Donald D. Peters

Scanning electron microscopic investigation of the smeared layer on root canal walls

The scanning electron microscope was used to investigate the morphological characteristics of the smeared layer on the walls of root canals that had been instrumented with K-type files and irrigated with a 5.25% solution of NaOCl. The smeared material was examined from two perspectives. First, the scanning electron microscope was used to “look down onto” the smeared layer covering the canal wall. Second, the smeared material was looked at from the side or profile view. This was done by using the scanning electron microscope to scan the junction between the fractured dentinal tubules and the surface of the canal wall. The smeared material was found to consist of two confluent components; the smeared layer on the surface of the canal wall and the smeared material which had been packed into some of the dentinal tubules. The smeared layer on the canal wall was typically about 1- to 2-μm thick. The depth of the tubular packing varied from a few micrometers up to 40 μm.

Incidence and configuration of canal systems in the mesiobuccal root of Maxillary first and second molars

The anatomy of the mesiobuccal (MB) root of 51 maxillary first and 32 maxillary second molars was studied. Initially, an attempt was made to locate all canals using a standard access and hand instruments. A bur was next used carefully to locate any additional second mesiobuccal (mesiolingual (ML)) canals. Finally, after crown removal, the teeth were reduced horizontally in 1-mm increments and examined by microscope. A second ML canal was located in the coronal half of 95.2% of the roots: by hand instruments in 54.2%; bur in 31.3%; and microscope in 9.6%. There were no root perforations when the bur was used as described. The ML canal orifice averaged 1.82 mm lingual to the MB canal orifice. The difference in incidence of ML canals between the first and second molars was not statistically significant. The canal systems were type 1, 4.8%; type 2, 49.4%, and type 3, 45.8%.

Microcomputed tomography: An advanced system for detailed endodontic research

This study evaluated the value of microcomputed tomography (MCT) for use in endodontic research. Four periodontally involved highly calcified maxillary first molars were extracted and then scanned for evaluation by a MCT system. The teeth were then instrumented, and 2 of the 4 obturated before rescanning for comparison evaluation. Several capabilities of the MCT to advance endodontic research significantly were observed: the ability of the MCT to present accurately the external and internal morphologies of the tooth without tooth destruction; the possibility of showing changes over time in surface areas and volumes of tissues; the ability to assess area and volume changes after instrumentation or obturation; and the capability of evaluating canal transportation following instrumentation or instrumentation and obturation. The tremendous potential of this scientific tool was discussed.

A scanning electron microscopic evaluation of root canal debridement using saline, sodium hypochlorite, and citric acid***

This study used a scanning electron microscope and a rank-ordered scoring system to evaluate statistically the amount of superficial debris and the smeared layer that remained on the canal wall following root canal preparation with six different debridement regimens. Regimens which used citric acid or a combination of NaOCl and citric acid for irrigation were more effective than NaOCl alone in removing the smeared layer from the surface of the prepared root canal walls.

Two-year in vitro solubility evaluation of four gutta-percha sealer obturation techniques

The in vitro solubility of the gutta-percha and sealer present in 236 tooth sections obturated by four different techniques was evaluated after 2 yr. In only two of the techniques (lateral and vertical) was the sealer loss significant. The difference between techniques was at a p

Adult pulpal diagnosis. I. Evaluation of the positive and negative responses to cold and electrical pulp tests

This study investigated the positive and negative responses of 1488 teeth in 60 patients to two electric pulp testers and a cold thermal pulp test. Three subgroups of known pulpless or pulpally diseased teeth (teeth receiving root canal therapy, teeth with root canal fillings, or teeth with confirmed associated apical radiolucencies) were identified and their responses evaluated separately. Testing was performed on two tooth surfaces, the facio-occlusal and faciocervical, and on all restorations. The gingival tissue of each patient also was tested using both electrical tests. The primary findings were: (a) teeth not responding to cold and either not responding or responding at readings greater than the tissue response to electrical had a high probability of being in the known pulpless or pulpally diseased subgroups; (b) the only false positive responses to cold in the three subgroups were in multirooted teeth with probable vital tissue remaining in at least one canal; and (c) in the three subgroups, if the false positive responses to electrical that responded at levels higher than the patients tissue response were considered to be negative responses, the difference in false positives between cold and electrical became not statistically significant (p = 0.07).

Comparison of the relative risk of molar root perforations using various endodontic instrumentation techniques

One hundred canals in the mesial roots of 60 mandibularmolars were instrumented using five techniques. The remaining 20 canals became uninstrumented controls. A standard technique without flaring and four techniques with flaring were evaluated. In two of the flare techniques only hand instrumentation (circumferential and anticurvature) was used while in two others additional engine-driven instrumentation (round burs and Gates-Glidden burs) was used. Of the flare techniques, hand instrumentation used in an anticurvature manner showed significantly less risk (p

A comparison of the area of the canal space occupied by gutta-percha following four gutta-percha obturation techniques using procosol sealer

Sixty anterior teeth were filled using four gutta-percha sealer techniques: lateral, vertical, mechanical, and chloroform dip. The teeth were mounted in groups and sectioned. Four levels were evaluated for area of canal obturated by gutta-percha versus area empty or obturated with sealer. Lateral condensation had significantly less gutta-percha in the apical two levels than the other three techniques. By the third and fourth levels, the vertical technique had significantly more sealer present than the chloroform dip and mechanical techniques. The mechanical and chloroform dip techniques were not significantly different at any level.

The effect of immediate versus delayed dowel space preparation on the integrity of the apical seal

Abstract This in vitro study evaluated the effect of immediate vs delayed preparation of dowel space on the integrity of the apical seal. Twenty human teeth were obturated by lateral compaction of gutta-percha and cement and stored. Two weeks later, 20 more were similarly filled. Using warm endodontic pluggers, dowel spaces were prepared so that either 3 mm or 7 mm of apical fill remained. The specimens were treated in 45 CaCl 2 , horizontally sectioned, and autoradiographs were made. Analysis of the incidence and degree of microleakage showed that delayed preparations significantly increased leakage ( P

A technique for staining extracted teeth: a research and teaching aid for bleaching

This study developed a technique for staining extracted teeth. Its value in research to compare of bleaching techniques and as an aid in teaching students bleaching techniques is discussed.