Development of gingivitis around aged restorations of resin-modified glass ionomer cement, polyacid-modified resin composite (compomer) and resin composite

Resin-modified glass ionomer cements (RMGIC) and polyacid-modified resin composites (PMC, compomers) are two recently introduced material groups supposed to replace traditional cements in operative dentistry. The new restoratives release initially fluoride in different relatively high concentrations, which decrease gradually during the first weeks in vivo. Earlier studies showed a stronger subclinical inflammatory reaction around different conventional tooth colored restorative materials than around intact enamel. The aim of this study was to compare intra-individually the initiation of gingival inflammation around, aged RMGIC, PMC and resin composite restorations. Subgingivally located Class III restorations were placed in 17 patients. Each patient received one of each of the experimental materials. All patients were placed on an oral hygiene regime 1-year after finishing of the restorations. Gingivitis was induced during a one-week period without oral hygiene. The gingival condition was assessed by sampling of gingival crevicular fluid (GCF), registration of the amount of bacterial plaque and by registration of bleeding after gentle probing of the entrance of the gingival sulcus (SBI) on the experimental filling- and control-enamel surfaces at days 0 and 7. No differences were seen in plaque and gingival index scores between the materials at both days. The GCF increased significantly for all surfaces during the experimental gingivitis period. At day 7 significantly lower GCF was sampled around the enamel surfaces. In conclusion, the differences between the materials did not result in measurable differences concerning clinical or subclinical signs of gingivitis. Received: 19 September 1998 / Accepted: 26 November 1998     

Interfacial adaptation of in vivo aged polyacid-modified resin composite (compomer) restorations in primary molars

Polyacid-modified resin composite (PMC) restorations are being increasingly used in class II cavities in primary teeth. The aim of this study was to evaluate the interfacial adaptation of 1-month- and 30-month-old in vivo restorations by quantitative scanning electron microscopy (SEM) evaluation. Twelve PMC restorations were performed under clinically controlled conditions in primary molars planned for extraction 1 month later for orthodontic reasons. Eleven other PMC restorations, aged 30 months (range 1.5–3 years) and part of a multicenter study, were collected after exfoliation. To observe the interfacial adaptation of each restoration at several levels a thin layer of the proximal surface was ground off 2–3 times. Replica impressions of each level were prepared for SEM. The interfaces of the replicas were evaluated at ×200 and ×1000. In the 1-month-old restorations gap-free adaptation to enamel was found in 87% and to dentin in 84% of the total interfacial length investigated. For the 30-month-old restorations gap-free adaptation was registered in 59 and 63%, respectively. The interfacial quality was significantly better in the 1-month-old restorations than in those 30 months of age. Adaptation to enamel was significantly better in the cervical part of the 1-month-old restorations than in the axial walls, whereas there was no significant difference in dentin. No significant difference was found between the cervical and axial cavity walls of the 30-month-old restorations. Enamel fractures were registered in 31 and 24%, respectively of the interfacial length of the 1-month- and 30-month-old restorations. The corresponding findings in dentin were 0 and 0.9%. It can be concluded that restorations aged for a short time showed a high percentage of sealing, which decreased significantly for the 30-month-old ones. Received: 24 June 1998 / Accepted: 7 October 1998     

Longevity of a resin-modified glass ionomer cement and a polyacid-modified resin composite restoring non-carious cervical lesions in a general dental practice

BACKGROUND: Long-term prospective survival studies of resin-modified glass ionomer cements (RMGICs) and polyacid-modified resin composites (compomers) placed in non-carious cervical lesions (NCCLs) are lacking from general dental practice. Short-term studies have shown an unsatisfactory clinical performance for several materials. METHODS: One practitioner placed 87 compomer (Compoglass, Vivadent-Ivoclar) and 73 encapsulated RMGIC (Fuji II LC, GC Int.) restorations in NCCLs for 61 adults. Compoglass was placed using SCA primer, and Fuji II LC using GC Dentin Conditioner. No cavity preparation was undertaken. The Kaplan-Meier method was used for estimating the cumulative survivals for those restorations that were replaced, with the probability level set at alpha = 0.05 for statistical significance. RESULTS: Restorations were judged unsatisfactory (by the practitioner and the subjects) because of surface and marginal loss of material (68.8 per cent), dislodgement (18.8 per cent) and discoloration (12.4 per cent), these modes being similar for both materials (P = 0.35). Unsatisfactory restorations were replaced in 121 (75.6 per cent) instances. After periods of up to five years, cumulative survival estimates were 14.9 (5.8 Standard Error) per cent for Compoglass and zero per cent for Fuji II LC (P = 0.74). Median survivals were 30 months for Compoglass and 42 months for Fuji II LC. CONCLUSION: Both materials had high long-term unsatisfactory performances when placed in non-prepared NCCLs in a general dental practice.     

Two-year evaluation of Class II resin-modified glass ionomer cement/composite open sandwich and composite restorations

Restorations made of a combination of resin modified glass ionomer cement (RMGIC) and composite resin (CR) – open sandwich fillings – have been recommended for use in proximal boxes of molar cavities. The aim of this study was to compare the clinical behaviour over time of RMGIC/CR sandwich restorations versus CR restorations in Class II molar cavities. During a period of 2 years, a total of 220 restorations were placed in 118 patients by one operator (VV). A random block allocation was used to allocate cavities to one of the two restorative techniques. Bitewing radiographs and photographs were taken at baseline and at annual recall appointments. At present, a total of 210 restorations have been evaluated after 1 year and 141 restorations after 2 years. All restorations were evaluated using a modification of USPHS criteria. A total of three RMGIC/CR and two CR restorations (2.8%) were rated as failures caused by endodontic complications or major fractures. Twenty-eight teeth were reported to have postoperative sensitivity at the baseline evaluation 1 week following placement. Nine RMGIC/CR (8.5%) and four CR (4.9%) restorations with minor fractures were rated Charlie but were still acceptable. Bitewing radiographs revealed progression of carious lesions in proximal surfaces of originally intact or restored teeth adjacent to five (5.9%) RMGIC/CR restorations and eight (10.9%) CR restorations. No statistically significant differences between the two types of restoration were observed with respect to marginal adaptation, discoloration and caries progression. However, a higher number of large CR fillings exhibited postoperative sensitivity at baseline compared to moderate CR or extensive and moderate RMGIC/CR restorations. Received: 28. January 2000 / Accepted: 8 May 2000     

Occlusal wear of a resin-modified glass ionomer cement following three surface treatments

Unacceptable occlusal wear has been report- ed for resin-modified glass ionomer cements (RMGICs) placed in permanent molar teeth. Three different surface treatments of a RMGIC were evaluated over periods of up to 2 years for their effects on restoration wear behaviour: (a) sealing with a thin layer of low viscosity unfilled resin (sealed restoration), (b) sealing with a thicker layer of a lightly-filled pit and fissure sealant (sealant restoration), and (c) co-curing the RMGIC with a posterior resin composite (co-cured restoration). After 2 years the cumulative median (quartiles) wear was for (a) 100 (50–150) μm, (b) 25 (0–50) μm, and (c) 25 (25–38) μm. Although method (b) effectively reduced the surface wear of the RMGIC, this treatment required frequent re-sealing, involving 52% of the restorations. Sealing the surface of a RMGIC placed in permanent molars was not a satisfactory method for reducing occlusal wear. However, co-curing the RMGIC with a posterior resin composite reduced occlusal wear significantly (P<0.0001), without the need for frequent re-applications of a pit and fissure sealant to the RMGIC. Received: 23 May 2000 / Accepted: 26 September 2000     

Comparative study of the physical properties of a polyacid-modified composite resin and a resin-modified glass ionomer cement.

OBJECTIVES: The physical properties of the resin-modified composite resin Dyract (Detrey Dentsply) and the resin-modified glass ionomer cement Fuji II LC (GC) were compared, and the effect of water sorption on these properties was studied. METHODS: Compressive, diametral compressive and flexural strengths were measured using specimens aged up to three months. The Vickers hardness and the water erosion were also determined. The specimens were stored at 37 degrees C under five different conditions, chosen to vary the water sorption of the samples. The results were analyzed using a multi-factor analysis of variance. RESULTS: Dry specimens of Dyract and Fuji II LC showed similar properties. However, the two materials behaved differently when stored in presence of water. In contrast to Fuji II LC, Dyract showed very little expansion for the first 24 h (1.5 +/- 0.3 and 0.03 +/- 0.01%, respectively), leached small quantities of ions and retained its mechanical strength. Those differences are related to their chemical composition. Fuji II LC is hydrophilic, as it contains polyHEMA. In the presence of water, Fuji II LC behaves like a hydrogel, but the network resulting from the copolymerization of acidic and UDMA monomers is less hydrophilic, and the effect of water on Dyract is retarded. SIGNIFICANCE: The significant properties of Dyract are determined by its composite character. This certainly represents some advantages, for instance, a higher mechanical strength, a better protection against initial dehydration and subsequent water effects. However, Dyract shows some disadvantages over Fuji II LC, like a lower amount of fluoride release or the interference of oxygen during polymerization.     

A 4-year clinical study on amalgam, resin composite and resin-modified glass ionomer cement restorations in overdenture abutments

Objective: To assess the performance of three different filling materials in overdenture abutment teeth.

Methods: In 49 patients amalgam, resin composite and resin-modified glass ionomer cement were used to seal the root canal orifices of 155 overdenture abutment teeth. After initial preparation of the cavities, the three restorative materials were randomly assigned to the abutment teeth using a number of balancing criteria. All patients were reviewed every six months and received the same preventive regimen. Survival was assessed at two levels: S_orig (survival of the restoration independent from eventual maintenance treatments) and S_comp (restorations survived even without maintenance treatments).

Results: The calculated overall survival percentage of the original restorations (S_orig) after four years was 63±6% (mean±SE). Calculation for the overall complete survival (S_comp) revealed a percentage survival of 57±6%. At both levels, the differences between the survivals of the investigated materials were not statistically significant (p-values>0.05). Two abutments were lost, severe caries was the reason for one extraction and another abutment tooth was extracted for periodontal reasons.

Conclusions: The results of this study did not point out a superior restorative material for the seal of root canal orifices of overdenture abutments. The distribution of failures over the patients indicates a certain patient dependency.     

Adhesion of composite resin to etched glass ionomer cement

A laboratory study was undertaken to determine the tensile bond strengths of three glass ionomer cements to dentine and the tensile bond strengths of composite to the three glass ionomers after etching. The tensile bond strength to untreated dentine was in the range of 4.47–5.52 MPa, being approximately twice that of a glass ionomer restorative material. After etching the glass ionomer, the bond strength to composite resin ranged from 1.83 MPa to 6.17 MPa, depending on the ionomer and on the time after mixing at which it was etched. In the majority of clinical situations, retention of a composite restoration via etched glass ionomer cement would probably need to be supplemented by additional mechanical retention.     

正畸粘接用玻璃离子粘固剂防治托槽周围釉质脱矿的体外pH循环实验

目的　通过体外pH循环实验研究树脂改良型玻璃离子粘固剂 (resin modifiedglassionomercement)对托槽周围釉质脱矿的抑制作用。方法　选择 5对离体前磨牙 ,实验组用树脂改良型玻璃离子粘固剂粘接托槽 ,对照组用复合树脂粘接剂粘接托槽。全部样本每天进行pH循环实验 ,共60d。用偏振光显微镜观察托槽周围釉质脱矿病损并测量病损体部的深度、面积以及病损边缘与粘接材料边缘的距离。结果　对照组托槽周围釉质脱矿病损的深度和面积均大于实验组 ,配对t检验表明 2组间差异有非常显著性 (P <0 0 0 1 )。实验组病损均远离玻璃离子粘固剂边缘 ,而对照组病损均深入复合树脂粘接剂边缘的下方。结论　树脂改良型玻璃离子粘固剂是一种可以减少正畸治疗中釉质脱矿的粘接材料     

Surface pH of resin-modified glass polyalkenoate (ionomer) cements

The recently developed group of materials known as light-activated, or resin-modified, glass polyalkenoate (ionomer) cements have been produced in response to clinical demands for a command set cavity base material. This study monitored the surface pH of three commercially available resin-modified glass ionomer cements over a 60-min period following either mixing alone or mixing followed by a 30-s exposure to a curing lamp. The results indicate that each material behaves in a unique manner. For all materials and conditions the pH reached after a 60-min period was significantly (P < 0.001) higher than the initial value. Light curing the materials significantly increased (P < 0.01) the surface pH of two of the materials (Baseline VLC and Vitrebond) as compared to the same materials in the uncured state. In the case of XR-Ionomer, however, no significant (P > 0.05) effect of light curing upon the surface pH was apparent. The precise clinical consequences of a low surface pH are unclear but may be an aetiological factor in postoperative pulpal sensitivity. It is therefore recommended that a sublining of a proprietary calcium hydroxide lining material should be placed routinely beneath these materials and every effort made to ensure effective light curing.     

The impact of glass ionomer cement and composite resin on microscale pH in cariogenic biofilms and demineralization of dental tissues

ObjectiveSecondary caries is among the most frequent reasons for the failure of dental restorations. Glass ionomer cement (GIC) restorations have been proposed to protect the surrounding dental tissues from demineralization through the release of fluoride and by buffering the acid attack from dental biofilms. In contrast, the lack of buffering by composite resin (CR) restorations has been suggested as a promoting factor for the development of secondary caries.MethodsThe present study employed transversal microradiography and confocal microscopy based pH ratiometry to quantify mineral loss and map microscale pH gradients inside Streptococcus mutans biofilms grown on compound specimens consisting of enamel, dentin and either GIC or CR.ResultsMineral loss in dentin was significantly lower next to GIC than next to CR, but no significant differences in local biofilm pH were observed between the two restorative materials.SignificanceThe cariostatic effect of GIC relies predominantly on the provision of fluoride and not on a direct buffering action. The lack of buffering by CR did not affect local biofilm pH and may therefore be of minor importance for secondary caries development.     

Microleakage of glass ionomer/composite resin restorations: A laboratory study. 1. The influence of glass ionomer cement

Acid-etching of enamel margins, often combined with bevelling and use of a low viscosity resin, has resulted in improved sealing of composite restorations. When enamel is absent and margins involve dentine or cementum, microleakage is more often observed. The use of glass ionomer cement, as both a restorative material and as a base combined with a veneer of composite resin, has been advocated as a means of minimizing microleakage where margins are placed in dentine or cementum. Four restorative techniques incorporating glass ionomer cement were used, in vitro, to restore cervical cavities. After thermal cycling, dye penetration was scored along occlusal and gingival margins. In all instances the gingival margin exhibited a less reliable seal than the occlusal margin. The sandwich restorations produced a superior seal at both occlusal and gingival margins when compared with glass ionomer restorative cement.     

The effect of glass ionomer cement or composite resin bases on restoration of cuspal stiffness of endodontically treated premolars in vitro

The purpose of the present study was to decide whether composite resin or conventional glass ionomer cement should be preferred as a base material in endodontically treated premolars. Twelve extracted human maxillary premolars were mounted in a universal testing machine at a 35° angle. Cuspal stiffness was determined by applying a load of 75 N to the buccal cusp and recording the displacement of the cusp using inductive displacement transducers. In the same teeth, different cavity preparations and restorations were performed sequentially. Standard MOD cavities were enlarged to allow endodontic access. In addition, the cusps were undermined. Half of the teeth were restored to the level of the previous shallow cavities using conventional glass ionomer cement (Ketac Fil), in the rest of the teeth dentine bonding agent (Syntac) and composite resin (Tetric) were used instead. Finally, composite resin fillings (Tetric) were placed. All restorations were removed and the experiments were repeated twice. For each replication, the assignment of the base materials to the experimental groups was reversed, and ceramic inlays (Empress) were used as final restorations for the last replication. Improvement of cuspal stiffness achieved by conventional glass ionomer bases was very small, whereas composite resin bases increased cuspal stability by more than a factor of two. After placement of the final restorations, however, there was no longer a difference between teeth with different base materials. Nevertheless, composite resin bases might be preferred for two reasons. Firstly, deterioration of adhesive restorations will probably start at the cavosurface margins. The incidence of margin gaps, however, will not only compromise marginal seal but also the stabilizing effect of the restoration. In this situation, the resin base may still stabilize the tooth. Moreover, resin bases may reduce the risk of cusp fracture during the time between cavity preparation and the insertion of adhesive inlays. Received: 19 February 1998 / Accepted: 5 May 1998     

玻璃离子体粘固粉作为光固化复合树脂基底材料的密合度研究

将玻璃离子体粘固粉（ＧＩＣ）作为光固化复合树脂基底材料修复活体狗牙Ｖ类洞，经过７ｄ、６个月后，分别采用图象分析仪测量粘固粉与牙本质洞壁及光固化复合树脂之间的缝隙。结果显示：ＧＩＣ与牙本质洞壁之间缝隙为０．４３４～３．９２３μｍ，与光固化复合树脂之间缝隙为０．８９４～２．９５６μｍ，在近、远期观察组中密合度无显著差异     

Dentine bond strength and microleakage of flowable composite,compomer and glass ionomer cement

Background: To assess in vitro the dentine bond strength and microleakage of three Class V restorations viz. flowable composite, compomer and glass ionomer cement. Methods: Eighteen dentine specimens were prepared and randomly distributed among three groups. Three kinds of restoration materials were each bonded on prepared dentine surfaces in three groups as per the manufacturers’ instructions. Group Aelite: Tyrian SPE (a no‐rinse, self‐priming etchant) + One Step Plus (an universal dental adhesive) + Aeliteflo (a flowable composite); Group Dyract: Prime & Bond NT (a no‐rinse, self‐priming dental adhesive) + Dyract AP (a compomer); Group GlasIonomer: GlasIonomer Type II (a self‐cured restorative glass ionomer). Fifteen dentine/restoration microtensile bond test specimens were prepared from each group and were subjected to microtensile bond strength testing. The bond interfaces were observed morphologically using a scanning electron microscope (SEM). Twenty‐four cervical cavities of 4.0 mm mesiodistal length, 2.0 mm occlusogingival height and 1.5 mm depth were prepared at the cemento‐enamel junction (CEJ) on both buccal and lingual surfaces of each tooth. The cavities were each filled with flowable composite (Group Aelite), compomer (Group Dyract) and glass ionomer cement (Group GlasIonomer) using the same material and methods as for the microtensile bond tests. Microleakage of each restoration was evaluated by the ratio of the length of methylene blue penetration along the tooth‐restoration interface and the total length of the dentine cavity wall on the cut surface. Results: One‐way ANOVA and least significant difference (LSD) tests revealed statistically significant differences among the dentine bond strength for Group Aelite (28.4 MPa), Group Dyract (15.1 MPa) and Group GlasIonomer (2.5 MPa). SEM images showed intimate adaptation in the restoration/dentine interfaces of Group Aelite and Group Dyract. All of the systems tested in this study presented microleakage. However, both Group Aelite (0.808) and Group Dyract (0.863) had significantly less microleakage than Group GlasIonomer (0.964). There were no statistically significant microleakage differences between Group Aelite and Group Dyract, and no statistically significant microleakage differences between the occlusal margin and gingival margin. Conclusions: None of the systems tested in this study completely eliminated microleakage. However, both the flowable composite and compomer provided stronger dentine bond strengths and better margin sealing than the conventional glass ionomer cement. Occlusal forces exerted the same effects on microleakage of the occlusal margin and gingival margin in cervical cavities.     

Uptake of fluoride ions by the glass component of glass ionomer cement

OBJECTIVES: The uptake of F(-) ions by glass ionomer cement (GIC) has been extensively studied but the precise location of the F(-) ion in the GIC structure has not been reported. The aim of this study is to use model materials to elucidate the possible locations. GIC consists of residual particles of aluminosilicate glass surrounded by depleted glass in an ionically crosslinked polymeric matrix. This study evaluates uptake by both unreacted glass particles (RAW) and particles acid-treated to produce a depleted glass surface (DEPLETED). METHOD: Three glasses, previously studied as cements, were tested at the particle size used in GICs. LG30 contained Al, Ca, O, P, and Si; LG26 also contained F and AH2 contained Na as well. To produce depleted surfaces they were immersed in acetic acid washed and dried at room temperature. Test samples (N=5) were immersed in KF solution (900ppm F). Control solutions without glass were used. Both were stored at 37C for 48h. F concentrations were measured using ISE with TISAB IV. RESULTS: Uptake was Control-test expressed in micromol/g glass. RAW LG30=56 (16); LG26=35(17); AH2=17(31). DEPLETED LG30=285(41); LG26=431(42); AH2=286(50). The levels of F uptake by DEPLETED were comparable to those found with GICs formed with these glasses. CONCLUSIONS: The glass particles of GIC, and particularly the depleted zones surrounding them, can account for an appreciable amount of the F uptake observed with cements but do not show the same relation between F content and F uptake previously observed with cements.     

Clinical requirements for a successful 'sandwich'--dentine to glass ionomer cement to composite resin

The composite resins are now being used extensively in restorative dentistry although there are still some problems remaining. Long-term prevention of microleakage continues to be an area of controversy particularly in relation to the margins between dentine and composite resin. Chemical adhesion between glass ionomer cement and dentine is accepted as being a long-term union and it has recently been shown that a mechanical union is possible between composite resin and glass ionomer cement. This has led to the development of the so-called 'sandwich technique' where glass ionomer cement is used as a lining under composite resin restorations particularly where the cavo-surface margin is in dentine. This paper discusses the various levels of adhesion in the 'sandwich' and suggests the best methods of obtaining optimum results from the clinical application of the technique. Particular attention is drawn to the wide variation in the strength of the union depending on the materials used and the methods of handling.     

Effect of air polishing on the fluoride release of (resin-modified) glass ionomer cements and of a polyacid-modified composite resin

Eight different conventional and resin-modified glass ionomers as well as a polyacid-modified composite were air polished and their fluoride release was determined in comparison to untreated controls. The air polishing was done with two different devices at medium and maximum setting for powder and water. Ninety discs of 1.5 mm thickness and 7.0 mm diameter were produced from each cement. These discs were stored in 5 ml deionized water at 37°C. After 1 day and 1, 4, 8, 12, and 16 weeks, the specimens were transferred into new vials with fresh deionized water. From the 4th week onward, the specimens (except for the untreated controls) were air polished on half of their upper and lower surfaces for 2 s each before being put into a new vial. After 20 weeks the fluoride released during the previous 4 weeks was determined with a fluoride ion-sensitive electrode. With the exception of Ketac-Cem, all cements released significantly more fluoride ions after air polishing, irrespective of the devices' settings. The differences in the amount of fluoride released among the investigated materials were greater than the changes in fluoride release patterns caused by air polishing. Air polishing increased the fluoride release by 20–60% in most of the materials investigated. Received: 10 February 1998 / Accepted: 25 May 1998     

Laboratory evaluation of a compomer and a resin-modified glass ionomer cement for orthodontic bonding

The mean shear debonding force of stainless steel orthodontic brackets with microetched bases bonded with either a compomer or a resin-modified glass ionomer cement was assessed. In addition, the amount of cement remaining on the enamel surface following bracket removal was evaluated. Finally, survival time of orthodontic brackets bonded with these materials was assessed following simulated mechanical stress in a ball mill. Debonding force and survival time data were compared with those obtained for brackets bonded with a chemically cured resin adhesive, a light-cured resin adhesive, and a conventional glass ionomer cement. There were no significant differences in mean shear debonding force of brackets bonded with the compomer, resin-modified glass ionomer, chemically cured resin adhesive, or the light-cured resin adhesive. Brackets bonded with a conventional glass ionomer cement had a significantly lower mean shear debonding force than that recorded for the other materials. The Adhesive Remnant Index (ARI) mode score indicated that significantly less cement remained on the enamel following debonding of brackets cemented with resin-modified or conventional glass ionomers compared with other adhesives. The median survival time for brackets cemented with the compomer, resin-modified glass ionomer, chemically cured resin, or light-cured resin were significantly longer than for brackets cemented with conventional glass ionomer. The compomer and the resin-modified glass ionomer adhesive appear to offer viable alternatives to the more commonly used resin adhesives for bracket bonding.