Evaluation of Matrix Band Systems for Posterior Proximal Restorations among Egyptian Dentists: A Cross-Sectional Survey.

OBJECTIVES: This study aimed to investigate the techniques of matricing used by Egyptian dentists, and evaluate the influence of these techniques on the reproduction of optimum proximal contacts for posterior proximal resin composite restorations.
MATERIAL AND METHODS: An online questionnaire was developed and sent to 785 dentists via e-mail and social media platforms. The survey asked the participants about the following: the highest academic degree achieved and their experience, techniques of matricing used, brands of matricing systems used, assessment of proximal contact points, their evaluation of the contact points they reproduced, and their assessment of the restorations' emergence profiles.
RESULTS: A total of 415 dentists participated in the study (response rate 52.8%). 308, (74%), dentists preferred using the sectional matrix system, while 107 dentists, (26%), preferred using the circumferential matrix system. One hundred twenty-six dentists, (31%), reported that the circumferential matrix systems reproduced optimum contacts, 105 dentists, (25%), reported tight contacts and 184 dentists, (44%), reported open contacts. However, for the sectional matrix systems, the optimum contacts were reported by 279 dentists, (67%), tight contacts by 109 dentists, (26%), and open contacts by 27 dentists, (7%). There was a statistically significant difference between the sectional matrix systems and the circumferential matrix systems regarding the tightness of the proximal contact points (P<0.0001).
CONCLUSIONS: Egyptian dentists preferred using the sectional matrix systems. The survey indicated that optimum contact points were highly associated with the sectional matrix systems, while poor (open and tight) contacts were highly associated with the circumferential matrix systems.

Introduction:

Proximal contact points between the teeth protect the integrity of the stomatognathic system by providing a balance against the anterior component of the force created by the tendency of teeth for mesial drifting (). Failure to recreate contact points will break the equilibrium and harmony, and the remaining components of the stomatognathic system will spontaneously try to establish a new equilibrium ().

A great challenge for dentists is to reproduce optimum contact points while trying to achieve clinically well-accepted restorations, especially with resin composite materials. Proximal restorations should compensate for the thickness of the matrix band, and for inevitable polymerization shrinkage of the resin restorative material. Numerous techniques have been implemented to achieve optimum contact points with proximal resin composite restorations (). In this respect, the selection of a proper matrix system and separation technique is a significant factor. In the past, traditional circumferential matrix systems were the most common matrices used by dentists, although they exhibited limitations in reproducing correct proximal contact points, and improper flat matrix contour ().

The introduction of the separation ring and pre-contoured sectional matrix systems had a substantial influence on the tightness of the resultant proximal contacts of dental restorations, along with a consistent contact tightness (–). However, the reliability and repeatability of the recreation of optimum, anatomically correct proximal contact points can sometimes be unpredictable. Thus, dental practitioners must develop the essential skills, gain the necessary experience and acquire an appropriate armamentarium to provide optimum oral health care for their patients, to be able to restore missing surfaces of teeth back to normal function and esthetics without compromising any biological or mechanical aspect (). Based on the above-mentioned data, the current cross-sectional survey aimed to investigate the techniques of matricing used by Egyptian dentists and evaluate the influence of these techniques on the reproduction of optimum proximal contacts for posterior proximal resin composite restorations.

Material and Methods

An online questionnaire was developed by a staff member at the Faculty of Dentistry, Cairo University, via Google forms. It was sent to 785 dentists who were representing faculties of dentistry among the Greater Cairo Governate through the period of one month, between the 8th of June and the 8th of July 2020, either via e-mail or social media platforms (Facebook and WhatsApp, San Francisco, California, USA). The questionnaire included eleven questions asking the participants about their highest academic degree achieved, experience, techniques of matricing used, brands of matricing systems used, assessment of proximal contact points, their evaluation of the contact points they reproduced and their assessment of the emergence profiles of restorations (Table 1). Proximal contacts were categorized as optimum, open and tight. If dental floss passed through the contact area as natural dentition on the other side, it was considered as optimum contact point. Open contact points were considered when dental floss passed through the contact area without resistance, while proximal contact was considered as tight when dental floss could not be passed at all or was torn ().

Table 1

Questionnaire

Questions	Answers
a- What is your highest academic degree?	1. BDS     2. MSc     3. DDSc/PhD     4. Egyptian fellowship board
b- Which technique of matricing do you prefer to use?	1. Circumferential     2. Sectional
c- Which technique is the easiest to apply?	1. Circumferential     2. Sectional
d- If you use circumferential matricing, which holder do you use?	1. Tofflemire (not branded).     2. Ivory no. 2 (not branded).     3. Ivory no. 8 (not branded).     4. Automatrix, Dentsply Sirona, Konstanz, Germany.     5. Do not use
e- If you use sectional matrix, which system do you use?	1. Classic ring and pre-contoured matrix, TOR VM, Moscow, Russia.     2. Delta ring and pre-contoured matrix, TOR VM, Moscow, Russia.     3. MD ring and pre-contoured matrix, TOR VM, Moscow, Russia.     4. Saddle holder and pre-contoured matrix, TOR VM, Moscow, Russia.     5. Composi-Tight 3DFusion and pre-contoured matrix, Garrison Dental Solutions, Spring Lake, Michigan, USA.     6. Palodent V3 ring and pre-contoured matrix, Dentsply Sirona, Konstanz, Germany.     7. Ena ring and pre-contoured matrix, Micerium, Italy.     8. Twin ring and pre-contoured matrix, Bioclear, Tacoma/WA, USA.     9. Do not use     10. Other.
f- Which kind of wedge do you use?	1. Wooden wedges (not branded).     2. Diamond, Bioclear, Tacoma/WA, USA.     3. Elastic wedges, TOR VM, Moscow, Russia.     4. Plastic wedges, TOR VM, Moscow, Russia.     5. Other.
g- Do you use dental floss to check contact tightness after restoration?	1. Yes     2. No
h- When you use circumferential matrix systems, describe tightness of the contact produced?	1. Optimum: Dental floss pass through contact area as natural dentition on the other side     2. Open: Dental floss pass without resistance.     3. Tight: Dental floss could not be passed at all or was torn.
i- Describe emergence profile (cervical outline of restoration as it emerges from periodontium) produced with circumferential matrix	1. Proper     2. Improper
j- When you use sectional matrix systems, describe tightness of the contact produced?	1. Optimum: Dental floss pass through contact area as natural dentition on the other side     2. Open: Dental floss pass without resistance.     3. Tight: Dental floss could not be passed at all or was torn.
k. Describe emergence profile (cervical outline of restoration as it emerges from periodontium) produced with sectional matrix	1. Proper     2. Improper

The sample size was calculated using StatCalc version 1.4.3 (Epi InfoTM, CDC, Atlanta, Georgia, USA) using the random sampling test, implementing 120000 population size, 95% of confidence level and 5% of confidence limits. To be able to represent the total dentist population, the calculated sample size was a total of 383 participants. Data were collected anonymously from Google forms.

Statistical analysis

Statistical analysis was performed using the MedCalc software (MedCalc Software bvba) version 19 for Windows. Data were analyzed using descriptive statistics and represented as frequency and percentage in pie charts. The Chi-square test was used to compare the tightness of proximal contact points reported by participants, either for circumferential matrix systems or sectional matrix systems. A P value ≤ 0.05 was considered statistically significant.

Results

A total of 415 dentists participated in the current survey with a response rate of 52.8%. Figure 1 is a pie chart representing the results of the questionnaire. Two hundred fifteen dentists, (52%), were Bachelor of Dental Surgery (BDS) holders, 136 (33%) were Master of Science (MSc) holders, 44 (10%) were Doctor of Dental Sciences/ Doctor of Philosophy (DDSc/PhD) holders and 20 dentists, (5%),were holders of the Egyptian Fellowship Board of Dentistry. Three hundred eight dentists, (74%), preferred using the sectional matrix system, while 107 dentists, (26%), preferred using the circumferential matrix system. Two hundred sixty-three dentists, (63%), selected the sectional matrix systems as easily used and placed, while 152 dentists, (37%), selected the circumferential matrix systems as easily used and placed. Regarding the dentists who used the circumferential matrix systems, 333 dentists, (80.2%), used the Tofflemire holder, while 19 dentists, (4.6%), used the Ivory no.2 holder, 8 dentists, (2%), used the Ivory no. 8 holder, and 3 dentists, (0.7%), used the Automatrix holder (Dentsply Sirona, Konstanz, Germany). Fifty-two dentists, (12.5%), reported not using the circumferential matrix systems at all, and they used only the sectional matrix systems.

Figure 1

Pie charts denoting results of the questionnaire

Concerning the dentists who used the sectional matrix systems, 95 dentists, (22.9%), used the classic ring system (TOR VM, Moscow, Russia), 86 dentists, (20.7%), used the Composi-Tight system (Garrison Dental Solutions, Spring Lake, MI, USA) 68 dentists, (16.4%), used the delta ring system (TOR VM, Moscow, Russia), 63 dentists, (15.2%), used the Palodent V3 system (Dentsply Sirona, Konstanz, Germany), 26 dentists, (6.3%), used the MD ring system (TOR VM, Moscow, Russia), 12 dentists, (2.9%), used the Ena ring system (Micerium, Avegno, Genoa, Italy), 4 dentists, (1%), used the saddle system (TOR VM, Moscow, Russia) and 3 dentists, (0.7%), used the Twin ring system (Bioclear, Tacoma, WA, USA). Fifty-eight dentists, (13.9%), reported not using the sectional matrix systems at all, and they used only the circumferential matrix systems. Two hundred forty-six dentists, (59%), used wooden wedges, while 75 dentists, (18%), used diamond wedges, 68 dentists, (17%,) used plastic wedges and 26 dentists, (6%), used elastic wedges. Three hundred thirty-eight dentists, (81%), out of 415 dentists checked the tightness of proximal contact after restorations, while 77 dentists, (19%), did not check the tightness of proximal contacts.

One hundred twenty-six dentists, (31%), reported optimum contacts, 105 dentists, (25%), reported tight contacts and 184 dentists, (44%), reported open contacts with the circumferential matrix systems. The improper emergence profile of proximal contour was reported by 348 dentists, (95.8%). However, regarding the sectional matrix systems, optimum contacts were reported by 279 dentists, (67%), tight contacts by 109 dentists, (26%), and open contacts by 27 dentists, (7%). The proper emergence profile of proximal contour was reported by 347 dentists, (97.2%). There was a statistically significant difference between the sectional matrix systems and the circumferential matrix systems regarding the tightness of the proximal contact points as reported by dentists (P<0.0001)

Discussion:

Mastering proximal tooth-colored restorations with resin composite is very critical. The success of posterior composite restorations is attributed to the operator’s skills, the characteristics of the material as well as the placement techniques used (). Numerous studies confirmed that pre-contoured sectional matrix bands provided the resin restorations with optimum contours and emergence profiles when compared to conventional flat circumferential matrix bands (, ). It has been confirmed by several studies that the use of pre-contoured sectional matrix bands in combination with a separation ring achieved superior contact tightness owing to the interdental separation exerted by the ring during restoration, as well as the contour of the matrix, which mimics the natural proximal contours and emergence profiles of the teeth (, –).

In the current study, most of the dentists did not believe that the circumferential matrix systems produce consistent contact points. The reason behind the less-than-optimal proximal contact with circumferential matrix systems might be attributed to the insufficient movement of adjacent teeth from wedge placement compared to the interdental separation ring and the flat matrix band. Tight contact points were reported at a higher level occlusally, as dental floss could not pass or was torn upon placement (). Optimum contact points with circumferential matrix systems were mostly reported by some more experienced dentists (DDSc/PhD), which might be accredited to the long period of practice using the circumferential matrix systems. Nevertheless, they described the emergence profiles as improper ().

The results of the current survey showed that 74% of the dentists preferred using the sectional matrix systems and 63% of the dentists considered the sectional matrix systems to be easily used and applied compared to the circumferential matrix systems. This may be attributed to the shift in dental restorations done by dentists from amalgam to resin composites, based on a patient’s esthetic demands and the development in physical and mechanical properties of resin composites, which requires the training on the new techniques and restorative procedures at dental. However, these findings were contradicted by another study where 83.3% of dental students preferred using the circumferential matrix systems (). Nowadays, the sectional matrix systems are implemented in most of the dental schools in Egypt, both in daily practice and training. These findings confirm the fact that the sectional matricing techniques are the most commonly used techniques by Egyptian dentists to achieve consistent and reliable contact points of posterior proximal resin composite restorations.

Among the circumferential matrix systems in the current survey, the Tofflemire matrix holder and bands were most commonly used (80.2%, n=333). In most of dental schools in Egypt, this system is most commonly used in the pre-clinical simulation laboratory course (). The circumferential matrix systems were conventionally used for proximal restorations (), and the regression in its use was due to the fact that the sectional matrix systems proved to produce anatomically optimal contact points (, –). Among the sectional matrix systems, 54% of Egyptian dentists mainly used matrix systems manufactured by TOR VM (Moscow, Russia) because they are relatively cheap and abundant in the Egyptian dental market with a wide variety of separation rings and matrices. Twenty percent of dentists in the current study used Composi-tight (Garrison Dental Solutions, Spring Lake, Michigan, USA), while 15.2% of them used the Palodent V3 system (Dentsply Sirona, Konstanz, Germany). Both systems have proven to have reliable reproduction and consistent proximal contact and contour, but they are expensive.

Wooden and diamond wedges were the most commonly used during the placement of posterior restorations. Many dentists preferred to use wooden wedges since they are cheap and can expand when exposed to oral fluids, which helps in interdental separation and adaption of the matrix band gingivally (). However, when wooden wedges absorb fluids they become weak and flexible, and they adapt only to the natural anatomic proximal contour, resulting in less interdental separation (). On the other hand, compared to wooden wedges, diamond wedges need less effort during placement. The diamond shaped cut-out in the tip collapses upon placement, facilitating its insertion inside the embrasure. The diamond wedge then springs open once inside the embrasure, producing a tight gingival seal and preventing the wedge from getting out ().

In a previous survey investigating into the range of techniques used by UK general dental practitioners when placing posterior composites, 155 dentists, (61%), used the circumferential metal matrix system and a wooden wedge, 74 dentists, (29%), used the transparent matrix system, and only 25 dentists, (10%), used the sectional metal matrix and a wooden wedge. These results were obtained 11 years ago when the use of the sectional matrix systems was not universally implemented in evidence-based guidelines and amalgam restorations were preferred over the posterior composite restorations ().

The sectional matrix systems are sensitive due to their rounded contours and thin thickness, which can cause a depression or bending in the matrix material during placement, rendering it unusable (). Previous studies observed statistically significant differences in contact tightness with different circumferential compared to the sectional matrix systems (, , ). In the current study, the dentists reported that the sectional matrix systems produced optimum contact points with proper emergence profiles. This was in agreement with another study () where sectional matrices combined with separation rings resulted in increased contact tightness, while the use of a circumferential matrix resulted in decreased contact tightness. ().

In the current survey, the dentists using the sectional matrix systems reported that a minimal number of restorations exhibited open or tight proximal contact. This can be explained by the fact that the separation ring was not effective in separating the teeth, or the clinicians were unable to place the matrix system effectively. The dentists reported that even open or tight contacts produced with sectional matrix systems had proper emergence profiles ().

Conclusions

The results of this survey have shown that Egyptian dentists preferred using the sectional matrix systems. Optimum contact points were highly associated with the sectional matrix systems. However, poor (open and tight) contacts were highly associated with the circumferential matrix systems.

Clinical recommendations: Various restorative techniques have been recommended to reproduce and recreate optimum proximal contact points and contours for compound proximal restorations. It is advocated to embrace the use of sectional matrix systems accompanied with interdental separation rings in daily practice for all dental practitioners. Undergraduate dental students and fresh graduates should be qualified for using the sectional matrix systems to provide the finest dental health services for patients.