A 1-year comparative evaluation of clinical performance of conventional direct composite restoration technique with a novel "custom shield" technique in class I compound lesions - A randomized clinical study.

Aim: The aim of the study is to evaluate and compare the 1-year clinical performance of conventional direct composite restoration technique with a novel "custom shield" technique in class I compound lesions. Subjects and
Methods: After ethical approval, 72 patients who signed the informed consent form participated in the study. They were divided into two groups - Group A: Conventional direct composite restoration (n = 36) and Group B: Composite restoration using custom shield technique (n = 36) by computer randomization. In Group A, composite restoration was performed by the incremental layering technique. In Group B, restoration was performed using a novel custom shield and occlusal stamp along with the incremental layering technique. Patients were evaluated using the modified USPHS criteria by blinded evaluators for 1 year. Statistical Analysis: Chi-square test and Friedman test using SPSS version 21.0.
Results: A statistically significant difference was obtained for marginal adaptation (P = 0.024), retention (P = 0.23), surface texture, and anatomic form (P < 0.001), and time taken to perform the procedure for Group B was higher than Group A.
Conclusion: Conventional composite restoration and custom shield technique can be successfully used in class I compound lesions with custom shield technique having a higher edge over the conventional technique. Copyright:

INTRODUCTION

The frequency of dental caries has diminished in recent decades through the efficacious usage of fluorides, especially on smooth surfaces. The massive introduction of various fluoridated agents appears to have altered the morphological factor in the development of dental caries. This led to hidden carious lesions which have an intact occlusal surface and hence are occult.[1] These lesions can be identified as an area of blackish stain beneath the enamel surface or on radiographic evaluation.[2] In such cases, direct restorations are time-consuming, technically sensitive, and may not result in correct replication of the form and occlusion. The different matrices available for restorations allow the contacts and contour of the proximal surfaces to be achieved.[3] However, they do not contribute to the precision of the occlusal and mesiodistal contours.

To resolve all these problems in the class I compound lesions, Gaetano Paolone and Salvatore Scolavino and the style Italiano team introduced the custom shield technique.[4] This technique utilizes putty index for recording the height and anatomy of the buccal/palatal cusp before its reduction and thus, does not require much finishing and polishing. There is only a case report found on this technique and no studies comparing the clinical performance of conventional direct composite restoration and custom shield technique.[5] Thus, the null hypothesis was that there will be no difference between the clinical performance of conventional direct composite restoration and custom shield technique in class I compound at the end of 1 year.

SUBJECTS AND METHODS

Prior permission from the institutional ethics committee (SVIEC/ON/Dent/SRP/19129) was taken and informed consent was obtained from patients.

Patient selection

Patients between 18 and 60 years of age with moderately deep class I compound lesions in maxillary and mandibular molars, radiograph with radiolucency in coronal dentin, secondary decay, or fractured fillings were included in the study. Patients with poor oral hygiene, pulpal and/or periapical pathology, heavy bruxism, developmental anomaly were excluded. Patients were subjected to a bitewing radiograph for the confirmation of the extent of the lesion.

Sample size calculation

The sample size calculation formula was N = (Z1*sqrt (2PQ) +Z2*sqrt (p1q1+ p2q2))2/(p1-p2)2, where Z1 and Z2= z-values corresponding to 95% CI and 80% power, respectively, p1= 99% and p2= 76%, q1 and q2= 100-p1 and 100-p2, P = average of two Ps, and Q = 100-P A total sample size of 62 (31 per group) achieves 80% power and 95% CI and to compensate for the 20% dropout five additional samples were considered per group, so the final sample size of 72 was considered.

Randomization method

The teeth were divided into two groups – Group A: Conventional direct composite restoration (n = 36) and Group B: Composite restoration using custom shield technique (n = 36) by computer randomization method on www.randomizer.org. Sealed envelopes were utilized for allocation concealment.

Clinical procedure

Group A – Conventional direct composite restoration

The clinical procedure was started by performing dental prophylaxis. Shade selection was done using composite buttons of enamel and dentin shades with a Canon DSLR (Digital Single-Lens Reflex) camera with a 100 mm macro lens and ring flash. Cavity preparation was carried out and the remaining caries was removed using spoon excavators (Hu-friedy, Chicago). A gauge was used to assess the thickness of the remaining enamel walls. If the enamel wall was less than two millimeters in thickness, it was reduced in its height. After the complete removal of caries, quadrant isolation was done with a heavy rubber dam sheet (Nictone). Light-cured calcium hydroxide (Calcimol LC, Voco, Germany) was utilized for pulp protection, if necessary. Selective enamel etching was done with 37% phosphoric acid (D-tech, dental technologies, India) followed by the application of a universal bonding agent (Tokuyama Palfique bond). This was followed by the incremental layering of nano-hybrid resin composite (Palfique LX5, Tokuyama, Japan) with the body and enamel shade. Before application of the last layer of the enamel, tint application (Kolor + plus resin color modifier) was done. The final cure of composite was completed through the application of glycerine. The standard finishing and polishing regimen were carried out by coarse (black) to superfine (red) disks (Shofu super snap rainbow kit, India). The occlusion with the opposite arch was checked using progressive color transfer concept with 40 and 15-microns articulating paper (Baush), and the marked areas were reduced using finishing burs.

Group B – Composite restoration with custom shield technique

A custom shield was prepared by mixing a small amount of putty and then placed buccally and occlusally to record the anatomy. In case of a cavitated lesion, temporary restoration was placed in the cavity and carved, and then, the custom shield was fabricated. An occlusal stamp was obtained to record the occlusal anatomy. A single coat of petroleum jelly was applied to the occlusal surface. Flowable composite (Estelite flow quick, Tokuyama, Japan) was applied to the occlusal surface, and the micro brush was placed and then light-cured for 20 s. Moreover, the occlusal stamp was fabricated. The shade selection and cavity preparation were carried out. After selective etching and bonding procedure, a thin layer of enamel shade was placed on the putty index and adjusted onto the smooth surface and light cured. After curing, the buccal/lingual, palatal cusp anatomy was restored followed by the incremental layering of composite. The final translucent enamel layer was applied uniformly. Then, a Teflon tape (M-seal, Pidilite, India) was adapted on the final increment, followed by the accurate placement of the stamp with slight pressure. Then, it was cured for 20 s with curing light. Then, after stamp removal, the occlusal anatomy was evaluated. Finishing and polishing were done using standard procedures [Figure 1].

Figure 1

(a) Preoperative clinical view, (b) Rubber dam isolation, (c) Custom shield fabrication, (d) Custom shield, (e) Occlusal stamp, (f) Caries excavation, (g) Selective etching, (h) Application of bonding agent, (i) Placement of custom shield for buccal wall replacement, (j) Buccal wall restored, (k) Placement of occlusal stamp, (l) Postoperative clinical view

Evaluation

The restorations were evaluated by two calibrated evaluators having interobserver variability value (kappa >0.80) according to the modified USPHS criteria at the baseline, 6 months, and 1 year. The time taken to perform both the techniques at baseline was recorded and compared. Both the evaluators and statisticians were blinded.

Statistical analysis

The data obtained were tabulated and sent for analysis. The statistical analysis was carried out with the Chi-square test and Friedman test using SPSS version 21 (IBM Corp., Armonk, NY, USA). 0 with (P < 0.05) and 95% confidence interval.

RESULTS

Of the 72 patients treated, 38 were male, while 34 were female. The age of eight patients was between 46–60 years, age of 24 patients was 31–45 years, while age of rest 40 patients was between 18 and 30 years. Of the 72 class I compound lesions, 35 were in maxilla and 37 were in mandible. Two lesions with secondary caries and one patient with fractured filling were included in each group. The dropout percentage was 11.1% for both Group A and Group B which was compensated under 20% dropout included in the sample size and thus did not affect the power of the study [Chart 1]. For Group A, there was a statistically significant difference (P < 0.001) within the group for marginal adaptation (P = 0.011), surface texture (P = 0.002), anatomic form (P = 0.001), and color match (P = 0.005), by the end of the 1-year evaluation. For Group B, there was a statistically significant difference within the group for marginal discoloration (P = 0.05), marginal adaptation (P = 0.03), surface texture (P = 0.018), postoperative sensitivity (P = 0.05), and color match (P = 0.018), by the end of the 1-year evaluation. On intergroup comparison, it was found that there was a statistically significant difference in terms of marginal adaptation (P = 0.024) and retention (P = 0.023), while a highly significant difference was observed in terms of surface texture and anatomic form (P < 0.001) at the end of 1 year [Table 1]. Comparison of the time taken between the two groups shows that time taken was higher in Group B [Table 2].

Chart 1

CONSORT flow diagram

Table 1

Clinical performance of conventional restoration and custom shield technique

Evaluation criteria	Group A – conventional composite restoration			Group B – composite restoration with custom shield technique			P
	Baseline	6 months	1 year	Baseline	6 months	1 year
Retention
Alpha	36	31	25	36	34	31	0.023
Charlie	0	4	7	0	1	1
Marginal adaptation
Alpha	36	30	18	36	31	27	0.024
Bravo	0	4	10	0	4	5
Charlie	0	1	4	0	0	0
Surface texture
Alpha	36	6	0	36	31	28	<0.001
Bravo	0	24	24	0	4	4
Charlie	0	5	8	0	0	0
Anatomic form
Alpha	36	3	1	36	33	30	<0.001
Bravo	0	29	19	0	2	2
Charlie	0	3	12	0	0	0

Table 2

Comparison of time taken to perform conventional direct composite restoration and composite restoration with custom shield technique

Independent t-test	Mean±SD		T	P
	Group A (n=36)	Group B (n=36)
Time taken - baseline (min)	51.53±6.07	65.83±10.32	−7.17	<0.001

SD: Standard deviation

DISCUSSION

Pit and fissures present on the occlusal surfaces are the most vulnerable for caries, followed by smooth (labial and lingual) surfaces.[6] Frequently, along with occlusal surfaces, the buccal and lingual surfaces can be affected by hidden caries and be lost during caries excavation.[7] Nanohybrid resin composite is the gold-standard material for posterior restorations.[8]

To minimize the shrinkage due to polymerization, different incremental techniques have been designed. Reduction of the configuration factor because of incremental layering aids in decreasing the stress created by polymerization shrinkage.[9] Thus, this study used incremental cusp by cusp technique for conventional composite restorations.

However, in direct free-hand restorations, the height, and shape of the cusp are frequently challenging to re-establish. This results in restorations that are either over or under-filled which need a great amount of occlusal modification. This causes periodontal damage if the convexities and concavities on smooth surfaces are not replicated.[10] This has generated a plethora of techniques and equipment to help overcome the difficulties of establishing proper contacts and contours. The use of a putty index for palatal shelf creation for class IV lesions in anterior teeth has been advocated by Fahl and Dietschi.[11] Similar to this technique, Gaetano Paolone, Salvatore Scolavino, and the style Italiano team pioneered the custom shield technique in posterior teeth.[3] It can be used in case of undermined lesions that involve the buccal or lingual cusps. The advantage of using this method is the replication of the original buccal/palatal anatomy which does not necessitate many corrections. There is a decrease in the time required for finishing and polishing the restoration.[4] The benefit of a putty index is that the precise buccal/palatal/lingual contour and shape can be acquired. Putty index perfectly defines the sagittal dimensions, the length, and the cuspal position of the desired final restoration and labial or palatal curvature of the restoration.[12] The stamp technique also has multiple benefits. First, the original occlusal anatomy of the tooth is easily restored with composites in contrast to free-hand restorations. Second, voids are limited in the permanent restoration. It helps prevent oxygen from reaching the top layer of the composite and may hinder the curing inhibition action. Thus, the longevity of the restoration increases. This approach has been implemented in several cases by Shikha,[13] Martos et al.,[1] and Araujo et al.[14] The modified USPHS criteria were considered as a reliable criterion for the evaluation of restorations as used in various studies by Folwaczny et al.,[15] Hussainy et al.,[16] Menezes-Silva et al.[17]

The results of the present study exhibited a statistically significant difference in the clinical performance of conventional direct composite restoration group and composite restoration using custom shield technique group in terms of marginal adaptation (at 1 year, P = 0.024), surface texture (at 6 months and 1 year, P < 0.001), anatomic form (at 6 months and 1 year, P < 0.001), and retention (at 1 year, P = 0.023). There are no studies conducted to compare the clinical performance of conventional direct composite restoration and custom shield techniques, but the probable reason for a better marginal adaptation in custom shield technique can be due to the use of an index of the intact surface which serves as a firm matrix for the composite to be applied onto the buccal or lingual surface. Furthermore, the stamp technique aids in the creation of occlusal anatomy, both techniques require minimal finishing and polishing. Thus, there is no excess reduction of the composite, promoting better marginal integrity. Since the custom shield and stamp technique recreates the original anatomy and requires minimal occlusal reduction, the surface texture acquired is much more homogenous and smoother than the conventional technique. The bonding regime plays an important role in the retention of the restoration and an identical protocol was utilized for both techniques. Frankenberger determined that the enamel bonding efficiency of two-step adhesives increased when phosphoric acid was applied to the enamel only.[18] Thus, the selective etching technique was utilized in the present study. The marginal adaptation was better in the custom shield technique; thus, much marginal discoloration was not seen. Thus, composite restoration using the custom shield technique group was superior in terms of marginal adaptation, surface texture, postoperative sensitivity, and anatomic form in both the techniques at the end of baseline, 6 months, and 1 year. The time taken to perform composite restoration with the custom shield technique was higher due to the time required for index and stamp fabrication. However, the clinical performance was better than the conventional technique. Thus, the null hypothesis for the current study was partly rejected. The limitations of the present study comprise of comparatively lesser sample size and follow-up time. Hence, studies with a larger sample size and extended follow-up are required to provide a more precise knowledge concerning the longevity and clinical performance of the restorations.

CONCLUSION

Within the limitations of the study, it can be concluded that clinically, both conventional and custom shield technique can be successfully used to restore class I compound carious lesions.

Custom shield technique has a slight edge in respect to creation of original buccal or lingual contours and occlusal anatomy showing better performance over the conventional technique.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.