|Year : 2021 | Volume
| Issue : 1 | Page : 10-16
Clinical evaluation of sectional matrix versus circumferential matrix for reproduction of proximal contact by undergraduate students and postgraduate dentists: A randomized controlled trial
Omar Osama Shaalan, Shereen Hafez Ibrahim
Conservative Dentistry Department, Faculty of Dentistry, Cairo University, Cairo, Egypt
|Date of Submission||26-Sep-2020|
|Date of Decision||29-Oct-2020|
|Date of Acceptance||23-Nov-2020|
|Date of Web Publication||28-Jan-2021|
Dr. Omar Osama Shaalan
Conservative Dentistry Department, Faculty of Dentistry, Cairo University, Cairo, Egypt, Postal address: 35 Mohamad Farid Street El Hay El Motamayz, Sixth of October City, Giza.
Source of Support: None, Conflict of Interest: None
Aim: In clinical practice, obtaining physiologic proximal contact points is essential for protection of balance and harmony of the stomatognathic system. Consequently, challenges have emerged due to the technique sensitivity of the restorative procedures of posterior proximal resin composite restorations. This study aimed at assessing the influence of different matricing techniques; either sectional matrix or circumferential matrix and operator experience; either undergraduate students or postgraduate dentists on reproduction of optimum proximal contacts for posterior proximal resin composite restorations. Materials and Methods: A total of 60 patients were enrolled; after class II cavity preparation, matrix systems were applied by undergraduate students or postgraduate dentists, by using either sectional matrix or circumferential matrix systems. Cavity preparations were restored by using resin composite restorations according to manufacturers’ instructions. Tightness of proximal contacts was evaluated by using dental floss according to FDI recommendations to be either optimum, tight, or open contact. Chi-square test was used to compare between groups; P value ≤ 0.05 was considered statistically significant. Relative risk (RR) was used to determine the clinical significance. Results: There was a statistically significant difference between the sectional matricing technique and the circumferential matricing technique (P < 0.0001). There was less risk of poor proximal contact (tight or open) with the sectional matrix system, and the risk was 70% less than the circumferential matrix. Conclusions: Optimum contact points were highly associated with the sectional matrix system. Open and tight contacts were highly associated with the circumferential matrix system regardless of operator experience.
Keywords: Circumferential, Class II, Contact, FDI, Matrix Band, Proximal, Resin Composite, Sectional
|How to cite this article:|
Shaalan OO, Ibrahim SH. Clinical evaluation of sectional matrix versus circumferential matrix for reproduction of proximal contact by undergraduate students and postgraduate dentists: A randomized controlled trial. J Int Oral Health 2021;13:10-6
|How to cite this URL:|
Shaalan OO, Ibrahim SH. Clinical evaluation of sectional matrix versus circumferential matrix for reproduction of proximal contact by undergraduate students and postgraduate dentists: A randomized controlled trial. J Int Oral Health [serial online] 2021 [cited 2021 Mar 5];13:10-6. Available from: https://www.jioh.org/text.asp?2021/13/1/10/308366
| Introduction|| |
The proximal contacts protect the stomatognathic system as well as the periodontium against damage by providing harmony and balance. Failure to reproduce contact area will cause subsequent periodontal diseases and tooth movements. It continues to represent a great obstacle for dental practitioners to restore optimum proximal contours and contact points with resin composites. Restorations should compensate for the volumetric polymerization shrinkage of restorations as well as thickness of the matrix band. Several restorative approaches have been encouraged to obtain optimum proximal contacts using resin composite restorations. In this perspective, the selection of the matricing system and interdental separation method has a significant influence. In daily dental practice, conventional circumferential matricing systems are the most commonly used, but they show some limitations regarding the reproduction of correct proximal contacts, in addition to their inappropriate matrix contour.
The development of unique matrix armamentarium appropriate to non-condensing composite resin was a vital challenge. The consistent creation of optimum, anatomically correct proximal contacts can be unpredictable. Further, there is an increased demand for the superior aesthetics afforded by resin composite restorative materials; the competitive practitioner must, thus, develop the skills required to place multiple restorations in a single visit, without compromising the quality of the final restorations. The interdental separation technique and the introduction of several matrix systems seem to have a substantial effect on the reproduced proximal contours and contact points. In previous laboratory and clinical studies, sectional matrix systems in conjunction with separation rings proved to produce proximal contact with consistent contact tightness in compound proximal restorations.,, Several laboratory studies,,,, have verified that using an interdental separation ring may arrange for optimum contact tightness and contours in proximal composite restoration; these findings have been recently proven in clinical trials.,
Looking forward in providing advanced dental health care to patients, it is essential that dental graduates be skilled in a range of techniques, including posterior proximal resin composite restorations. In clinical practice, obtaining physiologically optimum proximal contours and contact points is similarly important.,,,,, Consequently, new challenges have emerged due to the technique sensitivity of the restorative procedures during posterior proximal resin composite restorations; operator experience and skills may have an influence on the resulting outcome. The current randomized clinical trial aimed at assessing the influence of different matricing techniques; either sectional matrix or circumferential matrix and the influence of operator experience; either undergraduate students or postgraduate dentists on reproduction of optimum proximal contacts for posterior proximal resin composite restorations. The null hypothesis tested was that there will be no difference between the matricing technique and operator experience on reproduction of optimal proximal contact points in posterior teeth.
| Materials and Methods|| |
Setting and design
This study was conducted at the clinic of the conservative dentistry department, Faculty of Dentistry, Cairo University. Protocol of this study was registered in clinicaltrials.gov (NCT03795727) after approval of Research Ethics Committee (No.2-2-20). The type of the current study is a randomized controlled trial, with four parallel groups and a 1:1 allocation ratio. The study started in spring semester from February 2019 till May 2019. The sampling method was convenient consecutive sampling by selecting every subject meeting the inclusion criteria until the required sample was achieved. The selection criteria for recruitment of the participants were patients with compound class II cavities, good oral hygiene, no spacing or crowding, and healthy periodontium; however, patients with complex class II cavities, poor oral hygiene, spacing or crowding, or any evidence of periodontal disease were excluded.
Sample size calculation
Sample size was calculated by using G*Power version 18.104.22.168 based on the previous study, which indicated that the probability of open contact among controls (circumferential matrix) is 0.949, probability of tight contact is 0.051, and probability of optimum contact is 0.001. If the probability of open contact among the intervention group (sectional matrix) is 0.282, probability of tight contact is 0.069, and probability of optimum contact is 0.649, we will need to study a total of 48 restorations (n = 12) in each group to be able to reject the null hypothesis that the success rates for cases and controls are equal with a probability (power) of 0.8. The Type I error probability associated with the test of this null hypothesis is 0.05. After the patient’s recruitment and due to availability of cases, sample size was increased to a total of 60 cases. Proximal cavity preparations were randomly divided into four groups according to the matrix system and operator experience: group 1: sectional matrix and undergraduate students; group 2: sectional matrix and postgraduate dentists; group 3: circumferential matrix and undergraduate students; and group 4: circumferential matrix and postgraduate dentists (n = 15). Consort flow diagram shows the flow of participants through each stage of the current randomized clinical trial [Figure 1].
Sequence generation, allocation concealment, and blinding
A total of 60 patients ranging from 18 to 40 years old were enrolled. Sequence generation was accomplished by using simple randomization by generating numbers from 1:60 using (www.random.org) into four columns. The care givers obtained random numbers from an opaque sealed envelope, which was prepared by the dental assistant, who was not involved in any phases of this clinical trial. Due to the variations in application protocol of the matricing systems, caregivers were not blinded to the matrix assignment; but the outcome assessors and participants were blinded.
Local anesthesia was administrated, and the whole quadrant containing the offending tooth was isolated by using a rubber dam. After caries removal and cavity preparation, matrix systems were applied by undergraduate students or postgraduate dentists; using either a sectional matrix system (MD ring (TOR VM, Moscow, Russia) and pre-contoured sectional matrix with 0.035 mm thickness) or a circumferential matrix system (Tofflemire retainer device, Kerr, CA, USA) and circumferential matrix with 0.038 mm thickness). A properly sized wedge was used with both systems to secure both matrices in place cervically and to prevent gingival overhangs [Figure 2], Resin composite restorations were completed according to the manufacturer’s instructions [Table 1].
|Figure 2: Dental matrix systems: (a) circumferential matrix system; (b) sectional matrix system|
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|Table 1: Materials’ specifications, manufacturer’s instructions, and composition|
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Selective enamel etching was performed by using ScotchbondTM Universal etchant (3M ESPE, USA), followed by applying Single Bond Universal adhesive (3M ESPE, USA) to the entire surface of the enamel and dentin. Then, a thin layer of Filtek™ Z350XT flowable (3M ESPE, USA) was applied to ensure adaptation at the gingival margin. Finally, prepared cavities were restored by using resin composite Filtek™ Z350XT (3M ESPE, USA) using the centripetal technique to build a proximal wall initially followed by successive cusp building. Restorations were finished by using a flame-shaped finishing stone (MANI, Japan) and polished by using Opti1 step (Kerr, CA, USA), and the occlusal contact points were checked by using a 40-mm articulating paper (Bausch, Nashua, New Hampshire, USA).
Assessment of proximal contacts
Tightness of proximal contacts was evaluated using dental floss by two blinded assessors. For assessment of the restoration, the patients were sitting in a dental unit with a standardized seating position, which was reproduced by the unit’s preset positioning system, and assessors evaluated the proximal contact by using unwaxed dental floss (Oral-B, Procter and Gamble, USA) following the FDI recommendations accordingly to be either optimum, tight, or open contact. Proximal contacts were categorized as optimum, open, and tight; if the dental floss passed through the contact area as natural dentition on the other side, it was considered as an optimum contact point. Open contact points were considered when the dental floss passed through the contact area without resistance; however, when the dental floss could not be passed at all or tore, proximal contact was considered as tight.
Statistical analysis was performed with MedCalc software (MedCalc Software bvba) version 19 for Windows. Chi-square test was used to compare between different groups, to investigate the association between the type of matrix system or operator experience and tightness of the proximal contact area. A value of P ≤ 0.05 was considered statistically significant. RR was used to determine the clinical significance.
| Results|| |
There was a statistically significant difference between the sectional matricing technique and the circumferential matricing technique (P < 0.0001). [Table 2] shows frequency (n) and percentage of tightness of proximal contacts produced by the sectional matrix system or the circumferential matrix system for undergraduate students and postgraduate dentists.
|Table 2: Frequency (n) and percentage of tightness of proximal contacts produced by sectional matrix system or circumferential matrix system for under-graduate students and post-graduate dentists|
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| Discussion|| |
In the current study, regardless of the operator experience; optimum contacts were present in 21 teeth (35%); 21 of optimum contacts (100%) were present with the sectional matrix system, and none were found with the circumferential matrix system (0%). Tight contacts were present in 11 teeth (18.3%), two were present with the sectional matrix system (18.2%), and nine were found with the circumferential matrix system (81.8%). Open contacts were present in 28 teeth (46.7%), seven were present with the sectional matrix system (25%), and 21 were found with the circumferential matrix system (75%). The results of the current study revealed that operator experience has no statistically significant influence on tightness of proximal contact regardless of the matrix system used; within either the sectional matrix system (P = 0.2765) or the circumferential matrix system (P = 0.2399). However, among undergraduate students, there was a statistically significant difference between the sectional matrix system and the circumferential matrix system (P = 0.0014). Further, among postgraduate dentists, there was a statistically significant difference between the sectional matrix system and the circumferential matrix system (P < 0.0001).
Among all groups, there was a statistically significant difference between the sectional matricing technique and the circumferential matricing technique (P < 0.0001). Optimum contacts were highly associated with the sectional matrix system, whereas open and tight contacts were highly associated with the circumferential matrix system regardless of operator experience; poor (tight or open) contacts were found generally in undergraduate students using the circumferential matrix system, therefore the null hypothesis was rejected. There is less risk of poor proximal contact (tight or open) with the sectional matrix system; the risk was 70% lower than the circumferential matrix (RR= 0.3 (95% CI 0.1737 to 0.5182; P < 0.0001)), and this was clinically significant.
Mastering proximal restoration with direct resin composite restoration is very crucial. It is commonly believed that the success of posterior composite restorations is due to: the skill of the operator as well as the material’s characteristics and placement techniques. The matrix systems and wedges are essentially required for proximal contact reproduction and adaptation to the cavity margins.
Dental students may experience some difficulties in the placement of posterior composite restorations, with subsequent failure if the procedure is not performed properly. Experts recommend that dental students have an obvious understanding of the basics and principles as well as technicality of clinical restorative procedures.,,, A survey investigated the techniques used by UK dentists when placing posterior proximal resin composite restorations: 61% of dentists used circumferential matrix systems, whereas only 10% used sectional matrix systems; these finding emphasize that sectional matrix systems were not universally applied for matricing during posterior proximal restorations.
In the current study, sectional matrix systems produced optimum proximal contact points when compared with circumferential matrix systems; this was in agreement with various studies that demonstrated that pre-contoured sectional matrix bands had superior contours in comparison to flat circumferential matrix bands.,, Standardized restorative procedures were implemented for all carious teeth. However, the only differences were using a separation ring in association with a pre-contoured sectional matrix or the circumferential matrix system combined only with the pressure of interdental wedges. Therefore, the enhanced contact tightness can be accredited to the combination of the pre-contoured sectional matrix and the interdental separation ring or to the sectional matrix only or to the separation ring only.
Previous studies,, observed statistically significant differences in contact tightness between circumferential and sectional matrix systems. Pre-contoured sectional matrices accompanied with interdental separation rings produced a substantial increase in the overall contact tightness of proximal restorations, and the use of flat circumferential matrices produced a considerable decrease in the contact tightness compared with the baseline situation before restorative treatment; this was in accordance with the current study. A possible factor affecting the contact tightness is the matrix thickness and shape.
A recent clinical trial found a strong association between restoration overhang and different matrix band systems. It was observed that there was absence of any restoration overhang in cavities restored with sectional matrix systems. An optimum proximal contour was achieved with sectional matrix systems accompanied with a separation ring; these findings support the outcomes of the current clinical trial. Minimal number of restorations in the pre-contoured sectional matrix group exhibited poor proximal contacts or contours; this is probably due to the fact that either the interdental separation ring itself was not effective in teeth separation, or the clinician was incapable of placing it efficiently.
It is well known that the use of sectional matrices is technique sensitive due to their rounded contours; sometimes, it is difficult for them to be applied correctly, especially when the contact between neighboring teeth is broad and tight without causing a depression or bending in the matrix. Further, such a pre-contoured matrix contravenes with matrix customization in the contact area for each case individually. These limitations will allow skilled and experienced operators to reproduce proximal contact points with sectional matrix systems better than inexperienced operators.,
Likewise, the reasons behind open proximal contact in the circumferential matrix group could be attributed to reasonably insufficient movement of adjacent teeth resulting from wedge placement and a flat matrix band. Wooden wedges swell on exposure to moisture in the oral cavity, this was believed to aid in interdental separation and adaption of the matrix band cervically. However, when wooden wedges absorb oral fluids they become fragile and flexible, and they adapt only to the natural anatomic proximal contour, resulting in a less amount of interdental separation. Tight contact points were present with the circumferential matrix system at a higher level occlusally; dental floss could not pass or tore on placement. A randomized clinical trial found that open contact points were highly associated with the circumferential matrix system and there are more chances of proximal overhangs and faulty contact points when restorations are done by using the circumferential matrix system. The current results were consistent with previous research where optimum proximal contact points and contours of posterior proximal resin composite restorations were present with sectional matrix systems and absent with conventional circumferential matrix systems with a wooden wedge.,,
Failure to reproduce contact area will cause subsequent periodontal diseases and tooth movements. Conventional circumferential matrix systems produced poor proximal contact points with proximal overhangs or open contacts, and they failed to produce optimum contact points; thus, their usage should be prohibited. Sectional matrix systems with separation rings should be implemented as the first choice in clinical decision making for proximal posterior restorations.
| Conclusions|| |
Outcomes of the current research revealed that optimum contact points were highly associated with the sectional matrix system; there was a 70% lower risk for non-optimum contact points than the circumferential matrix system. Open and tight contacts were highly associated with the circumferential matrix system regardless of operator experience. These findings highlighted the fact that contact tightness of proximal restorations is not only related with the contours. Actually, proximal contact tightness is greatly dependent on the restorative technique applied, skills of the clinician, as well as the operator experience.
Future scope/clinical significance
It is recommended to generalize and implement the use of sectional matrix systems with separation rings in daily practice for all dental practitioners. Dental students and less experienced dentists must be trained to master using sectional matrix systems to provide optimum oral health care to their patients.
Financial support and sponsorship
Conflict of interest
The authors declare that there are no conflicts of interest.
Omar Osama Shaalan: Concepts, design, definition of intellectual content, literature search, data acquisition, data analysis, statistical analysis, sample size calculation, manuscript preparation, manuscript editing, manuscript review, and guarantor. Shereen Hafez Ibrahim: Concepts, design, definition of intellectual content, literature search, data acquisition, data analysis, manuscript preparation, manuscript editing, manuscript review, and guarantor.
Ethical policy and institutional review board statement
This randomized controlled trial was accomplished at the clinic of the conservative dentistry department, after approval of the Research Ethics Committee (No.2-2-20). Protocol of this study was registered in clinicaltrials.gov with unique identification number NCT03795727.
Patient declaration of consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/ have given his/ her/ their consent for his/ her/ their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Data availability statement
The data that support the findings of this study are available from the corresponding author, on reasonable request.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]