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ORIGINAL ARTICLE
Year : 2021 | Volume
: 24
| Issue : 3 | Page : 425-434
Evaluation of success of stainless steel crowns placed using the hall technique in children with high caries risk: A randomized clinical trial
A Kaptan, E Korkmaz
Department of Pediatric Dentistry, Faculty of Dentistry, Sivas Cumhuriyet University, Sivas, Turkey
Correspondence Address:
Dr. A Kaptan
Department of Pediatric Dentistry, Faculty of Dentistry, Sivas Cumhuriyet University, Sivas
Turkey
Source of Support: None, Conflict of Interest: None
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1DOI: 10.4103/njcp.njcp_112_20
Abstract
Objective: This study aimed to compare the clinical efficacy and survival rates of the hall technique (HT), and conventional restoration (CR) for the management of occlusoproximal carious lesions in primary molars. Materials and Methods: This clinical study observed 35 children (aged 4–8 years). Exclusion criteria included symptoms of pulpal or periradicular pathology or systemic conditions requiring special dental considerations. For each child, at least one tooth was treated with HT and one with CR. The primary outcome measures were minor and major clinical failure rates. Plaque and gingival scores of the teeth were also evaluated. Friedman test and Wilcoxon signed ranks test were used to compare the plaque and gingival index scores for each arm. Chi-square tests were used for comparisons of clinical outcomes, plaque-gingival index, and distribution of ICDAS categories among treatment arms (P < 0.05). Results: Thirty-three of 35 (94.2%) participants returned for 1-year follow-up. HT showed statistically significantly higher treatment survival rate and fewer minor failures than CR (P = 0.040). The rate of major failures was minimal (2 of 84 teeth) and did not differ between treatments (P = 0.092). In both treatment groups, the gingival score and plaque score were significantly decreased at the 1-year follow-up (P < 0.05). Conclusion: HT was a more successful method for managing caries in primary molars than CR, both for symptoms of pulpal disease and longevity of the restorations. HT is a simplified method of managing carious primary molars using SSCs cemented with no local anesthesia, caries removal, or tooth preparation.
Keywords: Caries treatment, conventional restoration, Hall technique, primary molar teeth, stainless steel crowns
Introduction 
Cavitated lesions are a common problem in both developed and developing countries.[1] Although there has been a decline in the prevalence of caries worldwide, this is at odds with the increasing prevalence in developing countries.[2] Successfully managing dental caries in the pediatric population is a long-standing problem involving a number of challenges, including behavior management primarily and the need for definitive treatment until tooth exfoliation. The enamel and dentin tissues in primary teeth are thinner and less mineralized than that of permanent teeth. Further, the pulp size of the primary teeth is relatively larger in comparison. Due to this, carious lesions progress rapidly and reach the pulp in primary teeth quicker than permanent teeth. Pediatric patients often present difficulties cooperating with treatment courses, and require effective treatment modalities in a more limited period than adult patients. Treatment of decayed primary teeth is of particular importance due to their role in chewing and speaking, as well as being placeholders in the arch.[3],[4] Early loss of primary teeth may cause temporary or permanent occlusion disorders, aesthetic problems, nutritional problems, abnormal tongue/sucking habits, speech disorders, and psychological problems in the future. Because of these reasons, restorative treatment of decayed primary teeth has an important role in the pediatric dentistry.[5]
Recently, the standards regarding the ideal management of carious lesions has been changing. Studies have shown that children report less discomfort and lower physiological and behavioral indicators of stress when hand instruments are used, compared to rotary instruments.[6],[7] Conventional restoration (CR) completely removes the carious lesion and replaces the tooth with a restoration.[8],[9] CR[8],[9] is routinely being replaced by less invasive approaches that focus on biofilm control and disruption of the cariogenic biofilm environment to arrest caries.[10],[11],[12] One such alternative treatment is the Hall Technique (HT), developed by Norna Hall.[13]
HT is a method of managing carious lesions on primary molar teeth by cementing a stainless-steel crown (SSC) without local anesthetic, caries removal, or dental preparation. The SSCs placed with this method seal the cariogenic flora within the tooth cavity and halt the dental caries progression by starving the bacteria of refined carbohydrate/sugars.[14] In a randomized, controlled, clinical trial conducted by Innes et al.[3] investigators found that SSCs placed by means of HT outperformed standard Class II restorations placed by general dentists. Two published randomized control trials have reported HT to be successful in managing dental caries at 1-year and 5-year follow-ups.[15],[16] In addition, a pilot trial[17] indicated that children and dentists find HT to be an acceptable process. This may be because the technique is less demanding on both children and their dental team due to the non-use of rotary instruments, less preparation time, and no removal of the dental caries.
Although HT provides a simple and precise treatment that can be applied quickly to limit the patient's anxiety, there is limited clinical data to support its use. Due to its noninvasive design, favorable view by patients and dentists, and rate of restoration longevity, HT may be an improved treatment option to increase access to care, reduce rates of untreated caries, and provide a restoration that will allow for natural tooth exfoliation. Although it has been shown that sealing carious primary molars with SSCs and glass ionomer cement is successful, additional studies are needed to confirm the techniques effectiveness compared with CRs. The aim of this study was to evaluate the clinical and radiographic success of SSCs placed by HT compared to CR treatment for carious lesions in primary molars. The study was longitudinal in nature and compared two arms: the control CR arm, which completely removed caries, and the HT arm, which sealed in caries with a SSC. The primary outcomes were success of treatment and rates of minor failure. The secondary outcomes were major failure and plaque and gingival scores. The null hypothesis was no difference at one year among any of the 2 arms for the primary outcomes and for the secondary outcomes.
Materials and Methods Ethics
The ethics committee report required for our study was obtained from the Clinical Research Ethics Committee of Cumhuriyet University (ID: 2018-03/15). Informed consent consent was obtained from each patient's parent on the day of the procedure.
Study design
Thirty-five children (4–8 years old; mean age = 6.36 ± 1.16 years) with a primary molar tooth with occlusoproximal caries into dentine (International Caries Detection and Assessment System [ICDAS] codes 3–5) were included in the study. Each child received at least one HT and one CR, for a total of 47 HT treatments and 41 CR treatments at baseline. The power to detect significant differences in this study was computed as P = 0.9086. During initial screening, two calibrated dentists (kappa >0.81) assessed all eligible lesions. When more than 2 teeth of the patients included in the study meet the study criteria, the treatment to be applied to the next tooth to be included in the study was determined by the physician. Treatment was re-assessed at 6-months and 1-year follow-up [Table 1]. Children were excluded if they had signs or symptoms of pulpal or periradicular pathology (including pain) or systemic conditions requiring special dental considerations. [Figure 1]a,[Figure 1]b shows the radiographs of teeth included into the trial. Details of outcome criteria are presented in [Table 1].[15]
Figure 1: Radiographs of teeth included into the trial (a) lower, and (b) upper jaw teeth
Table 1: Outcome Criteria for Procedures: Clinical Assessment in the 2 Treatment Arms[15]Baseline oral health status and carious lesions
All primary teeth were evaluated for decay with ICDAS, and ICDAS (3-5) teeth were included in the study. Plaque index and gingival index measurements were also scored in the study teeth [Table 1]. While determining the plaque and gingival index, the 4 surfaces of the teeth included in the study (mesial, distal, vestibule, lingual) were evaluated according to Silness & Loe criteria. Scores between 0 and 3 were given. The scores from the four areas of the tooth were added and divided by four in order to give the plaque index and gingival index for the tooth. The procedures were repeated during the initial, 6-month and 12-month examinations. Mean plaque and gingival index scores of treated teeth (HT and CR) were compared statistically. All measures were recorded on the initial examination form.
Treatment procedures
Conventional restorations
The protocol for the control CR followed currently accepted practices. Complete caries removal was carried out with a high-speed handpiece, then a slow handpiece and/or an excavator to clear carious dentine without causing pulpal exposure. Local anesthesia was given when needed. An automatrix band (Supermat ADAPT SupercapMatrix, DentalKerr, Bioggio, Switzerland) was used during placement of the restoration. All cavities were restored with light cured compomer (Glasiosite, Voco, Cuxhaven, Germany) under cotton wool roll isolation and continuous aspiration.
Hall technique
The protocol for HT SSC used the following steps[4]: The patient's tooth was evaluated for its shape, contact points, and areas of occlusion. Obvious food and debris were removed from the cavity without removal of caries. An SSC (3M™ ESPE™ Stainless Steel Primary Molar Crowns, Dental Products, Conway Avenue, USA) was selected to cover all cusps and provide a feeling of “spring-back” for the contact areas. The tooth was isolated and saliva contamination was prevented with a cotton roll while the tooth and SSC were dried. Glass ionomer cement (Nova Glass-F, Imicryl Konya, Turkey) was prepared according to the manufacturer's instruction and placed into the crown to at least 2/3rd fullness. The crown was then placed on the tooth and inserted using either finger pressure or the bite of the patient. Following placement, the crown position was checked, and the excess glass ionomer cement was removed. Finally, a cotton pellet was placed between the crown and the opposite tooth and the child was asked to bite down for 2–3 min to secure the crown placement.
Patient follow-up
Patients were reviewed at 6-month intervals by their dentists. Clinical and radiographic data (from periapical radiographs) were recorded at each visit. The patients were examined according to ICDAS scores, plaque index, gingival index scores, minor failure and major failure criteria [Table 1] and the data obtained were recorded. Details of emergency visits were also recorded. Data were evaluated according to the criteria specified in [Table 1].
Primary outcome evaluation
The primary outcome of the survival rate was first analyzed as a combination of “Minor Failures” and “Major Failures,” but a further analysis was made by dividing the results of the evaluation of treatment failure (Minor Failures) and tooth failure (Major Failures) into two levels [Table 1].
Treatment (Restoration) survival
HT and CR treatments scored as satisfactory were considered as “successful,” while those with minor and/or major failures were considered as “failed” [Table 1].
Tooth survival
Treatments were considered as being “successful” for teeth where treatments were scored as satisfactory or when there was a minor failure. Teeth that presented with major failures were considered as “failure for tooth” [Table 1].
Secondary outcomes evaluation
Major failure, plaque index, and gingival index were evaluated in secondary outcomes [Table 1].
Statistical analysis
The obtained data were analyzed using the SPSS software program (version 24.0; SPSS, Inc., Chicago, IL, USA). Friedman test and Wilcoxon signed ranks test were used to compare the plaque index scores and gingival index scores (baseline vs. 6 months and baseline vs. 1 year) for each arm. Chi-square tests were used for comparisons of clinical outcomes (successful, minor failure, major failure), plaque index, gingival index, and distribution of ICDAS categories among treatment arms. The significance level was set at P < 0.05.
Results Baseline characteristics (Participants and Teeth)
Thirty-five patients (18 boys, 17 girls) were included in the study. The mean age of children included in the study was 6.36 years (4–8 years old; standard deviation ± 1.16 year). Thirty-three of 35 (94.2%) participants presented for their 1-year follow-up. Eighty-four teeth of 33 patients were included in the study (HT; 45 teeth, CR: for 39 teeth).
Of the 84 baseline carious lesions, 42 (50%) were ICDAS code 5 (distinct cavity with visible dentin); 18 (21.4%) were ICDAS 4 (underline dentin shadow), and 24 (21.4%) were ICDAS 3 (localized enamel breakdown). Distribution among treatment groups was significantly different. More ICDAS code 5 received HT treatment, while more ICDAS code 4 received CR treatment (P = 0.002) [Table 2]. Initially, there was no statistical difference between the distribution of plaque and gingival index scores of the teeth in both groups (P = 0.080, P = 0.307, P = 0.945, respectively) [Table 2].
Table 2: Distribution of teeth in the study, ICDAS categories, plaque index and gingival index and, their association witht reatment groupsPrimary outcome
Treatment (restoration) survival
When the survival rate of treatment was evaluated at 6-months follow-up, no statistically significant difference was observed between HT (95.6%) and CR (82.1%) groups (P = 0.092) [Table 3]. However, 1-year survival rates were significantly different between HT (93.3%) and CR (73.4%) groups (P = 0.040) [Figure 2]a,[Figure 2]b,[Figure 2]c,[Figure 2]d,[Figure 2]e,[Figure 2]f and [Figure 3]a,[Figure 3]b,[Figure 3]c,[Figure 3]d,[Figure 3]e,[Figure 3]f [Table 3].
Table 3: Treatment Success Ratesafter 6 months- 1-year Follow-up by Allocated Treatment Group
Figure 2: Clinical and radiographic images of successful HT,and CR; (a/d; baseline treatment, b/e; 6 months after treatment, c/f; 1 year after treatment)
Figure 3: Clinical and radiographic images of successful HT, and CR (a/d; baseline treatment, b/e; 6 months after treatment, c/f; 1 year after treatment)Tooth survival
One year survival rates of primary molars treated with CR (97.4%), HT (97.8%) showed, with no significant differences in the survival rates among treatment groups (P = 0.918) [Table 4]. Major failures in the teeth were detected at the end of 6 months.
Table 4: Tooth survival rates after 6 months- 1-year follow-up by allocated treatment groupMinor failures
Seven of 84 treated teeth had minor failures at 6-months follow-up. Although this was 2.2% of HT treated teeth and 15.3% of CR treated teeth, these rates were not statistically different between groups (P = 0.092) [Figure 4]a,[Figure 4]b,[Figure 4]c,[Figure 4]d and [Figure 5]a,[Figure 5]b,[Figure 5]c,[Figure 5]d,[Figure 5]e,[Figure 5]f, [Table 3]. Reasons for failure were secondary caries (CR: n = 5) and restoration loss (wherein the tooth was restorable; HT: n = 1, CR: n = 1) [Table 5].
Figure 4: Clinical and radio graphic images of minor failure (restoration loss) HT (a/c; baseline treatment, b/d; 6 months after treatment)
Figure 5: Clinical and radiographic images of minör failure (restoration loss) CR (a/d; baseline treatment, b/e; 6 months after treatment, c/f; 1 year after treatment)
Table 5: Outcomes of After 6 months- 1-year Follow-up byAllocated Treatment GroupEleven of 84 treated teeth had minor failures at 1-year follow-up. The overall minor failure rate was significantly different between groups, at 4.4% of HT treated teeth and 23.1% of CR treated teeth (P = 0.040) [Table 3]. Reasons for failure were secondary caries (CR: n = 8) and restoration loss (wherein the tooth is restorable; HT: n = 2, CR: n = 1) [Table 5]. At 1-year follow-up, the majority of minor failures were first lower primary molars (n = 4 of 11, 36.4%).
Secondary outcomes
Major failure
Two of 84 treated teeth were major failures at the 6- and 12-months follow-ups. There were no statistically significant differences between treatment groups (P = 0.092) [Table 3]. Reasons for failures were abscess (HT: n = 1) and irreversible pulpitis (CR: n = 1) [Table 5]. The teeth presenting with major failures were endodontically treated and restored. At 1-year follow-up, the most of the major failures were second lower primary molars (n = 2 of 2, 100.0%). [Figure 6]a,[Figure 6]b,[Figure 6]c,[Figure 6]d shows the major failure of the HT.
Figure 6: Clinical and radio graphic images of majör failure (abscess) HT (a/c; baseline treatment, b/d; 6 months after treatment)Plaque index
Within both treatment groups, the plaque index score was significantly decreased from baseline-6 months and baseline- 1-year follow-up (HT: P = 0.001, CR: P = 0.006) [Table 6]. Between 6 months and 1 year, there was a further significant decrease in the HT teeth (P < 0.05), but not in the CR teeth (P > 0.05) [Table 6]. Moreover, the difference between the observed and the expected frequency in the HT teeth was greater than the CR teeth (HT: X2 = 49.85, CR: X2 = 10.32). [Table 7] shows the distribution of plaque index scores in treatment groups and baseline, 6 months and 1-year.
Table 6: Mean plaque and gingival index scores in treatment groups at 6 months and 1 year follow - up
Table 7: Distribution of Plaqueand Gingival Index Scores at Baseline, 6 Months and after 1 Year per Treatment GroupGingival index
In both treatment groups, the gingival score was significantly decreased after the baseline and 1-year follow-up (HT teeth: P = 0.001, CR teeth: P = 0.001) [Table 6]. When the scores were compared within treatment groups, there was a significant decrease in gingival scores in HT teeth and CR teeth at baseline-6 months and baseline-1 year (P < 0.05). Between 6 months and 1 year, there was a further significant decrease in the HT teeth (P < 0.05), but not in the CR teeth (P > 0.05) [Table 6]. Moreover, the difference between the observed and expected frequency in the HT teeth was greater than the CR teeth (HT: X2 = 42.63, CR: X2 = 25.87). [Table 7] shows the distribution of gingival index scores in treatment groups and baseline, 6 months and 1-year.
Discussion Managing occlusoproximal lesions in young children is highly challenging and has poor long-term outcomes. Advances in the field of cariology have challenged the conventional surgical approach to manage existing carious lesions.[22] Cavitated carious lesions can be managed successfully by non-operative methods, including biofilm disruption and remineralization by sealing the carious lesion, as in the case of HT.[16]
The current study compared the clinical success of HT and CR, demonstrating that HT showed significantly better performance at 1-year follow-up. In order to reach a larger sample size in our patients who prefer to participate in this study, other teeth that meet the criteria of study in the mouth are included in the study instead of only 2 teeth (1 HT and 1 CR). The null hypothesis of no difference between HT and CR for the primary outcome of treatment (restoration) survival was rejected.
Conventional SSCs have been found to outperform other restorations for multi-surface carious primary teeth. Failure rates range from 1.9% to 30.3% for preformed metal crowns (PMCs) and 11.6% to 88.7% for amalgam restorations.[3] In spite of recommendation of conventional SSCs,[23],[24] their use is mainly limited to pediatric specialists. General dentists report SSCs as too complex, time-consuming, expensive, and not cosmetically admissible.[25]
Santamaria et al.,[26] demonstrated that, at 2.5-year follow-up, HT (7.5%) showed a significant lower failure rate when compared with nonrestorative caries treatment (NRTC) (30.0%) and CR (33.0%). Further, HT makes relatively few demands on the child and the dentist when compared to the technique-sensitive CRs. Therefore, the use of HT could be favorable for practitioners in terms of reducing technique complexity and saving time.
ICDAS scores (3–5) were used to evaluate the caries status of the teeth included in our study, and whether the caries were active or passive was not evaluated. Marsh's[27] ecological plaque hypothesis has highlighted the very specific environment in which the potentially cariogenic bacteria are needed for the onset and progression of dental caries, suggesting that this is an opportunity for preventive intervention. The caries process can be stopped if the environment of an active cariogenic plaque biofilm can be changed by covering the caries with a restoration and thus isolating them from the food in the oral cavity. Higher success rate of HT may be attributable to crown durability due to complete isolation of the plaque biofilm from the oral environment, thereby slowing or arresting the lesion progression.[15] Also, glass ionomer cement used in HT may provide additional benefit in lesion remineralization.[28]
While occlusoproximal restorations generally have higher failure rates than single-surface restorations,[29] selection of material can influence restoration longevity.[30] Four practice based longitudinal studies[31] comparing different filling materials reported about one-year failure rate of approximately 10% for class II cavities restored with compomer.
The current study demonstrated that the HT group had statistically significant higher success than the CR group at 1-year follow-up [Table 3]. This is consistent with recent evidence on the high success of SSCs in the restoration of primary molar carious lesions.[16],[32] These results may be due to the excellent seal provided by SSCs, as seal quality is an important factor in restorative treatment outcomes.[33]
In the current study, HT exhibited minor failure in only 2 teeth (4.4%), while the CR exhibited 23.1% (9 teeth) minor failure rate at 1-year follow-up [Table 3]. Similar to the result of minor failure in our study, Santamaria et al.[15] found that minor failure of HT (minor = 3%, major = 0) was less than CR (minor = 20%, major = 15%) at 1 year follow-up. The greater success rates in the HT group may be due to its placement with glass ionomer cement, which may have offered additional benefit in lesion remineralization.[28]
In this study, the most common cause of failure was secondary caries associated with CR (CR: n = 8, HT: n = 0) [Table 5]. This discrepancy in rates of secondary caries between the HT and CR groups may be because the tooth was completely sealed, and the cariogenic flora was disconnected from the tooth in the HT group.
It might be assumed that the HT SSCs would be especially sensitive to occlusal perforation, as they are appointed without occlusal reduction of the tooth. The current study did not observe this issue. Minor failure due to restoration loss (decementation) was detected in only 2 of the 45 HT teeth [Table 5]. In the current study, decementation rates were lower than those reported in the literature with SSCs placed conventionally.[34]
In the current study, major failure was detected on only 2 teeth at 1-year follow-up (HT: n = 1, 2.2%; CR: n = 1, 2.6%). There was no statistically significant difference between the treatment groups in the major failure rates [Table 3]. The low failure rate of the HT SSCs (2.2%) appears to make them a successful restoration in their own right. This result is surprising given that there was no caries removal from HT teeth. Previous work observing a 23-month follow-up[4] point showed that HT had fewer failures (minor = 5%, major = 2%) than CR (minor = 46%, major = 15%). Moreover two published randomised control trials, of 1-year[15] and 5-year[16] follow-up, have reported the HT to be successful in managing dental caries. This supports our findings of HT as an efficient alternative to CR treatment.
Results of a systematic review by Schwendicke et al.[35] confirmed that incomplete caries removal could be considered favorable, and that sealing caries results in clinical and radiographic signs of inactivation of the caries lesion with tertiary dentin formation.
In both treatment groups, the plaque and gingival index scores were significantly decreased after the initial and 1-year follow-up [Table 6] and [Table 7]. Santamaria et al.,[15] also found significantly decreased plaque index scores in both HT and CR group at 1-year follow-up. Studies have demonstrated that good-to-moderate fitting crowns with well-contoured crown margins, similar to those used in the current HT SSCs, facilitate good oral hygiene, healthy gingiva, and minimal plaque accumulation.[36]
Effect of fitting hall crowns on the occlusal vertical dimension
Since there is no abrasion from the tooth or stainless steel crown while applying the HT, premature contact is observed in the tooth and an increase in the occluso vertical dimension (OVD) is expected after the crown cementation. However, for all the 33 cases where data were available, occlusal contact had re-established by the sixth-month follow-up [Figure 7]a,[Figure 7]b,[Figure 7]c. It has been previously shown that after HT, occlusal contact typically equilibrates within a matter of 15–30 days.[37] Although a 2-week follow-up with the dentists after crown fitting to assess occlusions would have been ideal, it was not possible within this study design. However, we can report that no child re-attended their dentist following placement of a HT SSC with signs or symptoms of occlusal dysfunction. Further, no child or parent reported difficulty with eating or symptoms of temporomandibular joint dysfunction syndrome when they were directly questioned by their dentist at 6-months or at 1-year follow-up. A recent review of the literature by Luther[38] found no evidence to support the premise that occlusal factors, including premature occlusal interferences, lead to temporomandibular joint dysfunction syndrome in young children.
Figure 7: Clinical images of a patient with SSC fitted using the HT (a; beforetreatment, b; after treatment c; 6 months later). Occlusal contact had re-established at the sixth months recallThe results of this study show that, after 1 year, HT was a more successful method for managing caries in primary molars than CR, for longevity of the restorations. The limitation of this study is that it is a 1-year follow-up. Because the patients participating in the study did not come to their long-term follow-up. However, it is thought that long-term follow-up studies are needed to evaluate the success of treatment methods. HT appears to offer an effective treatment option for managing dental caries in primary molar teeth. This study supports other work indicating that the progress of dentinal caries can be significantly slowed, and maybe even arrested, under a well-sealed restoration.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References 
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