Methods for the statistical analysis of binary data in split-mouth designs with baseline measurements

Performance of self-cured versus light-cured universal adhesive in patients with non-carious cervical lesions: 18-month randomized clinical trial

OBJECTIVE

To evaluate the clinical performance of self versus light-cured universal adhesive in non-carious cervical lesions (NCCLs) after 18 months.

MATERIALS AND METHODS

Sixty-eight NCCLs in 28 patients were divided into two equal groups; G1: self-cured universal adhesive (Palfique,Tokuyama,Japan) and G2: light-cured universal adhesive (Single Bond Universal,3 M ESPE,USA). Nanohybrid resin composite (Z350XT, 3 M ESPE, USA) was used as a final restoration. Evaluation for fracture, loss of retention, marginal adaptation and discoloration were done after 1 week, 6,12, and 18 months using FDI criteria. Postoperative sensitivity was assessed after 1 week. Chi-Square and Mann-Whitney tests with statistical significance at (P ≤ 0.05) were used for intergroup comparison,while the intragroup one was performed using the Cochran's Q and Friedman's tests. Survival rate was analyzed using Kaplan-meier and Log-rank test.

RESULTS

Both groups exhibited fracture and retention loss, however, there was statistically significant difference favoring the control group at 6 months (p = 0.0114,0.0016). For secondary outcomes, marginal adaptation and discoloration revealed no significant differences. For postoperative sensitivity, there was a significant difference favoring the control group (p = 0.0007, 0.0011). Palfique had 1.5 Relative-Risk (RR) after 6 months (95% CI 0.5659-4.2617; P = 0.3928) and 20% less risk of failure after 18 months (RR 0.8) (95% CI 0.4618-1.3858; P = 0.4260). Tested adhesives showed equal survival rate (P = 0.5685).

CONCLUSIONS

Both adhesives revealed similar clinical performance in restoring the NCCLs after 18 m, however, the early failure was more frequent in the self-cured universal adhesive.

Increasing character strength knowledge, interest, and skill: preliminary evidence for a collaborative and multimethod assessment procedure

Introduction

The study's objective was to evaluate whether a qualitative, collaborative, and multimethod assessment protocol increased reports of character strength interest, knowledge, and perceived skills.

Methods

Thirty-two participants completed three phases of data collection. Participants were first screened for well-being, which was used as an auxiliary covariate to order participants into experimental conditions. Selected participants were randomly assigned to a control or collaborative and multimethod assessment (card sort × qualitative interview) condition. Participants completed pre- and post-measures of strength interest, knowledge, and perceived skill. In the final phase, second phase participants were invited to report on strength-related outcomes 24 h post-administration using an online survey.

Results

A series of 2 (Assessment Condition) × 3 (Time) mixed ANOVAs were analyzed. Results revealed a significant assessment condition by time interaction for strength knowledge and perceived skill. Participants in the collaborative and multimethod assessment condition reported higher strength knowledge and perceived skills compared to control participants. These effects were maintained for 24 h.

Conclusion

The findings offer preliminary yet sizable support for using collaborative and multimethod assessment procedures to increase strength knowledge and perceived skill. Because of the qualitative, collaborative, and individualized nature of our assessment protocol, the findings offer a low-cost and contextually bound pathway to increase strength-based outcomes.

Efficacy of Dental Implants Placements between Lateral and Crestal Sinus Lift Techniques: A Split-Mouth Study

Background:

Bone atrophy and pneumatization of the maxillary sinus resulting from tooth loss, associated with low bone density in the region, do not usually allow adequate quantity and quality for the installation of osseointegrated implants.

Objective:

To evaluate the efficacy of crestal and lateral sinus lift techniques which are performed on same patients.

Materials and Methods:

Ten patients who required both crestal and lateral approaches in 20 sinus lifts were selected; 31 endosseous dental implants were placed into these patients, with a reported timeline for each approach. Assessment of the surgical procedures in all patients was done using a Visual Analog Scale (VAS). Clinical and radiographic parameters, including Pocket Probing Depth (PPD), distance between the implant shoulder and the mucosal margin (DIM) and distance between the implant shoulder and first visible bone-implant contact (DIB), were analyzed to compare implant survival for both approaches.

Results:

All implants were successfully osseointegrated. No significant differences were observed between lateral and crestal approaches in PPD, DIM and DIB (p-values = 0.0504, 0.7784 and 0.18170, respectively), and in the total VAS scores (p-value ≥ 0.05). Most of the patients preferred the crestal approach due to the delay in implant placements with the lateral approach.

Conclusion:

Evaluation of the sinus floor elevation is more precise when both techniques are performed on the same patient. Furthermore, although post-operative vertigo is a major concern with the crestal approach; patients preferred this approach over the lateral technique because it is less invasive and required less time for the procedure.

Effect of low-level laser therapy combined with 5000 parts per million fluoride dentifrice on postbleaching sensitivity: A clinical, randomized, and double-blind study

OBJECTIVE

The aim of this double-blind, randomized, controlled clinical study was to assess the efficacy of low-level laser therapy (LLLT) combined with 5000 ppm fluoride dentifrice on postbleaching sensitivity in teeth exposed to 35% hydrogen peroxide for four weeks.

MATERIALS AND METHODS

Twenty-five volunteers were evaluated using the split-mouth model in which the right and left maxillary/mandibular quadrants were randomized and allocated to one of two groups: GPLACEBO, in which the laser tip was positioned without the emission of light (placebo effect) + 5000 ppm sodium fluoride, or GLASER, which comprised LLLT + 5000 ppm sodium fluoride. For both groups, LLLT and placebo were used before bleaching, whereas fluoride was applied after bleaching. LLLT was applied at two points: on the central cervical and medial regions of the incisors, canines, and premolars in the corresponding hemi-arch. At each point, 60 J/cm² was applied for 16 seconds with an irradiance of 3.75 W/cm² using the therapeutic infrared device. To assess tooth sensitivity, a modified visual analogue scale was used after an evaporative stimulus, and a daily pain questionnaire was also applied.

RESULTS

The Wilcoxon and Friedman tests demonstrated a significant difference in the incidence of sensitivity pain between GPLACEBO and GLASER (P ≤ .05), with different evaluation times.

CONCLUSION

Teeth treated with laser therapy in combination with the topical use of sodium fluoride at each bleaching session demonstrated less sensitivity compared with the application of sodium fluoride only.

CLINICAL SIGNIFICANCE

The use of a low-level laser therapy in combination with topical use of sodium fluoride improves symptoms of dentin sensitivity at each bleaching session.

Sample size considerations for split-mouth design

Split-mouth designs are frequently used in dental clinical research, where a mouth is divided into two or more experimental segments that are randomly assigned to different treatments. It has the distinct advantage of removing a lot of inter-subject variability from the estimated treatment effect. Methods of statistical analyses for split-mouth design have been well developed. However, little work is available on sample size consideration at the design phase of a split-mouth trial, although many researchers pointed out that the split-mouth design can only be more efficient than a parallel-group design when within-subject correlation coefficient is substantial. In this paper, we propose to use the generalized estimating equation (GEE) approach to assess treatment effect in split-mouth trials, accounting for correlations among observations. Closed-form sample size formulas are introduced for the split-mouth design with continuous and binary outcomes, assuming exchangeable and "nested exchangeable" correlation structures for outcomes from the same subject. The statistical inference is based on the large sample approximation under the GEE approach. Simulation studies are conducted to investigate the finite-sample performance of the GEE sample size formulas. A dental clinical trial example is presented for illustration.

A Split-Mouth Design Comparison for Lateral and Crestal Sinus Lift Techniques with Dental Implants Placements: Short Communication

Objective:

The objective of this study is to compare and evaluate the effectiveness of implant placement and patient appraisal for two sinus lift techniques using both crestal and lateral techniques for bilateral sinus left in a split-mouth design.

Introduction:

All implants were successfully osseointegrated without any clinical complications or peri-implant radiolucency during the follow-up period of maximum 3 years.

Methods:

In terms of outcomes postoperative vertigo showed to be a major concern with the crestal approach, this approach is preferred over the lateral technique because of the reduced time required for the procedure and because it is less invasive.

Results:

Most patients preferred the crestal approach over the lateral approach due to the delay in implant placement.

Split-mouth designs in orthodontics: an overview with applications to orthodontic clinical trials

Split-mouth designs first appeared in dental clinical trials in the late sixties. The main advantage of this study design is its efficiency in terms of sample size as the patients act as their own controls. Cited disadvantages relate to carry-across effects, contamination or spilling of the effects of one intervention to another, period effects if the interventions are delivered at different time periods, difficulty in finding similar comparison sites within patients and the requirement for more complex data analysis. Although some additional thought is required when utilizing a split-mouth design, the efficiency of this design is attractive, particularly in orthodontic clinical studies where carry-across, period effects and dissimilarity between intervention sites does not pose a problem. Selection of the appropriate research design, intervention protocol and statistical method accounting for both the reduced variability and potential clustering effects within patients should be considered for the trial results to be valid.

Sample size estimation: an overview with applications to orthodontic clinical trial designs

Proper sample size estimation is an important part of clinical trial methodology and closely related to the precision and power of the trial's results. Trials with sufficient sample sizes are scientifically and ethically justified and more credible compared with trials with insufficient sizes. Planning clinical trials with inadequate sample sizes might be considered as a waste of time and resources, as well as unethical, since patients might be enrolled in a study in which the expected results will not be trusted and are unlikely to have an impact on clinical practice. Because of the low emphasis of sample size calculation in clinical trials in orthodontics, it is the objective of this article to introduce the orthodontic clinician to the importance and the general principles of sample size calculations for randomized controlled trials to serve as guidance for study designs and as a tool for quality assessment when reviewing published clinical trials in our specialty. Examples of calculations are shown for 2-arm parallel trials applicable to orthodontics. The working examples are analyzed, and the implications of design or inherent complexities in each category are discussed.