In this clinical trial, according to the clinical scenario, the digital impression technique was more efficient than the conventional impression technique. Thus, the first null hypothesis was rejected. The subjects also preferred the digital impression technique rather than the conventional impression technique because of its comfort. Thus, the second null hypothesis was also rejected.
The study population was standardized and homogenized by including subjects who had no experience with conventional or digital impressions in their dental history. To investigate the clinical outcomes of the two impression techniques, homogenizing the study population is an acceptable clinical research method to optimize objectivity and minimize bias. This approach is important to avoid reporting the bias of patients who had previous experience with the dental impression procedure.
In this present study, we focused primarily on the efficiency of the two impression techniques and the preference of the patients under controlled clinical conditions. Future investigations should include the assessment of the accuracy of the impressions produced by experienced versus non-experienced operators, comparison of using scanning powders versus non-powder scanning, and comparison of full arch and partial impressions.
There are some limitations of this study. The study was designed as a comparative-controlled clinical trial, and the sequence of the evaluation of the two impression techniques was chosen for psychological reasons. There is a 2–3-week interval between the two evaluation appointments. This time period was deemed sufficient to erase from memory an event or a process. The evaluation process focuses on the outcomes of the impression techniques by means of total treatment time in seconds, and the study does not analyze any differences in precision of the two impression techniques.
Another limitation of the study was that only one operator performed the impression techniques to avoid the possible inter-operator error, such as the prolonged processing time taken by an inexperienced operator. The main purpose of the study was to focus on the patients’ perceptions and comfort in using different impression techniques. Evaluation by a second operator was not preferred because of main purpose of the study. Further investigations are planned to evaluate the perceptions of patients treated by different dental specialties and operator experience to the digital impression technique.
The last limitation of this study is that it ignored the time factors involved in the conventional impression technique, such as pouring and mounting the cast, trimming the dies, painting the die spacer, etc. By eliminating these steps, time for the traditional workflow would be reduced significantly. Furthermore, the digital impression technique and digital workflow are designed as the “digital working model” directly from the intraoral scan, without any additional factors. By virtually eliminating the intermediate processes, error accumulation in treatment and in the manufacturing cycle is no longer an issue.
The results of this study have revealed clinical evidence that the digital impression technique can be applied successfully for the impressions of restorative procedures based on clinical outcomes and the patients’ preferences. However, this study was performed in a clinical scenario that excluded the effect of actual treatment conditions, perceived dental anxiety and stress associated with treatment. This is an additional limitation of this study.
The major advantage of digital impressions is reducing the chair time. The mean total treatment time (p < 0.001) and the subjects’ evaluation scores (p < 0.001) regarding the impression techniques were significantly different (Tables
2). Improving the level of the patients’ comfort and treatment acceptance (p < 0.001) were other advantages of the digital impression techniques (Tables
2). Digital impressions tend to reduce repeat visits and retreatment, while increasing treatment effectiveness
. Patients will benefit from more comfort and a pleasant experience in the dentist’s chair.
The results of study indicate that the efficiency outcomes of the digital impression technique were higher than that of the conventional impression technique, with respect to treatment time taken up and the perceptions of the subjects. The effectiveness and clinical outcomes of both impression techniques (Table
1) were evaluated by recording the treatment time of each step in seconds, and were significantly different from each other (p < 0.001). The scores of the evaluation criteria regarding the two impression techniques (Table
2) that affect the subjects’ perception differed from one another in a statistically significant manner (p < 0.001).
The differences in the level of treatment comfort evaluated by the subjects, including breathing difficulty, queasiness, discomfort in the TMJ, and discomfort while the mouth was kept open were statistically significant (p < 0.001). Thus, the digital impression technique is more patient-friendly than the conventional impression technique. The results of this study present the major reasons why the subjects preferred the digital impression technique instead of the conventional impression technique (Table