Effect of the smear layer on a pulp proximity-indicating instrument

Comparative evaluation and patient satisfaction with an electrical impedance-based device versus digital radiography in the estimation of remaining dentin thickness in carious posterior permanent teeth: (Diagnostic accuracy study)

BACKGROUND

Accurate assessment of remaining dentin thickness (RDT) is paramount for restorative decisions and treatment planning of vital teeth to avoid any pulpal injury. This diagnostic accuracy study compared the validity and patient satisfaction of an electrical impedance based device Prepometer™ (Hager & Werken, Duisburg, Germany) versus intraoral digital radiography for the estimation of remaining dentin thickness in carious posterior permanent teeth.

METHODS

Seventy patients aged 12-25 years with carious occlusal or proximal permanent vital posterior teeth were recruited. Tooth preparation was performed to receive an adhesive restoration. Pre- and post-excavation RDT were measured radiographically by two calibrated raters using the paralleling periapical technique. Prepometer™ measurements were performed by the operator. Patients rated their satisfaction level with each tool on a 4-point Likert scale and 100 mm visual analog scale (VAS). Inter and intragroup comparisons were analyzed using signed rank test, while agreement between devices and observations was tested using weight kappa (WK) coefficient.

RESULTS

the intergroup comparisons showed that, before and after excavation, there was a significant difference between measurements made by both techniques (p < 0.001). After excavation, there was a weak agreement between measurements (WK = 0.2, p < 0.001), whereas before excavation, the agreement was not statistically significant (p = 0.407). Patients were significantly more satisfied with Prepometer™ based on scales and VAS (p < 0.001).

CONCLUSION

Prepometer™ could be a viable clinical tool for determining RDT with high patient satisfaction, while radiographs tended to overestimate RDT in relation to the Prepometer™.

Accuracy of an electrical impedance device in estimation of remaining dentin thickness vs cone beam computed tomography

The objective of this study is to compare the estimated values of remaining dentin thickness (RDT) recorded by a newly introduced electrical impedance device (Prepometer) with cone beam computed tomography (CBCT) and histological in situ measurement. A total number of thirty human molars were used in this study. A deep class I cavity was prepared. The RDT for each cavity was measured with Prepometer in three different points (mesial, middle, and distal). Same specimens were imaged with high-resolution Cone Beam Computed Tomography CBCT (0.1 mm voxel size) using I CAT next Generation Machine (Imaging Science International, Hatfield, PA, USA), to provide the highest possible accuracy of linear measurements. Finally, the specimens were vertically sectioned parallel to the long axis of the tooth in a mesiodistal direction splitting the cavity into two halves through its center. Then, the actual RDT of each half will be measured in the same three points using a digital caliper. The outcome of one-way ANOVA revealed that there was no significant difference in RDT values measured by prepometer device, CBCT, or histological sectioning methods (p > 0.05). Within the limitations of this laboratory study, prepometer seems to be a potential non-invasive accurate measuring tool for RDT. Based on the findings of this study, the Prepometer can be considered as an easily handled and less-expensive method compared to CBCT to evaluate the RDT. Also, it can be used in dental schools and with less-experienced operators to avoid traumatic exposures of the dental pulp.

Construction and in vitro test of a new electrode for dentin resistance measurement

It is necessary to reduce the tooth substance before treating a tooth with a dental crown. The preparation often requires reduction of the dentin. This results in a dentin wound and a thinner substance over the pulp, increases the risk of inflammation, and could result in necrosis of the pulp. To give the dentist information about the amount of dentin over the pulp during preparation, the Prepometer was developed. The function of this device is based on the measurement of the electric resistance of the tooth substance. The measuring behavior of the first-generation Prepometer is characterized by smaller values of electric resistance before reaching full contact of the measuring head to the dentin surface and the actual value RT. This measuring behavior can mislead inexperienced therapists with inaccurate values that suggest thinner dentin than the reality. In this study, a new electrode based on the technology of active guard drive was constructed to overcome this issue. The results show that improvement in the measuring behavior of the new electrode could be achieved, eliminating the earlier disadvantage of the Prepometer.