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RESEARCH REPORT |
1 Department of Restorative Dentistry & Periodontology, Dental School, Ludwig-Maximilians-University, Goethestrasse 70, 80336 Munich, Germany;
2 Institute for Medical Statistics & Epidemiology, Klinikum rechts der Isar, Technical University, Munich, Germany; and
3 Department of Medical Informatics, Biometry & Epidemiology, Ludwig-Maximilians-University, Munich, Germany;
* corresponding author, khuth{at}dent.med.uni-muenchen.de
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
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KEY WORDS: pulpotomy • primary molars • RCT
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
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MATERIALS & METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
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8 yrs old), with at least 1 symptom-free, restorable primary molar with a cariously exposed vital pulp. Clinical exclusion criteria were spontaneous pain, swelling, tenderness to percussion, pathological mobility, and initially unsuccessful hemorrhage control. We excluded teeth with pre-operative radiographic pathology such as resorption, periradicular or furcal radiolucency, a widened periodontal ligament space, or physiological root resorption of more than one-third. Between November, 1999, and September, 2002, all children attending the Pedodontic Section, Department of Restorative Dentistry & Periodontology, University of Munich, and meeting the criteria were enrolled. After ethical approval (No. 281/99) and informed parental consent, two pedodontists performed the pulpotomies while the subjects were under local anesthesia or general anesthesia, without the additional use of local anesthetics.
Interventions
Dilute formocresol (1:5 Buckley’s solution), Erbium:Yttrium-Aluminum Garnet (Er:YAG) laser, calcium hydroxide, and ferric sulfate (15.5%) were used as parallel intervention methods. In all groups, after rubber dam isolation and caries removal, the pulp chamber was opened with a sterile high-speed diamond bur, and the coronal pulp was removed by a sterile slow-speed round bur (#830RL016, #H1SE.204021, Brasseler, Lemgo, Germany) under continuous water irrigation. Control of complete removal of the coronal pulp tissue down to the canal orifices was done by visual control and a sterile hand excavator in undercut areas. We controlled hemorrhage by placing sterile, saline-wetted cotton wool pellets on the radicular pulp stumps under slight pressure (Thompson et al., 2001), waiting 5 min for primary hemostasis (Mielke et al., 1969), followed by removal of blood clot remnants and drying the cavity. At this stage, the achievement of complete hemostasis was an inclusion criterion, before any of the 4 techniques was applied. When bleeding recommenced afterward, during placement of the medication or laser irradiation, the tooth was excluded from further follow-up.
Within the control group, formocresol-moistened pellets were placed on the pulp stumps for 5 min. Er:YAG laser radiation (wavelength, 2.94 µm) was delivered to the canal orifices with a special handpiece (KEY Laser 1242; handpiece 2051, KaVo, Biberach, Germany), with parameters set at 2 Hz and 180 mJ/pulse without water cooling (Keller and Hibst, 1991). The mean number of laser pulses per tooth was 31.5 ± 5.9, equally distributed to each pulp stump. In the calcium hydroxide group, the canal orifices were dressed with aqueous calcium hydroxide (Calxyl®, OCO Präparate GmbH, Dirmstein, Germany), slightly dampened and covered with a calcium hydroxide cement (Kerr® Life, Kerr GmbH, Karlsruhe, Germany). Ferric-sulfate-wetted pellets (Astringedent®, Ultradent Products Inc., Salt Lake City, UT, USA) were placed on the pulp stumps for 15 sec.
A reinforced zinc oxide eugenol base (IRM®, Dentsply DeTrey, Konstanz, Germany) was then applied to the cavity floor, followed by a glass-ionomer cement (KetacTM Bond, 3M ESPE, Seefeld, Germany) and a stainless steel crown (SSC, 3M ESPE) or a composite resin restoration (CRR, Tetric® Ceram, Ivoclar Vivadent, Schaan, Liechtenstein).
Follow-up
Clinical re-evaluations at 6, 12, 18, and 24 mos ± 2 wks, with additional radiographic examinations at 12 and 24 mos, were performed independently by two experienced dentists (not the operators) blinded to the technique, with forced consensus in cases of disagreement. The inter- and intra-examiner reproducibility was calculated by Cohen’s unweighted kappa statistic (Altman, 1991). The flow of participants and pulpotomies was followed from allocation to the final data analysis after 24 mos (Fig.
).
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Sample Size and Power Calculation
The sample size calculation [PS Power and Sample Size Calculation Program, Version 2.1.31 (Dupont and Plummer, 1990)] was based on an internal pilot study comparing the success rates of calcium hydroxide (55.9%) and formocresol (90.1%) (Benz et al., 1998), and on a study comparing ferric sulfate (96.55%) and formocresol (77.78%) (Fei et al., 1991). The first outcome difference led to a required sample size of 28 for the detection of a significant difference (80% power, two-sided 5% significance level), and the second to one of 50 per intervention group. For the Er:YAG laser group, no previous data for a sample size calculation were available. Therefore, a sample size of 50 in each intervention group was planned. Based on the results of the present study, a power analysis was performed (Dupont and Plummer, 1990).
Randomization and Blinding
Each tooth was randomly allocated to one of the 4 techniques by an assistant casting a concealed lot from a box containing 4 x 50 lots (block randomization) (Altman, 1991). All other contributors to the study were blinded to generation and implementation of the treatment assignment. The outcome assessment and data analysis were blinded, since the techniques were indistinguishable and coded.
Statistical Methods
During follow-up, a clinical failure was recorded if the pulpotomy failed due to clinical symptoms also showing radiographic pathology. Those with radiographic changes, but clinically symptom-free, were recorded separately. The total failure rate was comprised of the clinical and symptom-free radiographic failures.
The 12- and 24-month total and clinical success and failure rates of each pulpotomy technique were calculated according to the equation below (ADA, 2001). Additionally, the total success and failure rates for several parameters (type of anesthesia, two operators, tooth type, upper and lower jaw, final restoration) were calculated across all techniques:
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We used a logistic regression model to analyze the differences in effectiveness between formocresol and each of the other procedures (
-level = 0.05) (Altman, 1991); odds ratios with 95% confidence interval (OR ± 95% CI) were also given. Multiplicity and therefore dependence of more than one pulpotomy within a patient was accounted for within the statistical analysis by the generalized estimating equation (GEE) (Liang and Zeger, 1986). Exchangeable correlation structure was used, since the correlation between any 2 pulpotomies was assumed to be the same across patients. We applied the Wald Chi-square test to test differences in overall effectiveness regarding the abovementioned parameters. All tests were performed two-tailed, with p < 0.05 indicating statistical significance. We used SAS version 9 (SAS Inc., Cary, NC, USA) to perform the analyses.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
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) in 103 patients (56 males, 47 females; mean age, 4.8 ± 1.6 yrs; range, 2–8 yrs) were reevaluated. After 24 mos, 12 teeth had exfoliated physiologically, and 4 were lost to follow-up (drop-out of four patients who moved away), leaving 175 pulpotomies in 96 patients for the intention-to-treat statistical analysis (Fig.
).
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= 1, = 0.80), and the intra-examiner reproducibility was optimal for both the clinical and radiographical evaluations (Cohen’s = 1).
The clinical and radiographic evaluation after 12 mos revealed the following total and clinical (placed parenthetically) success rates for the different methods (%): formocresol, 96 (100); laser, 93 (98); calcium hydroxide, 86 (95); and ferric sulfate, 86 (100). There was no significant difference in effectiveness between formocresol and any of the other techniques after 12 mos (p > 0.05) (Table 2).
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).
Ten clinical failures and 31 radiographic failures without clinical symptoms were found within the 24-month evaluation period (Table 3).
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Over 2 yrs, 3 out of 109 SSC were lost, but the cement base remained intact; there was 1 pulpotomy failure (formocresol). Of the 82 CRR, 13 fillings were unacceptable (3 totally lost, 3 partially lost, 7 with secondary caries), with 2 pulpotomy failures (laser, ferric sulfate).
No adverse events or side-effects were recognized during the study.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
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), as had been suggested (Schröder, 1978). The total failure rate of 47% was higher than rates reported for two previous studies (20% and 23%) (Gruythuysen and Weerheijm, 1997; Waterhouse et al., 2000), but was comparable with reports from 2 studies showing failure rates of 41% and 43% (Schröder, 1978; Benz et al., 1998). The Er:YAG laser pulpotomies had a total success rate (78%) insignificantly lower than that of formocresol (85%) after 2 yrs. Since this laser type had not previously been used for pulpotomies in primary molars, its sample size had to be adapted from that calculated for ferric sulfate. From the data analysis, with a power of 15%, it became clear that the sample size was too small for us to answer this question: Does the non-significant result indicate that there is in fact no difference compared with formocresol?
A similar situation appeared when we compared the minimally different total success rate of ferric sulfate (86%) with that of formocresol (85%): No significance after 2 yrs was revealed (power 5%). Nevertheless, the success rate lies well between those previously reported: 61% after 2 yrs (Casas et al., 2003) and 97% after 20 mos (Ibricevic and Al-Jame, 2000). The distinct difference between the clinical (100%) and total success rates (86%), observed not only here but also by others (Casas et al., 2003), emphasizes the importance of regular radiographic control.
Dilute formocresol as the control technique in this study showed a total success rate (85%) that was comparable with those of previous studies reporting 84% after nearly 2 yrs (Fuks et al., 1997; Waterhouse et al., 2000).
Initial hemostasis was achieved in all 200 allocated teeth. However, 3 teeth allocated to the laser and 6 to the calcium hydroxide group were excluded from further follow-up, since uncontrollable bleeding recommenced during irradiation or placement of calcium hydroxide, indicating a hyperemic, inflamed radicular pulp. Aside from the use of non-medicated cotton pellets for primary hemostasis, the different mechanisms of bleeding control for the various applied techniques are interesting in this context: Formocresol fixes tissue in the coronal third of the radicular pulp and causes hemostasis by vessel thrombosis and impaired micro-circulation (Avram and Pulver, 1989; Ranly and García-Godoy, 2000; Thompson et al., 2001). The pulp’s microcirculation after irradiation with the Er:YAG laser, adjusted as here, showed an instant, reversible decrease of blood flow for 3 to 6 min, but with no signs of hyperemic reaction that might be caused by heat (Keller and Hibst, 1991). Calcium hydroxide has been reported to create a superficial coagulation necrosis, possibly inhibiting bleeding and fluid loss (Ranly and García-Godoy, 2000; Waterhouse et al., 2000). Ferric sulfate precipitates protein plugs, resulting from the reaction of blood with both the ferric and sulfate ions that occlude the capillary orifices, causing hemostasis (Lemon et al., 1993). Nevertheless, it might be assumed, from this and other studies, that the pulpal status is more crucial to a successful pulpotomy procedure when calcium hydroxide (Schröder, 1978; Waterhouse et al., 2000) and the Er:YAG laser are used, than when formocresol or ferric sulfate is used.
The external validity of this study—revealing new data concerning the controlled use of the Er:YAG laser for pulpotomies—is limited, due to the fact that the pulpotomies were performed by specialists in a hospital, with patients identified mainly following referral, and with special options offered, such as general anesthesia (Nadin et al., 2003).
After 24 mos, only calcium hydroxide was significantly less effective than formocresol. To answer the question whether the non-significant results comparing the Er:YAG laser or ferric sulfate with formocresol indicate that there is in fact no difference, an increased sample size and power would be required, e.g., within a large-scale multi-center study.
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ACKNOWLEDGMENTS |
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eljka Maruniza, Kathrin Braunmüller, and Kerstin Weidlich for their project assistance. The study was completely financed by Departmental funding. Received October 22, 2004; Last revision June 27, 2005; Accepted August 3, 2005
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REFERENCES |
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