Vol. 18, No. 4, April 1992 AAE Abstracts of Papers

(Abstract# 14, continued)

nonparametric statistical tests. The results of this study indicate the presence of specific GABA-

like and GRP-like immunoreactivitywithin the pulps of both normal and carious teeth. Overall staining for both ligands was found to be more intense within inflamed pulps. The implications for GABA and GRP localization in pulp are unknown; however, based upon their physiology elsewhere, they may respectively play a role in nociception, in neurogenic inflammation, or as tissue growth factors.

ABSTRACT # 15 - Isolation and characterization of cystine-rich peptides from dental pulp. S. Yamauchi*, A.J. Banes, M. Yamauchi University of North Carolina, Chapel Hill, North Carolina The dental pulp is known to be insoluble, which is probably due to the extensive network formed by collagen and other extracellular matrix (ECM) components. In order to characterize the insoluble ECM of pulp, we enzymatically solubilized the tissue, isolated the high molecular weight peptides and analyzed these for amino acid compositions. Pulpal tissues were collected from partially erupted incisors of bovine, pulverized, washed and lyophilized. The sample was suspended in 0.2 M NH4HCO 3, heat-denatured and trypsinized. This treatment solubilized more than 99% of the tissue. The trypsin digest was then applied to the calibrated molecular sieve column (Sephadex G50 superfine) for fractionation. A prominent peak was observed at the void volume of the column. This high molecular weight fraction was further purified by anion-exchange (Mono Q) and molecular sieve (Superose 6) chromatography and several major peptides were isolated. The common characteristics of these peptides were: I. The molecular weight was high (>100 kd). 2. These were noncotlagenous in nature (little of hydroxyproline). 3. The peptides were relatively rich in acidic amino acids and contained a remarkably high content of cystine residues (45-66 res/1000). The fact that the high molecular mass was remained even after the harsh treatment with trypsin is most likely due to the extensive disulfide bondings in the molecules. These cyctine- rich, high molecular weight proteins clearly represent one of the major noncollagenous ECM components in the pulp and may play an important role in providing this tissue with integrity and stability.

This work was partly supported by NIH grants DE05596, DE08522, DE00233, and DE08611.

ABSTRACT #16 - Vital tooth bleaching: histopathological examination of the human pulp. C.J. Tyler* and J.A. Wallace Case Western Reserve University, Cleveland, Ohio Presently, there are many techniques available for vital tooth bleaching. The objective of this study was to evaluate effects of vital bleaching techniques on normal human pulp. Patients undergoing orthodontic treatment requiring extraction of normal vital teeth were used in this study. These teeth were bleached with one of two vital bleaching techniques. The first technique involves a take-home technique containing 10% carbamide peroxide. The second technique utilized 35% hydrogen peroxide. Prior to extraction, patients were evaluated clinically with standard techniques. Post-treatment, the teeth were extracted and placed in formalin. The apical half of the root removed. The teeth were processed utilizing standard histological techniques and evaluated histopathologically. The teeth were sent to a lab to be decalcified, embedded in paraffin, sectioned, mounted and stained in hematoxylin and eosin. The control was the contralateral normal vital human tooth. The results and conclusions are being statistically evaluated, and they will be forwarded to you in 3-4 weeks. The pathology will be scored and related to the control as suggested by Harold Stanley and modified by the American Dental Association's Council on Dental Materials and Devices.

ABSTRACT #17 - Evaluation of ultrasonic and sonic instruments for endodontic post removal. J.R. Buoncristiani*, B.G. Seto, A.A. Caputo UCLA School of Dentistry, Los Angeles, California Ultrasonic instrumentation is a valuable asset for removing endodontic posts from root canals prior to non-surgical therapy. However, previous studies have not addressed the differences between the available units, or the ability of sonic devices to perform this task. The purpose of this study was to evaluate the relative efficacy of post removal by ultrasonic and sonic devices.

Fifty extracted teeth were instrumented, obturated and prepared for Parapost R #5 stainless steel posts. After cementing the posts with ZnPO, cement at a depth of 4mm, the teeth were randomly divided into five groups. A constant traction was applied while the teeth were subjected to ultrasonic or sonic instrumentation, and the time measured until post removal. Retention was determined by dislodging five posts with the Instron testing machine.

Median values in minutes for the post extractions in each group were: Cavitron = 6.0, ENAC = 8.3 and Neosonic = 41.2. Sonic instruments were generally unable to remove the posts within the one hour maximum time allowed for this experiment. Statistical analysis by the Mann Whitney U test showed no differences between the Cavitron and the ENAC (P=.II), but both were significantly faster than the Neosonic (P=.00014) for removing the experimentally cemented posts. The Instron testing showed a mean post retention value of 33.5 (+ 5) kg.

The results of this experiment indicate that the Cavitron and the ENAC ultrasonic units are significantly more efficient for removing posts than the Neosonic ultrasonic or the sonic instruments.

ABSTRACT # 18 - Identification of human pulp for blood and lymphatic vessels using immunohistochemistry. T.L. Green*, J. Beckstead, R.E. Walton, R. Waiters University of Iowa, Iowa City, Iowa and University of Oregon, Portland, Oregon Although blood vessel characteristics are well known, the presence of lymphatics in human pulp tissue has been controversial. Investigators have conflicting conclusions following the examination of pulps utilizing physiologic techniques, light or lectron microscopy. Our experiments examined human pulps using immunohistochemistry to identify lymphatic and blood vessels. Five freshly extracted third molars were split longitudinally and the pulps removed intact. Pulps were initially placed in transport media and later fixed and embedded in paraffin. Sections were cut and labeled immunohistochemically (ABC- peroxidase). Antibodies specific against the endothelial markers were Ulex europeans lectin, Factor VIII related antigen, CD 34, additionally antibodies for ATPase, 5'-nucleotidase, and alkaline phosphates were used to identify lymphatics. Controls were unreacted sections; positive controls consisted of gingival tissue and fresh frozen human tissue.

Vessels were readily identified in the experimental sections. Specifically, all morpholgically identifiable small vessels within the tissue stained strongly with Ulex and F VIII related antigen, while CD 34 marked only about 50% of the vessels. This demonstrated the presence of blood vessels but did not differentiate lymphatics. In addition, staining for ATPase, 5'-nucleotidase, and alkaline phosphatase could not be demonstrated in the pulps or gingival control tissue, but were positive in fresh frozen tissue.

In conclusion, these data demonstrate vessels consistent with blood vessels but did not allow positive identification of lymphatic vessels. Experiments are currently underway to utilize fresh frozen human gingival and pulpal tissue to provide more specific information as to the pulp vasculature.

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