of 10mm diameter and 2mm thickness (fig 2) were made using the Giomer. They were divided into three groups: a)control, b) exposure to fluoride containing toothpaste and c)exposure to fluoride containing toothpaste and mouthrinse. They were stored in distilled water4 and the fluoride release was assessed using spectrophotometer5 at the intervals of 24 hours, 3,7 and 14 days.

 
   
Fig 1  Fluoride release and recharge from Giomer

Fig 2   Samples used in the study.

Results

According to the values obtained after the spectrophotometric analysis it was found that the fluoride release was maximum when the toothpaste and mouthrinse both were used and minimum in the control group.

 

Samples

After 24 hours

After 3 days

After 5 days

After 7 days

After 14 days

Control

48.6

44.3 – 46.2

42.8-43.6

39.2- 40.9

31.8-33.5

With toothpaste

48.6

46.1-47.7

45.3-47.1

43.8-44.2

39.9-41.3

With toothpaste and mouthwash

48.6

47.3-48.3

45.8-47.3

43.8-44.5

40.2- 41.5

Discussion

The principal role in the treatment of the diseased tooth is to maintain and improve the quality of treatment procedures in restoring them not only in structure but also in physical form. Even though a wide variety of materials have been used as tooth replacement materials, there are few materials which have been given primary attention and show a great improvement in the technology of obtaining better mechanical properties. Porcelain fused to metal crowns are widely accepted and used in clinical practice. These restorations have high esthetic characteristics and are considered very durable because of its long lasting physical and mechanical properties. Although these materials provide an excellent restorative service there are occasional failures occur in these restorations in the form of debonding of ceramic veneers, chipping and cracking.

There are various reasons that have been suggested for fracture of porcelain veneer such as impact and fatigue load, occlusal forces, incompatible thermal expansion coefficients between the porcelain and metal substructure, use of metal with low-elastic modulus, seating force during trial insertion or cementation, improper design, microdefects within the material, and trauma. Failure resulting from porcelain fracture has been reported to range from 2.3% to 8%. 6 Hence there arises a need for the intraoral repair of metal ceramic restorations and for this the composites are most frequently used.

Also there is a high incidence of caries in patients having crowns therefore a material which releases fluoride was used for the repair to reduce the incidence of caries. The results from the present study clearly indicates that the Giomer (Beautifil II) has the capability of releasing fluoride when the fluoride is less in mouth and also getting recharged when the concentration of the fluoride increases in the oral cavity.

Conclusion

The Giomer used in this study shows dual characteristics of fluoride release and recharge and hence the results were in the favour when both toothpaste and mouth rinse were used.

References:

  1. Rosenstiel SF, Land M, Fujimoto J. Contemporary fixed prosthodontics. 3rd ed. St. Louis: Elsevier; 2000. p. 795-800.
  2. Shillingburg HT, Hobo S, Whitsett LD. Fundamentals of fixed prosthodontics. 3rd ed. Chicago: Quintessence Publishing Co; 1997. p. 419-42.
  3. Prabhu PS, Neetika Prabhu. Composite as a ceramic repair material- An invitro study. JIADS 2010;1(4):27-32.
  4. Kazuko KAMIJO, Yoshiharu MUKAI, Takatoshi TOMINAGA, Izumi IWAYA, Fukue FUJINO, Yukio HIRATA and Toshio TERANAKA. Fluoride release and recharge characteristics of denture base resins containing surface pre-reacted glass-ionomer filler. Dental Materials Journal 2009; 28(2): 227-233.
  5. R. S ndulescu, E. Florean, L. Roman, S. Mirel, R. Oprean, P. Suciu Spectrophotometric determination of fluoride in dosage forms and dental preparations Journal of Pharmaceutical and Biomedical Analysis 14 (1996) 951-958.
  6. Aristidis A. Galiatsatos, DDS, Dr Dent. An indirect repair technique for fractured metal-ceramic restorations: A clinical report. J Prosthet Dent 2005;93:321-3.

More references are avaiable on request.

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