Study finds stainless steel crowns most effective in special needs patients

2015 01 30 12 24 24 385 Kid Open Mouth 200

Stainless steel crowns had a lower failure rate when compared with amalgam, composite, and glass ionomer restorations in more than 1,900 procedures on patients with special needs, according to a recent study. The researchers focused on both the effectiveness of certain restorative materials and clinical outcomes of treatment under general anesthesia.

A number of studies have looked at the clinical outcomes of patients under general anesthesia, but this current study is one of only a few that focused on patients with special needs, the authors noted (Science World Journal, December 24, 2014). They aimed to study the failure rate of different treatment procedures and restorative materials in this population, while also evaluating the follow-up rates.

The study included a total of 177 patients (67 females, 110 males), with a mean age of 12.3 ± 10.5 years (range, 1.8 to 50 years), who were treated under general anesthesia at Queen Mary Hospital in Hong Kong from 2005 to 2009. Operative procedures were done under rubber dam isolation, while extractions were done after the restorative treatment and with local anesthetic. If there were no complications from the anesthesia, the patients were discharged on the same day. If there were complications, the patients were kept under observation until their vital signs were stable. The follow-up appointment was scheduled two weeks after treatment under general anesthesia.

A total of 1,978 treatment procedures were completed over a six-year period, including 343 (17%) preventive procedures, 985 (50%) restorative treatments, 152 (7.6%) pulp therapies, 490 (25%) extractions, and 8 (0.4%) root canal treatments.

The researchers collected data from up to five follow-up appointments (two weeks, six months, 12 months, 18 months, and 24 months). At these follow-up appointments, clinical and radiographic examinations were done to evaluate the treatment provided (see table below).

Failures rates of different restorative procedures
Restorative materials Total No. of restorations No. of failed restorations Failure rate (%)
Amalgam 46 6 13.0
Composite 611 139 22.7
Glass ionomer cement 39 4 10.2
Stainless steel crowns 289 11 3.8

Stainless steel crowns had the lowest failure rate when compared with amalgam, composite, and glass ionomer restorations, and more than 20% of teeth restored with composite restorations required further treatment. While the failure rate of amalgam restorations was lower than in previous studies, amalgam use was considerably lower in this study, the authors noted.

“Stainless steel crowns are the most reliable restorations and also a more cost-effective restorative material for primary molars in special needs patients.”

Overall, restorative procedures had a higher failure rate than preventive procedures, pulp therapies, and root canal treatments, with pulp treatments having the lowest failure rate. Pulp treatments in primary incisors had a higher failure rate than canines and molars, and almost 50% of pulp therapy performed in primary incisors required further treatment.

The researchers found that the failure rate of restorative procedures with composite restorations was high in primary canines, higher than in incisors and molars. The high failure rates may be caused by difficulties encountered in restoring badly broken down primary canines, the study authors wrote. Practitioners should consider that extraction may be a better option for the badly broken down primary canines in this population. They did urge that more attention be given to improving the "retention of the composite restorations during cavity preparation, bonding, and placement of restorations."

In terms of follow-up, more than 96% of the patients attended the first postoperative appointment two weeks after treatment, but that number fell to 36% of patients who completed the 24-month follow-up. Additionally, 18% of these patients did not have postoperative radiographs at follow-up.


Stainless steel crowns are the most reliable restorations and also a more cost-effective restorative material for primary molars in special needs patients, the authors concluded. They recommended that procedures with lower success rates be avoided to achieve the best possible clinical outcomes. For example, extraction should be considered for severely broken down primary incisors.

The authors also urged the implementation of a postoperative review program, which would provide the opportunity to implement preventive care to this population, potentially modify their behaviors, and motivate the parents/caregivers in prevention of dental disease, noting that it is vital to reduce the risk of repeat dental anesthesia.

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