A Clinical Evaluation of Onlay and Inlay in the Posterior Ceramic Restorations: An Original Study

Abstract

Introduction:

The extensively damaged teeth can be treated with the inlay and onlay. The ceramic inlays and onlays can be prescribed for the esthetic needs of the patient. Hence in our study, we aim to evaluate clinically the outcomes of the ceramic inlays and onlays for the posterior teeth.

Materials and Methods:

We piloted a retrospective analytical study from the departmental records. We included 70 patients who had a total of 160 ceramic inlays and onlays prepared between the years 2010–2020. The survival and the failure rates were noted and compared using the “Kruskal–Wallis H statistics and the Chi-square tests” deliberating P < 0.05 as significant.

Results:

The mean survival was 6.1 ± 1.8 years. The success rate was 92.21% and the failure was 7.6%. Significant variation was seen with the survival rate between the vital and nonvital teeth and between the molars and premolars.

Conclusions:

The ceramic inlays and onlays were performed successfully in the posterior teeth with a high survival rate and very low failure.

INTRODUCTION

With the advance of material science, the teeth that are previously deemed for extraction are being successfully treated. For the gross decayed teeth, the inlays and the onlays are commonly recommended besides the crowns.[1,2] They are comparatively economic and acceptable than a full-crown restoration. Ceramic is a frequently used esthetic material for anterior crowns. However, the ceramic is brittle and seldom a choice for posterior restorations. The success of the ceramics in the posterior teeth as inlay/onlay is debatable.[1,2,3,4] Various factors such as the para-functional habits, the loads applied, and secondary caries may alter the success of the ceramic inlays/onlays.[4,5] Hence in our study, we aim to evaluate the clinical outcomes of the ceramic inlays and onlays in the posterior teeth.

MATERIALS AND METHODS

We piloted a retrospective analytical study from the departmental records. The ethics clearance and the patient consent were obtained. The data were collected for the number of cases of the ceramic posterior restoration with inlays and onlays during the period of 10 years from 2010 to 2020. The patient demographics along with the follow-up period, para-functional habits, and type of the teeth were noted. We finalized 70 patients who had a total of 110 inlays and 50 onlays. The survival and the failure rates were recorded at the end of 2, 4, 6, 8, and 10 years. The values thus obtained were compared using the “Kruskal–Wallis H statistics and the Chi–square tests” deliberating P < 0.05 as significant. IBM Corp. Released 2016. IBM SPSS Statistics for Windows, Version 24.0. Armonk, NY: IBM Corp. was used for the statistical investigation.

RESULTS

We observed that there was no significant difference between the genders; the mean age was 39 ± 5.6 years. Only 12 patients had bruxism. There was a significant difference between the molar and premolar restorations (P < 0.001). The mean survival was 6.1 ± 1.8 years. The success rate was 92.21% and the failure was 7.6%. Among the restorations for the vital and nonvital teeth, a significant variation was seen (P = 0.04) [Table 1].

Table 1.

Comparison of the various parameters for the failure and survival of the restorations

	Onlays	Inlays	P
Male: female	1:1.7	1:1.5	NS
Age (mean)	36.1	42.5	NS
Mean survival (years)	6.45±1.89	5.89±2.4	NS
Debonding	0	0	-
Hypersensitivity	10	0	NS
Fracture of the tooth	0	5	NS
Esthetics, color	0	5	NS
Marginal integrity	0	10	NS
Caries	10	33	NS
Ceramic factors	20	41	NS
Fracture of the ceramic	10	28	NS
Crack in the ceramic	0	14	NS
Chipping	10	0	NS
Bruxism	3	9	NS
Teeth
Premolars	12	24	<0.001
Molars	34	86
Survival	48	102
Vital	40	96	0.04
Nonvital	8	6
Failed	2	8
Vital	0	1	NS
Nonvital	2	7

NS: Not significant

DISCUSSION

The current retrospective study analyzes the clinical outcomes in the posterior ceramic inlays and onlays. Our findings suggest a highly successful posterior restoration with ceramics (survival rate = 92.21%). This observation is in concordance with the studies of Beier et al.,[3] Land et al.,[4] and Zimmer et al.[5] Significant variations were observed for the survival rates when compared between the premolar and molar and the vital and nonvital teeth. The significant difference between the vital and nonvital teeth may be due to the enhanced affinity of the dentin primer to the vital dentinal tubules that are hydrophilic similar to the primer, while this affinity is lower for the sclerotic dentin of the nonvital teeth.[6,7] Most failures were due to hypersensitivity, caries, and ceramic factors in our study, similar to previous studies.[1,2,3,7] An appropriate and accurately placed dentin bonding agent will lower the caries and the subsequent hypersensitivity that was seen was a secondary cause of failure.

The limitations of the study apart from being retrospective were a small sample size, the lack of data regarding the procedural details, the type of inlay, and the type of dentin bonding used for the restorations. Further studies are suggested amending these limitations to corroborate our findings.

CONCLUSIONS

The ceramic inlays and onlays can be suggested for the extensively damaged posterior teeth. They have exhibited a high survival rate and are esthetic.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.