David E. Witherspoon

Retrospective Analysis of Open Apex Teeth Obturated with Mineral Trioxide Aggregate

This study is a retrospective analysis of the outcome of initial nonsurgical root canal treatment of teeth with open apices, obturated with mineral trioxide aggregate when no apical barrier existed. One hundred sixteen patients from a single private endodontic office were treated between 1999 and 2006. Treatments on 144 teeth were completed either in one (92/144) or two visits with an interim calcium hydroxide interappointment medication (52/144). Fifty-four percent (78/144) of the teeth were available for recall (60.3% one visit and 39.7% two visits). The maximum time to recall was 4.87 years. The mean time to recall was 19.4 months. Of the cases recalled for period of 1 year or longer, 93.5% of teeth treated in 1 visit healed, and 90.5% of teeth treated in 2 visits healed.

Histological and Scanning Electron Microscopy Assessment of Various Vital Pulp-Therapy Materials

Pulp capping and pulpotomy procedures were performed on 15 male mongrel dogs. Three materials were used: calcium hydroxide, acid-etched dentin bonding, and mineral trioxide aggregate. Six of the animals were killed at 50 days and nine were killed at 150 days. Samples from 11 dogs were used for histological evaluation, and the remaining dog samples were used for scanning electron microscopy evaluation. Each slide was graded histologically according to previously published criteria. Scanning electron microscopy analysis was performed, and the weight percentage of elements found in the dentin of a nontreated tooth versus the bridge formed in the exposed specimen was established. By evaluating pulp inflammation in vital pulp-therapy treatments, it was found that mineral trioxide aggregate was not significantly different from the untreated control group, both in pulp-capping procedures at 50 days (p = 0.357) or 150 days (p = 0.198) and pulpotomy procedures at 50 days (p = 0.357) or 150 days (p = 0.198). Moreover, histologically mineral trioxide aggregate was a considerably better material than calcium hydroxide or acid-etched dentin bonding in maintaining the integrity of the pulp.

Vital pulp therapy with new materials: new directions and treatment perspectives--permanent teeth.

Pulp necrosis in immature teeth subsequent to caries has a major impact on long-term tooth retention. The aim of vital pulp therapy is to maintain pulp viability by eliminating bacteria from the dentin-pulp complex and to establish an environment in which apexogenesis can occur. A complicating factor in treating immature teeth is the difficulty predicting the degree of pulpal damage. The ability of the clinician to manage the health of the remaining pulpal tissue during the procedure is paramount. Currently, the best method appears to be the ability to control pulpal hemorrhage by using sodium hypochlorite. Mineral trioxide aggregate (MTA) currently is the optimum material for use in vital pulp therapy. Compared with the traditional material of calcium hydroxide, it has superior long-term sealing ability and stimulates a higher quality and greater amount of reparative dentin. In the medium-term clinical assessment, it has demonstrated a high success rate. Thus, MTA is a good substitute for calcium hydroxide in vital pulp procedures.

Histologic Assessment of Healing after the Use of a Bioresorbable Membrane in the Management of Buccal Bone Loss Concomitant with Periradicular Surgery

Histological and morphometric assessment of periradicular wound healing was made after the use of a bioresorbable membrane over a buccal dehiscence. The third and fourth premolar teeth of nine dogs were resected and buccal defects created. Teeth were assigned randomly to the membrane or control group. One tooth in each quadrant received a membrane, covering both roots. The other tooth received no further treatment and served as a control. The animals were killed and specimens were assessed at two time periods: 9 wk and 27 wk. The 27-wk membrane group exhibited significantly more (p = 0.004) connective tissue height than the control group or either of the 9-wk groups. The amount of regenerated alveolar bone was significantly greater for the 27-wk membrane group than for the control (p = 0.001) and 9-wk groups. Mean junctional epithelium measurements were significantly greater (p = 0.012) for the control. The use of a bioresorbable membrane enhances bone regeneration when a buccal defect exists at the time of periradicular surgery.

Effects of Calcium Hydroxide and Tumor Growth Factor-β on Collagen Synthesis in Subcultures I and V of Osteoblasts

Collagen protein synthesis by osteoblasts is influenced by transforming growth factor-β (TGF-β1) and is essential to bone formation. The effectiveness of TGF-β1 depends on efficient delivery of the growth factor to target cells, adequate binding to cell surface receptors, and an optimum environment for promotion of collagen synthesis. The effects of calcium hydroxide (Ca(OH) 2 ), TGF-β1, and Ca(OH) 2 /TGF-β1 co-administration on total protein, collagen protein, and noncollagen protein synthesis by early (subculture I) and late (subculture V) osteoblast cultures were tested. TGF-β1 significantly increased all protein synthesis in subculture I osteoblasts (p = 0.001; p 2 /TGF-β1 co-administration significantly increased total protein and collagen protein levels in subculture I osteoblasts as well (p = 0.048; p = 0.012). TGF-β1 increased total protein and collagen protein synthesis significantly in subculture V cells (p = 0.025; p = 0.01). These data indicate that co-administration of Ca(OH) 2 and TGF-β1 enhances collagen synthesis by osteoblasts and may have implications for the clinical setting.

Feline Immunodeficiency Virus Model to Study Human Immunodeficiency Virus/Acquired Immune Deficiency Syndrome Conditions

This study was designed to induce rapid progression of the feline immunodeficiency virus (FIV) infection in cats. Predictably inducing the FIV disease state in the cat would yield an excellent tool to study endodontic disease processes under immunosuppressed conditions. Eight cats were immunosuppressed with steroids before infection with FIV. Another eight cats, age- and sex-matched littermates, served as uninoculated seronegative controls. Complete blood counts were taken for 10 mo in the FIV group, and 10 wk in the control group, including lymphocyte subsets. ELISAs were used to detect FIV infection. Statistical analysis was performed with generalized estimating equation models. All cats were positive at one point in time. The FIV group had significantly lower peripheral blood CD4+ counts compared with the control group. Therefore the FIV model presented gives the desired outcome and simulates what occurs in human immunodeficiency virus infection.

Diagnosis in Molar Endodontics

Developing a diagnosis is, in essence, a process in information gathering. This information is gathered from the patient’s history of pain, trauma or restorative procedures, clinical examinations, results of clinical tests, and radiographic examination of the teeth and the surrounding tissues. The diagnostic process begins with a patient interview and review of the medical history, dental history, and pain history. A thorough patient and pain assessment interview will often enable a clinician to differentiate between odontogenic and non-odontogenic pain. Non-odontogenic pain will often become chronic and debilitating in nature. Furthermore, this pain can be further exacerbated by incorrect or unnecessary treatments frequently resulting in the establishment of chronic pain pathways.