Endodontic and implant algorithms.

Dental professionals are often faced with challenges when formulating a treatment plan for patients presenting with a compromised tooth. A common dilemma involves the decision between tooth retention using endodontic treatment with crown restoration, and extraction and an implant-borne restoration. In this article the authors evaluate the 2 treatment modes, and observe that because outcomes are similar with both treatments, decisions should be based on the patient's informed decision concerning restorability, costs associated with the procedures, esthetics, potential adverse outcomes, and ethical factors.

Pilot study of correlation of pulp stones with cardiovascular disease.

We propose that calcification of dental pulp may have a similar pathogenesis as calcified atheromas and could lead to use of routine dental radiographs as a rapid screening method for early identification of potential cardiovascular disease (CVD). Fifty-five dental patients ages 20 to 55 were chosen because pulp stones in pulpally noninflamed teeth were not expected in this age group. They completed a questionnaire regarding their CVD status and that of their parents and siblings. Entry criteria included at least one asymptomatic, minimally restored, noncarious molar and no history of gout, renal disease, or renal lithiasis. Patients' periapical radiographs of record were viewed to determine the presence of pulp stones. There was a significant relationship between pre-existing CVD and pulp stones (odds ratio of 4.4 with a 95% confidence interval of 1.1, 18.7), but no relationship was found for family history of CVD and pulp stones (odds ratio of 1.7 with a 95% confidence interval of 0.5, 5.5). Seventy-four percent (14/19) of patients with reported CVD had detectable pulp stones while only 39% (14/36) of patients without a history of CVD had pulp stones. This pilot study demonstrates that patients with CVD have an increased incidence of pulp stones in teeth with noninflamed pulps compared to patients with no history of CVD. No relationship was found between presence of pulp stones and family history of CVD. The findings suggest that dental radiographic determination of the presence or absence of pulp stones may have possibilities for use in CVD screening.

Aerotolerance of an endodontic pathogen.

The purpose of this study was to determine the length of time it takes to kill obligate anaerobic bacteria in a root canal exposed to room air or 3% hydrogen peroxide. Twenty-five extracted, human, permanent teeth with single canals were used. All teeth were contaminated with the anaerobe, Porphyromonas endodontalis (ATCC #35406), and were divided into five groups of five teeth each. Group I was exposed to 5 min of atmospheric air. Group II was exposed to 3% hydrogen peroxide for 5 min. Group III was exposed to 45 min of atmospheric air. Group IV was exposed to 3% hydrogen peroxide for 45 min. Group V, the control teeth, never left the anaerobic gas chamber. The results showed that atmospheric air exposure for up to 45 min is inadequate for eliminating P. endodontalis. The groups that were exposed to hydrogen peroxide showed no growth of bacteria.

Removal of organic debris from bovine dentin shavings.

A common problem with root canal failures is chronic inflammation at the apex caused by overfilling of root canal materials. Dentin filings have been suggested as an apical plug to create a biocompatible barrier between the filling material and the periapical tissue. Unfortunately residual organic material, such as pulp remnants or bacteria, still may be part of the filings. Dentin filings removed from the tooth, cleaned, and then used to form a barrier might serve as an effective barrier. The purpose of this study was to evaluate methods of cleaning dentin of organic debris. NaOCl, sodium dodecyl sulfate, and 1% Triton X-100 were used to treat dentin shavings and were evaluated by a micro bicinchoninic acid protein analysis assay. Two series of experiments were performed. One compared the effect of temperature while using phosphate-buffered saline as a control and the second compared exposure times. The percentage of protein extracted from dentin samples increased with temperature. Sodium hypochlorite at room temperature extracted 24.6%, NaOCl at 37 degrees C extracted 26.9%, and NaOCl at 70 degrees C extracted 33.9%. Only NaOCl at 37 degrees C and 70 degrees C showed statistically significant differences from phosphate-buffered saline at room temperature with p-values of 0.028 and 0.019, respectively. The exposure time series showed a difference between a phosphate-buffered saline solution and 6.25% NaOCl. NaOCl removed approximately 90% of protein compared with 60% for the phosphate-buffered saline. A 10-min exposure to 70 degrees C 6.25% NaOCl may be an efficient means of removing organic material from dentin shavings.

Apical pressures developed by needles for canal irrigation.

Drying instrumented canals with pressurized air may result in patient morbidity or even fatality. Low pressure and side vent needles have been suggested to lessen the danger. This study observed apical pressures from different needles inserted deeply into small round and ovoid canals as instrumentation progressed. Low-pressure (5 psi) air was injected through the needles, and apical pressures were recorded after each instrument. Pressures varied greatly within each test group. Generalities that can be drawn are that binding the needle within the canal gives higher pressures than with the needle slightly short of binding and that pressures were higher with apexes instrumented to size 30 and higher. With the needle tightly bound, neither needle size, needle design, nor canal shape resulted in statistically significant mean pressure differences. With the needle slightly withdrawn, larger bore needles gave higher pressures than small diameter needles. Caution is advised with the clinical use of pressurized air in the drying of root canals.

Detoxification of endotoxin by endodontic irrigants and calcium hydroxide.

The effects of endodontic irrigants and calcium hydroxide on lipopolysaccharide (LPS; endotoxin) were analyzed using the highly selective technique of mass spectrometry/gas chromatography with selected ion monitoring. An aqueous solution of LPS was mixed with one of a variety of endodontic irrigants for 30 min. Because it is a commonly used interappointment dressing, calcium hydroxide was also applied to LPS for 1, 2, or 5 days. LPS inactivation was measured by quantitation of free fatty acid release. Water, EDTA, ethanol, 0.12% chlorhexidine, chlorhexidine + sodium hypochlorite, and sodium hypochlorite alone showed little breakdown of LPS. Long-term calcium hydroxide--as well as 30-min exposure to an alkaline mixture of chlorhexidine, ethanol, and sodium hypochlorite--did detoxify LPS molecules by hydrolysis of ester bonds in the fatty acid chains of the lipid A moiety.

Wet and dry deep cavity preparations compared by a novel odontoblast culture technique.

The human odontoblast's unique cellular extension within dentin does not easily allow culturing by traditional methods. This study leaves these cells in their natural position in the dentin. Deep preparations were made through the occlusal surfaces of extracted human third molars. The crowns were separated from the roots and the pulps gently teased from the chambers, leaving the odontoblast layer intact. These inverted pulp chambers were then incubated in cell culture medium for 2 to 4 days. Trypan blue staining was used to detect non-vital odontoblasts, and the differentiation between vital and nonvital cells was verified by SEM and toluidine vital staining. Control teeth and areas not adjacent to the preparation showed no blue staining, indicating intact cells. Areas of nonvital cells were greatest with wider preparation. Irrigation decreased odontoblast death with wide preparations. No difference due to irrigation was detected in narrow preps. A comparison of wet preparations to which heat was applied versus dry preparations showed statistically similar results. This study provides a simple in vitro method for the study of odontoblasts with their processes intact within dentin.

Measurement of intraosseous pressures generated by the Wand, high-pressure periodontal ligament syringe, and the Stabident system.

Intraosseous pressure generated by the use of three anesthetic systems-the Wand; a hand-operated high-pressure periodontal ligament (PDL) syringe; and the Stabident system-were studied in fresh mandibles of 14 large swine. The mandibles were drilled and tapped in one area of both the right and left posterior molar regions. Pressure gauges were attached via threaded fittings. Pressures during injection were recorded for the Wand first, then the PDL syringe, and finally Stabident. Results showed averages of 8.3 mm Hg generated by the Wand, 16.3 mm Hg with the high-pressure PDL syringe, and 43.7 mm Hg from the Stabident system. Results were corroborated with data from three human cadaver mandibles.

Effectiveness of three endodontic irrigants at various tubular depths in human dentin.

Bacteria from infected root canals can invade dentinal tubules, thus dentin disinfection is an important aspect of endodontic therapy. This study compares three endodontic irrigants for efficiency in killing bacteria established within human dentinal tubules. Root canals in extracted teeth were prepared and sterilized. Broth cultures of Enterococcus faecalis were allowed to grow within the canals to penetrate dentinal tubules. The infected canals were exposed individually to each of the irrigants for 1 min. Irrigants were 0.525% sodium hypochlorite, Tubulicid (0.2% EDTA), and 0.12% chlorhexidine (Peridex). Sterile water was the control. Viable bacteria were analyzed by drilling incrementally into dentin from the cementum toward the canal. Smaller diameter drills were used for each depth. Shavings were cultured at three depths, for each of three root levels: coronal, midroot, and apical. Although considerable variation occurred between roots, sodium hypochlorite seemed to be superior. Tubulicid and Peridex were better than water. More bacteria remained viable at greater distances from the pulp. These observations apparently apply to all levels in the canal.

Array-projection geometry and depth discrimination with Tuned-Aperture Computed Tomography for assessing the relationship between tooth roots and the inferior alveolar canal.

OBJECTIVES: The purpose of this study is to compare Tuned-Aperture Computed Tomography (TACT) image sets made with linear vertical, linear horizontal, conical, and x-shaped x-ray projection arrays with regard to observer accuracy in (1) measuring the distance from the apex of a tooth root to the middle of the inferior alveolar canal (IAC), (2) measuring the shortest distance from the surface of a tooth root to the surface of the IAC, and (3) determining whether the root is buccal or lingual to the IAC. The same relationships were also examined by means of pairs of images and the buccal object rule. STUDY DESIGN: Two artificial mandible sections with simulated IACs were fabricated. The same human mandibular premolar root was used in both models to prevent development of learning cues to differentiate between models. The models were imaged from both sides, resulting in 4 orientations. An optical bench was designed to precisely orient different beam projection arrays for production of TACT image sets and pairs of images for use with the buccal object rule. Twelve dentists participated as observers to independently assess the relationships between the tooth root and the IAC with regard to the 4 orientations. RESULTS: For measuring the distance from the tooth apex to the middle of the IAC, TACT image sets made from conical and x-shaped arrays proved significantly more accurate than TACT image sets made from linear vertical or linear horizontal projections or pairs of digital images used with the buccal object rule (P <.05). For measuring the shortest distance between the tooth surface and the IAC surface, TACT image sets made from linear vertical, conical, and x-shaped projection arrays were significantly more accurate than measurements made through use of the buccal object rule or TACT image sets made through use of a linear horizontal projection array (P <.05). The following percentages of mistakes were made in determining whether the tooth root was buccal or lingual to the IAC: buccal object rule (58%), linear horizontal array (31%), linear vertical array (2%), conical array (0%), and x-shaped array (0%). CONCLUSIONS: For TACT, images acquired with conical and x-shaped beam projection arrays are preferred to those acquired with linear arrays for assessing the relationship between tooth roots and the IAC. TACT was found to be significantly more accurate than standard application of the buccal object rule for the relationships investigated.

Clearance of biofilms from dental unit waterlines through the use of hydroperoxide ion-phase transfer catalysts.

OBJECTIVES: The purpose of this research was to demonstrate the effectiveness of hydroperoxide ion-phase transfer catalyst (HPI-PTC) cleaners and disinfectants for maintaining dental unit waterlines free of planktonic organisms. METHOD AND MATERIALS: Water samples were taken from 117 sites, which included a variety of dental units and samples from the sink faucets of most operatories. Samples were plated on appropriate bacteriologic media and incubated. The presence or absence of biofilms was confirmed by scanning electron microscopy. Twenty-two of the dental units were retrofitted with independent water systems; the cleaning procedure involved an overnight application of an HPI-PTC cleaner followed by a 2-minute water rinse. RESULTS: Water from both the air-water syringe and the high-speed handpiece lines from all untreated units contained at least 6 x 10(2) colony-forming units per milliliter of planktonic or free-floating bacteria; the average was 1.4 x 10(5) CFU/mL. An initial 5% solution of HPI-PTC successfully cleared the lines of any apparent biofilm when applied for 3 consecutive days. Thereafter, once weekly use of the cleaner maintained the dental unit water supplies free of significant numbers of planktonic organisms. CONCLUSION: Routine weekly use of an HPI-PTC cleaner controlled dental unit waterline biofilm and reduced, with minimum effort, the microbial contamination level of water used for patient treatment to less than 200 CFU/mL.

Disinfection/sterilization of extracted teeth for dental student use.

Extracted human teeth are used in many preclinical courses. While there has been no report of disease transmission with extracted teeth, sterilization of teeth used in the teaching laboratory should be a concern. The purpose of this study was to determine the effectiveness of different sterilization/disinfection methods of extracted human teeth using Bacillus stearothermophilus, a bacteria resistant to heat and frequently used to test sterilizers. In this study, 110 extracted molars with no carious lesions were collected and stored in buffered saline. An endodontic occlusal access preparation was cut into the pulp chamber of each tooth. Pulp tissue in the chamber was removed with a broach. Approximately 1 x 10(5) B. stearothermophilus endospores in culture medium were injected into the pulp chamber, sealed with Cavit G, and then placed in sterile saline for twelve hours. Ten teeth were placed into each of eleven groups. Seven groups were immersed for one week in one of the following solutions: a) sterile saline (control group), b) 5.25% NaOCl, c) 2.6% NaOCl, d) 1% NaOCl, e) 10% buffered formalin, f) 2% gluteraldehyde, g) 0.28% quaternary ammonium. Four additional groups were treated by h) 10% formalin for two days, i) 10% formalin for four days, j) autoclaving at 240 degrees F and 20 psi for twenty minutes, and k) autoclaving at 240 degrees F and twenty psi for forty minutes. Each tooth was then aseptically split and placed in an individual test tube with growth medium. Samples were examined for evidence of growth (turbidity) at forty-eight hours. Only autoclaving for forty minutes at 240 degrees F and 20 psi or soaking in 10 percent formalin for one week were 100 percent effective in preventing growth. A chi-square analysis of the data indicates these two methods were significantly better than all other methods (p<0.001).

Degradation of the sealing properties of a zinc oxide-calcium sulfate-based temporary filling material by entrapped cotton fibers.

During root canal therapy cotton may be placed in the pulp chamber before placement of a temporary filling. This study evaluated the effect on the sealing of a zinc oxide-calcium sulfate-based temporary filling material when fibers of the internal cotton passed through the filling material and reached the external surface of the temporary filling. Glass tubes were filled with a 3.5 mm thickness of the temporary filling incorporating a bundle of cotton fibers that passed from the inner surface of the restoration to the outer surface. The time for methylene blue stain to penetrate the filling was compared among four groups. Group 1 (large bundles of fibers) had 20 to 40 fibers, group 2 (medium bundles) had 10 to 15 fibers, group 3 (small bundles) had 3 to 5 fibers, and group 4 (negative controls) had no cotton fibers. All samples with cotton fibers leaked within 12 min. None of the negative controls leaked within the 21 -day observation time. These results demonstrate that even a very small amount of cotton trapped between the wall of the tube and the filling material dramatically reduced the sealing quality of the temporary restoration.

Stress analysis of human tooth root using various root canal instruments.

This study compared external root stresses from instrumentation by several motor-driven nickel-titanium instruments to stresses developed by hand files. Twelve curved first molar mesial roots were invested in PLM-9 photoelastic material to disclose net stress transmitted from the canal through the dentin. Minimal fringe patterns were observed during instrumentation with all techniques. Light-speed yielded the least change. In no case was a complete 60 psi fringe change noted.

Innovative uses for hypodermic needles in endodontics.

Hypodermic needles have sharp cutting edges along their bevels. These can be used to enlarge canal openings and to cut around a broken instrument or other object to be removed. Means of attaching the needle to such foreign objects for removal are discussed.

In vitro disinfection of dentinal tubules by various endodontics irrigants.

Effectiveness of endodontic irrigants within dentinal tubules of human teeth was evaluated. Mid-sections of single-rooted teeth were prepared into dentin wedges. The pulpal sides of the sections were exposed to Micrococcus luteus or Bacillus megaterium that grew into the tubules. Irrigants used in the study included: 0.525% NaOCl, 0.12% chlorhexidine, RC Prep, 0.5% betadine iodine, and sterile H2O (as a control). Pulpal surfaces were exposed to an irrigant and then rinsed in sterile water. The samples were then cracked, exposing a fresh surface. Culture of the exposed dentin surfaces showed that selected irrigants reached to the far ends of the dentinal tubules in a concentration sufficient to kill 100% of the M. luteus. However B. megaterium was neither killed nor apparently inhibited by any irrigant. We conclude that endodontic irrigants permeate throughout dentinal tubules, but their effectiveness is dependent on the type of bacteria found within the tubules.

Evaluation of prilocaine for the reduction of pain associated with transmucosal anesthetic administration.

This investigation evaluated the use and efficacy of prilocaine HCl (4% plain Citanest) for minimizing pain associated with the intraoral administration of local anesthesia. Clinical anecdotes support the hypothesis that prilocaine without a vasoconstrictor reduces pain during injection. To determine relative injection discomfort, use of 4% plain prilocaine was compared with use of 2% lidocaine with 1:100,000 epinephrine and 2% mepivacaine with 1:20,000 levonordefrin. Prior to routine endodontic procedures, 150 adult patients received 0.3 to 1.8 mL of local anesthetic via the same gauge needle without the use of a topical local anesthetic. Injection methods included buccal infiltration, labial infiltration, palatal infiltration, and inferior alveolar nerve block. Following each injection, patients were asked to describe the level of discomfort by scoring on a visual analog scale of 1 to 10, where 1 = painless and 10 = severe pain. Analyses via 2-way analysis of variance revealed no interaction between anesthetic and site of injection. However, there were statistically significant differences among the injection sites. Post hoc analysis revealed that prilocaine was associated with significantly less pain perception when compared to mepivacaine and lidocaine. These results suggest that differences in initial pain perception during transmucosal injection may be a function of the local anesthetic use, and prilocaine can produce less discomfort than the others tested.

Change in pain threshold by meperidine, naproxen sodium, and acetaminophen as determined by electric pulp testing.

The purpose of this study was to compare changes in pain threshold caused by meperidine, naproxen sodium, acetaminophen, and placebo. The change in pain threshold was measured by electric pulp testing. Acetaminophen elevated the pain threshold statistically significantly. Clinically, however, the superiority of acetaminophen is questionable. No elevation of the pain threshold occurred with narcotic drugs or with nonsteroidal anti-inflammatory drugs: our research shows that the electric pulp tests of patients who have taken these drugs preoperatively will have results similar to those of patients who have taken no drugs. We question the philosophy of administering these drugs for change in pain threshold at the levels used here preoperatively.

Flare-up rate in pulpally necrotic molars in one-visit versus two-visit endodontic treatment.

This retrospective study compared one-visit versus two-visit endodontic treatment. The same technique and materials were used before and after making the sole change to one-visit endodontic treatment in 1991. Treatment records of 402 consecutive patients with pulpally necrotic first and second molars were compared. In 201 patients, treatment was provided by debridement and instrumentation, followed by obturation at a second visit; whereas the second group received single visit therapy. Flare-ups were defined as either patient reports of pain not controlled with over-the-counter medication or as increasing swelling. Sixteen flare-ups (8%) occurred in the two-visit group versus six flare-ups (3%) for the one-visit group. This showed an advantage for one-visit treatment at a 95% confidence level. In a second comparison, one-visit patients who had previously received two-visit treatment for a different pulpally necrotic molar served as their own control. No significant differences were present in this subgroup of 17 patients.

Air pressures developed beyond the apex from drying root canals with pressurized air.

Air introduced into tissues during invasive procedures can be harmful. Endodontic treatment is not frequently associated with this phenomenon, but serious results can occur if air forced into tissues impinges on critical anatomical structures and/or carries infection into deeper areas. Extracted teeth were connected to a pressure gauge during and after canal instrumentation and pressures measured. Also, a fresh porcine jaw was instrumented in the presence of a radiopaque tracer during air drying. Significant pressures were detected beyond the apex of the roots, especially with root apical diameters of file sizes larger than 20.