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Week of January 9, 2001

Title: Frequency of Second Mesiobuccal canals in Maxillary Molars as Determined by Use of an Operating Microscope: A Clinical Study

Author: Sempira, HN. et al

Journal: Journal of Endodontics, 26(11): 673-674, November 2000

Prepared by: Andrew W. Chan, DDS

Purpose: To determine in an in vivo clinical study if the use of an operating microscope would increase the number of second mesiobuccal canals located and obturated in maxillary first and second molars.

Materials & Methods: Two hundred maxillary first and second molars were included in this study. Residents used the microscope (Global Protégé, Model M705F) in each maxillary first and second molar case in an attempt to locate two mesiobuccal canals; magnification varied from 2 to 16 times. To be included and recorded as a second mesiobuccal canal, the canal had to be negotiable and obturated to within 4mm of the apex.

Results: The final sample of 200 cases was comprised of 130 maxillary first molars and 70 maxillary second molars. Of the 200 maxillary first and second molars treated, 30% had negotiable second mesiobuccal canals. Evaluated separately, 33.1% of maxillary first molars and 24.3% of second maxillary molars had negotiable second mesiobuccal canals.

Discussion: Although the operating microscope has many useful functions in endodontic therapy, the results of this study indicate that there was not a significant increase in the number of second mesiobuccal canals located in maxillary molars when compared with the number reported when only the access was modified and no microscope was used.

Title: Effect of Varying the Depth of Heat Application on the Adaptability of Gutta-Percha During Warm Vertical Compaction

Author: Smith et al

Journal: JOE 26(10): 668, November 2000

Prepared by: Brian Frey

Purpose: To compare the adaptability of GP while varying the depth of heat application to obturate a standard root canal

M&M:

A split-tooth model was made using a human maxillary central incisors- all obturations were done on this model
Root canal was cleaned and shaped using a step-back preparation to a size #60 Flex-O-File at the working length (WL)
5 shallow depressions (0.5mm deep) were made on the root canal wall
Thin film of silicone applied with cotton applicator to root canal walls- to prevent GP from adhering thus allowing subsequent obturations on the same model system
20 obturations without sealer were performed for each technique (thermoplastic injectable (TI) i.e. Obtura II, lateral condensation (LC), and warm vertical compaction (WVC) with heat applications at 3,4,5, and 7mm from the working length
After each obturation- the model was separated and the mesial and distal sides of each obturation were examined and videotaped at (x32) magnification
The quality of obturation was graded based on the replication to WL, replication of artificial depressions, surface adaptation, and homogeneity of gutta-percha

Results:

All techniques were significantly different from each other, except for the Thermoplastic group and the warm vertical @3mm
The Thermoplastic group replicated all the depressions and reached all the WL’s and was homogenous and excellent surface adaptation
Warm vertical @3mm was better than @4-7mm
Lateral condensation had the lowest scores for criteria
TI was best, followed by warm vertical, then lateral

Conclusion: Thermoplastic gutta percha has the best adaptability for obturating the root canal in 3 dimensions

Title: Root canal morphology of human maxillary and mandibular third molars

Author: Sidow et al.

Journal: JOE 26(10): 675, November 2000

Prepared by: Barry Hoch

Purpose: To investigate and characterize the anatomy of maxillary and mandibular third molars.

Materials and Methods:

150 maxillary and 150 mandibular extracted third molars were accessed, vacuum-injected with dye, decalcified, and rendered transparent. The internal anatomy of the root canal system was examined under X5 magnification and the results were recorded.

Results:

17% of mandibular 3^rd molars had one root (40% of which contained 2 canals), 77% had 2 roots, 5% had 3 roots, and 1% had 4 roots.
Mandibular 3^rd molars with 2 roots exhibited highly variable canal morphology, containing from 1 to 6 canals, including 2.2% that were "c-shaped."
15% of maxillary 3^rd molars had one root, 32% had 2 roots, 45% had 3 roots, and 7% had 4 roots. Maxillary 3^rd molars with one root showed the most unusual morphology, with 1 to 6 canals.

Discussion:

An in vitro study using clearing techniques provided a reliable method for viewing the entire root canal system. This study illustrated the canal complexities associated with 3^rd molars, and emphasized that the various possibilities should be appreciated when attempting root canal treatment.

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Week of January 16, 2001

Title: Determination of Periodontal Ligament Cell Viability in Long Shelf-life Milk

Author: Marino et al.

Journal: JOE 26(12):699-702, December 2000.

Prepared by: Tom Goebel

Purpose: To determine the ability of long shelf-life milk to serve as a temporary storage medium for the maintenance of periodontal ligament cell viability on avulsed teeth.

M & M:

PDL cells were plated onto 24-well culture plates & allowed to attach for 24 hr
Tissue culture medium was removed after 24 hours
Cells were bathed with regular pasteurized milk (refrigerator milk), long shelf-life milk (Parmalat) or Save-A-Tooth
Tap water was negative control, Minimal Essential Medium was positive control
Plates were incubated at 37° C for 1, 2, 4 or 8 hr
Cell viability was determined using a cell proliferation assay, absorbency was read @ 490 nm
ANOVA statistical analysis was performed

Results:

All media performed significantly better than tap water at all time periods
At 8 hr, PDL cell viability in regular milk & long shelf-life milk were significantly greater than Save-A-Tooth
No significant difference b/t regular milk & long shelf-life milk at any time interval

Conclusion: Long shelf-life milk is as effective a storage medium for avulsed teeth as regular pasteurized milk & more effective than Save-A-Tooth.

Title: Cytotoxicity of Root Canal Filling Materials to Three Different Human Cell Lines.

Author: Willershausen, B. et al.

Journal: JOE 26(12):703. December 2000.

Prepared by: G. Altenburg

Purpose: To test the biological compatibility of five root canal sealers and regular and Ca(OH)₂ based gutta-percha in three different human cell lines.

M&M:

The materials tested were two glass-ionomer based sealers (Endion and Ketac-Endo), one calcium hydroxide-based sealer (Sealapex), one resin-based sealer (AH Plus), and one zinc oxide-eugenol based sealer (Super-EBA) and regular and calcium hydroxide-based gutta-percha points.
Gingival fibroblasts, nasal fibroblasts, and epithelial tumor cells were selected to allow comparisons between cell lines.
Cell growth, cell morphology, cell viability, protein content of the cells, and prostaglandin E₂(PGE₂) release were used as parameters to determine the cytotoxicity of the materials.
For the determination of cell proliferation, cell numbers, and protein content of the cell lines, the sealers were placed in 24-well dishes and covered with 30,000 cells per well. The samples were incubated for 6 days and the medium was changed every 2 days.
For the determination of PGE₂release the root canal sealers were placed in 96-well dishes and covered with 10,000 cells per well. The incubation time for this trial was 30 min.

Results:

Cell growth, cell morphology and cell viability was maintained with varying zones of inhibition.
Cellular response to materials varied between cell lines, with epithelial tumor cells being less sensitive.
The protein content of the three cell lines was reduced by all materials tested, the most significant being AH Plus and Ketac-Endo.
No significant increased PGE₂release values were found with Sealapex, Endion, and Super-EBA.
Significantly increased PGE₂levels were measured with Ketac-Endo, AH Plus, regular and calcium hydroxide-based gutta-percha points.

Conclusions: Human diploid fibroblasts are quite sensitive to the root canal materials tested. The transformed epithelial tumor cells proved to be less sensitive. All the root canal filling materials tested were cytotoxic to fibroblasts to some degree.

Title: Occurrence of Candida albicans in Infections of Endodontic Origin

Author: Baumgartner, JC et al

Journal: JOE 26: 12; pg. 695, Dec., 2000

Reviewer: M.Oller

Purpose: To evaluate the contents of infected root canals and aspirates of cellulitis/abscesses of endodontic origin for the presence of C. albicans using the polymerase chain reaction (PCR).

Materials and Methods: Microbial samples were collected form 24 root canals and 19 aspirates of cellulitis/abscesses of patients seen in the Oregon Health Sciences U. Dental School. Selection was based on clinical examination and the presence of periapical radiolucency determined to be of endodontic origin.

- Samples were taken after disinfecting the tooth surface upon rubber dam placement.

Access was made and the samples were collected and placed in sterilized transport fluid. If the canal was dry after accessing, the transport fluid was placed in the canal and the sample was collected with paper points.
Aseptic aspirates of cellulitis/abscesses of endodontic origin were obtained using a 16-guage needle after having the patient rinse with CHG (.12%).

- DNA was isolated using a qiAmp Tissue Kit (this method included a preincubation step with lysozyme to lyse the fungi cells before the cells were digested with proteinase K).

- The sequence of DNA from C. albicans was determined and a primer pair used was designed to amplify a 276 base pair region form the 18S r-RNA gene. (The specificity of the primer pair designed to amplify the 18S r-RNA gene was tested against several common bacteria found in the root canal. No other DNA amplification other than the 276 base pair for C. albicans was found à thus, the test was specific just for C. albicans).

PCR products were separated by electrophoresis and visualized by ethidium bromide fluorescence.

Results:

5 PCR products of DNA extracted from 24 root canals was found to be positive for C. albicans.
19 samples taken from cellulitis/abscesses were found to be negative for the presence for C. albicans DNA.

Conclusion: The study confirms that C. albicans may be involved in root canal infection more often then previously believed

Comments: The paper notes other studies regarding the presence of fungi within root canals:

- Waltimo et al found 80% of the species of fungi were C. albicans.

- Sen et al used SEM to observe bacteria and fungi in the root canals and dentinal tubules of 10 extracted teeth. 4 teeth the root canals were infected with fungi and hyphal networks were seen.

- Several studies evaluate the effects of endodontic irrigants against C. albicans. It has been found to be more resistant that S. faecalis or Bacillus sp. to citric acid and sodium hypochlorite.

Irrigants have been shown to have greater effect upon the removal of the smear layer (NaOCl alone showed antifungal effects after 30min upon removal of smear layer).

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Week of January 26, 2001

Title: The effectiveness of prophylactic Etodolac on post-endodontic pain

Author: Menke et al

Journal: JOE 26(12): 712, 2000

Reviewed by: Brian Frey

Purpose: To determine if prophylactic etodolac will significantly reduce post-endodontic pain, when compared with prophylactic ibuprofen and prophylactic placebo

M&M:

36 patients who underwent one appointment conventional root canal treatment were administered either
1) 400 mg Etodolac (COX-2 inhibitor)
2) 600mg ibuprofen
3) placebo before endodontic treatment
Pain of patients was recorded on a Visual Analog Scale (VAS) before root canal treatment, immediately postoperative, 4,8,12,24,48, and 72 hours after initiation of root canal treatment
Patients were given extra pain medication after treatment to take only as needed and to record the time it was taken on the pain survey
Results were analyzed comparing
1)VAS values of medications vs. time periods
2) the need for extra medication after RCT corresponding with pulpal and periapical diagnosis

Results:

Prophylactic 600mg ibuprofen administration significantly reduced post-endodontic pain and was more effective at 4 and 8 hours after RCT, when compared with 400mg etodolac and a placebo
Additional pain medication needed based on preoperative periapical status --Patients who presented with a periapical diagnosis of an acute apical periodontitis or a Phoenix abscess were more likely to require additional medication for post-endodontic pain than patients who presented with a normal periapex, chronic apical periodontitis, or a chronic apical abscess
Additional pain medication needed based on preoperative pulpal status – no significant difference existed for pulpal diagnosis and the need for additional medication

Conclusion: Prophylactic ibuprofen(600mg) provides and effective and inexpensive reduction in post-endodontic pain.
Patients with a periapical diagnosis of acute apical periodontitis or Phoenix abscess are more likely to require additional doses of pain medication for post-endodontic pain.

Title: The Walking Bleach Procedure: An In Vitro Study To Measure Microleakage of Five Temporary Sealing Agents.

Author: Hosoya, N. et al.

Journal: JOE 26(12): 716, December 2000.

Reviewed by: Barry Hoch

Purpose: To evaluate the sealing ability of five materials used as a temporary seal of the cavosurface margin during the walking bleach procedure.

Materials and Methods:

125 freshly extracted human maxillary incisors were instrumented by "traditional biomechanical" root canal preparation.
After instrumentation, a paste of 30% H₂O₂ and sodium perborate was mixed and used as the bleaching agent. It was placed into each prepared canal (it is assumed that these teeth were obturated?) 2mm below the CEJ and into the access.
The 5 materials used for temporary sealing of the accesses were Cavit and Coltosol as common hydraulic materials, Fermit as the photoactivated resin material, Eugedain as the ZOE cement, and Crown & Bridge-Inlay cement as the Zn(PO)₄ cement.
In one group a small piece of rubber sheet was placed between the bleach paste and the temporary material.
The teeth were subsequently placed in a 1% Alcian blue solution and thermocycled for 1 week.
Teeth were vertically sectioned and sealing ability was graded in relation to dye penetration and presence/loss of temporary material from the access.

Results:

There was significantly less dye microleakage observed in the two hydraulic materials (Cavit and Coltosol) than in the other groups.
The photoactivated resin showed less microleakage than the ZOE and Zn(PO)₄ cements.
The presence of a rubber sheet did not significantly reduce leakage.

Discussion:

This is yet another study focusing on the use of certain temporary restorative materials during endodontic procedures. It is interesting that the authors hypothesized that the ZOE and Zn(PO)₄ were "more strongly influenced by the bleaching agent than were the hydraulic filling materials."
The authors seemed most concerned about preventing leakage not from the oral cavity into the root canal system, but rather leakage of the bleaching material into the oral cavity and periradicular tissues. I’m not quite sure that using this dye penetration study was a proper design to assess their concerns.

Title: Immunohistochemical Localization of Tenascin, Fibronectin, and Type III Collagen in Human Dental Pulp

Author: Martinez, EF. et al

Journal: Journal of Endodontics, 26(12): 708-711, December 2000

Prepared by: Andrew W. Chan, DDS

Purpose: To examine the expression of tenascin, fibronectin, and type III collagen in normal and in histopathologically modified human dental pulp.

Materials & Methods:

- 54 human dental pulps with different clinicohistopathological diagnoses were studied.

- H&E stained sections were reviewed to confirm the diagnoses.

- Formalin-fixed tissue sections (3um) were used for immunohistochemical staining.

- Paraffin sections were treated and the specimens were observed with a light microscope.

- The distribution of tenascin, fibronectin, and type III collagen in the extracellular matrix of the connective tissue of normal, inflamed, and hyalinized human dental pulp was studied immunohistochemically by staining with monoclonal antibodies against these molecules.

Results:

Normal Human Dental Pulp: Immunohistochemistry showed a strong staining for tenascin, fibronectin, and type III collagen.

Human Dental Pulp with Inflammatory Process: Immunohistochemically none of the molecules studied were seen in the inflammatory areas.

Hyalinized Human Dental Pulp: These areas stained for type III collagen, but not fibronectin and tenascin.

Discussion: The maintenance of tenascin and fibronectin expression in adult human dental pulp seems to be associated with regulation of cell differentiation involved in the formation of hard tissues matrices. Both tenascin and fibronectin were strongly stained in the periphery of the tissue (next to the odontoblastic layer). In the cell-free zone, type III collagen was absent but fibronectin was present. Tenascin and fibronectin is important for cell migration as in healing wounds. Type III collagen is responsible for tissue architecture. The absence of tenascin and fibronectin in hyalinized human dental pulp may be related to the aging process. In conclusion this study demonstrated the expression of tenascin, fibronectin, and type III collagen in adult normal and histopathologically modified human dental pulp.

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Roy H. Stevens, DDS, MS; Wanda Gordon, D.M.D. - Comments to author:	wgordon@dental.temple.edu
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