Journal of Oral Rehabilitation, 1992, Volume 19, pages 231-237
The clinical performance of a posterior composite resin restorative material, Heliomolar R.O.®: 3-year report P . J . K N I B B S and E . R . S M A R T Department of Operative Dentistry. The Dental School, University of Newcastle upon Tyne, Newcastle upon Tyne. U. K.
Summary
A posterior composite resin restorative material was evaluated over a 3-year period by means of a controlled clinical trial. A total of 52 composite resin restorations and 52 amalgam alloy restorations were included in this trial, and were examined with regard to marginal integrity, surface texture, anatomical form and proximal contact with adjacent teeth. There were no significant differences in clinical performance between test and eontrol materials, whieh both gave good service over the period of evaluation. Only five restorations (one of amalgam and four of composite resin) failed during the trial. Plastic replica dies were used to support the elinieal examinations of the restorations, and sueh dies were found to be helpful.
Introduction
A large number of composite resin materials have been recommended for use in posterior teeth. Early reports on the use of the material in this situation were unfavourable, particularly with regard to wear (Osborne, Gale & Ferguson. 1973; Phillips et al., 1973; Leinfelder et al., 1975). However, there is now growing optimism about their use, due in part to recognition of their indications and eontraindieations, i.e. improved formulations, manufacture and dispensing, and greater awareness amongst clinieians of eorreet elinieal teehnique (Burke, 1986; Clinieal Research Associates, 1989). Some products are now supported by published elinieal data (Boksman et al., 1986; Wilson, Smith & Wilson, 1986), and others are currently under evaluation. Heliomolar R.O.®* is a material that is supported by elinieal data (Christensen, 1987; Mazer, Leinfelder & Russell, 1989), and ongoing research will provide a full elinieal profile of the material in due course. The material is a monoeomponent resin restorative, and is eured by halogen light. The monomer is a mixture of urethane dimethaerylate and BisGMA. The filler system is of the mierofil type, consisting of mierofillers and pre-polymerized particles of the material in an organie matrix. The filler eontent is claimed to be 65-67% of the volume {11-19% of the weight), and the maximum partiele size is reported to be 0-04 |a. A elinieal trial was designed to eompare the elinieal performance of Heliomolar Correspondence: Mr P.J. Knibbs, Newcastle Regional Dental Office, Government Buildings, Kenton Lane, Newcastle upon Tyne NEl 2YR, U.K. * Vivadent, Sehaan, LJeehtenstcin.
231
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R.O. with that of the amalgam alloy, Dispersalloy*. This paper deseribes the findings of the trial after the restorations had been in plaee for 3 years. Trial design Ciinieally necessary elass I or elass II restorations were plaeed in the mouths of dental students at Newcastle upon Tyne Dental Sehool. Eaeh composite restoration was paired with a eontrol amalgam restoration in the same mouth. Cavity designs were based on the traditional eoneepts of Blaek, modified b}current views that eavities should be as small as possible, commensurate with eomplete elimination of earies at the periphery. All eavities were prepared with high and low speed rotary instruments and hand instruments in aeeordanee with normal elinieal praetiee. The amalgam alloy was meehanieally triturated aeeording to the manufaeturer's instruetions, and was hand eondensed into eavities that had previously been protected against thermal irritation by a reinforced zine oxide-eugenol material when neeessary. Metal Siqveiand matriees were used to make eontaet with adjaeent teeth in elass II eavities for both amalgam and composite restorations. Pre-wedging was used to ereate adequate interproximal eontaet of elass II eomposite resin restorations. All restorations were plaeed with eareful attention to moisture eontrol; this was most often achieved by the use of eotton wool rolls and saliva ejeetors, although in certain eases rubber dam was used. The Heliomolar R.O. was provided as a single-shade produet packaged in Cavifil eompules. The latter were designed for use with the Cavifil injeetor and adaptor. This system was easy to set up, and enabled increments of the material to be plaeed accurately in eavities in all parts of the mouth. The trial protoeol demanded that all the eomposite eavities be lined with a setting ealeium hydroxide eement prior to aeid etehing. An etehing kit eonsisting of 5 ml of 37% phosphoric aeid gel, 10ml ligh-euring bonding resin (Heliobond), applieator tips and brushes, and instruetions for use were provided by the manufacturers. The enamel of the eavities was etehed for 60s, thoroughly rinsed for 20s and then dried. A thin layer of Heliobond was applied to the etehed surfaces and air-blown to produce an even layer whieh was light eured for 20s. The eomposite material was plaeed in small increments, starting with the least aeeessible site. Onee dispensed from the eompule, inerements were eondensed with a ball-ended burnisher. The eomposite was light eured in layers 1—2 mm thiek in order to minimize the effeet of polymerization eontraetion. The surface layers were earved to an anatomieally aeeeptable form prior to light euring. Curing of eaeh inerement was achieved by exposure to the Heliomat lamp for 40 s. After euring, the matrix strip was removed and the hardened eomposite was finished and polished. Gross excess was removed by water-eooled diamond burs. The oeelusion was then eheeked and adjusted as neeessary. Final finishing and polishing was aehieved by rubber abrasive points of various shapes provided for the purpose in a convenient kit by the manufacturers. The protoeol was approved by the ethies committee of Newcastle University, and the trial began in the aeademie year 1986/1987. A produet report and the results after 1 year have been published previously (Knibbs, 1988; Knibbs & Smart, 1989). * Johnson & Johnson Dental Products Co.. East Windsor, NJ 08520, U.S.A.
Evaluation of a posterior composite resin restorative material
233
Assessment of restorations
Patients were examined by two clinicians (PJK and ERS) annually until trial restorations had been in the mouth for 3 years. A thorough dental history was taken, followed by a full elinieal examination. All trial restorations were photographed and repliea impressions were taken using addition-eured silieone putty/wash impression material. Dies were poured using a elear plastie resin eured in an oven aeeording to the manufacturer's instructions'^. The restorations were assessed elinieally for marginal integrity, lustre, surface roughness, eontour, eolour mateh and eontaet with adjaeent teeth using modified United States Publie Health Serviee eriteria (see Table 1). Repliea dies were examined in standard room lighting by two assessors (PJK and ERS) with a probe blunted to 0-4 mm. Assessment of marginal integrity, eontour and surface roughness was reeorded in aeeordanee with the eriteria shown in Table 2. Dies were examined in sueh a way that the material type was not known to the assessors. Results
Thirty dental students (14 men and 16 women) were examined 3 years after initial plaeement of test and eontrol restorations (mean period 35-1 months, range 24-41 Table 1. Clinical examination of restorations Dispersalloy
Heliomolar R.O.
Marginal integrity No crevice to eatch probe Probe catches Dentine or base visible Restoration fracture or loss
35 (67) 16 (31) 0 (0) 1 (2)
35 (67) 13 (25) 0(0) 4(8)
Surface texture Smooth Slight roughness Rough
46 (90) 5(10) 0(0)
34(71) 14 (29) 0 (0) {n = 48)
{n = 5l)
Anatomical form Matches tooth Slight excess Slight deficiency Gross excess Gross deficiency
46 (90) 0 (0) 5(10) 0(0) 0(0) {n = 5\)
Contact with adjacent tooth Good Poor Not applicable
33 (65) 0 (0) 18 (35) (n = 5\)
38 (79) 6(13) 4(8) 0(0) 0 (0) (n = 48)
30 (62) 0(0) 18 (38) (n = 48)
Percentage values are shown in parentheses. * Spurr Low Viscosity Resin Kit; Polaron Equipment Ltd, Holywcll Industrial Estate. Watford, Herts, U.K.
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Table 2. Examination of replica dies of restorations
Die margin No crevice Probe catches in both directions Restoration fracture of loss Anatomical form of die No obvious contour loss Slight loss of contour Obviours contour loss
Surface texture of die Smooth Slight roughness Rough
Dispcrsalloy
Heliomolar R.O.
40 (77) 11 (21) 1 (2)
37 (71) 11 (21) 4(8)
49 (96) 2(4) 0(0) (« = 51)
46 (96) 2(4) 0(0) (« = 48)
45 (88) 6(12) 0(0) (« = 51)
38 (79) 9(19) 1 (2) {n = 48)
Percentage values are shown in parentheses.
months). The mean age of the patients at the time of restoration placement was 18-8 years (range 17—23 years). All patients commenced the trial with good oral hygiene and healthy gingival conditions, and maintained these high standards throughout the trial. No test or control restorations were associated with plaque stagnation or gingival pathology throughout the trial. Three patients were deemed to have a high caries rate on entry to the trial. A total of 104 restorations were examined, consisting of class I and class II restorations in molars and premolars (see Table 3). Clinical examination revealed that all restorations were performing well except for one class II amalgam that had fractured and was replaced at 24 months, and four composites which had failed and been replaced. Three of these failures were the result of recurrent caries (one occlusally, two interproximally), and the other failure was due to a poor proximal contact, allowing food impaction. Over half of the amalgam restorations (54%) had lost their initial high shine during the 3 years of service, although the remaining restorations (46%) were assessed as having a good lustre finish. Thirty-nine (81%) of the Heliomolar R.O. restorations were assessed as exhibiting a good colour match to the tooth, with nine (19%) showing a degree of mismatch. Such mismatch was not observed by any of the patients, nor did it warrant treatment. No composite restorations showed staining, either at the margins or on the restoration surface. The results of the clinical assessment of marginal integrity, surface texture, anatomical form and contact with adjacent teeth are shown in Table 1. These results showed no significant difference in assessment between the materials for the various criteria, and all restorations except for the five mentioned previously were clinically acceptable. The results of the examination of the replica dies are shown in Table 2. These correlate closely with the clinical examinations which confirm the accuracy and impar-
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235
Table 3. Summary of the restorations placed in the clinical trial of Heliomolar®
Class I Class II Total
Heliomolar
Amalgam
Total
18 34 52
18 34 52
36 68 104
A total of 26 restorations were placed with rubber dam. A total of 78 restorations were placed without rubber dam. No patients reported post-operative hypersensitivity.
tiality of the clinical assessments, because the replicas do not allow ready identification of material type due to the translucent plastic construction. Discussion This trial was designed using dental students as patients so as to ensure a high recall rate. One student who received a pair of restorations withdrew from the dental course, and the data for her restorations have not been included in the report. All other restorations that were placed have been reviewed annually to the 3-year stage. The patients, by virtue of their occupation, were all dentally aware and well motivated. They had good oral hygiene and general dental health, although three patients entered the trial with a high level of caries experience. These individuals all required other restorative treatment during the trial, but their trial restorations were satisfactory at the 3-year review. Two composite restorations in the mouths of other patients failed due to recurrent caries at the margins of interproximal boxes by 24 months. A third composite in an ocelusal surface of a premolar appeared intact clinically, but was correctly diagnosed as having recurrent caries from a bitewing radiograph at 24 months. This trial showed a higher probability of caries in the composite sample than in the amalgam sample, although this observation was not statistically significant. It is not possible to determine whether the recurrent caries was due to chance site-related factors in the patient's mouth, poor placement technique, or a weakness of the material. The latter is unlikely because advances have been made in the formulation of composite resin systems, whereby low concentrations of fiuoride ion leach out of the filler, and Heliomolar R.O. has been shown to possess this potentially caries-inhibiting property (Arends & Ruben, 1988). Clinicians experienced in the handling of Class II composite resins are aware of the difficulties of creating adequate contact with adjacent teeth (Burke, 1986). In this trial teeth were wedged slightly apart prior to restoration with composite, and such pre-wedging appeared to be successful as only one tooth failed due to inadequate contact with the neighbouring tooth. No evidence of contact area wear was noted for either material during this trial. One class II amalgam restoration failed due to bulk fracture of the interproximal box. The amalgam alloy performed well over the observation period, and proved to be a reliable restorative. Initial high shine was lost in over 50% of the amalgam resto-
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P.J. Knibbs and E.R. Smart
rations, but this was of no clinical significance. Minor marginal deficiencies were noted in 16 restorations but none of these constituted clinical failure. The assessment of marginal integrity of the composite resin showed similar results to those for amalgam. Thirteen restorations showed evidence of slight marginal deficiency. Composites with submicron-particle-size fillers are known to exhibit mild marginal degradation caused by tensile fatigue failure (particularly close to oeelusal contacts) and the low elastic modulus of such materials (Mazer, Leinfelder & Russell, 1989). The restorations in this trial showed little clinical evidence of wear over the 3-year observation period, and this is in agreement with the results of Mazer, Leinfelder and Russell (1989), who found Heliomolar R.O. to be the best composite resin restorative out of nine studied with regard to wear. Loss of overall contour due to three-body abrasion of the opposing tooth with an intermediate abrasive slurry was noted in only four restorations. Slight roughness of the oeelusal surface in localized areas was most probably due to two-body abrasion of the opposing tooth directly impinging on the composite surface in oeelusal contact. This was noted more frequently, being apparent to a mild degree in 14 restorations. The trial eomposite was supplied by the manufaeturers as a single-shade roduct, although it is now available in a range of shades. Despite the single-shade provision, marked mismatch with natural tooth was only noted in nine restorations, and several of these were in the same mouths. Such mismatch did not warrant treatment, and indeed made examination of the restoration easier, as the cavity margins were clearly defined. No composite restorations were found to have surface or marginal staining, an observation which may be related to the properties of the material, or to the generally low level of staining observed in the mouths of these dental students. All the trial restorations were placed with eareful attention to moisture eontrol. In the well-motivated, co-operative patients in this sample, this was most frequently aehieved using cotton wool rolls and saliva ejectors only. Rubber dam was used for 26 restorations where moisture control would otherwise have been diffieult to ensure. There was no differenee in performanee between those restorations plaeed with and without a rubber dam. The latter does not appear to be mandatory for successful composite restorations, although its use is recommended where other methods are unlikely to ensure a dry field throughout the restorative phase of treatment. Clear plastie repliea dies were used in this trial to supplement the clinical examinations with regard to marginal integrity, contour and surface texture. The advantage of dies is that the type of material is not readily discernible, and they can be examined and re-examined at leisure under standard conditions. They can also be stored for future eomparison with subsequent dies of the same tooth, and may also be examined mieroscopically if required. The results of die examination were slightly more favourable than those of the elinieal examinations, but these differences were not statistically significant. The dies therefore represent a useful supplement to the elinieal observations. Clinieal Research Associates (1989), in a Newsletter considering the current evidence with regard to class II composite resins, brought together the findings of 2-to 5-year evaluations of 21 brands of eomposite resin. They considered wear, marginal adaptation, proximal contact, post-operative hypersensitivity, recurrent caries, surface texture, stain and colour match, and they eoncluded that Heliomolar R.O. had been shown to perform well, and that it showed the least deterioration with time of all
Evaluation of a posterior composite resin restorative material
237
the brands examined. The results of the present trial add further clinical support to their observations. References & RUBEN, J. (1988) Fluoride release from a posterior composite resin. Quintessence International, 19, 513. BOKSMAN, L . , JORDAN, R.E., SUZUKI, M . & CHARLKS, D . H . (1986) A visible hght-cured posterior composite resin: results of a three-year clinieal evaluation. Journal of the American Dental Association, 112, 627. BURKE, F . J . T . (1986) Posterior composites: the current status. Dental Update, 13, 227. CHRISFENSEN, G . (1987) Three year in-vivo eomparison of seven posterior resins with silver amalgam. Journal of Dental Research, 66, Abstraet 833. CLINICAL RESEARCH ASSOCIAIES (1989) Class 2 resins — update review. Clinical Research Associates Newsletter, 10, 1. KNIBBS, P.J. (1988) The presentation and manipulation of a posterior eomposite material (Heliomolar). Dental Practice. 26(3), 20. KNIBBS, P.J. & SMART, E.R. (1989) Clinieal performance of a postrior composite. Dental Practice, 27(10), 16. LEINEELDER, K.F., SLUDER, T.B., SOCKWELL, C.L., STRICKLAND, W . D . & WALL, J.T. (1975) Clinieal evaluation of eomposite resins as anterior and posterior restorative materials. Journal of Prosthetic Dentistry, 33, 407. MAZER, R.B., LEtNEELDER, K.F. & RUSSELL, C . (1989) Meehanisms of failure in a mierofilled eomposite resin. Journal of Dental Research, 68, Abstraet 418. OSBORNE, J.W., GALE, E . N . & FERGUSON, G . W . (1973) One-year and two-year elinieal evaluation of a eomposite resin versus amalgam. Journal of Prosthetic Dentistry. 30, 795. PHILLIPS, R.W., AVERY, R.A., MEHRA, R . , SWARTZ, M . L . & MCCUNE, R . J . (1973) Observations on a composite resin for elass 2 restorations: three-year report. Journal of Prosthetic Dentistry, 30, 891. WILSON, N.H.F., SMITH, G.A. & WILSON, M.A. (1986) A elinieal trial of a visible light-eured posterior eomposite resin restorative material: three-year results. Quintessence International, 17, 643.
ARENDS, J.
The clinical performance of a posterior composite resin restorative material, Heliomolar R.O.®: 3-year report P . J . K N I B B S and E . R . S M A R T Department of Operative Dentistry. The Dental School, University of Newcastle upon Tyne, Newcastle upon Tyne. U. K.
Summary
A posterior composite resin restorative material was evaluated over a 3-year period by means of a controlled clinical trial. A total of 52 composite resin restorations and 52 amalgam alloy restorations were included in this trial, and were examined with regard to marginal integrity, surface texture, anatomical form and proximal contact with adjacent teeth. There were no significant differences in clinical performance between test and eontrol materials, whieh both gave good service over the period of evaluation. Only five restorations (one of amalgam and four of composite resin) failed during the trial. Plastic replica dies were used to support the elinieal examinations of the restorations, and sueh dies were found to be helpful.
Introduction
A large number of composite resin materials have been recommended for use in posterior teeth. Early reports on the use of the material in this situation were unfavourable, particularly with regard to wear (Osborne, Gale & Ferguson. 1973; Phillips et al., 1973; Leinfelder et al., 1975). However, there is now growing optimism about their use, due in part to recognition of their indications and eontraindieations, i.e. improved formulations, manufacture and dispensing, and greater awareness amongst clinieians of eorreet elinieal teehnique (Burke, 1986; Clinieal Research Associates, 1989). Some products are now supported by published elinieal data (Boksman et al., 1986; Wilson, Smith & Wilson, 1986), and others are currently under evaluation. Heliomolar R.O.®* is a material that is supported by elinieal data (Christensen, 1987; Mazer, Leinfelder & Russell, 1989), and ongoing research will provide a full elinieal profile of the material in due course. The material is a monoeomponent resin restorative, and is eured by halogen light. The monomer is a mixture of urethane dimethaerylate and BisGMA. The filler system is of the mierofil type, consisting of mierofillers and pre-polymerized particles of the material in an organie matrix. The filler eontent is claimed to be 65-67% of the volume {11-19% of the weight), and the maximum partiele size is reported to be 0-04 |a. A elinieal trial was designed to eompare the elinieal performance of Heliomolar Correspondence: Mr P.J. Knibbs, Newcastle Regional Dental Office, Government Buildings, Kenton Lane, Newcastle upon Tyne NEl 2YR, U.K. * Vivadent, Sehaan, LJeehtenstcin.
231
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P.J. Knihhs and E.R. Smart
R.O. with that of the amalgam alloy, Dispersalloy*. This paper deseribes the findings of the trial after the restorations had been in plaee for 3 years. Trial design Ciinieally necessary elass I or elass II restorations were plaeed in the mouths of dental students at Newcastle upon Tyne Dental Sehool. Eaeh composite restoration was paired with a eontrol amalgam restoration in the same mouth. Cavity designs were based on the traditional eoneepts of Blaek, modified b}current views that eavities should be as small as possible, commensurate with eomplete elimination of earies at the periphery. All eavities were prepared with high and low speed rotary instruments and hand instruments in aeeordanee with normal elinieal praetiee. The amalgam alloy was meehanieally triturated aeeording to the manufaeturer's instruetions, and was hand eondensed into eavities that had previously been protected against thermal irritation by a reinforced zine oxide-eugenol material when neeessary. Metal Siqveiand matriees were used to make eontaet with adjaeent teeth in elass II eavities for both amalgam and composite restorations. Pre-wedging was used to ereate adequate interproximal eontaet of elass II eomposite resin restorations. All restorations were plaeed with eareful attention to moisture eontrol; this was most often achieved by the use of eotton wool rolls and saliva ejeetors, although in certain eases rubber dam was used. The Heliomolar R.O. was provided as a single-shade produet packaged in Cavifil eompules. The latter were designed for use with the Cavifil injeetor and adaptor. This system was easy to set up, and enabled increments of the material to be plaeed accurately in eavities in all parts of the mouth. The trial protoeol demanded that all the eomposite eavities be lined with a setting ealeium hydroxide eement prior to aeid etehing. An etehing kit eonsisting of 5 ml of 37% phosphoric aeid gel, 10ml ligh-euring bonding resin (Heliobond), applieator tips and brushes, and instruetions for use were provided by the manufacturers. The enamel of the eavities was etehed for 60s, thoroughly rinsed for 20s and then dried. A thin layer of Heliobond was applied to the etehed surfaces and air-blown to produce an even layer whieh was light eured for 20s. The eomposite material was plaeed in small increments, starting with the least aeeessible site. Onee dispensed from the eompule, inerements were eondensed with a ball-ended burnisher. The eomposite was light eured in layers 1—2 mm thiek in order to minimize the effeet of polymerization eontraetion. The surface layers were earved to an anatomieally aeeeptable form prior to light euring. Curing of eaeh inerement was achieved by exposure to the Heliomat lamp for 40 s. After euring, the matrix strip was removed and the hardened eomposite was finished and polished. Gross excess was removed by water-eooled diamond burs. The oeelusion was then eheeked and adjusted as neeessary. Final finishing and polishing was aehieved by rubber abrasive points of various shapes provided for the purpose in a convenient kit by the manufacturers. The protoeol was approved by the ethies committee of Newcastle University, and the trial began in the aeademie year 1986/1987. A produet report and the results after 1 year have been published previously (Knibbs, 1988; Knibbs & Smart, 1989). * Johnson & Johnson Dental Products Co.. East Windsor, NJ 08520, U.S.A.
Evaluation of a posterior composite resin restorative material
233
Assessment of restorations
Patients were examined by two clinicians (PJK and ERS) annually until trial restorations had been in the mouth for 3 years. A thorough dental history was taken, followed by a full elinieal examination. All trial restorations were photographed and repliea impressions were taken using addition-eured silieone putty/wash impression material. Dies were poured using a elear plastie resin eured in an oven aeeording to the manufacturer's instructions'^. The restorations were assessed elinieally for marginal integrity, lustre, surface roughness, eontour, eolour mateh and eontaet with adjaeent teeth using modified United States Publie Health Serviee eriteria (see Table 1). Repliea dies were examined in standard room lighting by two assessors (PJK and ERS) with a probe blunted to 0-4 mm. Assessment of marginal integrity, eontour and surface roughness was reeorded in aeeordanee with the eriteria shown in Table 2. Dies were examined in sueh a way that the material type was not known to the assessors. Results
Thirty dental students (14 men and 16 women) were examined 3 years after initial plaeement of test and eontrol restorations (mean period 35-1 months, range 24-41 Table 1. Clinical examination of restorations Dispersalloy
Heliomolar R.O.
Marginal integrity No crevice to eatch probe Probe catches Dentine or base visible Restoration fracture or loss
35 (67) 16 (31) 0 (0) 1 (2)
35 (67) 13 (25) 0(0) 4(8)
Surface texture Smooth Slight roughness Rough
46 (90) 5(10) 0(0)
34(71) 14 (29) 0 (0) {n = 48)
{n = 5l)
Anatomical form Matches tooth Slight excess Slight deficiency Gross excess Gross deficiency
46 (90) 0 (0) 5(10) 0(0) 0(0) {n = 5\)
Contact with adjacent tooth Good Poor Not applicable
33 (65) 0 (0) 18 (35) (n = 5\)
38 (79) 6(13) 4(8) 0(0) 0 (0) (n = 48)
30 (62) 0(0) 18 (38) (n = 48)
Percentage values are shown in parentheses. * Spurr Low Viscosity Resin Kit; Polaron Equipment Ltd, Holywcll Industrial Estate. Watford, Herts, U.K.
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P.J. Knibbs and E.R. Smart
Table 2. Examination of replica dies of restorations
Die margin No crevice Probe catches in both directions Restoration fracture of loss Anatomical form of die No obvious contour loss Slight loss of contour Obviours contour loss
Surface texture of die Smooth Slight roughness Rough
Dispcrsalloy
Heliomolar R.O.
40 (77) 11 (21) 1 (2)
37 (71) 11 (21) 4(8)
49 (96) 2(4) 0(0) (« = 51)
46 (96) 2(4) 0(0) (« = 48)
45 (88) 6(12) 0(0) (« = 51)
38 (79) 9(19) 1 (2) {n = 48)
Percentage values are shown in parentheses.
months). The mean age of the patients at the time of restoration placement was 18-8 years (range 17—23 years). All patients commenced the trial with good oral hygiene and healthy gingival conditions, and maintained these high standards throughout the trial. No test or control restorations were associated with plaque stagnation or gingival pathology throughout the trial. Three patients were deemed to have a high caries rate on entry to the trial. A total of 104 restorations were examined, consisting of class I and class II restorations in molars and premolars (see Table 3). Clinical examination revealed that all restorations were performing well except for one class II amalgam that had fractured and was replaced at 24 months, and four composites which had failed and been replaced. Three of these failures were the result of recurrent caries (one occlusally, two interproximally), and the other failure was due to a poor proximal contact, allowing food impaction. Over half of the amalgam restorations (54%) had lost their initial high shine during the 3 years of service, although the remaining restorations (46%) were assessed as having a good lustre finish. Thirty-nine (81%) of the Heliomolar R.O. restorations were assessed as exhibiting a good colour match to the tooth, with nine (19%) showing a degree of mismatch. Such mismatch was not observed by any of the patients, nor did it warrant treatment. No composite restorations showed staining, either at the margins or on the restoration surface. The results of the clinical assessment of marginal integrity, surface texture, anatomical form and contact with adjacent teeth are shown in Table 1. These results showed no significant difference in assessment between the materials for the various criteria, and all restorations except for the five mentioned previously were clinically acceptable. The results of the examination of the replica dies are shown in Table 2. These correlate closely with the clinical examinations which confirm the accuracy and impar-
Evaluation of a posterior composite resin restorative material
235
Table 3. Summary of the restorations placed in the clinical trial of Heliomolar®
Class I Class II Total
Heliomolar
Amalgam
Total
18 34 52
18 34 52
36 68 104
A total of 26 restorations were placed with rubber dam. A total of 78 restorations were placed without rubber dam. No patients reported post-operative hypersensitivity.
tiality of the clinical assessments, because the replicas do not allow ready identification of material type due to the translucent plastic construction. Discussion This trial was designed using dental students as patients so as to ensure a high recall rate. One student who received a pair of restorations withdrew from the dental course, and the data for her restorations have not been included in the report. All other restorations that were placed have been reviewed annually to the 3-year stage. The patients, by virtue of their occupation, were all dentally aware and well motivated. They had good oral hygiene and general dental health, although three patients entered the trial with a high level of caries experience. These individuals all required other restorative treatment during the trial, but their trial restorations were satisfactory at the 3-year review. Two composite restorations in the mouths of other patients failed due to recurrent caries at the margins of interproximal boxes by 24 months. A third composite in an ocelusal surface of a premolar appeared intact clinically, but was correctly diagnosed as having recurrent caries from a bitewing radiograph at 24 months. This trial showed a higher probability of caries in the composite sample than in the amalgam sample, although this observation was not statistically significant. It is not possible to determine whether the recurrent caries was due to chance site-related factors in the patient's mouth, poor placement technique, or a weakness of the material. The latter is unlikely because advances have been made in the formulation of composite resin systems, whereby low concentrations of fiuoride ion leach out of the filler, and Heliomolar R.O. has been shown to possess this potentially caries-inhibiting property (Arends & Ruben, 1988). Clinicians experienced in the handling of Class II composite resins are aware of the difficulties of creating adequate contact with adjacent teeth (Burke, 1986). In this trial teeth were wedged slightly apart prior to restoration with composite, and such pre-wedging appeared to be successful as only one tooth failed due to inadequate contact with the neighbouring tooth. No evidence of contact area wear was noted for either material during this trial. One class II amalgam restoration failed due to bulk fracture of the interproximal box. The amalgam alloy performed well over the observation period, and proved to be a reliable restorative. Initial high shine was lost in over 50% of the amalgam resto-
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rations, but this was of no clinical significance. Minor marginal deficiencies were noted in 16 restorations but none of these constituted clinical failure. The assessment of marginal integrity of the composite resin showed similar results to those for amalgam. Thirteen restorations showed evidence of slight marginal deficiency. Composites with submicron-particle-size fillers are known to exhibit mild marginal degradation caused by tensile fatigue failure (particularly close to oeelusal contacts) and the low elastic modulus of such materials (Mazer, Leinfelder & Russell, 1989). The restorations in this trial showed little clinical evidence of wear over the 3-year observation period, and this is in agreement with the results of Mazer, Leinfelder and Russell (1989), who found Heliomolar R.O. to be the best composite resin restorative out of nine studied with regard to wear. Loss of overall contour due to three-body abrasion of the opposing tooth with an intermediate abrasive slurry was noted in only four restorations. Slight roughness of the oeelusal surface in localized areas was most probably due to two-body abrasion of the opposing tooth directly impinging on the composite surface in oeelusal contact. This was noted more frequently, being apparent to a mild degree in 14 restorations. The trial eomposite was supplied by the manufaeturers as a single-shade roduct, although it is now available in a range of shades. Despite the single-shade provision, marked mismatch with natural tooth was only noted in nine restorations, and several of these were in the same mouths. Such mismatch did not warrant treatment, and indeed made examination of the restoration easier, as the cavity margins were clearly defined. No composite restorations were found to have surface or marginal staining, an observation which may be related to the properties of the material, or to the generally low level of staining observed in the mouths of these dental students. All the trial restorations were placed with eareful attention to moisture eontrol. In the well-motivated, co-operative patients in this sample, this was most frequently aehieved using cotton wool rolls and saliva ejectors only. Rubber dam was used for 26 restorations where moisture control would otherwise have been diffieult to ensure. There was no differenee in performanee between those restorations plaeed with and without a rubber dam. The latter does not appear to be mandatory for successful composite restorations, although its use is recommended where other methods are unlikely to ensure a dry field throughout the restorative phase of treatment. Clear plastie repliea dies were used in this trial to supplement the clinical examinations with regard to marginal integrity, contour and surface texture. The advantage of dies is that the type of material is not readily discernible, and they can be examined and re-examined at leisure under standard conditions. They can also be stored for future eomparison with subsequent dies of the same tooth, and may also be examined mieroscopically if required. The results of die examination were slightly more favourable than those of the elinieal examinations, but these differences were not statistically significant. The dies therefore represent a useful supplement to the elinieal observations. Clinieal Research Associates (1989), in a Newsletter considering the current evidence with regard to class II composite resins, brought together the findings of 2-to 5-year evaluations of 21 brands of eomposite resin. They considered wear, marginal adaptation, proximal contact, post-operative hypersensitivity, recurrent caries, surface texture, stain and colour match, and they eoncluded that Heliomolar R.O. had been shown to perform well, and that it showed the least deterioration with time of all
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the brands examined. The results of the present trial add further clinical support to their observations. References & RUBEN, J. (1988) Fluoride release from a posterior composite resin. Quintessence International, 19, 513. BOKSMAN, L . , JORDAN, R.E., SUZUKI, M . & CHARLKS, D . H . (1986) A visible hght-cured posterior composite resin: results of a three-year clinieal evaluation. Journal of the American Dental Association, 112, 627. BURKE, F . J . T . (1986) Posterior composites: the current status. Dental Update, 13, 227. CHRISFENSEN, G . (1987) Three year in-vivo eomparison of seven posterior resins with silver amalgam. Journal of Dental Research, 66, Abstraet 833. CLINICAL RESEARCH ASSOCIAIES (1989) Class 2 resins — update review. Clinical Research Associates Newsletter, 10, 1. KNIBBS, P.J. (1988) The presentation and manipulation of a posterior eomposite material (Heliomolar). Dental Practice. 26(3), 20. KNIBBS, P.J. & SMART, E.R. (1989) Clinieal performance of a postrior composite. Dental Practice, 27(10), 16. LEINEELDER, K.F., SLUDER, T.B., SOCKWELL, C.L., STRICKLAND, W . D . & WALL, J.T. (1975) Clinieal evaluation of eomposite resins as anterior and posterior restorative materials. Journal of Prosthetic Dentistry, 33, 407. MAZER, R.B., LEtNEELDER, K.F. & RUSSELL, C . (1989) Meehanisms of failure in a mierofilled eomposite resin. Journal of Dental Research, 68, Abstraet 418. OSBORNE, J.W., GALE, E . N . & FERGUSON, G . W . (1973) One-year and two-year elinieal evaluation of a eomposite resin versus amalgam. Journal of Prosthetic Dentistry. 30, 795. PHILLIPS, R.W., AVERY, R.A., MEHRA, R . , SWARTZ, M . L . & MCCUNE, R . J . (1973) Observations on a composite resin for elass 2 restorations: three-year report. Journal of Prosthetic Dentistry, 30, 891. WILSON, N.H.F., SMITH, G.A. & WILSON, M.A. (1986) A elinieal trial of a visible light-eured posterior eomposite resin restorative material: three-year results. Quintessence International, 17, 643.
ARENDS, J.
