Biomedical subjects
Publications and source records attributed to E S Reeh.
This case report examines a mandibular first molar retreatment in which seven canals were cleaned, shaped, and filled/refilled, thus leading to resolution. This report points out the importance of looking for additional canals and an unusual canal morphology associated with a mandibular first molar.
One of the properties of an ideal retrofilling material is little or no microleakage. A new dentin bonding agent based on polyacrylic acid (PAA) is ideally suited to the moist apical environment because of its hydrophilic nature. PAA as a dentin bonding agent for apical retrofillings was tested in an in vivo leakage study using single canal roots of extracted human teeth. Bonding was attained by pretreatment of the dentin in apical retrofilling preparations with a solution of PAA, followed by placement of a nonaqueous restorative material. Using PAA as dentin bonding agent reduced apical leakage at statistically significant levels with Super EBA as a restorative material. In vivo testing is required to validate these findings.
Mechanisms of salivary lubrication can be quantitatively measured by a reduction in the coefficient of friction. It is important that lubrication be assessed under the conditions of the oral cavity to properly assess lubrication regimes. The relative lubricity of three artificial salivas and two controls were assessed at a bovine enamel interface in an artificial mouth with a range of conditions that approximate oral function. Statistical analysis indicated that the enamel lubricity of sodium dodecylsulfate (SDS) and Oracare-D saliva substitutes were different from the other saliva substitutes and water. The low friction with Oracare-D and SDS saliva substitutes was because of resident amphipaths adsorbed at the enamel interface. Amphipaths adsorbed on enamel may provide a reduction in interocculsal friction and its resulting complications for patients with xerostomia.
Bovine enamel has been a good model for human enamel across a broad range of studies. The present work sought to consider if bovine enamel would be a suitable substitute for human enamel in experiments on simulated oral lubrication. Enamel samples of the same size were prepared from bovine and human teeth for use as maxillary and mandibular elements in a miniature artificial mouth. Sliding speeds from 1.99 to 7.84 mm/s and occlusal forces of 3.8-19.5 N were used. Water and four solutions consisting of a mucin-rich fraction, a statherin-rich fraction, 3[(3-cholamidopropyl)-dimethylammonio]-1-propanesulphonate and sodium dodecyl sulphate were evaluated. The high correlations between widely different lubricants on the two enamel substrates gives confidence in the use of bovine enamel as a model for human enamel in salivary lubrication studies. Knoop hardness indentations on enamel samples were combined with friction data and calculations of the true contact area to give a method for the indirect determination of surface shear. The calculated surface shear value was compared with published values obtained by punch shear testing.
OBJECTIVES: This study was conducted to determine the impact of composite veneer procedures on the functional properties of incisors. METHODS: Ten extracted human maxillary central incisors were mounted in pairs in a nylon ring. One strain gauge was bonded along the long axis of each tooth on the center of the lingual surface. Each pair formed half of a Wheatstone bridge circuit and was wired to eliminate all but the voltage resulting from experimentally applied procedures. The teeth were ramp-loaded to 50 N near the incisal edge on the lingual surface. Loading was performed on the unaltered teeth, teeth with preparations and restored teeth. Two-dimensional finite element (FE) models were generated to evaluate each test condition. Relative stiffness, compared with the unaltered tooth, was calculated from measurements with the strain gauge steps and from the FE models. RESULTS: A relative stiffness value of unity represents recovery of stiffness to the level of the unaltered tooth. Both methods of evaluation demonstrated a decrease in mean relative stiffness with each subsequent reduction in tooth structure. The composite restoration increased its mean relative stiffness compared to its corresponding preparation but never to the level of the unaltered tooth. Across all procedures, the two-dimensional FE model correlated well in both direction and magnitude with the experimental strain gauge method (R = 0.83). SIGNIFICANCE: A resin composite veneer does not restore the stiffness to the level of an unaltered tooth.
The lubricating properties of human submandibular-sublingual salivary fractions were examined using a servohydraulic model of mandibular movement. Fractions containing statherin exhibited a strong tendency to boundary lubrication. The lubricity of purified statherin was confirmed and compared to the amphipathic molecules gramacidin S and sodium dodecyl sulfate. Contact angle measurements of statherin paralleled the other amphipathic molecules. The helical content of statherin increased in trifluoroethanol indicating the presence of amphipathic helical regions. CD studies and hydrophobic moment calculations indicated that statherin adopts an amphipathic helical conformation at the N-terminus. An energy-minimized model of the polar N-terminal residues 1-15 suggested that this domain could be positioned in space to interact with a hydroxyapatite substrate. These data imply that under appropriate conditions statherin may display an amphipathic nature which enables it to function as a boundary lubricant on enamel.
Referred pain is common in the orofacial region and can cause considerable difficulties in diagnosis. Referred pain is defined as pain that is referred to a part of the body other than the site of origin, and as a result, severe pain may arise without an associated causative lesion. A muscular trigger point that resembled a tooth with endodontic involvement is discussed.
Literature reports and journal articles on endodontic-periodontic relationships are numerous. Presented is a brief review of the diagnostic tests, the classification of endoperiodontic lesions, and a clinical report that covers an unusually rapid development of furcation involvement associated with a tooth that became nonvital.
This clinical report briefly describes the appearance, frequency, and treatment of fused teeth. Presented is a tooth showing the unusual canal morphology and root lengths of a unilateral mandibular canine and lateral incisor fusion.
Endodontically treated teeth are thought to be more susceptible to fracture as a result of the loss of tooth vitality and tooth structure. This study was designed to compare the contributions of endodontic and restorative procedures to the loss of strength by using nondestructive occlusal loading on extracted intact, maxillary, second bicuspids. An encapsulated strain gauge was bonded on enamel just above the cementoenamel junction on both the buccal and lingual surfaces, and the teeth were mounted in nylon rings leaving 2 mm of root surface exposed. Under load control, each tooth was loaded at a rate of 37 N per s for 3 s and unloaded at the same rate in a closed loop servo-hydraulic system to measure stiffness. A stress-strain curve was generated from each gauge prior to alteration of the tooth and after each procedure performed on the tooth. Cuspal stiffness, as a measure of tooth strength, was evaluated on one of two series of sequentially performed procedures: 1. (a) unaltered tooth, (b) access preparation, (c) instrumentation, (d) obturation, and (e) MOD cavity preparation; or 2. (a) unaltered tooth, (b) occlusal cavity preparation, (c) two-surface cavity preparation, (d) MOD cavity preparation, (e) access, (f) instrumentation, and (g) obturation. Results on 42 teeth indicate that endodontic procedures have only a small effect on the tooth, reducing the relative stiffness by 5%. This was less than that of an occlusal cavity preparation (20%). The largest losses in stiffness were related to the loss of marginal ridge integrity. MOD cavity preparation resulted in an average of a 63% loss in relative cuspal stiffness.(ABSTRACT TRUNCATED AT 250 WORDS)
During endodontic retreatment of a maxillary central incisor, a midroot buccal perforation was created, and sodium hypochlorite was inadvertently forced through the perforation into surrounding tissue. The consequences of this incident included immediate severe pain and swelling, with the subsequent development of a fistula, and in the long term (15 months), paresthesia of the floor and ala of the nose and the infraorbital area.
Endodontically-treated posterior teeth are susceptible to fracture; consequently, full-occlusal-coverage restorations are recommended. We designed this study to examine the potential for alternative restorative techniques for pulpless teeth, using strain gauges mounted on extracted maxillary second premolars to measure strains generated by nondestructive occlusal loading. Cuspal stiffness was evaluated on the following sequentially performed procedures: unaltered tooth, completion of all endodontic procedures, appropriate restorative preparation, and restoration. The restorative procedures evaluated were: (1) amalgam, (2) cast gold onlay, (3) composite restoration with enamel etch, and (4) composite restoration with enamel and dentin etch. Finally, all teeth were loaded to fracture. Cast gold was the strongest restorative material tested (2.11 relative stiffness, compared with that of the unaltered tooth at 1.00), and amalgam was the weakest (0.35 relative stiffness). Composite restoration and enamel plus dentin etch were almost as strong as the unaltered tooth (0.87 relative stiffness), while enamel-etch-only yielded lower stiffness (0.51).