Randomization in clinical trials: stratification or minimization? The HERMES free simulation software

PROTOCOL: Key characteristics of effective preschool-based interventions to promote self-regulation: A systematic review and meta-analysis

This is the protocol for a Cochrane Review. The objectives are as follows: The aim of this systematic review is to advance our understanding of the key characteristics of effective preschool-based interventions designed to foster self-regulation. To accomplish this, the review addresses the following questions: 1. What types of preschool-based interventions have been developed to promote self-regulation? 2. What is the average effect of these preschool-based interventions on self-regulation, focusing on four key constructs: integrative effortful control, integrative executive function, self-regulation, and self-regulated learning? 3. What characteristics-such as Resource Allocation, Activity Type, and Instruction Method-could potentially contribute to the effects of preschool-based interventions in promoting self-regulation?

Choosing and evaluating randomisation methods in clinical trials: a qualitative study

BACKGROUND

There exist many different methods of allocating participants to treatment groups during a randomised controlled trial. Although there is research that explores trial characteristics that are associated with the choice of method, there is still a lot of variety in practice not explained. This study used qualitative methods to explore more deeply the motivations behind researchers' choice of randomisation, and which features of the method they use to evaluate the performance of these methods.

METHODS

Data was collected from online focus groups with various stakeholders involved in the randomisation process. Focus groups were recorded and then transcribed verbatim. A thematic analysis was used to analyse the transcripts.

RESULTS

Twenty-five participants from twenty clinical trials units across the UK were recruited to take part in one of four focus groups. Four main themes were identified: how randomisation methods are selected; researchers' opinions of the different methods; which features of the method are desirable and ways to measure method features. Most researchers agree that the randomisation method should be selected based on key trial characteristics; however, for many, a unit standard is in place. Opinions of methods were varied with some participants favouring stratified blocks and others favouring minimisation. This was generally due to researchers' perception of the effect these methods had on balance and predictability. Generally, predictability was considered more important than balance as adjustments cannot be made for it; however, most researchers felt that the importance of these two methods was dependent on the design of the study. Balance is usually evaluated by tabulating variables by treatment arm and looking for perceived imbalances, predictability was generally considered much harder to measure, partly due to differing definitions.

CONCLUSION

There is a wide variety in practice on how randomisation methods are selected and researcher's opinions on methods. The difference in practice observed when looking at randomisation method selection can be explained by a difference in unit practice, and also by a difference in researchers prioritisation of balance and predictability. The findings of this study show a need for more guidance on randomisation method selection.

Efficacy of bone substitute material in preserving volume when placing a maxillary immediate complete denture: study protocol for the PANORAMIX randomized controlled trial

BACKGROUND

Bone preservation is an essential issue in the context of last teeth extraction and complete edentulism. The intended treatment, whether a complete denture or an implant placement, is facilitated with a voluminous residual ridge. Bone resorption after multiple extractions has not been as well studied as the bone resorption that occurs after the extraction of a single tooth. Recent advances in bone substitute materials have revived this issue. The purpose of this study is to evaluate the interest in using bone substitute material to fill the socket after last teeth extraction in a maxillary immediate complete denture procedure compared with the conventional protocol without socket filling.

METHODS/DESIGN

A randomized, controlled, clinical trial was designed. The 34 participants eligible for maxillary immediate complete denture were divided into two groups. Complete dentures were prepared despite persistence of the last anterior teeth. The control group received a conventional treatment including denture placement immediately after extractions. In the experimental group, in addition to the immediate denture placement, a xenograft bone-substitute material (Bio-Oss Collagen®) was placed in the fresh sockets. The primary outcome of the study is to compare mean bone ridge height loss 1 year after maxillary immediate complete denture placement, with or without bone-substitute material, in incisor and canine sockets. The secondary outcomes are to compare the average bone ridge height and width loss for each extraction site. An original quantitative evaluation method using cone beam computed tomography was designed for reproducible measurements, with a radio-opaque denture duplicate. Two independent operators perform the radiologic measurements.

DISCUSSION

The immediate complete denture technique limits bone resorption in multiple extraction situations and thus allows better denture retention and better options for implant placement. To compare the benefit of using any bone socket-filling material, we proposed a quantitative evaluation protocol of resorption in the specific case of the last anterior maxillary teeth extraction with immediate denture placement.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02120053 . Registered on 18 April 2014.

Efficacy of composite versus ceramic inlays and onlays: study protocol for the CECOIA randomized controlled trial

Background

Dental caries is a common disease and affects many adults worldwide. Inlay or onlay restoration is widely used to treat the resulting tooth substance loss. Two esthetic materials can be used to manufacture an inlay/onlay restoration of the tooth: ceramic or composite. Here, we present the protocol of a multicenter randomized controlled trial (RCT) comparing the clinical efficacy of both materials for tooth restoration. Other objectives are analysis of overall quality, wear, restoration survival and prognosis.

Methods

The CEramic and COmposite Inlays Assessment (CECOIA) trial is an open-label, parallel-group, multicenter RCT involving two hospitals and five private practices. In all, 400 patients will be included. Inclusion criteria are adults who need an inlay/onlay restoration for one tooth (that can be isolated with use of a dental dam and has at least one intact cusp), can tolerate restorative procedures and do not have severe bruxism, periodontal or carious disease or poor oral hygiene. The decayed tissue will be evicted, the cavity will be prepared for receiving an inlay/onlay and the patient will be randomized by use of a centralized web-based interface to receive: 1) a ceramic or 2) composite inlay or onlay. Treatment allocation will be balanced (1:1). The inlay/onlay will be adhesively luted. Follow-up will be for 2 years and may be extended; two independent examiners will perform the evaluations. The primary outcome measure will be the score obtained with use of the consensus instrument of the Fédération Dentaire Internationale (FDI) World Dental Federation. Secondary outcomes include this instrument’s items, inlay/onlay wear, overall quality and survival of the inlay/onlay. Data will be analyzed by a statistician blinded to treatments and an adjusted ordinal logistic regression model will be used to compare the efficacy of both materials.

Discussion

For clinicians, the CECOIA trial results may help with evidence-based recommendations concerning the choice of materials for inlay/onlay restoration. For patients, the results may lead to improvement in long-term restoration. For researchers, the results may provide ideas for further research concerning inlay/onlay materials and prognosis.

This trial is funded by a grant from the French Ministry of Health.

Trial registration

ClinicalTrials.gov Identifier: NCT01724827