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 Table of Contents  
Year : 2017  |  Volume : 9  |  Issue : 3  |  Page : 110-111

Sharpness of dental explorers at King Saud University College of Dentistry

Department of Prosthetic Dentistry, King Saud University, Riyadh, Saudi Arabia

Date of Web Publication27-Jun-2017

Correspondence Address:
Huda Ahmed Al-Shehri
P.O. Box 60542, Riyadh 11555
Saudi Arabia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jioh.jioh_12_17

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Aim: This study aims to measure sharpness of a sample of randomly chosen dental explorers (DEs) from King Saud University, College of Dentistry (KSUCD) compared to new ones. Materials and Methods: Sixty DEs were drawn out of random examination kits at KSUCD to be measured as a study group. Ten new DEs were measured to serve as control group. Tip diameter measurements were done for all seventy DEs under digital light microscope (n = 70) (μm). The comparison was done using SPSS (v. 16) at significance level P ≤ 0.05. Results: Mean tip diameter of the study group was 57.58 ± 20.06 while it was 30.34 ± 5.62 for control group. Independent sample t-test shows a significant difference between the two groups (P < 0.001). Conclusion: There is wide variation in tip diameter of study sample and difference in sharpness between study and control DEs.
Clinical significance: Dull explorers might negatively affect the clinical judgment of marginal integrity of crowns.

Keywords: Crown fit, dental explorer, marginal adaptation

How to cite this article:
Al-Shehri HA. Sharpness of dental explorers at King Saud University College of Dentistry. J Int Oral Health 2017;9:110-1

How to cite this URL:
Al-Shehri HA. Sharpness of dental explorers at King Saud University College of Dentistry. J Int Oral Health [serial online] 2017 [cited 2023 Dec 4];9:110-1. Available from:

  Introduction Top

Marginal integrity is essential to the long-term success of indirect restorations.[1] Loss of good marginal adaptation leads to plaque accumulation and subsequent recurrent caries and periodontal disease.[2] The American Dental Association (ADA) has stated cement film thickness of zinc phosphate cement to be 40 μ.[3] However, on clinical practice, the acceptable marginal gap is highly variable. McLean and Fraunhofer examined over 1000 crowns and found that 120 μ was the maximum tolerable marginal gap [4] while Blackman et al. stated that an acceptable gap should not be more than 50 μ.[5]

Methods to measure marginal gap in vitro are variable such as using direct microscopy,[6] profilometry,[7] replication of cement space with silicone material and microcomputed tomography.[8] However, in clinic, the evaluation of marginal gap is most commonly done subjectively with the use of dental explorer (DE) tip. When the tip of the explorer can penetrate the junction between unprepared tooth structure and the crown, the margin is considered not acceptable. One study evaluated the ability of experienced operative dentists to detect marginal gaps of varying degrees using DEs and found that explorer dullness significantly affected their decision regarding marginal fidelity.[9]

Up to the author's knowledge, no previous studies have surveyed the tip diameter of regularly used DEs used in dental schools. The aim of the study is to measure tip diameter of a sample of DEs used in the College of Dentistry, King Saud University, Riyadh, Saudi Arabia.

  Materials and Methods Top

The study was approved by the College of Dentistry Research Center (#00275). The study took place between April and May 2016. A total of sixty DEs (n = 60) were randomly chosen out of sterilized examination kits that are ready to be used in clinical courses in the college in both campuses (test group). Furthermore, additional unused explorers were measured to serve as control group (n = 10). Tip diameter was measured in microns (μm). All measurements were done using a digital microscope (Hirox KH-7700, Tokyo, Japan) by the same investigator. Intra-examiner reliability was measured by repeating measurements of ten explorers on a 1 week interval (97%).

Statistical analysis

Descriptive statistics as well as independent sample t-test were carried out using Statistical Package for Social Sciences version 16 (IBM corp., NY, United States) at a significance level of 0.05 (P = 0.05) and 95% confidence interval.

  Results Top

The mean and standard deviations of DEs are presented in [Table 1]. Mean tip diameter of control group was 30.34 ± 5.62 μm while it was 57.58 ± 20.06 μm for the test group.
Table 1: Means and standard deviations of unused (control) and used (test) dental explorers

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Comparison of the two groups was done using independent sample t-test, and there was a highly significant difference between the two groups (P < 0.001) df = 9 and 59 for control and test groups respectively.

  Discussion Top

Marginal integrity is one of the most important mechanical factors in the success of full coverage crowns.[1],[10],[11] The ability of the dentist to evaluate crown margins in clinic accurately is essential to the success of the cemented crowns. Many factors could obscure that ability; these might include visibility, location of the margin, presence of vertical steps (over contouring), and use of a dull explorer. A dull explorer that looks sharp to the naked eye can influence the decision of the dentist to accept or discard a restoration or a crown. Explorers measured in this study were randomly selected from daily used examination kits that could be used by students and faculty to evaluate the integrity of direct and indirect dental restorations.

According to ADA, cement film thickness should be 40 μ, and in order for an explorer to effectively detect a gap larger than 40 μ, its tip should be equal or less than that number. In the current study, there was a wide range in tip diameter of the measured explorers with a minimum of 22.78 μ to a maximum of 124.67 μ. Only thirteen explorers examined were below 40 μ (23.33%). The clinical use of the remaining explorers might cause errors by acceptance of faulty restorations that might consequently affect teeth and periodontal health of many patients.

Unused sharp explorers showed a mean tip diameter of 30.34 ± 5.62 μm compared to use explorers 57.58 ± 20.06 μm with highly significant difference (P < 0.001). Hayashi et al. found that tip diameter of DEs had a significant effect on the detection of horizontal gaps. They suggest that diagnosis of restoration marginal discrepancies in clinical trials is best achieved using techniques other than using DE to probe margins. However, this could be argued that DE is the most affordable and accessible instrument to measure marginal gap of crowns. Instead, we recommend regular sharpening protocol and random microscopic measurement of DEs in clinical practice as a quality control measure in dental settings.

This cross-sectional survey over DEs sheds light on the importance of today's dentists to use accurate instruments to evaluate marginal validity that ensures teeth and periodontal health. One of the limitations is the small sample size and that the study is limited to one facility only. More studies should measure the accuracy of instruments used in clinical diagnosis and determination of the acceptability of treatment as this is crucial to patient care.

  Conclusion Top

Within the limitations of the study, it can be concluded that diameter of the tips of study sample were highly variant and some can affect clinical judgment of whether to accept or reject a dental restoration.


The author would like to thank the College of Dentistry Research Center and Deanship of Scientific Research at King Saud University, Saudi Arabia for funding this research project (#00275) and Dr. Hessa Al-Huwaish for statistical help.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Hunter AJ, Hunter AR. Gingival margins for crowns: A review and discussion. Part II: Discrepancies and configurations. J Prosthet Dent 1990;64:636-42.  Back to cited text no. 1
Behrend DA. Crown margins and gingival health. Ann R Australas Coll Dent Surg 1984;8:138-45.  Back to cited text no. 2
American Dental Association. ANSI/ADA Specification no. 8 for zinc phosphate cement. In: Guide to Dental Materials and Devices. 5th ed. Chicago: American Dental Association; 1970. p. 87-8.  Back to cited text no. 3
McLean JW, von Fraunhofer JA. The estimation of cement film thickness by an in vivo technique. Br Dent J 1971;131:107-11.  Back to cited text no. 4
Blackman R, Baez R, Barghi N. Marginal accuracy and geometry of cast titanium copings. J Prosthet Dent 1992;67:435-40.  Back to cited text no. 5
Ha SJ, Cho JH. Comparison of the fit accuracy of zirconia-based prostheses generated by two CAD/CAM systems. J Adv Prosthodont 2016;8:439-48.  Back to cited text no. 6
Yildirim G, Uzun IH, Keles A. Evaluation of marginal and internal adaptation of hybrid and nanoceramic systems with microcomputed tomography: An in vitro study. J Prosthet Dent 2017. pii: S0022-391330622-9.  Back to cited text no. 7
Contrepois M, Soenen A, Bartala M, Laviole O. Marginal adaptation of ceramic crowns: A systematic review. J Prosthet Dent 2013;110:447-54.e10.  Back to cited text no. 8
Rappold AP, Ripps AH, Ireland EJ. Explorer sharpness as related to margin evaluations. Oper Dent 1992;17:2-6.  Back to cited text no. 9
de Paula Silveira AC, Chaves SB, Hilgert LA, Ribeiro AP. Marginal and internal fit of CAD-CAM-fabricated composite resin and ceramic crowns scanned by 2 intraoral cameras. J Prosthet Dent 2017;117:386-92.  Back to cited text no. 10
Valente VS, Francischone CE, Vilarinho Soares de Moura CD, Francischone CE Jr., Silva AM, Ribeiro IS, et al. Marginal fit metal-ceramic and in-ceram single crown cement retained in implant-supported abutments. J Contemp Dent Pract 2016;17:969-72.  Back to cited text no. 11


  [Table 1]


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