Effectiveness of atraumatic restorative treatment , Hall Technique and conventional restoration using resin or amalgam after 18 months of follow-up : a randomized controlled trial

There are different options for restorations of deciduous teeth. The aim of this study was to evaluate the success rate of conventional and atraumatic restorations, Class I and Class II lesions in primary molars. This is a randomized controlled trial in Olinda, Brazil. The control groups were the conventional restorations with resin (205) and amalgam (198), and the case groups were atraumatic approaches with the ART (211) and the Hall technique (117). A total of 731 restorations were performed in a dental office setting in 731 children (4to 8-yearolds). All the restorations were evaluated after 6, 12 and 18 months. The survival rate of Class I restorations was higher (> 85% success) for all restorations compared to Class II (16.9%99.1%, success/minor failure). The success rates of Class II restorations after 18 months were not satisfactory for conventional restorations with resin (16.9%, success/minor failure) and ART (31%, success/minor failure), while were satisfactory for conventional restorations with amalgam (70,3%, success), and outstanding for Hall technique (99,1%, success). The success rate for Class I was higher than II for all restorations. Considering Class II, the success rate was low for ART and conventional restorations with resin, satisfactory for amalgam, and excellent for Hall Technique.

The use of ART contributes to smaller cavity preparations and greater acceptance of dental treatment by children. ART has been implemented in the public oral health services of several countries (Frencken et al., 2012). The ART approach has characteristics that favor patient acceptance and cooperation, promoting an "atraumatic" treatment (Carvalho, Ribeiro, Bönecker, Pinheiro & Colares, 2009).
On the other hand, Amalgam is a restorative material used in conventional restorations, with the use of high speed and manual instruments for the removal of caries (Amorim, Leal, Mulder, Creugers & Frencken, 2014) .Conventional restorations with the use of composite resin restorations have been widely used with children, because in addition to adopting a more conservative cavity preparation, preserving dental tissue structure, resin restorations present a better aesthetic result, similar to the deciduous tooth (Ersin et al.,2006).
Another option for the treatment of caries in primary teeth are steel crowns, manufactured in different sizes. These crowns can be placed on decayed teeth or teeth with developmental defects. Conventionally, the teeth are trimmed so that the crowns are placed under local anaesthetic. With the Hall technique, the crowns are pushed over the tooth without tooth preparation. Thus, in the Hall technique, the use of steel crowns is a simpler procedure and a broader indication (Innes et al., 2015). Then, the objective of this randomized controlled trial was to compare the success rate of atraumatic (ART and Hall technique) and conventional restorations (amalgam and resin), in Class I and Class II lesions in primary molars of children over 18 months.

Material and Methods
It was a randomized controlled trial, that evaluated the longevity of atraumatic and conventional restorations performed at dental offices in Olinda, state of Pernambuco-Brazil.
Data collection occurred in 8 health units of the public system of health. The inclusion criteria were children between 4 and eight years old with occlusal and proximal caries in primary molars, without fistula, abscesses, mobility, and other pulp involvements. Seven hundred and thirty-one primary school children who had a primary molar with carious lesion of a similar size extending into the dentine with an entrance just large enough to allow access by hand instruments-were selected for treatment. A total of 731 restorations were placed being 211 ART (124 class I and 87 class II); 117 Hall technique class II; 198 with amalgam (104 class I Research, Society and Development, v. 9, n. 11, e1339118567, 2020 (CC BY 4  Data collection was carried out in four months, one for each material used (amalgam, resin, glass ionomer cement -ART and steel crown -Hall technique). The order of the types of restorations per month was randomized, and all children who went to the health unit with decayed teeth and met the inclusion criteria, were treated with the same technique each month. For each child, one molar was selected for treatment. When the child had more than Eight dental offices recruited to participate and children aged 4-8 yrs assessed for eligibility.
Operators: eight dentists from the public health service in the city of Olinda.
The children should be subscribed in the public health care system. Prior to treatment, signed written consent was obtained from parents or guardians of the children.
Fifteen dentists from the public health units did training composed of three phases: theoretical, laboratory, and clinical. Each dentist had to perform the different types of restorations during the clinical training phase. After the evaluations of the restorations performed during the training, eight dentists were selected to participate in the operative phase of the research. The evaluation of the restorations made by the dentists during the training period was performed to calibrate the evaluator for the operative phase. The codes and criteria for the restorations assessment is summarized in Table 1, according to Innes et al. (2015) and Roeleveld, Amerongen and Mandari (2006). The restorations made during the training were evaluated by a Ph.D. paediatric dentistry student, who did thereafter the evaluations during the entire clinical study. Source: According to Roeleveld et al., 2006 andInnes et al, (2015).
The Ph.D. student who was not involved in the placement of the restorations, evaluated the restorations after 6, 12 and 18 months using sharp sickle-shaped explorers, plane mirrors, and a portable light source (Kappa inter-examiner was 0.88). The ball end of the CPI probe (0.5-mm in diameter) was used to measure the size of any marginal defect and the amount of wear.
Research, Society and Development, v. 9, n. 11, e1339118567, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i11.8567 7 The data were analyzed using a software program (Epi info). All conclusions of the applied tests were taken considering the level of significance of 5%. Kaplan-Meier test was used to assess the significance of the success rates of the restorations. Also were used Log Rank, Breslow, Tarone Ware, and Wald tests to verify the longevity of the restorations according to the material used and the surface of the cavities.
This study was approved by the ethical committee of research of the University of Pernambuco (protocol no. 447.607). It was also approved by the Brazilian clinical trial registry through the number (RBR-8JQRW7).
The type of restoration is a determinant factor to alter the survival time of the material in the evaluated patients. The restoration with more prolonged survival was the crown (Hall technique), followed by conventional restoration using amalgam, and the shorter longevity was for the conventional restoration using resin. The average of time was 17.8 months (95% CI:17.6-18.1), 17.3 months (95% CI :16.9-17.7), 16 months (95% CI: 15.5-16.5), and 12 months (95% CI: 11.2-12.9) for crowns (Hall technique), amalgam, glass ionomer (ART) and, resin, respectively (Table 3 and Figure 2).

Discussion
For Class I restorations, in the sample evaluated in this study, good results were obtained for all types of restorations, with success above 85% after 18 months of follow-up.
However, there was a difference between the types of restorations, with better results for amalgam and resin. Differences in results may be related to the complexity and quantity of the cavities involved, as well as, depending on the accuracy of the technique and other factors (Roshan & Sakeenabi, 2011). Good results observed for class I restorations have been reported in other studies. In a study carried out by Menezes, Rosenblatt and Medeiros (2006), where the teeth restored with ART in one surface lesions achieved a success rate of 95% at 6 months and 82% at 12 months, without recurrent caries or pulpal infection evidence.
Similarly, Ersin et al. (2006) Franca et al. (2011) study the restorations were performed in the school environment in a way less comfortable for the dentist than in the dental office.
For conventional resin restorations, only 2% success was observed after 12 months in this study. However, the inclusion of minor failures should be considered to assess longevity and the satisfactory outcome of restorations. The sensibility of the protocol might be taken into account, since the resin is much more sensitive to moisture than glass ionomer and, in general, a rubber dam is not available in public services in Olinda. Crowns placed on primary molars teeth with carious lesions are likely to reduce the risk of major failure or pain in the long term compared to conventional fillings. Crowns fitted using the Hall Technique may reduce discomfort at the time of treatment compared to conventional fillings (Innes et al., 2015). In this study, using the Hall Technique, it was successful above 99% after 18 months for class II restorations, which was much higher than that observed for other types of restorations.
Stainless steel crowns have demonstrated better longevity compared with amalgam restorations for primary molars, although amalgam has shown a notable clinical success for Class II. It is necessary to keep in mind two points: the need to reduce the use of amalgam as a mercury-containing material when aiming to reduce environmental contamination (Fuks, 2015), and also that the HT is more cost-effective than conventional restorations (Schwendicke et al., 2019). Hall technique restorations are more favorable with respect to discomfort when compared to the conventional steel crown restorations (Ayedun et al., 2020).
Besides that, Hall technique is an intervention with high clinical success and shorter treatment time, aspects that make this technique indicated as an alternative for decayed deciduous teeth with multisurface lesions (Ebrahimi et al., 2020).
In this study, the best results were found for Hall technique restorations, followed by conventional restorations with amalgam. The worst results were seen for conventional restorations using resin and ART using glass ionomer.
This study revealed that the success rate of restorations in primary molars was higher for class I compared with Class II. In addition, the restorations Class II presented better results when restored using metal crowns through the Hall technique and conventional technique using amalgam.

Conclusion
The success rate for Class I was higher than II for all restorations. Considering Class II, the success rate was low for ART and conventional restorations with resin, satisfactory for amalgam, and excellent for Hall Technique.