Clinical Evaluation of Ceramic Inlays and Onlays Made with Two Systems: a One-Year Follow-Up

Clinical Evaluation of Ceramic Inlays and Onlays Made with Two Systems: A One-year Follow-up

Maria Jacinta M. Coelho Santosa/Rafael Francisco Lia Mondellib/ Carlos Eduardo Francischonec/José Roberto Pereira Laurisd/Maria Fidela de Lima Navarroe

Purpose: The aim of this study was to evaluate the clinical performance of ceramic inlays and onlays made with two systems: sintered (Duceram [D], DeguDent) and pressable (IPS Empress [IPS], Ivoclar-Vivadent) after 1 year.

Materials and Methods: Seventy-four restorations – 37 IPS and 37 D – were cemented in 34 patients. Twenty-four premolars and 50 molars received Class II cavity preparations, totaling 28 onlays and 46 inlays. The restorations were evaluated by two independent investigators at baseline, 6 months, and 1 year, according to modified USPHS criteria. Fisher and McNemar statistical tests were employed to assess the survival rate.

Results: After one year, 100% of the restorations were assessed and all the restorations were considered clinically excellent or acceptable. Among the analyzed criteria, only the following received “Bravo” ratings: marginal discoloration: IPS (24.32%), D (13.51%); marginal integrity: IPS (10.81%), D (8.11%); color match: IPS (5.41%), D (5.41%); surface texture: IPS (2.70%), D (10.81%). No “Charlie” or “Delta” scores were given to the restorations.

Conclusion: Among the analyzed criteria, only marginal discoloration differed statistically significantly from the results of the baseline examination for IPS Empress ceramic restorations (p = 0.008). No significant differences were found between the two ceramics. The two ceramic systems demonstrated excellent clinical performance after a period of 1 year.

Key words: ceramic, onlays, inlays, clinical study.

J Adhes Dent 2004; 6: 333–338. Submitted for publication: 14.05.03; accepted for publication: 18.12.03.

n dental care, a good esthetic result has become an All-ceramic materials have been extensively developed Iimportant goal to be achieved by the patients and in the last decade, and different systems with high shear clinicians, while at the same time, a great number of and tensile strengths have been marketed. Several tech- tooth-colored materials have been released onto the mar- niques are available for the fabrication of all-ceramic ket.16 Esthetic alternatives to metal restorations include restorations. They may be sintered, milled, infiltrated, direct composites and indirect composites and ceramics. pressed, or cast.19 A comparison of different systems is an important way to identify the differences between them and to point out the advantages and disadvantages a Assistant Professor, Department of Operative Dentistry, School of Dentistry, of each kind. Federal University of Bahia, BA, Brazil. Many laboratory studies have been designed to com- b Assistant Professor, Department of Operative Dentistry, Bauru School of 3,15 Dentistry, University of São Paulo, Bauru, SP, Brazil. pare different types of ceramics to predict their dura- c Professor, Department of Operative Dentistry, Bauru School of Dentistry, bility under clinical situations. Although these in vitro University of São Paulo, Bauru, SP, Brazil. studies may bring additional and valuable information, d Assistant Professor, Department of Pedodontics, Orthodontics and Commu- clinical studies offer the most reliable means of evaluat- nity Health Dentistry, Bauru School of Dentistry, University of São Paulo, ing materials under diverse aspects simultaneously. A Bauru, SP, Brazil. great number of clinical investigations have shown high e Professor, Department of Operative Dentistry, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil. success rates for different systems. Studer et al24 investigated 130 IPS Empress ceramic restorations for two years and found a success rate of 97.5%. Fradeani et al5 Reprint requests: Prof. M. Navarro, Al. Octávio Pinheiro Brisola 9-75, Vila Universitária, CEP. 17012-901 Bauru, SP, Brazil. Tel: +55-14-3234-7688, Fax: investigated 125 IPS Empress inlays and reported a suc- +55-14-3223-4679. e-mail: [email protected] cess rate of 95.63% after 4 years. Fuzzi and Rappelli7

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Table 1 Number of ceramic restorations Dent, Hanau, Germany) and pressed (IPS Empress [IPS], Ivoclar-Vivadent, Schaan, Liechtenstein) ceramic restora- IPS Empress Duceram Total tions. A total of 28 onlays and 46 inlays were placed in Inlay 23 23 46 24 premolars and 50 molars, as is shown in Table 1. At Onlay 14 14 28 least two restorations were placed in each patient (one IPS and one D), with a maximum of four restorations. All Total 37 37 74 preparation and luting procedures were carried out by one operator. For each patient, the operator selected the material for the first tooth by random, and the alternate material for the next tooth in order to have a paired design. evaluated the clinical performance of ceramic inlays and The isthmus width was established between 1.5 and onlays made with two adhesively luted sintered systems 2.0 mm, the pulpal floor depth was between 1.5 and and showed a success rate of 95% after 11 years. Krejci 2.0 mm, the axial wall depth was 1.5 mm, the internal et al13 found no failures in IPS Empress ceramic inlays line angles were rounded, and the divergence angle of the after 1.5 years. The cavity design allowing for adequate cavity was approximately 10 to 15 degrees with no bevel. thickness of the ceramic material and an adhesive ce- If it was found to be necessary after caries removal, cal- mentation technique were considered important factors cium hydroxide cement (Dycal, Dentsply, Konstanz, Ger- to prevent fractures.1,2,9,10,26 many) was applied as indirect pulp capping and undercuts The long-term purpose of this study was to evaluate were blocked out with a resin-modified glass ionomer the clinical behavior of all-ceramic inlays and onlays made (Vitremer, 3M, St Paul, MN, USA) to help standardize the with two systems, IPS Empress and Duceram, according depth of the cavities (from 1.5 to 2.0 mm). The tooth was to USPHS criteria. The aim of this study was to provide a prepared using a tapered rounded diamond tip at high survey of 1-year results and compare the clinical behavior speed (#4137, #2133, #4138; KG Sorensen, São Paulo, of the two ceramic systems. Re-evaluation of these resto- SP, Brazil) under water spray. The enamel margins were rations was planned after 1 year and then at 2-year fol- subsequently finished using hand instruments. low-up intervals until they have been investigated for no Full-arch impressions were taken with a polyvinyl-silox- fewer than 6 years. ane material (Express, 3M) and the cavities were provi- sionally restored with self-curing acrylic resin (Duralay; Reliance Dental, Worth, IL, USA) luted with eugenol-free MATERIALS AND METHODS cement (Temp Bond NE, Kerr, Karlsruhe, Germany). Two dental ceramists were selected to produce the inlays and Thirty-four patients (17 females and 18 males) with a onlays, the colors of which were selected from the Vita mean age of 34 years, who required at least two inlay or shade guide (Vita Zahnfabrik, Bad Säckingen, Germany). onlay restorations, were selected for this study. The During the second appointment, the restorations were following items were considered as exclusion criteria: fitted into the cavities and adhesively luted under rubber- dam by means of the following techniques. The internal –high caries risk surfaces were sandblasted with 50-µm aluminum oxide – periodontal disease particles at a pressure of 6 bars (Opiblast, Buffalo Dental, – presence of removable or fixed orthodontic appliances Buffalo, NY, USA). Then these surfaces were etched with – signs of bruxism or clenching 10% hydrofluoric acid for 60 s. After rinsing, the silane – absence of more than one unit in the posterior region agent (Monobond S, Ivoclar-Vivadent) was applied for – poor oral hygiene 60 s and dried. The cavity was cleaned with pumice slurry – pregnancy and etched with 35% phosphoric acid gel for 15 s, rinsed with water, and gently air dried, taking care to avoid des- All patients were treated at the Bauru Dental School, Uni- iccation of the tooth substrate. The dentinal surface was versity of São Paulo, SP, Brazil. The patients were in- treated with a dentin bonding agent (Syntac Primer and formed about the research methodology, risks and bene- Adhesive, Ivoclar-Vivadent). Subsequently, the cavity prep- fits, as well as about their rights to discontinue participa- aration and inner surface of the ceramic inlays were cov- tion in this study at any time. Written informed consent ered with a layer of bonding agent (Heliobond, Ivoclar-Vi- was requested. The study was carried out according to re- vadent), which was air thinned but not light cured. The search norms and guidelines for humans, as determined dual resin cement Variolink II (Ivoclar-Vivadent) was used by the University of São Paulo ethics committee. according to the manufacturer’s instructions to cement all In order to have a paired design in terms of materials, the inlays and onlays. The luting agent was photopolymer- if a patient needed an odd number of restorations, one ized from different positions (60 s in each direction). restoration was randomly excluded from the study. Thus, Excess luting composite was removed and the occlus- only 74 of the initial 86 restorations were analyzed in this al contacts were adjusted with diamond finishing burs study. #3202F and #3203 FF (KG Sorensen) under water cool- Seventy-four Class II cavities were restored with adhe- ing. The surfaces were carefully polished with rubber tips sively luted, sintered (Duceram Plus and LFC [D], Degu- (Cerapol Plus, Edenta Dental Rotary Instruments, Switzer-

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Table 2 Modified USPHS criteria for the clinical evaluation of ceramic inlays and onlays used in this study

Characteristic Rating Criteria

Postoperative Alpha No postoperative sensitivity sensitivity Bravo Postoperative sensitivity

Secondary Alpha No evidence of caries contiguous with the margin of the restoration caries Bravo Caries evident contiguous with the margin of the restoration

Marginal Alpha No discoloration on the margin between the restoration and the tooth structure discoloration Bravo Discoloration on the margin between the restoration and the tooth structure Charlie Discoloration has penetrated along the margin of the restorative material in a pulpal direction

Surface Alpha Smooth surface texture Bravo Slightly rough or pitted, can be refinished Charlie Rough, cannot be refinished

Marginal Alpha No visible evidence of ditching along the margin integrity Bravo Visible evidence of ditching along the margin not extending to the DE junction Charlie Dentin or base is exposed along the margin Delta Restoration is mobile, fractured or missing

Color match Alpha No mismatch in color, shade or translucency between restoration and adjacent tooth structure Bravo Mismatch between restoration and tooth structure within the normal range of color, shade and translucency Charlie Mismatch between restoration and tooth structure outside the normal range of color, shade and translucency

Fracture Alpha No evidence of fracture Bravo Evidence of fracture

land) and the final polishing was conducted using felt Table 3 “Alpha” results of the clinical investigation with the disks with diamond polishing gel (KG Sorensen). modified USPHS criteria All restorations were assessed using mirrors and Investigation Baseline 1 year probes one week following placement according to the “Alpha” modified United States Public Health Service (USPHS) IPS DIPSD criteria20 (Table 2) by two calibrated, independent investi- (%) (%) gators. To eliminate bias, the two dentists who evaluated Postoperative 97.30 91.89 100.00 100.00 all the restorations had no preliminary information about sensitivity the type of restoration they investigated. Additional bite- Secondary 100.00 100.00 100.00 100.00 wing radiographs and intraoral photographs were made. caries Figures 1 to 6 depict the teeth before cementation (under rubber-dam), at baseline, and after 1 year. Fracture 100.00 100.00 100.00 100.00 The same evaluation procedures performed at baseline were performed again after 6 months and 1 year. To Color match 97.30 95.95 94.59 94.59 compare materials and compare baseline with one-year results, the McNemar test for paired data was used. Marginal 100.00 100.00 75.68 86.49 The comparison between molars/premolars and in- discoloration lays/onlays was performed with the Fisher test because Marginal 100.00 100.00 89.19 91.89 the data was not completely paired. This result should be integrity analyzed cautiously because it deviates from statistical Surface texture 97.30 89.19 97.30 89.19 assumption of independence. SEM photographs (JSM T220A, JEOL, Tokyo, Japan) were taken to illustrate the wear of the resin cement with time. patients were satisfied with the treatment carried out. No recurrent caries or fractures were observed in this period RESULTS and no Charlie or Delta ratings were given. The McNemar statistical test revealed no significant The results of the clinical examination for ceramic inlays difference between Duceram and IPS Empress ceramic at baseline and 1 year are summarized in Table 3. All systems for all aspects evaluated at the recall appoint-

Vol 6, No 4, 2004 335 Santos et al

Fig 1 Cavity preparations prior to cementation of the ceramic Fig 2 Aspect of the restorations after cementation and removing restorations. the rubber-dam: IPS Empress inlay (45) and Duceram inlay (46).

were detected during this period. These results are sup- ported by the findings of Studer et al25 and Scheibenborg et al,22 who evaluated the clinical performance of ceramic inlays and onlays for the same period. At the 1 year recall, there was an increase in Bravo ratings for marginal discoloration for both ceramics, showing a significant difference for IPS Empress restorations compared with baseline (p = 0.008). The wear of the resin cement was considered the main reason for deterioration of the interface inlay/luting agent with consequent marginal discoloration.4-6,8,12,14,17,22,26 The high wear rate of the luting cement may result from the transfer of chewing forces to the margins of the ceramic restorations with very high modulus of elasticity.13,18 The SEM photo- Fig 3 Final result of IPS Empress inlay (45) and Duceram inlay graphs illustrated the wear of resin cement with time (46) after 1 year in service. (Figs 7 and 8). Using SEM, Gladys et al8 and Van Meer- beek et al28 verified a significant decrease in marginal adaptation at the inlay/cement interface after 6 months of ments (p > 0.05). After 1 year, all 74 restorations were clinical use, indicating a severe wear of the resin cement. analyzed and considered clinically excellent or acceptable The wear resistance of resin cements must be increased. (Alpha and Bravo). The following aspects received Bravo Marginal integrity is also related to luting cement wear. ratings: marginal discoloration: IPS (24.32%), D (13.51%); Alpha ratings decreased from 100% at baseline to marginal integrity: IPS (10.81%), D (8.11%); color match: 91.89% (D) and 89.19% (IPS) after 1 year. Krejci et al13 IPS (5.41%), D (5.41%); surface texture: IPS (2.70%), pointed out the drawbacks in rating marginal integrity due D (10.81%). Marginal discoloration for IPS Empress to the coarse tip of the explorer, which may not adquately ceramic restorations at 1 year differed significantly com- penetrate a fine marginal gap. pared with the results of the baseline examination (p = The Duceram ceramic system presented a higher inci- 0.008). With regard to the clinical behavior of ceramic dence of Bravo ratings (10.81%) in surface texture when inlays and onlays as well as the restorations placed in the compared with the IPS Empress ceramics (2.70%); how- premolar or molar regions, the Fisher Test showed no sta- ever, the Fisher Test showed that these values were not tistically significant difference (p > 0.05). Determination significantly different (p = 0.358). The results obtained of interexaminer reliability yielded Kappa values above from baseline to 1 year remained stable. 0.65 for all criteria. The estimated survival rate over a A relatively low percentage of postoperative sensitivity period of 1 year was 100%. was observed at baseline (2.70% for IPS and 8.19% for D), but it diminished rapidly within 2 weeks at most. After 1 year, none of the teeth exhibited sensitivity. The pres- DISCUSSION ence of postoperative sensitivity has been reported in some clinical investigations and is related to the incom- The results of the clinical evaluation indicate that both plete sealing of the dentin.6,12,23,24,26,27 The reduced ceramic systems presented satisfactory results after one postoperative sensitivity in the present study may be year of clinical service. No fractures or recurrent caries explained by the use of calcium hydroxide cement (Dycal,

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Fig 4 Cavity preparations prior to cementation of the ceramic Fig 5 Aspect of the restorations after cementation and removing restorations. the rubber-dam: Duceram inlay (25) and IPS Empress onlay (26).

Fig 6 Final result of Duceram inlay (25) and IPS Empress onlay Fig 7 Photomicrograph illustrating a perfect margin at baseline; (26) after 1 year in service. I (inlay: IPS Empress), C (resin cement), E (enamel).

Dentsply) and resin-modified glass ionomer (Vitremer, 3M Dental) to protect the deep dentin. Furthermore, the dentin adhesive system Syntac Primer/Syntac Adhesive/He- liobond was used during the cementation procedures, taking care to avoid desiccation of the tooth structure. The determination of interexaminer reliability was verified by a Kappa test for each clinical criterion. The Co- hen’s Kappa yielded values above 0.65 giving evidence of good to excellent agreement, depending on the aspect evaluated. The Kappa test takes into consideration the in- dividual and independent evaluation made by each examiner.11,21 Neither examiner was associated with the operative procedures of the restorations to eliminate bias. Whenever there was a disagreement on the rating of a given restoration, joint examination was performed until agreement was reached. Fig 8 Photomicrograph of submargination indicating occlusal wear After 1 year of clinical service, no statistically signifi- after 1 year of function; I (inlay: IPS Empress), C (resin cement), cant difference was observed between inlays and onlays E (enamel). or among the restorations placed in premolar or molar regions. One hundred percent success (“Alpha” and “Bra- vo”) was achieved for all restorations. “Alpha” character- defects, but with no need of intervention. No “Charlie” or ized an ideal condition of the restorations, while “Bravo” “Delta” ratings were attributed to the restorations. Fur- was attributed to the restorations that presented minor ther results of the clinical investigation of the ceramic

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