Influence of Vision on the Evaluation of Marginal Discrepancies in Restorations.
Hayashi M, Watts, DC, Ebisu S, Wilson NHF. Oper Dent. 2005;30(5):598-601.
This study investigated the influence of visual inspection in the detection and discrimination between principle types of marginal discrepancies in restorations. Using devices simulating vertical steps, horizontal gaps, the combination of a vertical step and horizontal gap at the margin of a restoration and explorers with 4 different tip diameters, 10 experienced dental faculty members were asked to identify discrepancies and the boundary between Alpha (excellent) and Bravo (clinically acceptable) marginal adaptation ratings under 3 different visual combinations: with and without visual inspection and visual inspection aided with binocular loupes. A significant correlation was found to exist between explorer tip diameter and the Alpha/Bravo boundary for horizontal gaps, but not for vertical steps. There was no significant difference in the detection of the Alpha/Bravo boundary for the 3 visual conditions. It was concluded that visual inspection aided and unaided with loupes had no significant effect on the evaluation of simulated marginal discrepancies. These findings highlight the importance of the traditional dental explorer in the absence of a more discriminatory device in the assessment of marginal discrepancies in restorations.
When direct and indirect restorations are placed, clinicians assess the marginal fit with instruments, usually an explorer, and visualization. How good are we at detecting marginal discrepancies (gaps, steps, and ledges)? The authors of this paper provide us with the answer. Seeing is not believing; feeling the margin to assess its adaptation is more valuable. The research design took many variables into account. The use of 10 examiners implementing 12 different combinations of 4 explorer diameters (the examiners did not know which explorer diameter they were using) and 3 devices with 5 assessments of each combined with a 3-week period between the examinations eliminated any examiner bias. All margins were accessible for exploration and visualization. The results indicated that visual inspection with and without 2X loupes had no significant effect on the evaluation of marginal discrepancies, but the use of an explorer was significant. The conclusion was that until a more discriminatory device for assessing margins is developed, the explorer is the gold standard.
What does this mean to the practitioner? First, it is extremely important to evaluate marginal adaptation and gaps of all surfaces of restorations with an explorer. Visual inspection alone will provide a false sense of security. At times, especially at the interproximal margin where there is a lack of certainty, consider making a radiograph.
Even though in this study the use of loupes was not a defining parameter, the importance of enhanced visualization with loupes should not be discounted. Using magnification loupes contributes to better caries detection; improved visualization of calculus, internal tooth fractures, and cracks within teeth; access for endodontic treatment and exploration of the canal orifices and the root canal; and more refined surgical procedures. When restorations are returned from the laboratory, a larger image will help the clinician evaluate irregularities within the restoration and allow for a more precise adjustment of any discrepancies. One aspect of magnification that is sometimes not emphasized is the use of loupes to improve posture when practicing. Instead of bending over and putting your back at risk, the working distance of the loupes forces one to sit straighter with better visualization for improved back health over a lifetimeof practice.
Howard E. Strassler, DMD