Robert Spears

Evaluation of Photodynamic Therapy Using a Light- emitting Diode Lamp against Enterococcus faecalis in Extracted Human Teeth

INTRODUCTION Photodynamic therapy (PDT) with high-power lasers as the light source has been proven to be effective in disinfecting root canals. The aim of this study was to evaluate the antimicrobial effect of PDT using toluidine blue O (TBO) and a low-energy light-emitting diode (LED) lamp after the conventional disinfection protocol of 6% NaOCl. METHODS Single-rooted extracted teeth were cleaned, shaped, and sealed at the apex before incubation with Enterococcus faecalis for 2 weeks. Roots were randomly assigned to five experimental groups and three control groups. Dentin shavings were collected from the root canals of all groups with a #50/.06 rotary file, colony-forming units were determined, and the bacterial survival rate was calculated for each treatment. RESULTS The bacterial survival rate of the NaOCl/TBO/light group (0.1%) was significantly lower (P < .005) than the NaOCl (0.66%) and TBO/light groups (2.9%). CONCLUSIONS PDT using TBO and a LED lamp has the potential to be used as an adjunctive antimicrobial procedure in conventional endodontic therapy.

Calcitonin gene-related peptide and substance P immunoreactivity in rat trigeminal ganglia and brainstem following adjuvant-induced inflammation of the temporomandibular joint

The immunoreactivity of two inflammatory mediators, calcitonin gene-related peptide (CGRP) and substance P, was measured in the trigeminal ganglia and brainstem to characterize an adjuvant-induced inflammation within the rat temporomandibular joint at various acute (6, 24 and 48 h) and intermediate (10 day) time intervals. Concentrations of adjuvant-related neuropeptides were compared to those in both contralateral vehicle-related tissues and non-injected controls. By 6 h, CGRP immunoreactivity in the trigeminal ganglia was significantly above that in contralateral vehicle-injected tissue. The CGRP had decreased at each of the following time-points, but remained significantly elevated at 10 days. Substance P in the ganglion on the injected side was significantly increased for all four time periods. In brainstem subnucleus caudalis, CGRP was significantly increased for all four time periods. Substance P immunoreactivity in the subnucleus caudalis was significantly increased for the initial three time periods, but by day 10 had been reduced to that of the control. These data show that the pattern of changes in neuropeptides following the induction of inflammation is different between substance P and CGRP. Moreover, the pattern of change varies between the brainstem and the trigeminal ganglion. This suggests that the two neuropeptides may have different roles in the inflammatory process, and that this process may be modulated by different mechanisms at the brainstem and ganglion.

Healing of the roots and surrounding structures after intentional damage with miniscrew implants

INTRODUCTION In this study, we evaluated the healing potential of the roots and surrounding periodontium (cementum, periodontal ligament [PDL], and bone) after intentional damage during miniscrew implant (MSI) placement. METHODS A randomized split-mouth design was used to evaluate healing 6 and 12 weeks after intentional root damage. Seven skeletally mature male beagle dogs had MSIs placed into the roots of 8 mandibular teeth (6 premolars, 2 first molars). After root contact had been verified by using insertion torques and radiographs, the MSIs were immediately removed, and the sites were allowed to heal for 6 or 12 weeks. Sequential point labeling was performed at 6-week intervals with tetracycline and calcein. Demineralized and undemineralized sections were stained, and healing was histologically evaluated. RESULTS The placement torque was twice as high with root contact than without contact (23.8 vs 50.7 Ncm). Damage to the roots and periodontium ranged from cementum interruption to pulp invasion. New bone, PDL, and cementum were observed in 64.3% of the teeth, with significant (P <0.05) increases in the percentages of cementum over time. Sequential labeling confirmed healing at both 6 and 12 weeks. Abnormal healing was found in 35.7% of teeth; it included lack of PDL and bone regeneration, bone degeneration in the furcation area, ankylosis, and no healing associated with inflammatory infiltrate or pulpal invasion. CONCLUSIONS Under favorable conditions (no inflammatory infiltrate or pulpal invasion), healing can occur when root damage caused by MSIs is limited to the cementum or the dentin. Increased resistance should be used as an indicator of possible root contact during MSI placement.

The effects of bisphosphonates on osteoblasts in vitro

OBJECTIVE The purpose of this study was to test the effects of bisphosphonates on osteoblast viability and function. STUDY DESIGN Primary rat osteoblasts were cultured in normal media or media containing increasing concentrations of 2 bisphosphonates, alendronate and zoledronate. Enzyme-linked immunoabsorbent assays (ELISAs) were used to measure interleukin (IL)-6, transforming growth factor (TGF) beta1, and receptor activator of nuclear factor kappaB ligand (RANKL) expression in supernatants after 24, 48, and 72 h. Live and necrotic cell numbers were assessed with trypan blue assays. RESULTS As drug concentrations increased, cell viability decreased significantly. The ELISAs revealed significant increases in TGF-beta1 in treatment groups, but no significant change in RANKL or IL-6. CONCLUSIONS High concentrations of alendronate and zoledronate were cytotoxic, decreasing cell viability at 72 h. Transforming growth factor beta1 increased even as viability decreased, suggesting a mechanism for bisphosphonate action. These data suggest that lower concentrations of bisphosphonates may have therapeutic benefits without the cytotoxic effects which may result in osteonecrosis.

Effects of intentional damage of the roots and surrounding structures with miniscrew implants

INTRODUCTION The purposes of the study were to evaluate the immediate damage to roots and periodontal structures after initial miniscrew implant (MSI) placement and the short- and long-term damage after MSIs were left in situ. METHODS The roots of the maxillary second, third, and fourth premolars of 7 mature beagle dogs were randomly assigned to undergo immediate, short-term (left for 6 weeks), or long-term (left for 12 weeks) damage. Intentional damage was inflicted with self-tapping screws (1.8 x 8 mm) placed with a stent. Alternating tetracycline and calcein labels were administered at 6-week intervals. Undecalcified sections were stained and evaluated histologically to determine the extent of damage; healing was evaluated by using fluorescence labels. RESULTS Histology showed damage to 73.8% of the teeth, ranging from displacement of bone into the periodontal ligament to invasion of the pulp chamber. Displacement of bone into the periodontal ligament and direct damage to the periodontal ligament occurred in 3 (7.2%) instances. Damage was isolated to the cementum of 8 (19.0%) teeth, whereas damage occurred in the dentin of 11 (26.2%) teeth. Loss of bone in the furcation was evident in 3 (7.2%) teeth, and severe damage into the pulp occurred in 6 (14.2%) teeth. No differences in the amounts of damage were evident between the immediate, short-, and long-term groups. Healing often occurred with cementum around the unloaded MSIs. CONCLUSIONS Extensive damage can be caused by MSIs, with little to no differences evident over time. Unloaded MSIs that remain in contact with roots of teeth can show varying degrees of healing.

Meal Pattern Analysis in Response to Temporomandibular Joint Inflammation in the Rat

Inflammation of the temporomandibular joint (TMJ) can alter behavioral responses such as food intake and mobilize stress hormones. The hypothesis of this study was that food intake and diurnal corticosterone analysis can be used as indicators of adjuvant-induced TMJ inflammation. Groups of rats received adjuvant or no injections at the beginning of the resting (AM) or activity (PM) phase. Forty-eight hours (early) or 6 weeks (late) after adjuvant injection, plasma corticosterone was assayed and food intake was recorded. Food intake was suppressed up to 4 days post-injection. As expected, the non-injected group showed low AM and high PM corticosterone. AM corticosterone was elevated, but PM corticosterone was attenuated in both early- and late-stage-injected rats. A computerized pair-fed experiment showed that adjuvant-induced hypophagia did not alter corticosterone levels. Meal pattern analysis revealed decreased food intake due to a decrease in the number of meals taken. Notably, meal size remained the same but meal duration increased. This model demonstrated that food intake and stress hormone analysis could be used as indicators for sequelae of adjuvant-induced TMJ inflammation.

Retreatability of a bioceramic root canal sealing material.

INTRODUCTION The efficacy of retreatment techniques for BC Sealer (BCS) (Brasseler USA, Savannah, GA) removal has not yet been assessed. The purpose of this study was to evaluate the efficacy of solvent and rotary instrumentation in the removal of BCS when used in combination with gutta-percha (GP) as compared with AH Plus sealer (Dentsply, Tulsa, OK). METHODS The mesiobuccal canals of 40 mandibular molars were instrumented and obturated with either GP/AH Plus with warm vertical compaction or GP/BCS using a single cone. The groups were subdivided into samples with the master GP cone placed to the working length (WL) or intentionally 2 mm short of the WL. Canals were then retreated using heat, chloroform, rotary instruments, and hand files. The ability to regain the WL and patency were evaluated as well as the time required to remove obturation material. Representative samples were also analyzed via scanning electron microscopy. RESULTS The WL was not regained in 70% of samples with BCS/master cone short of the WL. Patency was not re-established in 20% of samples with BCS/master cone to the WL or in 70% of samples with BCS/master cone short of the WL. CONCLUSIONS Conventional retreatment techniques are not able to fully remove BCS.

In Vitro Evaluation of Dentinal Tubule Penetration and Biomineralization Ability of a New Root-end Filling Material

INTRODUCTION Capasio is being developed as a new generation of endodontic material with potential use as a root-end filling material. The aim of this study was to compare the ability of Capasio and mineral trioxide aggregate (MTA) to penetrate human dentinal tubules and examine the interaction of Capasio and MTA with a synthetic tissue fluid (STF) and root canal walls in extracted human teeth. METHODS Root-end preparations were filled with Capasio or MTA, allowed to set for 4 weeks in STF, and then sectioned at 1, 2, and 3 mm from resected surface. Depth of penetration was evaluated by using scanning electron microscopy (SEM). Next, Capasio and MTA samples were prepared both in 1-g pellets and in root-end preparations. Samples were placed in STF, allowed to set, and then characterized by using SEM, energy dispersive x-ray analysis (EDXA), and x-ray diffraction (XRD) techniques. RESULTS Penetration of Capasio into dentinal tubules was observed at all levels. No penetration of MTA into dentinal tubules was observed at any level. Both Capasio and MTA formed apatite crystals in the supernatant, on their exposed surfaces, and in the interfacial layers that were similar in structure and elemental composition when evaluated by using SEM and EDXA. XRD analysis of these crystals corresponds with those reported for hydroxyapatite. CONCLUSIONS When used as a root-end filling material, Capasio is more likely to penetrate dentinal tubules. Both Capasio and MTA promote apatite deposition when exposed to STF.

Cultured primary osteoblast viability and apoptosis in the presence of root canal sealers

This study was designed to test the hypothesis that Roekoseal is less cytotoxic than eugenol-based Sealapex or calcium hydroxide-based Kerrs Pulp Canal Sealer. Embryonic, day-19, rat calvarial osteoblasts were cultured at 4 x 10(5) cells/well. The concentration of conditioned medium from each sealer producing 50% surviving cells (ED50) was determined and long-term viability and apoptosis of cells assessed after exposure to the ED50 of each sealer. Low concentrations of Kerrs Pulp Canal Sealer (190 mm(2)/1 ml) and high concentrations of Sealapex and Roekoseal (190 mm(2)/300 microl) produced the ED50. ED50 challenged osteoblasts had fewer viable cells at 72 h than at 24 h, with significantly more viable cells in the Roekoseal group. There was significantly less apoptotic activity in cells exposed to Roekoseal ED50 than in cells exposed to Kerrs Pulp Canal Sealer (p < 0.05) ED50. Roekoseal may be less cytotoxic than Kerrs Pulp Canal Sealer, but further studies of this new sealer are required.

The Efficacy of IntraFlow Intraosseous Injection as a Primary Anesthesia Technique

The purpose of this study was to compare the efficacy of intraosseous injection and inferior alveolar (IA) nerve block in anesthetizing mandibular posterior teeth with irreversible pulpitis. Thirty human subjects were randomly assigned to receive either intraosseous injection using the IntraFlow system (Pro-Dex Inc, Santa Ana, CA) or IA block as the primary anesthesia method. Pulpal anesthesia was evaluated via electric pulp testing at 4-minute intervals for 20 minutes. Two consecutive 80/80 readings were considered successful pulpal anesthesia. Anesthesia success or failure was recorded and groups compared. Intraosseous injection provided successful anesthesia in 13 of 15 subjects (87%). The IA block provided successful anesthesia in 9 of 15 subjects (60%). Although this difference was not statistically significant (p = 0.2148), the results of this preliminary study indicate that the IntraFlow system can be used as the primary anesthesia method in teeth with irreversible pulpitis to achieve predictable pulpal anesthesia.