- Email: [email protected]
Push-out bond strength of obturation system
Clinical Significance.—Irrigation has been demonstrated essential to debridement of root canals. Traditional irrigation methods, using a needle to deliver the solution, become less effective as the critical apical area is approached. The device reported here demonstrated more effective cleaning of the critical last millimeter of canal length compared with the conventional needle technique.
Nielsen BA, Craig Baumgartner J: Comparison of the EndoVac system to needle irrigation of root canals. J Endod 33:611-615, 2007 Reprints available from J Craig Baumgartner, Dept of Endodontology, 611 Campus Dr, Portland, OR 97239-3097; e-mail: baumgarc@ ohsu.edu
Endodontics Push-out bond strength of obturation system Background.—The canal space is obturated to prevent leakage from the oral cavity and periradicular tissues into the root canal system and to seal up any microorganisms that were not removed when the canal was cleaned and shaped. Ideally endodontic sealers also adhere to dentin, increasing the chance of obtaining successful endodontic treatment. Adhering to dentin and bonding to the tooth structure contribute to the resistance to tooth fracture, helping to ensure greater clinical survival for the treated tooth. The effectiveness of an endodontic obturation technique or material can be assessed using a push-out bond strength test. The push-out bond strengths to intraradicular dentin of Epiphany/Resilon, a new thermoplastic synthetic polymer-based root canal filling material, and gutta-percha/AH26 were evaluated.
material that were created by air trapped in the seal when the primer or sealer was placed. Another explanation for the lower bond strength in the EP group is polymerization shrinkage of the sealer. The stress of this shrinkage may cause the resin-based sealer to separate from the dentinal walls. Claims have been made that the Epiphany Soft Resin Endodontic Obturation System performs as well as gutta-
Methods.—Thirty roots were divided into 2 groups for treatment using the 2 endodontic obturation systems. Epiphany Soft Resin Endodontic Obturation System was used for 1 group (EP) and gutta-percha points plus AH26 Root Canal Sealing for the other (GP). The roots were sliced horizontally so a push-out strength test could be performed from apical to coronal in a universal testing machine (Fig 1). The values were analyzed statistically and compared between groups. Results.—Seventy-eight slices were tested for each group. The EP group had a mean push-out bond strength of 0.51 MPa, whereas the GP group had a mean value of 1.70 MPa (Table 1). The groups were also assessed by location of the bond strength distribution, but there was no correlation between location and group. Discussion.—Gutta-percha had greater push-out bond strength than the new obturation system. The difference between the 2 groups may be a function of the presence of voids between the dentinal walls and the obturation
40
Dental Abstracts
Fig 1.—Diagram for the push-out bond strength test. (This article was published in J Endod, 33, Sly MM, Moore BK, Platt JA, et al, Pushout bond strength of a new endodontic obturation system [Resilon/Epiphany], 120-162, Copyright American Association of Endodontics (2007).)
Table 1.—Push-out Bond Strength Group
N
Mean (MPa)
SD
SE
Min.
Max.
EP GP
78 78
0.51 1.70
0.30 0.71
0.08 0.18
0.06 0.99
1.29 3.43
P value obtained from the rank transformation (not shown) (P < .0001). (This article was published in J Endod, 33, Sly MM, Moore BK, Platt JA, et al, Push-out bond strength of a new endodontic obturation system [Resilon/ Epiphany], 120-162, Copyright American Association of Endodontics (2007).)
percha and offers the advantage of forming a monoblock bonding to the dentinal walls. It looks and handles like gutta-percha. The monoblock results when the Resilon core bonds to the resin sealer, which attaches to the primed root dentin. The core part of the Epiphany system may not be optimized for effective chemical coupling to methacrylate-based sealers. This would include both the Epiphany and RealSeal sealers. The ability of both sealer and core material to bond together requires further study.
Clinical Significance.—Hermetic sealing and obturation of the canal space is 1 requirement of successful endodontic therapy. Bonding of the filling material to the canal walls would seem to provide a superior seal compared with conventional gutta-percha and sealer. In this study using push-out bond strength as the benchmark of sealing effectiveness, gutta-percha outperformed the bonded material. Further testing for leakage at the apical foramen is in order.
Sly MM, Moore BK, Platt JA, et al: Push-out bond strength of a new endodontic obturation system (Resilon/Epiphany). J Endod 33:120162, 2007 Reprints available from MM Sly, Indiana Univ School of Dentistry, Dental Materials, 1121 W Michigan St, Room 118, Indianapolis, IN 46202; e-mail: [email protected]
Esthetic Dentistry Cryosurgery for gingival melanin pigmentation Background.—High levels of oral melanin pigmentation are normal in African, East Asian, Mediterranean, and Hispanic populations but fairly rare in light-skinned individuals. Gingival melanin pigmentation (GMP) results from an excessive deposition of melanin and can be produced naturally or triggered by smoking tobacco, endocrine disturbances, Albright’s syndrome, malignant melanoma, antimalarial therapy, Peutz-Jeghers syndrome, trauma, hemochromatosis, or chronic pulmonary disease. With the increasing emphasis on esthetic factors, a need to manage GMP has arisen. No medical problem is at issue here; the concern is esthetic. Approaches have included gingivectomy, free gingival grafting, acellular dermal matrix, laser surgery, electrosurgery, and gas expansion cryosurgery. The treatment of choice has been laser surgery, although cryosurgery offers the advantages of not requiring sutures and dressings, being free of bleeding, nonscarring, having a rare incidence of secondary infection, and producing minimal disruption of surrounding tissues. Its expense and the safety and practical concerns attending the storage of liquid gases are likely the reasons it is used so infrequently.The nonchlorofluorocarbon, nonflammable gas 1,1,1,2 tetrafluoroethane (TFE) is used as a coolant for refrigeration systems and electron circuits. Exposures of healthy persons to TFE through short-term inhalation or skin contact have demonstrated no adverse effect on pulse, blood pressure, electrocardiographic status, or lung function. Animal exposures have been linked to no adverse effects
on development, maturation, or reproduction and show no genotoxic and oncogenic tendencies. TFE is used in dentistry for cold-pulp testing. Cryosurgical procedures have been reported to cause hypopigmentation as an adverse effect. Whether TFE-cooled cotton swab applications could produce depigmentation of GMP-affected tissues was investigated. Methods.—The 21 healthy women (age 18 to 53 years) who volunteered complained of dissatisfaction with the esthetics of GMP. Two were nonsmokers; the others smoked over 10 cigarettes daily. The pigmented areas were isolated and air dried (Fig 1). Topical anesthesia using 4% Xylocaine spray was used to minimize discomfort. A cotton swab was sprayed with TFE and immediately rolled gently over the treatment area. For each area, a freezing zone was maintained continuously for 30 to 40 seconds. A single treatment was given, then the patients were reexamined after 1, 2, and 4 weeks. Recalls at 6-month intervals were done for 30 months. Preoperative and postoperative digital photographs of the treated areas were obtained and compared. Results.—The women had slight erythema of the gingiva immediately after cryosurgery. A superficial necrosis then became apparent until a whitish slough of tissue could be removed, revealing a clean pink surface. Gingival appearance returned to normal within a week; the return of keratinization required 3 to 4 weeks. Patient acceptance of the
Volume 53
Issue 1
2008
41
Nielsen BA, Craig Baumgartner J: Comparison of the EndoVac system to needle irrigation of root canals. J Endod 33:611-615, 2007 Reprints available from J Craig Baumgartner, Dept of Endodontology, 611 Campus Dr, Portland, OR 97239-3097; e-mail: baumgarc@ ohsu.edu
Endodontics Push-out bond strength of obturation system Background.—The canal space is obturated to prevent leakage from the oral cavity and periradicular tissues into the root canal system and to seal up any microorganisms that were not removed when the canal was cleaned and shaped. Ideally endodontic sealers also adhere to dentin, increasing the chance of obtaining successful endodontic treatment. Adhering to dentin and bonding to the tooth structure contribute to the resistance to tooth fracture, helping to ensure greater clinical survival for the treated tooth. The effectiveness of an endodontic obturation technique or material can be assessed using a push-out bond strength test. The push-out bond strengths to intraradicular dentin of Epiphany/Resilon, a new thermoplastic synthetic polymer-based root canal filling material, and gutta-percha/AH26 were evaluated.
material that were created by air trapped in the seal when the primer or sealer was placed. Another explanation for the lower bond strength in the EP group is polymerization shrinkage of the sealer. The stress of this shrinkage may cause the resin-based sealer to separate from the dentinal walls. Claims have been made that the Epiphany Soft Resin Endodontic Obturation System performs as well as gutta-
Methods.—Thirty roots were divided into 2 groups for treatment using the 2 endodontic obturation systems. Epiphany Soft Resin Endodontic Obturation System was used for 1 group (EP) and gutta-percha points plus AH26 Root Canal Sealing for the other (GP). The roots were sliced horizontally so a push-out strength test could be performed from apical to coronal in a universal testing machine (Fig 1). The values were analyzed statistically and compared between groups. Results.—Seventy-eight slices were tested for each group. The EP group had a mean push-out bond strength of 0.51 MPa, whereas the GP group had a mean value of 1.70 MPa (Table 1). The groups were also assessed by location of the bond strength distribution, but there was no correlation between location and group. Discussion.—Gutta-percha had greater push-out bond strength than the new obturation system. The difference between the 2 groups may be a function of the presence of voids between the dentinal walls and the obturation
40
Dental Abstracts
Fig 1.—Diagram for the push-out bond strength test. (This article was published in J Endod, 33, Sly MM, Moore BK, Platt JA, et al, Pushout bond strength of a new endodontic obturation system [Resilon/Epiphany], 120-162, Copyright American Association of Endodontics (2007).)
Table 1.—Push-out Bond Strength Group
N
Mean (MPa)
SD
SE
Min.
Max.
EP GP
78 78
0.51 1.70
0.30 0.71
0.08 0.18
0.06 0.99
1.29 3.43
P value obtained from the rank transformation (not shown) (P < .0001). (This article was published in J Endod, 33, Sly MM, Moore BK, Platt JA, et al, Push-out bond strength of a new endodontic obturation system [Resilon/ Epiphany], 120-162, Copyright American Association of Endodontics (2007).)
percha and offers the advantage of forming a monoblock bonding to the dentinal walls. It looks and handles like gutta-percha. The monoblock results when the Resilon core bonds to the resin sealer, which attaches to the primed root dentin. The core part of the Epiphany system may not be optimized for effective chemical coupling to methacrylate-based sealers. This would include both the Epiphany and RealSeal sealers. The ability of both sealer and core material to bond together requires further study.
Clinical Significance.—Hermetic sealing and obturation of the canal space is 1 requirement of successful endodontic therapy. Bonding of the filling material to the canal walls would seem to provide a superior seal compared with conventional gutta-percha and sealer. In this study using push-out bond strength as the benchmark of sealing effectiveness, gutta-percha outperformed the bonded material. Further testing for leakage at the apical foramen is in order.
Sly MM, Moore BK, Platt JA, et al: Push-out bond strength of a new endodontic obturation system (Resilon/Epiphany). J Endod 33:120162, 2007 Reprints available from MM Sly, Indiana Univ School of Dentistry, Dental Materials, 1121 W Michigan St, Room 118, Indianapolis, IN 46202; e-mail: [email protected]
Esthetic Dentistry Cryosurgery for gingival melanin pigmentation Background.—High levels of oral melanin pigmentation are normal in African, East Asian, Mediterranean, and Hispanic populations but fairly rare in light-skinned individuals. Gingival melanin pigmentation (GMP) results from an excessive deposition of melanin and can be produced naturally or triggered by smoking tobacco, endocrine disturbances, Albright’s syndrome, malignant melanoma, antimalarial therapy, Peutz-Jeghers syndrome, trauma, hemochromatosis, or chronic pulmonary disease. With the increasing emphasis on esthetic factors, a need to manage GMP has arisen. No medical problem is at issue here; the concern is esthetic. Approaches have included gingivectomy, free gingival grafting, acellular dermal matrix, laser surgery, electrosurgery, and gas expansion cryosurgery. The treatment of choice has been laser surgery, although cryosurgery offers the advantages of not requiring sutures and dressings, being free of bleeding, nonscarring, having a rare incidence of secondary infection, and producing minimal disruption of surrounding tissues. Its expense and the safety and practical concerns attending the storage of liquid gases are likely the reasons it is used so infrequently.The nonchlorofluorocarbon, nonflammable gas 1,1,1,2 tetrafluoroethane (TFE) is used as a coolant for refrigeration systems and electron circuits. Exposures of healthy persons to TFE through short-term inhalation or skin contact have demonstrated no adverse effect on pulse, blood pressure, electrocardiographic status, or lung function. Animal exposures have been linked to no adverse effects
on development, maturation, or reproduction and show no genotoxic and oncogenic tendencies. TFE is used in dentistry for cold-pulp testing. Cryosurgical procedures have been reported to cause hypopigmentation as an adverse effect. Whether TFE-cooled cotton swab applications could produce depigmentation of GMP-affected tissues was investigated. Methods.—The 21 healthy women (age 18 to 53 years) who volunteered complained of dissatisfaction with the esthetics of GMP. Two were nonsmokers; the others smoked over 10 cigarettes daily. The pigmented areas were isolated and air dried (Fig 1). Topical anesthesia using 4% Xylocaine spray was used to minimize discomfort. A cotton swab was sprayed with TFE and immediately rolled gently over the treatment area. For each area, a freezing zone was maintained continuously for 30 to 40 seconds. A single treatment was given, then the patients were reexamined after 1, 2, and 4 weeks. Recalls at 6-month intervals were done for 30 months. Preoperative and postoperative digital photographs of the treated areas were obtained and compared. Results.—The women had slight erythema of the gingiva immediately after cryosurgery. A superficial necrosis then became apparent until a whitish slough of tissue could be removed, revealing a clean pink surface. Gingival appearance returned to normal within a week; the return of keratinization required 3 to 4 weeks. Patient acceptance of the
Volume 53
Issue 1
2008
41