Mandibles Of Guinea Pigs Research Articles

Assessing Macrophage Polarization in Nanoparticle-Guided Wound Repair Using a Lipopolysaccharide Contaminated Intraosseous Model

IntroductionMacrophages regulate the processes of inflammation and tissue regeneration/repair through their plasticity and phenotypes of different activation states. Previous studies have shown that disinfection of lipopolysaccharide (LPS)-contaminated dentin with photoactivated rose bengal–functionalized chitosan nanoparticles (CSRBnps) in vivo supported neotissue formation without signs of inflammation and root resorption. The aim of this study was to understand the mechanism underlying CSRBnp-guided attenuation of inflammation in LPS-contaminated dentin using macrophage polarization as an indicator of inflammation and repair. MethodsTo quantify the polarized macrophage populations, M1/M2-specific surface markers CD68, CD80, and CD206 and transcriptional factors signal transducer and activator of transcription (STAT) 1, STAT3, and STAT6 were determined using immunohistochemistry among previously obtained root specimens implanted into mandibles of guinea pigs for 4 weeks. In group 1, the canals were not inoculated; in group 2, the canals were inoculated with Pseudomonas aeruginosa LPS; in group 3, the canals were inoculated and disinfected with sodium hypochlorite; in group 4, the canals were inoculated and disinfected with sodium hypochlorite and calcium hydroxide; and in group 5, the canals were inoculated and disinfected with sodium hypochlorite, and CSRBnps (300 μg/mL) with photoactivation (λ = 540 nm, 40 J/cm2) were analyzed. ResultsAn increased expression of M2-specific markers was observed in the group treated with CSRBnps compared with the groups treated with either conventional or no root canal disinfection. A statistically significant population of macrophages expressing both M1- and M2-specific markers was observed in all the tested groups. ConclusionsDisinfection of LPS-contaminated dentin with CSRBnps demonstrated M2-type polarization of macrophages, which corresponded to repair and neotissue formation.

Bioactivity of Photoactivated Functionalized Nanoparticles Assessed in Lipopolysaccharide-contaminated Root Canals In Vivo

IntroductionThe persistence of dentin-bound lipopolysaccharides (LPS) in disinfected root canals impedes treatment outcomes of endodontic procedures. This study assessed the effects of photoactivated rose bengal–functionalized chitosan nanoparticles (CSRBnps) on LPS-contaminated root dentin in vivo using an intraosseous implantation model and neotissue formation as a marker. MethodsFifty human, 3-mm-long root segments with a 1.2-mm canal lumen were divided into 5 groups (n = 10): group 1, canals not contaminated; group 2, canals contaminated with Pseudomonas aeruginosa LPS; group 3, canals contaminated and disinfected with sodium hypochlorite (NaOCl); group 4, canals contaminated and disinfected with NaOCl and calcium hydroxide; and group 5, canals contaminated and disinfected with NaOCl and CSRBnps (300 μg/mL) with photoactivation (λ = 540 nm, 40 J/cm2). Specimens were implanted into mandibles of guinea pigs, block dissected after 4 weeks, and the canal content evaluated histologically and immunohistochemically. The ingrown neotissue interface (50 μm) with dentin was characterized for fibroblasts, osteoclasts, inflammatory markers, dentin resorption, mineralization, and angiogenesis and dichotomized as type 1 (no inflammation and resorption, indicative of LPS inactivation) or type 2 (inflammation and resorption). The frequency of the observed parameters was analyzed using the Fisher exact test. ResultsThe outcome was categorized as type 1 in groups 1 and 5, type 2 in group 2, and mixed type 1 and 2 in groups 3 and 4. The outcomes in groups 1 and 5 (P > .05) differed significantly (P < .05) from those in groups 2, 3, and 4. ConclusionsDisinfection of LPS-contaminated root canals with photoactivated CSRBnps in vivo supported ingrowth of neotissue without signs of inflammation or resorption, suggestive of effective inactivation of dentin-bound LPS.

Surgical endodontics

Failures of conventional endodontic treatment can be multifactorial: presence of bacteria in the root canal system may cause persistent apical leakage, the anatomy of the tooth may inhibit adequate orthograde preparation, or debris forced out the apex may cause continual symptoms for the patient. Although alternative treatments exist such as extraction and implant reconstruction, many teeth and prostheses can be maintained with the use of apical surgery procedures.The provision of surgical treatment of endodontic failures should be recognized as an exploratory procedure. Decisions made during the surgery include the possibility of a limited apical resection with retrograde filling, removal of a root, or the extraction of the tooth if the situation is deemed to have a poor prognosis. Guidance preoperatively including a focused periodontal examination as well as radiographic evidence may provide indicators as to the potential success or failure of the planned apical surgical procedure.Recent developments in apical surgery include the continued development of an ideal retrograde filling material. Although materials such as amalgam have been shown to have excellent characteristics, the concerns with implanting this material as well as its potential for staining tissues has lead to the search for newer agents. Formulations of an intermediate restorative material (Super-EBA) and more recently the utilization of mineral trioxide aggregate (MTA) have been shown to adequately seal the root canal system and provide biocompatibility with the local tissues.Lastly, technical improvements in the preparation of the apex have contributed to the improved success of this surgical technique. The ultrasonic device permits a deep enough preparation to seal the apex without requiring a substantial amount of bone removal for visualization. Ultrasonic devices facilitate the preparation of isthmus regions and un(der)filled canals as well.ReferencesLieblich SE: Periapical surgery: Clinical decision making. Oral Maxillofac Surg Clin North Am 14:179, 2002Torabinejad M, Hong CU, Pitt Ford TR: Tissue reaction to implanted super-EBA and mineral trioxide aggregate in the mandible of guinea pigs: A preliminary report. J Endodont 21:569, 1995Von Arx T, Kurl B: Root-end cavity preparation after apicoectomy using a new type of sonic and diamond surfaced retrotip: A 1 year follow up study. J Oral Maxillofac Surg 57:656, 1999 Failures of conventional endodontic treatment can be multifactorial: presence of bacteria in the root canal system may cause persistent apical leakage, the anatomy of the tooth may inhibit adequate orthograde preparation, or debris forced out the apex may cause continual symptoms for the patient. Although alternative treatments exist such as extraction and implant reconstruction, many teeth and prostheses can be maintained with the use of apical surgery procedures. The provision of surgical treatment of endodontic failures should be recognized as an exploratory procedure. Decisions made during the surgery include the possibility of a limited apical resection with retrograde filling, removal of a root, or the extraction of the tooth if the situation is deemed to have a poor prognosis. Guidance preoperatively including a focused periodontal examination as well as radiographic evidence may provide indicators as to the potential success or failure of the planned apical surgical procedure. Recent developments in apical surgery include the continued development of an ideal retrograde filling material. Although materials such as amalgam have been shown to have excellent characteristics, the concerns with implanting this material as well as its potential for staining tissues has lead to the search for newer agents. Formulations of an intermediate restorative material (Super-EBA) and more recently the utilization of mineral trioxide aggregate (MTA) have been shown to adequately seal the root canal system and provide biocompatibility with the local tissues. Lastly, technical improvements in the preparation of the apex have contributed to the improved success of this surgical technique. The ultrasonic device permits a deep enough preparation to seal the apex without requiring a substantial amount of bone removal for visualization. Ultrasonic devices facilitate the preparation of isthmus regions and un(der)filled canals as well. References Lieblich SE: Periapical surgery: Clinical decision making. Oral Maxillofac Surg Clin North Am 14:179, 2002 Torabinejad M, Hong CU, Pitt Ford TR: Tissue reaction to implanted super-EBA and mineral trioxide aggregate in the mandible of guinea pigs: A preliminary report. J Endodont 21:569, 1995 Von Arx T, Kurl B: Root-end cavity preparation after apicoectomy using a new type of sonic and diamond surfaced retrotip: A 1 year follow up study. J Oral Maxillofac Surg 57:656, 1999

The Effect of Calcitonin on Osseous Healing in Guinea Pig Mandible

Calcitonin (CT) is reported to be an effective medication for the treatment of inflammatory root resorption and to be capable of stimulating osteoblast proliferation in cell culture studies. In this study the effect of CT on the healing of osseous defects was evaluated in the mandibles of guinea pigs. After raising tissue flaps two experimental cavities were created on both sides of the corpus mandible of 33 guinea pigs. CT was applied into cavities either in hydroxypropyl methycellulose (HPMC) gel or gelatin as carrier. HPMC and gelatin alone and an empty cavity were also examined as control groups. Histopathological examinations under light microscopy were performed on weeks 1, 3, and 6. At week 1 in CT+gelatin and CT+HPMC groups, prominent osteoblastic activity was observed when compared with control groups. At week 3 the presence of woven bone in the experimental cavity areas reflected the increased osteoblastic activity in all groups. At the end of week 6 woven bone was gradually replaced by osteogenic tissue undergoing remodelization with Haversian systems in all groups. It is suggested that the osseous healing of the experimental cavity was enhanced by CT application in early stages (i.e. at week 1). However there was no significant difference of osteogenic activity between the control and CT-treated groups at the end of weeks 3 and 6.

Tissue reaction to implanted root-end filling materials in the tibia and mandible of guinea pigs

The purpose of this study was to examine the tissue reaction to implanted mineral trioxide aggregate (MTA), amalgam, Intermediate Restorative Material, and Super-EBA in the tibias and mandibles of guinea pigs. After anesthetizing 20 guinea pigs, raising tissue flaps, and preparing bony cavities, the test materials were placed in Teflon cups and implanted in the tibias and 10 days later in the mandibles. The animals were euthanized 80 days later and the tissues prepared for histological examination. The presence of inflammation, predominant cell type, and thickness of fibrous connective tissue adjacent to each implant were recorded. The tissue reaction to MTA implantation was the most favorable observed at both sites; as in every specimen, it was free of inflammation (p < 0.01). In the tibia, MTA was the material most often observed with direct bone apposition. Based on these results, MTA seems to be a biocompatible material.

Tissue reaction to implanted super-EBA and mineral trioxide aggregate in the mandible of guinea pigs: A preliminary report

In vitro sealing ability and biocompatibility tests on mineral trioxide aggregate (MTA) have shown similar or better properties for this material than for existing root-end filling substances. The purpose of this study was to examine the tissue reaction of implanted Super-EBA and MTA in the mandibles of guinea pigs. After anesthetizing seven guinea pigs, raising a tissue flap and preparing two bony cavities, the test materials were placed in Teflon cups and implanted in the mandibles. Two bony cavities without implanted materials were left to heal and used as negative controls. The presence of inflammation, predominant cell type, and thickness of fibrous connective tissue adjacent to each implant was recorded. The tissue reaction to MTA implantation was slightly than that observed with Super-EBA implantation. Based on these results , it seems that both Super-EBA and MTA are biocompatible.

Tissue reactions to endodontic materials implanted in the mandibles of guinea pigs

Teflon, Intermediate Restorative Material, and Prisma VLC Dycal were implanted in the mandibles of 16 guinea pigs. After experimental periods of 4 and 12 weeks, the animals were killed and tissue sections were prepared. No severe inflammatory response was noted in any of the groups except for a persistence of moderate inflammation in the poorly condensed Teflon group. Bone apposition occurred in the Prisma VLC Dycal group; none-to-mild inflammation and a thin fibrous capsule characterized the IRM group; and the Teflon group had a thick fibrous encapsulation except for samples where the Teflon material appeared to be poorly condensed and dispersed into the bony tissue. In areas where the teflon was loosely condensed, chronic inflammation and active phagocytosis were seen along the surface of the material.

Tissue responses to Hydron, assessed by intraosseou simplantation

Teflon tubes containing freshly mixed, polymerized Hydron root canal filling material, fully set AH26 or Teflon were implanted into the mandible of guinea pigs and assessed histologically at 2 days, 1, 2, 4, 12 and 26 weeks. None of the materials tested elicited signs of overt or significant tissue damage, and polymerized Hydron was assessed to be as biocompatible as fully set AH26 and Teflon. Bone formed in very close apposition to the polymerized Hydron, whereas a soft tissue capsule separated the regenerated bone from implants of AH26 and Teflon.

Tissue irritating properties of bis-dequalinium acetate solutions for endodontic use

Bis-dequalinium acetate has been suggested as an endodontic antiseptic and irrigant because of its low surface tension and ability to aid in the removal of the smear layer formed during instrumentation. Recently, bis-dequalinium acetate for endodontic use was marketed as solvidont. In order to comprehensively assess its biological effect, the compound was tested for early tissue irritating effect through evaluation of enhanced vascular permeability. Various concentrations of the test substance were injected intradermally into the backs of rats and the capillary leakage was evaluated by spectroscopy. controls were 2% iodine-potassium iodide and 1% buffered sodium hypochlorite. Tissue reaction through intrabony implantation in the mandible of guinea pigs after observation periods of 4 and 12 wks was evaluated using the histological criteria outlined by the FDI Technical Report 9. Controls were the smooth surface of the carrier and polyethylene glycol. The results indicate that bis-dequalinium acetate causes only minor tissue irritation, has low toxicity, and compared with the reference medicaments may be a good alternative for clinical endodontics. Bis-dequalinium acetate has been suggested as an endodontic antiseptic and irrigant because of its low surface tension and ability to aid in the removal of the smear layer formed during instrumentation. Recently, bis-dequalinium acetate for endodontic use was marketed as solvidont. In order to comprehensively assess its biological effect, the compound was tested for early tissue irritating effect through evaluation of enhanced vascular permeability. Various concentrations of the test substance were injected intradermally into the backs of rats and the capillary leakage was evaluated by spectroscopy. controls were 2% iodine-potassium iodide and 1% buffered sodium hypochlorite. Tissue reaction through intrabony implantation in the mandible of guinea pigs after observation periods of 4 and 12 wks was evaluated using the histological criteria outlined by the FDI Technical Report 9. Controls were the smooth surface of the carrier and polyethylene glycol. The results indicate that bis-dequalinium acetate causes only minor tissue irritation, has low toxicity, and compared with the reference medicaments may be a good alternative for clinical endodontics.

Biologic effects of root canal filling materials: The effect on bone tissue of two formaldehyde-containing root canal filling pastes: N2 and Riebler's paste

Freshly prepared N2 and Riebler's paste were implanted in the mandibles of guinea pigs. Fifty-two implants of each root canal filling material were inserted. Thirteen implants of each type of paste were removed after 3 days, 1 week, 2 weeks, and 12 weeks. Histologic examination revealed extensive tissue necrosis in the form of so-called fixation intra vitam. In the cases treated with N2 the necrosis reached its maximum within 1 week; and in those treated with Riebler's paste, within 3 days. The tissue damage by N2 also persisted 2 weeks after implantation, but by 12 weeks the necrotic tissue had been largely resorbed and replaced by granulation tissue without signs of bone regeneration. The damage caused by Riebler's paste also persisted unchanged 12 weeks after implantation. N2 and Riebler's paste in contact with vital tissue produced extensive damage in the form of necrosis.

Craniometric analysis of growth patterns in guinea pig mandibles

Craniometric analyses were conducted to determine the patterns of growth in different areas of the mandibles of guinea pigs of known age and sex groups. One dental measurement and eleven skeletal measurements were taken from the mandible. Variables considered were sex, age groups, and differences between the right and left sides of the mandible. Analyses of variance were calculated for each of the skeletal and dental measurement factors. The 0.01 level of significance was used; any differences at the 1 per cent or better level of significance were considered to be statistically significant. Statistically significant age-associated differences were observed in all the distances measured; sex differences were noted in seven distances; sex-age interactions were observed in ten out of twleve distances measured, and the presence of such an interaction meant that the sex differences were not constant for each age group. Side differences were nonsignificant except in the distance measured between the anterior and posterior borders of the alveolar crest. The percentile incremental growth values varied considerably during different periods. In most instances approximately half of the total growth was attained at 30 days when comparisons were made with 5-day dimensions.

The effect of x-ray irradiation upon the mandibles of guinea pigs treated with large and small doses of ascorbic acid.

The effect of x-ray irradiation upon the mandibles of guinea pigs treated with large and small doses of ascorbic acid.