|Year : 2023 | Volume
| Issue : 1 | Page : 61-67
Clinical evaluation and parental and child satisfaction with restoration of primary teeth using zirconia and stainless steel crowns: A randomised clinical study
Rohan Bhatt1, Dipti Shah2, Megha Patel1, Srushti Khurana3
1 Department of Pediatric and Preventive Dentistry, Karnavati School of Dentistry, Karnavati University, Gandhinagar, Gujarat, India
2 Department of Prosthodontics and Crown and Bridge, Karnavati School of Dentistry, Karnavati University, Gandhinagar, Gujarat, India
3 Chopra Dental Clinic, Chandigarh, India
|Date of Submission||26-Feb-2022|
|Date of Acceptance||14-Oct-2022|
|Date of Web Publication||25-Nov-2022|
Dr. Megha Patel
47, Swami Akhand Anand Soc, Ranna Park, Ghatlodia, Ahmedabad, Gujarat
Source of Support: None, Conflict of Interest: None
Introduction: Full-coronal restoration is the choice of treatment for restoring pulpally treated tooth or tooth with multiple surface involvement. In paediatric dentistry, semi-permanent stainless steel crowns (SSCs) are considered gold standard, but with increasing need of aesthetics, zirconia crowns have started gaining importance. Hence, this study was conducted to evaluate the clinical performance of SSCs and zirconia crowns and to compare the child satisfaction and parental ratings of impact of treatment using these preformed crowns. Materials and Methodology: This study was a part of randomised controlled trial performed on 60 children of 4–8 years old. The primary molars were cemented with either SSCs or zirconia crowns and were evaluated clinically at baseline, 6-month and 12-month follow-up for crown retention, crown fracture, gingival and debris index, wear, marginal integrity and recurrent caries. The trials also evaluated parental satisfaction and child satisfaction based on five-point Likert scale at the end of 12-month follow-up. The data were analysed using Chi-square test for categorical data and independent sample t-test for quantitative data. Results: Both the crowns were 100% retentive at 12-month follow-up. Fair debris score and mild gingivitis were reported in 3% with SSC at 6–12 months. One zirconia crown fractured at 12 months. Fifty-four per cent of parents in zirconia and 57% in SSC stated that the crowns improved masticatory function. Children reported a mean Likert score of 3.0 for SSC and 4.89 for zirconia which was highly significant. Conclusion: Both the crowns increased the overall health of crowned tooth and were fully retentive for the studied duration. However, zirconia crowns were more gingival friendly and had an edge over SSC in terms of aesthetics.
Keywords: Aesthetics, parental satisfaction, primary molars, stainless steel crowns, zirconia crowns
|How to cite this article:|
Bhatt R, Shah D, Patel M, Khurana S. Clinical evaluation and parental and child satisfaction with restoration of primary teeth using zirconia and stainless steel crowns: A randomised clinical study. Adv Hum Biol 2023;13:61-7
|How to cite this URL:|
Bhatt R, Shah D, Patel M, Khurana S. Clinical evaluation and parental and child satisfaction with restoration of primary teeth using zirconia and stainless steel crowns: A randomised clinical study. Adv Hum Biol [serial online] 2023 [cited 2023 Feb 7];13:61-7. Available from: https://www.aihbonline.com/text.asp?2023/13/1/61/361968
| Introduction|| |
Dental caries is still the most wide spreading chronic disease prevailing in mankind. It is a multifactorial disease characterised by destruction of dental hard tissues. The overall prevalence rate of early childhood caries in India is 49.6%.
In human life, we are gifted with two sets of teeth both contributing an amble importance in healthy living. First set of teeth called primary dentition, undergo shedding. However, they play an important role for mastication, as a natural space maintainer and to establish proper occlusion. Early loss of them results into space loss, malocclusion and impaction of succedeneous teeth. Hence, maintenance of primary teeth becomes mandatory. However, these issues are overlooked by most of the parents resulting in difficulties in eating, establishing social contacts and speaking. Caries on primary molars can result in loss of arch circumference, pain, tooth loss and disrupted occlusion. Hence, restoration of carious tooth is must. Previously, extraction was done for such teeth, but now, pulp therapy is a treatment choice to preserve such non-restorable grossly carious teeth in the oral cavity.
After proper pulp therapy, it is very essential to provide a hermetic seal to the treated teeth for the prevention of re-infection. A full-coronal restoration provides proper coronal seal, thus increasing the success and longevity of the treated teeth. Stainless steel crowns (SSCs) have been the gold standard semi-permanent full-coronal restoration for deciduous teeth since its invention in 1950 by Humphrey. They have outperformed traditional amalgam restorations and even the newer composite restorations in terms of longevity, durability and cost.
The only notable shortcoming for SSC is its aesthetics. Hence, there arouse a need for aesthetic crowns such as pre-veneered SSC, strip crowns and polycarbonate crowns. Paediatric preformed zirconia crowns are new, unique, aesthetic crowns introduced in the market as EZ-Pedo in 2008. Since then, many companies have introduced zirconia crowns that have advantage of both aesthetics and durability. Zirconia is a crystalline dioxide of zirconium. Its mechanical properties, which are similar to those of stainless steel, allow for a substantial reduction in core thickness. Ready-made primary zirconia crowns are now available for restoration of primary teeth including those that are directly bonded onto the tooth.
The millennial children as well as parents have become aware of the alternatives and are getting involved more in clinical decision-making process. Their expectations have increased from only functional requirement traditionally to functional and aesthetic demands currently.
Hence, the present study was performed to clinically evaluate zirconia crowns and SSCs in treatment of carious primary molars for a period of 12 months and to analyse parental and child satisfaction levels. The null hypothesis tested was there won't be a significant difference in clinical performance and parental and child satisfaction with SSC and zirconia crowns.
| Materials and Methodology|| |
Study design and patient selection
The proposed study was a prospective interceptive study in the Department of Pediatric and Preventive Dentistry, Karnavati School of Dentistry. Ethical approval for the study was taken from the Ethical Committee of the institution prior to the start of the study. The subjects as well as parents were explained about the whole procedure, and written consent was taken from the parents.
The children in 4–8 years' age group having primary molar with extensive carious lesions requiring full-coronal restorations/molars requiring pulp therapy or already pulp-treated molar, molars with Class 2 cavity with marginal ridge fracture, having natural (not crowned) opposing antagonist and with good oral hygiene were included in the trial. Children with special needs, mobility in molars to be crowned, molars used as abutment of space maintainer and children having bruxism/traumatic occlusion/mouth breathing were excluded.
The sample size was calculated using the formula N = Chi-square/W^2. After considering 20% dropout, a total of 60 participants, 30 in each group, were determined. The subjects were randomly allocated based on computer randomisation into one of the following groups.
- Group A: SSCs for primary molars (3M Espe, Minneapolis, USA)
- Group B: Zirconia crowns for primary molars (Signature Crowns, 3M Lava™).
Crown placement for stainless steel crowns and zirconia crowns for primary molars
Crown selection was done prior to crown cutting with the help of Boley's gauge by measuring the mesiodistal dimension of tooth. After the administration of local anaesthetic (LA) and placement of rubber dam, tooth preparation for both the crown types was done according to manufacturer guidelines. The crowns were filled with 2/3rd 3M Espe RelyX Luting 2 cement and all the inner walls of crown were covered with it. The crown was cemented and the excess cement was cleaned with 2 × 2 moist gauze and explorer. The floss was passed proximally to remove excess cement. The patient was then asked to close the mouth in centric relation. Occlusion was checked for proper fit.
Post-operative instruction after crown cementation to parents and patients
The parents and children were informed for numbness in lips and cheeks for approximately 3 h after crown placement due to anaesthetic effect from LA. They were instructed to be cautious and avoid lip/cheek biting. Parents were advised to watch the child's diet and avoid sticky foods such as chewing gum, fruit, snacks, caramel, toffees, hard candies, popcorn kernels and others. They were also advised to follow age-specific oral hygiene measures and report to the department if any discomfort occurred.
Variables for the clinical performance of crowns were scored using the following criteria at baseline (3 days after cementation of crown), 6 months and 12 months. Clinical evaluation was carried out visually and with a mirror and explorer.
A gingival index, based on the Loe and Silness scoring criteria (1963), was assessed for both types of groups at baseline, 6 months and 12 months' follow-up visit. Gingival index was measured by passing the explorer tip gently within the sulcus around each crowned tooth.
Oral hygiene index
It was determined using simplified Greene and Vermillion oral hygiene index. The crowned tooth was examined by running the side of the explorer over the buccal tooth surface and scores were recorded as follows: 0–¼ no debris, 1–¼ soft debris covering less than one-third of tooth surface, 2–¼ soft debris covering more than one-third but not more than two-thirds of tooth surface and 3–¼ soft debris covering more than two-thirds of tooth surface.
Crown marginal integrity
Marginal adaptation was measured at buccal and lingual walls and was either good with sealed margins or poor when the explorer detected an open margin.
Opposing tooth wear
The wear of the antagonist tooth was recorded 0: absence of wear and 1: wear on only the cusp point.
Clinical and visual examination was done to check the recurrent caries.
Crown fracture was scored as absent or present.
Parents' perception and their satisfaction following crown placement were assessed at recall examination to determine the impact of crowns on overall health and difficulty experienced by children with the crowns on a five-point Likert scale where one equals very dissatisfied and five equals very satisfied.
Children were also asked to rank their luted crowns based on the five-point Likert scale. Children explained the scale in their own language and simpler way and were asked to rank accordingly.
Follow-up and evaluation of crowns
Crowns were evaluated for clinical performance and treatment was delivered for the following:
- In case of decementation of any of the crowns, the crowns were cleaned, and the left-over cement was removed followed by recementation of crown. In case of deformed crown, the crown was replaced
- In case of chipping or fracture of preformed crown, the crown was replaced and luted after minor modification of crown cutting
- In case of gingivitis caused after crown placement, oral prophylaxis was performed and oral hygiene instructions were reinforced.
The data were analysed with IBM SPSS 20.0 software version (IBM SPSS Statistics for Windows, Version 20.0., NY:) for Windows statistical software. Statistical analysis was done using Chi-square test for categorical data and independent sample t-test for quantitative data. For all statistical analyses, probability levels of P < 0.05 were considered statistically significant.
| Results|| |
The crowned teeth were evaluated at follow-up for clinical performance and parent and child satisfaction. All 30 samples maintained the follow-up in the SSC group while 2 dropouts were reported in the zirconia crown group at 6 months as those children had moved out of the city. Hence, at 12 months, 30 crowns in the SSC group and 28 crowns were evaluated for the zirconia group.
All crowns in both the groups were retentive at the end of 12-month follow-up [Table 1].
|Table 1: Clinical outcomes of preformed primary stainless steel crowns and zirconia crowns|
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It was observed that at 6 months and at 12 months, 1 crown (3%) showed fair debris index in the SSC group, whereas at all follow-ups, all zirconia crown samples showed good/no debris score. However, the difference was not significant (P = 0.330).
The gingival index score at the baseline for SSC showed that 3 samples (10%) showed mild gingivitis, and at the 6 and 12 months, only 1 sample (3%) showed mild gingivitis, whereas all crowns in the zirconia group reported no gingival inflammation and had well-contoured gingival margins at 6 and 12 months (P = 0.960).
All the opposing teeth of the stainless steel and zirconia crown tooth were evaluated for occlusal wear. No wear was reported at baseline, 6-month and 12-month intervals for both the groups. The results mention that all the crowns showed closed margins even at 12-month follow-up and no recurrent caries was observed in either group at any follow-up.
The zirconia crown samples were individually evaluated for fracture. The fracture was categorised as absent and present. It was seen that out of 28 samples evaluated, only one crown fractured at 12-month follow-up. However, it was not statistically significant (P = 0.351).
Parental rating and satisfaction
The parental rating for the impact of the crowns depicts that only 27% of parents liked the child's appearance and gave the highest score at 12 months for SSC while, for the zirconia crowns, 71% of parents gave the highest ranking and liked the child's appearance very much. Parents stated that child's oral health has been improved by 50% and 44% in the zirconia and SSC groups, respectively [Table 2] and [Table 3].
|Table 2: Parental ratings of the impact of treatment on their children with primary stainless steel crowns and zirconia crowns|
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|Table 3: Parental evaluation of the difficulties the child experienced with the stainless steel crowns and zirconia crowns|
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After crown placement, bleeding around gums and sensitivity in crowned tooth were evaluated for both the groups. In the SSC group, 1 child and 3 children in the zirconia group had sensitivity at baseline though the difference was not statistically significant (P > 0.05).
The children were also asked to rate their likings for the cemented crown based on the Likert scale. Ninety per cent of children in the zirconia crown group gave the highest score while no child gave score 5 for the SSC group (P = 0.001) [Table 4].
| Discussion|| |
There has been a paradigm shift from extracting the carious deciduous tooth traditionally to preserving them currently until their natural exfoliation to maintain proper arch space for unerupted permanent teeth. Different types of preformed crowns are available that provide full-coronal restoration, thus increasing the success by providing hermetic seal and diminishing the chances of reinfection.
The SSC has been gold standard and has successfully replaced the traditional amalgam restorations. When the durability and lifespan of SSC and other restorations were compared by different authors, SSC proved to be better. Riyad Rawashdeh compared a success rate of SSC with other restoration for carious primary teeth and concluded that success rate for SSC was 88%, twice the percentage than the other restoration.
However, shiny steel appearance of SSC has been a major pitfall in todays' practice of aesthetic dentistry. The recently introduced zirconia crowns fulfil this increasing demand of aesthetic by parents and children. Although being costly as compared to SSC, the advantages of them being pleasing and durable have made them treatment of choice by many dentists and patients. Hence, the present study was conducted to provide the data of clinical success of studied crowns and the parental and child satisfaction regarding the cemented crown.
Our study reported that all crowns in both the groups, cemented using luting cement, were retentive even after 12-month follow-up in spite of the difference of SSC requiring snap fit while zirconia passive fit according to manufacturer guidelines. Mathewson et al., 1974, stated that cementing medium is the main influence on the retention of SSCs. All the crowns were luted using RMGIC RelyX Luting 2 cement. The luting cement helps to increase the retention of crown over the prepared tooth. The cement provides mechanical resistance to displacement of restoration and also resists fracture when load is applied to the restoration. The luting cement selected for crown cementation has a great role in establishing optimum marginal seal which can reduce the chances of microleakage around the crown margins.
Conventional glass ionomers are popular principally because they release fluoride that prevents recurrent caries. Glass ionomer cement (GIC), however, have prolonged maturity period and water sensitivity during the early setting reaction. The development of resin-modified GIC (RMGIC) offers the benefit of both resins and conventional GIC, i.e., adhesion and fluoride release, along with improved physical properties that reduce the chance of cohesive failure. A comparative study based on microleakage by different luting cement was compared by Al-Haj Ali and Farah and concluded that RMGIC showed lesser microleakage as compared to GIC. The RMGIC RelyX Luting 2 cement showed good results in this study also. Furthermore, though more aggressive preparation and subgingival reduction are required for zirconia crown, the comparative retentive success could be due to synergistic effect of luting medium and the internal surface treatment of these crowns. The results obtained were similar to the study conducted by Abdulhadi et al. 2017 who showed 100% retention for both the groups.
The fracture of zirconia crowns was evaluated at baseline, 6 months and 12 months, respectively. It was observed that one sample showed fracture of zirconia crown at 12-month follow-up. Overall 97% cemented zirconia crowns were intact at the end of 12-month follow-up. However, no such type of fracture in posterior zirconia crown has been reported by any long-term study till date.
The balanced masticatory force in normal human being ranges from 70 to 150 N. The acceptable compressive and flexural strength for monolithic zirconia crown ranges from 1000 to 1200 N. That is almost five times more than the masticatory force. However, the probable reason for zirconia crown fracture in our study may be any of under.
- Zirconia crowns require more vigorous crown preparation as compared to crown preparation for SSC. Instruction given by the manufacturer should be followed for crown preparation. An underprepared crown preparation or overprepared crown causes unbalanced force distribution which may lead to decementation or crown fracture. An adequate preparation will give higher mechanical retention to the zirconia crown and decrease the risk of breakage, especially in the posterior part where the bite forces are higher. Eliminating sharp edges will also help in reducing the risk for cracks in the crown
- The eruption of permanent first molar adjacent to the crowned tooth can transmit the eruptive forces on the crowned tooth making it more prone to dislodgement or fracture if it was not fitted properly. In this study, this can be the probable cause.
The crowns were evaluated for debris and gingival index at baseline, 6-month and 12-month follow-up, respectively. Soft debris accumulation was seen in the SSC group in only one case where oral hygiene measures were not followed by child. In our study, children received standard oral hygiene education as part of their routine care. This instruction, along with frequent follow-up appointments, might have motivated the children to maintain a good level of oral hygiene throughout the study.
Myers et al. reported that plaque will readily form on the surface of SSCs regardless of the polishing procedures and can be due to irregularities of festooned surface. However, Webber stated that preformed SSCs can be used successfully to restore primary molars without adversely affecting the health of the gingiva, provided that good status of the patient's oral hygiene is maintained.
Debris accumulation on crowns can also lead to gingival changes. Gingival changes are also witnessed due to local irritation caused by SSC as foreign body. This inflammation reduces by the time as tissues get accustomed to SSC. The gingival index in the present study showed a decline when baseline and 12-month follow-up was compared. At baseline, 10% of stainless steel group samples showed mild gingivitis which were reduced to 3% at 12 months. Our study observed good gingival health for all zirconia crowns at all follow-ups, and this is in accordance with Abdulhadi et al., who concluded that both SSC and zirconia crowns presented to be an excellent choice for posterior teeth restorations, but zirconia crowns performed better regarding gingival response to the material of restoration and plaque retention despite its high cost. Biofilm accumulation on zirconia has been reported to be minimal, due to its smooth surface and low affinity for plaque accumulation.
All the samples for zirconia and SSC showed closed margins presenting 100% results for both. The margins deteriorate as time progresses and degradation of luting cement can cause open margins sometime which causes the recurrent caries at margins. There was no occurrence of recurrent caries seen in any of the 60 samples studied.
Currently, efforts are directed for developing new materials that satisfy the functional and aesthetic needs of patients. The parents play a vital role in selection of the treatment procedure and materials for their children. This study also evaluated parental satisfaction after the cementation of sampled crown. The parents were asked to rate their satisfaction based on Likert scale.
The oral health of the child improved in almost all the cases irrespective of the crown cemented. The reason for improved health can be restoration of masticatory function and repeated oral hygiene instruction to parent as well as child. About 57% parents in SSC group and 54% in zirconia, were very satisfied with the cemented crown and stated that crowns improved the overall chewing efficiency of children. A multicarious molar affects the chewing efficacy of food as the food lodgement increases and the decayed tooth cannot bear the masticatory load. Crowns on contrary distribute the load and help in proper mastication of the food irrespective of the type. A significant difference was seen in ranking of parents when asked about child's appearance after crown cementation. Parents displayed more satisfaction for zirconia aesthetic crown as compared to SSC. A similar result was obtained by Taran and Kaya and Holsinger et al. who reported that zirconia crowns have a considerable advantage over SSC due to their aesthetic appearance.,
The difficulties child faced were also taken into consideration in this study at baseline, 6-month and 12-month follow-up periods. Usually, bleeding around gums is one of the major difficulties reported followed by minor sensitivity after crown placement. In the sampled crowns irrespective of the groups, no bleeding around the gums of crowned tooth was reported. When sensitivity was evaluated, 10% of patients reported sensitivity in the zirconia group at baseline only. This might be due to a more invasive crown preparation that has to be performed for zirconia as compared to SSC. A subgingival marginal preparation required for zirconia crowns may cause a minor sensitivity in some cases till the gingival margin contours back again over the crown surface. Furthermore, few (n = 6) of the selected samples for zirconia crown placement in our trial had class II lesions with marginal breakdown. In such cases, as the tooth was vital, a minor sensitivity can be seen due to more invasive tooth preparation. At 6 and 12 months, no sensitivity was reported by any sampled patient.
The millennial children themselves have high expectations due to influence of media and peers and play a major role in selecting their treatment. Hence, in our study, at the end of 12 months, the child was also asked to rank the appearance of crown based on Likert scale. The child was instructed about the scale in its own vernacular language and ranks were explained accordingly. It was seen that children were most happy with zirconia (90%) crown cemented in their mouth as compared to SSC (17%). The result of this study supports the findings by Mathew et al. The drastic difference can be due to a more aesthetically merging natural tooth colour of the zirconia crowns as compared to shinny silvery crown.
The strength of this study is 12-month evaluation of clinical performance of crowns along with consideration of parental and child preference for the cemented crowns. Furthermore, all the crowns were placed by a single operator which eliminates inter-operator variability. However, a long-term follow-up is required for more detailed clinical evaluation and with a larger sample size that would provide more adequate results. Furthermore, radiographical evaluation would have provided better comparison with clinical results.
| Conclusion|| |
The following can be concluded from the present study:
- Both SSCs and zirconia crowns can be used in primary dentition with successful clinical outcomes
- The teeth restored with zirconia crowns showed less debris and better gingival health than teeth restored with SSCs
- Parents and children both accepted zirconia crowns more as compared to SSC in terms of aesthetics.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]