Abstract
Objective
This clinical study aimed to assess the impact of utilizing loupes and dental operating microscopes (DOM) with varying magnifications on the success of class II direct composite restorations.
Methods
A total of 130 class II, moderately deep caries teeth from 85 patients were randomly assigned to four groups: naked eye, ×3 loupe, ×5 loupe, and ×8.5 DOM. Cavities were restored with or without magnification. The restorations were evaluated according to World Dental Federation criteria at 1, 6, and 12-month intervals by previously calibrated evaluators. Cochran's Q test was used to compare paired scores across three or more time points within groups, while the Friedman test was employed to compare scores at three or more time points. Multiple comparisons were adjusted using the Bonferroni correction. The significance level was set at p < 0.05.
Results
Statistical analysis revealed no significant differences among the groups at the 1-, 6-, and 12-month follow-up periods (p > 0.05). Although not statistically significant, the magnified groups exhibited higher scores in aesthetic anatomical form, proximal form, postoperative sensitivity, periodontal response, and adjacent mucosalcriteria compared to the naked eye group.
Conclusion
Although no statistically significant difference was observed at the 12-month follow-up between restorations performed with and without magnification, the groups using magnification showed higher scores.
Keywords: Clinical trial, Micromanipulation, Permanent dental restoration, FDI criteria
Clinical Significance: This study suggests that incorporating magnification into restorative procedures may provide practical benefits, leading to better clinical outcomes and enhanced patient satisfaction.
1. Introduction
With the development of resin-based composites, less invasive cavity preparation and aesthetic dentistry have become popular, leading to an increased demand for tooth-colored restorations in the posterior region [1]. Today, posterior direct composite restorations make up a significant portion of dental practice in restorative dentistry. In a review of the long-term performance of composites, it was found that the main reasons for the failure of composite restorations in the first 4 years of their life-span were marginal defects and fractures, followed by secondary caries. However, as restorations age, secondary caries and fractures became the primary causes of failure [2].
Regularly evaluating composite restorations is of great importance in assessing the materials and techniques used. The World Dental Federation (FDI)/Hickel Criteria provides an opportunity for current and comprehensive evaluation. In this system, both direct and indirect restorations are assessed based on aesthetic, functional, and biological parameters, with each criterion being scored on a scale of 1–5, where three scores are considered acceptable (Score 1-2-3), and two scores are considered unacceptable (Score 4–5).
The treatment's success is influenced by factors such as indication, preparation, matrix selection, polymerization, and polishing processes, the adhesive system used, composite materials, and patient and physician factors [3]. However, significant developments in resin composites and adhesive systems in the last 20 years have increased the clinical success of composite restorations. These developments in materials were followed by studies aimed at optimizing dental procedures.
Loupes are magnification systems that are used in microsurgery, such as eye, brain, and neurosurgery, in other fields of medicine. It has been shown that loupes can improve the results of the operation by providing a more accurate perception of the operative anatomy and the position of the instruments and facilitate procedures that are very difficult to perform without assisted vision [4]. They are classified into Galilean loupes and Keplerian (prismatic) loupes based on their design and lens system manufacturing techniques. Keplerian loupes offer a wider range of magnification power. Compared to Keplerian loupes, Galilean loupes are smaller in size and lighter in weight but provide a smaller field of view and shorter working distance [5].
Dental magnification systems are utilized in a variety of dental procedures, including endodontic treatments like the removal of broken instruments. These systems offer several advantages such as improved vision clarity, enhanced clinical performance, and supportive posture for operators [5]. Regardless of the lens system used, the most common magnification powers in general dental practice range from 2.0× to 3.5x. Loupes with 4.0x magnification and higher are preferred by experienced operators for endodontic surgeries, periodontal microsurgeries, and other applications requiring very high detail discrimination [6].
In the field of restorative dentistry, situations where magnification is particularly beneficial include: distinguishing and minimally invasively removing old restorations, identifying demineralized areas in enamel, detecting gaps and irregularities in restorative materials, seeing the boundaries of carious tissue, managing small, incidental pulp perforations without causing mechanical damage to the pulp, identifying enamel cracks or fractures at the gingival margins in Class II and MOD cavities, checking matrix adaptation and controlled application of liners, and evaluating preparation margins for inlay/onlay and overlay restorations [7]. Although disadvantages such as the high cost of loupes, the frustrations experienced during use, the relatively long learning curve, and the occasional need for replacement are mentioned, loupes help all types of clinical dentists demonstrate higher quality operative skills [8].
The use of loupes has become a subject of interest in this field due to the precision required in restorative procedures, and studies have been conducted on the topic. In these studies, it has been reported that loupes significantly improve student performance during preclinical dental education, reduce material loss when dental loupes are used for restoration removal, and result in fewer mistakes during crown preparation when magnification is employed [5,9,10].
Despite the known benefits of magnification systems in enhancing clinical performance during precision procedures, there is limited evidence-based information regarding their effectiveness in dental restorative treatments. A comprehensive literature review revealed no clinical studies examining the impact of magnification on the success of restorations. This study aims to evaluate the effect of using visual aids at different magnification levels on the one-year success of Class II direct composite restorations. By doing so, it seeks to provide valuable insights into the application of magnification systems in restorative dentistry and their potential influence on clinical outcomes.
The null hypothesis tested in the study is that there was no difference between the clinical performances of Class II direct composite restorations made with the naked eye and using 3 different magnification systems.
2. Materials and methods
2.1. Ethical considerations and study design
This is a prospective, randomized, parallel-group, and controlled clinical trial comparing the effects of three magnification aids on restoration clinical success. Restorations were evaluated by the World Dental Federation (FDI) Criteria at 1, 6, and 12 months after the operation. The study protocol was registered at ClinicalTrials.gov as NCT05959382 after approval was obtained by the Ataturk University Ethics Committee (Approval No: B.30.2.ATA.0.01.00/253), and the first participant was enrolled in October 2021. The study is in accordance with the Declaration of Helsinki. After the patients were informed about the study, they signed a consent form approved by the ethical committee of the Ataturk University after having received comprehensive information. All restorations were performed at a single center the Department of Restorative Dentistry.
2.2. Patient inclusion-exclusion criteria
Teeth requiring Class II restoration that are vital, have primary interproximal caries with radiological evidence showing that the carious lesion has reached the middle third of the dentin, and which give a negative response to percussion testing were included in the study. Participants had to report brushing their teeth twice a day, have no plaque on their tooth surfaces, and not have any chronic systemic conditions. Additionally, participants must agree to attend follow-up sessions at 1 month, 6 months, and 12 months. Patients receiving orthodontic treatment, those with severe bruxism, smokers, patients whose teeth could not be isolated, and those with malposed teeth were excluded from the study.
2.3. Sample size
Nonparametric single sample volume calculation was performed in the G Power package program, and it was determined that a minimum of 30 restorations were needed in each group by taking d = 0.29 (effect size), α = 0.05 (significance level of the test), and (1-β) = 0.95 (power). In this study, which had a 1-year follow-up, it was decided to start the study with 35 restorations in each group, with 5 restorations backed up per group, considering the possible loss of patient follow-up. Thus, the aim was to prevent a decrease in the power of the study and to avoid the loss of information.
2.4. Randomization and blinding protocol
A total of 140 teeth from 90 patients who met the inclusion criteria were included in the study for restoration. The 140 teeth were distributed into 4 groups using stratified randomization to ensure equality in the premolar/molar distribution. The study began with a total of 140 restorations. However, a total of 10 restorations of 5 patients were excluded because 2 patients moved out of the city during the control sessions, 1 patient started to receive orthodontic treatment, and 2 patients did not cooperate during the procedure. The working flow chart is given in Fig. 1.
Fig. 1.
CONSORT Flow diagram.
The teeth included in the study were randomly divided into 4 groups according to the type of enlargement to be used during the procedure.
-
1
Naked eye (with no magnification)
-
2
x3 loupe
-
3
x5 loupe
-
4
Dental operation microscope (DOM) with ×8,5 magnification.
All of the restorations were carried out by an operator experienced in the use of loupes and operating microscopes.
2.5. Restorative procedure
Following intraoral and radiographic examinations, caries tissue was removed. Isolation was achieved using suction and cotton rolls. A matrix band (Super Mat Adapt Supercap Matrix, Kerr, Switzerland) and a wooden wedge (Hawe Sycamore Interdental Wedges, Kerr, Orange, CA, USA) were then placed. Clearfil SE Bond 2 (Kuraray Noritake Dental Inc., Japan) was applied to the cavity with an applicator and polymerized with a curing pen (Eighteeth, Changzhou, China) at 1000 mW/cm2 for 10 s. Flowable composite (Clearfil Majesty Flow, Kuraray, Japan) was used as a liner on the cavity floor, followed by the placement of nanohybrid composite resin (Clearfil Majesty Posterior, Kuraray, Japan). Each layer was polymerized with an LED light device for 20 s. Polishing was performed using Sof-Lex Polishing Discs (3M ESPE), and contact areas were smoothed with Sof-Lex Finishing Strips (3M ESPE).
The same restorative procedure was applied to all groups by a single operator, and the procedure steps are shown in Fig. 2. The difference between the groups was determined by the magnification system used by the operator, with further details available in Table 2 and Fig. 3. A list of all materials used in the study, along with their contents, is provided in Table 1.
Fig. 2.
Restorative steps in the study.
Table 2.
Information on the magnification systems used in the study.
| Zumax Binocular ×3 loupe | Zumax SLH Prismatic ×5 loupe | Zeiss OPMI PICO Dental Operation Microscope (DOM) | |
|---|---|---|---|
| Magnification Ratios | 3.0 x | 5.0 x | 3.5x - 21x |
| Integrated light source | – | Wireless and magnetic light source 30.000Lx Curing filter: + | Halogen 12 V/100 W Orange polymerization filter: + |
| Pupillary distance | adjustable | adjustable | adjustable |
| Working distance | 420 mm | 430 mm | 200–300 mm |
| Depth of field | 65 mm | 55 mm | Provides a wide field of view with 3D image |
| Manufacturer | Zumax Medical Co.Ltd., Suzhou, China | Zumax Medical Co. Ltd., Suzhou, China | Carl Zeiss, Jena, Germany |
| Betch no | 201150 | 201256 | 6627507943 |
Fig. 3.
Magnification systems used in the study. (a) 3x loupe magnification, (b) 5x loupe, (c) dental operating microscope.
Table 1.
Descriptive table of materials used in the study.
| Material/Batch number | Composition | Manufacturer |
|---|---|---|
| Clearfil SE Bond 2 (3F0241) | Primer: 10-MDP, HEMA, camphorquinone, hydrophilic dimethacrylate, water | Kuraray Dental, Japan |
| Bonding: 10-MDP, Bis-GMA, HEMA, camphorquinone, hydrophobic dimethacrylate, N,N-diethanol p-toluidine bond, colloidal silica | ||
|
Clearfil Majesty Flow (A2) (1R0073) |
Matrix: TEGDMAc + D2.6E Filler: 75 wt%/62 vol%, silanated barium glass, silanated silica (silanated by proprietary silane coupling agent MUS) |
Kuraray Dental, Japan |
| Clearfil Majesty Posterior (A2) (9R0074) | Bis-GMA, TEGDMA, hydrophobic aromaticdimethacrylate, Glass ceramics, Surfacetreated alumina microfiller, silica | Kuraray Dental, Japan |
Information about the magnification systems used in the study is given in Table 2.
2.6. Clinical evaluation
Two experienced and calibrated dentists, not involved with the restoration procedures and therefore blinded to the group assignment, evaluated all the restorations once and independently using the FDI criteria at the 1-, 6- and 12-month follow-ups. Calibration was performed with published clinical samples [11] and illustrated documents of the revised FDI criteria, as specified in the calibration section of the recently published revised FDI criteria [12]. In a case of disagreement between the examiners, a consensus was reached by re-examination and discussion [[13], [14], [15], [16]].
Since this study focused on the effect of magnification use, not all of the FDI criteria were included. Criteria such as 'surface gloss,' 'staining,' 'color match and translucency,' and 'occlusal contour and wear' directly assess the material used. As only one filling material was used in this study, these criteria were not included. Criteria such as 'fracture and retention' and 'tooth integrity' were also not included as there were no fractures found in the teeth or restorations. Additionally, 'periodontal response' and 'oral and general health' were excluded from the study because they are individual-dependent criteria. Only clinically relevant measures for evaluating the performance of visual aids were used and scored, and not all features of the FDI criteria could be scored. The aesthetic anatomical form, proximal form, secondary caries, and adjacent mucosa criteria were visually assessed. The marginal adaptation parameter was assessed using a dental explorer with two sharp points of 150 μm and 250 μm (Deppeler, Geneva, Switzerland). In the patient's view criteria, patients were asked whether they were satisfied with the restorations by showing them restored teeth with the help of a mirror. In the evaluation of restorations,
Score 1: Clinically excellent.
Score 2: Clinically good.
Score 3: Clinically sufficient/satisfactory.
Score 4: Clinically unsatisfactory (but reparable)
Score 5: Clinically poor (replacement necessary) [11].
2.7. Statistical analysis
Data were analyzed with SPSS 23 (IBM, Chicago, IL, USA) package program. Conformity to the normal distribution was evaluated using the Shapiro‒Wilk test. The Kruskal‒Wallis test was used to compare the nonnormally distributed age in groups of three or more. The Kruskal‒Wallis test was used to compare categorical variables according to groups. Cochrans's Q test was used to compare pairwise scores three or more times within groups, the Friedman test was used to compare scores of three or more, and multiple comparisons were analyzed with Bonferroni correction. Analysis results are presented as the mean ± s for quantitative data. Categorical data are presented as the deviation and median (minimum–maximum) and as the frequency (percentage). The significance level was taken as p < 0.05.
3. Results
A total of 51 females (22.17 ± 1.29 years old) and 34 males (21.76 ± 2.49 years old), for a total of 85 volunteers (22 ± 1.88 years old), participated in this study. There was no difference between the mean age of the patients according to the groups (p = 0.984, Table 3).
Table 3.
Comparison of age by groups.
| Naked Eye | x3 loupe | x5 loupe | DOM | Total | p∗ | |
|---|---|---|---|---|---|---|
| Age | 22.16 ± 2.02 | 21.88 ± 1.67 | 21.88 ± 1.76 | 22.09 ± 2.13 | 22 ± 1.88 | 0.984 |
| 21 (20–28) | 22 (19–26) | 22 (19–27) | 22 (19–27) | 22 (19–28) |
The distribution of gender and restored tooth surfaces by groups is given in Table 4. Although the number of women (n = 76) whose teeth were restored in the study was higher than that of men (n = 54), no statistically significant difference was found between the groups in terms of gender distribution (p = 0.998). When the distribution of the restored tooth surface was examined, it was observed that the distal surface weight was dominant, but there was no significant difference between the groups (p = 0.996).
Table 4.
Comparison of gender and restored tooth surfaces by groups [n, (%)].
| Naked Eye | x3 loupe | x5 loupe | DOM | Total | p∗ | ||
|---|---|---|---|---|---|---|---|
| Gender | Women | 19 (59.4) | 19 (57.6) | 19 (57.6) | 19 (59.4) | 76 (58.5) | 0.998 |
| Men | 13 (40.6) | 14 (42.4) | 14 (42.4) | 13 (40.6) | 54 (41.5) | ||
| Surface | distal | 17 (53.1) | 18 (54.5) | 17 (51.5) | 17 (53.1) | 69 (53.1) | 0.996 |
| mesial | 15 (46.9) | 15 (45.5) | 16 (48.5) | 15 (46.9) | 61 (46.9) |
While clinical evaluation of the data was conducted, the groups (naked eye, ×3 loupe, ×5 loupe, and DOM) were compared in terms of the scores obtained during different control sessions (at 1, 6, and 12 months) for intergroup evaluation. Intragroup evaluations were performed by comparing the data obtained during different follow ups (at 1st, 6th, and 12th months) within each group (eye, ×3 loupe, ×5 loupe, and microscope). The scores from these evaluations and the data analysis are presented in Table 5.
Table 5.
Score distribution of restorations according to FDI criteria.
| 1 month |
6 months |
12 months |
|||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| NAKED EYE |
3x LOUPE |
5x LOUPE |
DOM |
NAKED EYE |
3x LOUPE |
5x LOUPE |
DOM |
NAKED EYE |
3x LOUPE |
5x LOUPE |
DOM |
||||||||||||||
| n | % | n | % | n | % | n | % | n | % | n | % | n | % | n | % | n | % | n | % | n | % | n | % | ||
| Aesthetic Anatomical Form | 1 | 23 | (71,9) | 29 | (87,9) | 30 | (90,9) | 27 | (84,4) | 23 | (71,9) | 29 | (87,9) | 30 | (90,9) | 27 | (84,4) | 23 | (71,9) | 28 | (84,8) | 30 | (90,9) | 27 | (84,4) |
| 2 | 8 | (25) | 4 | (12,1) | 3 | (9,1) | 5 | (15,6) | 7 | (21,9) | 4 | (12,1) | 3 | (9,1) | 5 | (15,6) | 7 | (21,9) | 5 | (15,2) | 3 | (9,1) | 5 | (15,6) | |
| 3 | 1 | (3,1) | 0 | – | 0 | – | 0 | – | 2 | (6,3) | 0 | – | 0 | – | 0 | – | 2 | (6,3) | 0 | – | 0 | – | 0 | – | |
| 4 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 5 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| Marginal Adaptation | 1 | 32 | (100) | 33 | (100) | 33 | (100) | 32 | (100) | 30 | (93,8) | 33 | (100) | 33 | (100) | 31 | (96,9) | 29 | (90,6) | 32 | (97) | 33 | (100) | 31 | (96,9) |
| 2 | 0 | – | 0 | – | 0 | – | 0 | – | 2 | (6,3) | 0 | – | 0 | – | 1 | (3,1) | 3 | (9,4) | 1 | (3) | 0 | – | 1 | (3,1) | |
| 3 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 4 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 5 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| Proximal Form | 1 | 26 | (81,3) | 29 | (87,9) | 31 | (93,9) | 29 | (90,6) | 26 | (81,3) | 30 | (90,9) | 31 | (93,9) | 28 | (87,5) | 25 | (78,1) | 30 | (90,9) | 31 | (93,9) | 28 | (87,5) |
| 2 | 4 | (12,5) | 4 | (12,1) | 2 | (6,1) | 2 | (6,3) | 4 | (12,5) | 3 | (9,1) | 2 | (6,1) | 3 | (9,4) | 5 | (15,6) | 3 | (9,1) | 2 | (6,1) | 3 | (9,4) | |
| 3 | 2 | (6,3) | 0 | – | 0 | – | 1 | (3,1) | 2 | (6,3) | 0 | – | 0 | – | 1 | (3,1) | 2 | (6,3) | 0 | – | 0 | – | 1 | (3,1) | |
| 4 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 5 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| Radiographic Examination | 1 | 32 | (100) | 33 | (100) | 33 | (100) | 32 | (100) | 32 | (100) | 33 | (100) | 33 | (100) | 32 | (100) | 32 | (100) | 33 | (100) | 33 | (100) | 32 | (100) |
| 2 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 3 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 4 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 5 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| Patient's View | 1 | 21 | (65,6) | 29 | (87,9) | 28a | (84,8) | 29 | (90,6) | 23 | (71,9) | 31 | (93,9) | 31 ab | (93,9) | 28 | (87,5) | 27 | (84,4) | 31 | (93,9) | 33b | (100) | 28 | (87,5) |
| 2 | 8 | (25) | 4 | (12,1) | 5 | (15,2) | 3 | (9,4) | 9 | (28,1) | 2 | (6,1) | 2 | (6,1) | 4 | (12,5) | 5 | (15,6) | 2 | (6,1) | 0 | – | 4 | (12,5) | |
| 3 | 3 | (9,4) | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 4 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 5 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| Post-op Sensitivity ve Vitality | 1 | 21 | (65,6) | 29 | (87,9) | 30 | (90,9) | 26 | (81,3) | 28 | (87,5) | 31 | (93,9) | 32 | (97) | 28 | (87,5) | 31 | (96,9) | 33 | (100) | 33 | (100) | 30 | (93,8) |
| 2 | 9 | (28,1) | 4 | (12,1) | 3 | (9,1) | 5 | (15,6) | 4 | (12,5) | 2 | (6,1) | 0 | – | 3 | (9,4) | 1 | (3,1) | 0 | – | 0 | – | 1 | (3,1) | |
| 3 | 2 | (6,3) | 0 | – | 0 | – | 1 | (3,1) | 0 | – | 0 | – | 0 | – | 1 | (3,1) | 0 | – | 0 | – | 0 | – | 1 | (3,1) | |
| 4 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 5 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| Secondary Caries | 1 | 32 | (100) | 33 | (100) | 33 | (100) | 32 | (100) | 32 | (100) | 33 | (100) | 33 | (100) | 32 | (100) | 32 | (100) | 33 | (100) | 33 | (100) | 32 | (100) |
| 2 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 3 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 4 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 5 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| Adjacent Mucosa | 1 | 27a | (84,4) | 30 | (90,9) | 33 | (100) | 31 | (96,9) | 32b | (100) | 33 | (100) | 33 | (100) | 32 | (100) | 32b | (100) | 33 | (100) | 33 | (100) | 32 | (100) |
| 2 | 5 | (15,6) | 3 | (9,1) | 0 | – | 1 | (3,1) | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 3 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 4 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| 5 | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | 0 | – | |
| Clinical Success Rate | 32 | (100) | 33 | (100) | 33 | (100) | 32 | (100) | 32 | (100) | 33 | (100) | 33 | (100) | 32 | (100) | 32 | (100) | 33 | (100) | 33 | (100) | 32 | (100) | |
Superscript letters indicate significant differences between groups follow times by Cochran's Q test.
For all the criteria assessed, including aesthetic anatomical form, marginal adaptation, proximal form, radiographic examination, patient's perspective, postoperative sensitivity and vitality, secondary caries, and adjacent mucosa, no statistically significant differences were found between the groups at 1, 6, and 12 months (p > 0.05).
In terms of the patient's view criteria, the ×5 loupe group scores showed a statistically significant improvement over time (p = 0.022). Regarding the adjacent mucosa criteria, the scores of the naked eye group in the 1st month were significantly worse than the scores in the 12th month (p = 0.007). All restorations achieved 100 % success, with scores of 1, 2, and 3 in all criteria at the 1-, 6-, and 12-month follow-ups.
4. Discussion
The study results showed no statistically significant difference between restorations made with different magnification systems (naked eye, ×3 loupe, ×5 loupe, DOM) according to the FDI criteria. Additionally, all of the direct composite restorations were deemed successful (Score 1, 2, 3) in the 12-month follow-up evaluation. Therefore, the hypothesis that there would be no difference in the clinical performance of restorations made using different magnification systems during the 12-month follow-up period was accepted.
When reviewed, many studies from the field of endodontics were found in the literature due to the more widespread use of dental loupes and the dental operating microscope [[17], [18], [19]]. In the literature, there are in vitro studies that investigate the effects of magnification aids on the marginal integrity of proximal composite resin restorations [20], initial occlusal caries diagnosis and treatment decisions [21], cavity dimensions during the removal of old restorations [22], and damage to adjacent teeth during Class II preparation [23]. Given the absence of any existing research in the literature assessing the impact of visual aids on the outcomes of posterior direct composite restorations, the authors believe that this study can be regarded as a valuable contribution to knowledge.
In a study designed to evaluate the quality of MO Class II cavity preparations performed by dental students using loupes and compare them to preparations made without loupes, the results indicated that cavity preparations were superior when loupes were used compared to those performed with the naked eye. These findings were attributed to the enhanced level of detail and clearer visualization of the operating area facilitated by the use of loupes [20]. Similarly, when examining the scores for the aesthetic anatomical form criteria in this study, the groups utilizing the magnification system received a Score 1, denoting more ideal forms compared to the naked-eye group.
The quality of marginal adaptation is the result of both the properties of the adhesive, luting resin/cement, and restorative material, as well as the operator's skill and knowledge to create a good restoration (adequate cavity preparation, isolation-moisture control, application of materials according to instructions for use) [11,24]. In a study evaluating the success of pit and fissure sealant application performed under the naked eye, loupe, and microscope, all of the fissure sealants made with the microscope were found to be very successful, while the pit and fissure sealant applications made with the loupe were found to be more successful than those performed with the naked eye [25]. Considering dental assistant and high patient cooperation requirements of the dental operating microscope, the use of loupes with ×3 and ×5 magnification is considered sufficient for the restoration of moderately deep decayed teeth, since there was no difference in terms of marginal adaptation criteria in this study.
In a study investigating the effect of using loupes on cavity size changes during removal of the old restoration, it was shown that there was an increase in cavity size in both groups with the naked eye and loupe; although it was not statistically significant, the use of loupe decreased the increase in size compared to the bare eye; in other words, it provided a more conservative study [22]. In another study investigating the effect of loupe use on damage to adjacent tooth surfaces during cavity preparation, no statistically significant difference was found between the use of 2.x5 loupe and naked eye groups [23]. In this study, the groups using the magnification system in the proximal form criteria were found to be more successful than the naked eye group, although it was not statistically significant. It is thought that the use of magnification to better visualize band adaptation and contact with the contact tooth, as well as reduce adjacent tooth damage, is effective in this result.
Frankenberger et al. found that the use of loupes reduces the risk of overhang formation by 40 % [26]. Atlas et al. evaluated the preparation using 10x and ×3 loupes with mCT and reported that 10x magnification provided a more sensitive marginal fit [27]. All of the restorations in this study received a clinically perfect 'Score 1′, as they did not show negative/positive steps or marginal spaces. It is thought that this result may be due to the absence of crowding in the teeth that would complicate the restoration, working with patients with good cooperation, and the caries lesion being above the gingival level.
When the notes taken about the restorations evaluated with a clinically good ‘Score 2’ and a clinically sufficient 'Score 3′ in the patient's view criteria were examined, it was seen that the patients had complaints about roughness and occlusion. Although the patients were asked questions about the roughness and feeling of height at the end of the restoration, it is thought that the fact that they noticed the possible height and roughness only at the 1st month control due to the effect of local anesthesia may have an effect on the 1st month scores.
Baumann et al. investigated the effect of the use of loupes during the debonding phase of orthodontic brackets on iatrogenic damage and residual composite residues on tooth surfaces and showed that the use of magnification significantly reduced enamel damage and the amount of composite residue remaining on the surface during adhesive removal [28]. Based on the fact that magnification provides a better visualization of the adhesive or composite residues remaining on the enamel surface, the fact that patients in the naked eye group reported a feeling of roughness and were evaluated with a greater 'Score 2’ in this study is consistent with the study of Baumann et al.
There was no significant difference between the groups in the postoperative sensitivity criteria. It is thought that the reason may be the same caries depth, cleaning method, bonding system, and restorative material, which are the main factors for postoperative sensitivity. In one study, the effect of magnification on the duration of nonsurgical endodontic treatment was investigated, and it was shown that the use of loupes shortened the treatment period [29]. Similar to that study, in this study, the groups using magnification in the 1st month controls received a 'Score 2′, which defines minor sensitivity for a limited time compared to the naked eye group and that working for a shorter time in noncarious tissue with better visual acuity during the restorative procedure reduces thermal damage to the tooth. can be attributed to its positive effect on postoperative sensitivity.
Since no secondary caries were observed in any restoration in our study, all of them received a ‘Score 1’. In the adjacent mucosa criteria, there was no significant difference between the groups. The presence of a 'Score 2′ in the 1st month of controls was caused by mechanical irritations during the restorative procedures, and an improvement was observed in the mucosa adjacent to the restoration in the following control sessions.
In this study, the difficulty of having four interproximal carious lesions with a depth of D2 in each mouth and the significant restriction this procedure would impose on the available patient pool made it impossible to use a split-mouth design for group assignment. Additionally, the maximum follow-up period being limited to 12 months is another limitation of this study. Furthermore, while there are generally in vitro studies on loupes and magnification in the literature, there are no clinical studies evaluating restorations performed with devices of different magnifications using FDI criteria. Consequently, the findings are primarily assessed within the context of our study data, and it was not possible to compare and discuss them with findings from similar studies in the literature. Nevertheless, this study may inspire future research involving larger populations, a greater number of restorations, or different types of restorations. Additionally, it could provide a foundation for further clinical studies on the use of magnification systems in restorative procedures.
5. Conclusion
Although there was no statistically significant difference in the 12-month follow-up period in total, restorations made using a magnification system (x3 loupe, ×5 loupe, DOM) were more successful than restorations made with the naked eye in terms of aesthetic anatomical form, marginal adaptation, proximal form, patient's view, and postoperative sensitivity. This suggests that magnification systems may boost the quality of restorations by improving precision and overall outcomes. While the improvements observed are promising, further research with longer follow-up periods is necessary to confirm the long-term benefits of magnification in restorative procedures. The current findings support the recommendation of incorporating magnification tools into clinical practice to potentially achieve better restorative results.
CRediT authorship contribution statement
İpek Çubukcu: Writing – review & editing, Writing – original draft, Visualization, Validation, Software, Resources, Project administration, Methodology, Formal analysis, Data curation, Conceptualization. Merve İşcan Yapar: Writing – original draft, Supervision, Project administration, Methodology, Formal analysis, Conceptualization.
Informed consent
The patients signed a consent form approved by the ethical committee of Ataturk University after having received comprehensive information.
Ethics approval
All procedures performed in this study were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments. The study design was approved by the Ataturk University ethics committee (Approval No: B.30.2.ATA.0.01.00/253). The study has been registered at ClinicalTrials.gov as NCT05959382.
Funding
This work was supported by the Scientific Research Project Fund of Ataturk University – Project Number: TDH-2021-9645.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
The authors would like to express their gratitude to Assoc. Prof. Dr. Fatih Şengül for his valuable contributions.
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