Limitations of the profit-volume model in analyzing dental teaching clinics.

Use of the cost center concept and the profit- volume model has been advocated to analyze the fiscal position of dental teaching clinics. While these methods are helpful in solving specific management dilemmas, they have three identifiable limitations in describing the overall fiscal position of dental teaching clinics. The purpose of this paper is to review these limitations and to discuss their implication.

Response to intracrevicular controlled delivery of 25% tetracycline from poly(lactide/glycolide) film strips in SPT patients.

Controlled local delivery of antibiotics has been shown to reduce periodontopathic micro-organisms with minimal side-effects. Clinical studies in our laboratory have shown that 25% tetracycline HCl delivered from poly(D,L-lactide/glycolide) film strips (25 TTC-PLGA) released therapeutic concentrations of tetracycline for 10 days. The present pilot study compared the intracrevicular delivery of 25% tetracycline HCl incorporated in these biodegradable film strips to scaling and root planing (SRP) in 10 adult periodontitis patients, who in spite of therapy and regular supportive periodontal treatment (SPT), continued to possess 5 bleeding periodontal pockets at least 5 mm deep. Sites were randomly selected to receive the following treatments: (1) 25 TTC-PLGA, (2) control strips without TTC (PLGA), (3) SRP, and (4) untreated control. Film-strip retention was augmented with a suture/cement technique, followed by strip removal after 2 weeks. Clinical parameters and subgingival bacterial morphotypes (darkfield analysis) were evaluated over time (0, 2.4, 8, 12, 26 weeks). Results indicated that, compared to baseline, 25 TTC-PLGA film strips caused significant (p < or = 0.01): (1) probing depth reduction for 26 weeks, (2) a clinical attachment level gain for 12 weeks, (3) lower %s of spirochetes for 4 weeks and motile rods for 8 weeks (p < or = 0.05), and (4) an accompanying increase in cocci for 4 weeks. In the scaled and root planed sites, probing depth was the only finding that demonstrated a significant change from baseline (p < or = 0.01). Controls and PLGA showed isolated reductions in probing depth and % of motile organisms. From these findings, applications of intracrevicular 25 TTC-PLGA, when compared to scaling and root planing, appears to have an enhanced antibacterial effect and a similar clinical effect in SPT patients. The results of this study indicate further investigation of 25 TTC-PLGA film strips should be undertaken using more subjects and sophisticated microbiological and clinical measurements.

Prostaglandin E (PGE) and interleukin-1 beta (IL-1 beta) levels in gingival crevicular fluid during human orthodontic tooth movement.

The purpose of this study was to examine gingival crevicular fluid (GCF) levels of two potent bone resorbing mediators, prostaglandin E (PGE) and interleukin-1 beta (IL-1 beta), during human orthodontic tooth movement. The study included 10 patients, each having one treatment tooth undergoing orthodontic movement and a contralateral control tooth. The GCF was sampled at control sites and treatment (compression) sites before activation and a 1, 24, 48, and 168 hours. Prevention of plaque-induced inflammation allowed this study to focus on the dynamics of mechanically stimulated PGE and IL-1 beta GCF levels. The PGE and IL-1 beta levels were determined with radioimmunoassay. At 1 and 24 hours, mean GCF IL-1 beta levels were significantly elevated at treatment teeth (8.9 +/- 2.0 and 19.2 +/- 6.0 pg, respectively) compared with control teeth (2.0 +/- 1.1 pg, p = 0.0049, and 2.9 +/- 1.0 pg, p = 0.0209, respectively). The GCF levels of PGE for the treatment teeth were significantly higher at 24 and 48 hours (108.9 +/- 11.9 and 97.9 +/- 7.3 pg) than the control teeth (61.8 +/- 7.2 pg, p = 0.0071, and 70.8 +/- 7.4 pg, p = 0.0021, respectively). The GCF levels of PGE and IL-1 beta remained at baseline levels throughout the study for the control teeth, whereas significant elevations from baseline in GCF IL-1 beta (24 hours) and PGE levels (24 and 48 hours) were observed over time in the treatment teeth (p < or = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Checklist for the removable prosthesis wax trial insertion appointment.

A checklist is described that is designed to permit a systematic evaluation of the factors involved in the trial insertion appointment. The checklist aids both the student and the instructor in assuring that items are not overlooked during this important appointment. More equitable grading of the student's preparation and knowledge is facilitated. The checklist also serves as an excellent patient approval form.

Gingival fluid IL-1 beta and IL-6 levels in menopause.

Menopause and oophorectomy without estrogen therapy (ED) have been associated with increased production of bone-active cytokines by peripheral blood mononuclear cells. The current study extended evaluation to gingival crevicular fluid (GCF) levels of interleukin (IL)-1 beta and IL-6 in such subjects compared to premenopausal and postmenopausal estrogen-treated females (ES). 13 ED and 13 ES Caucasians with a history of moderate-severe adult periodontitis provided GCF from 1-3 clinically identical sites each (5-6 mm probing depth, 5-7 mm clinical attachment loss, bleeding on probing). 30 s GCF samples were obtained and evaluated for IL-1 beta and IL-6 levels using two-site enzyme-linked immunosorbent assays (ELISAs). The frequency of GCF IL-1 beta-positive subjects was elevated in ED versus ES (92% versus 23%; p < 0.0004, chi 2 analysis). IL-6 was detected more frequently in ED subjects (23% versus 8%; not significant); however, the frequency of IL-6 detection was low in both groups due to short sampling times. These data support the concept that clinical conditions causing low estrogen environments allow increased local production of the bone-active cytokine IL-1 beta, and perhaps IL-6.

The magnitude of interproximal spaces between adjacent teeth.

Previous studies have shown that the human resting dentition naturally exhibits slight interproximal spacing between 80% to 90% of all adjacent teeth. The purpose of this study was to measure occurrence and dimension of interproximal spacing. Pieces of shim stock of various thicknesses were used to measure the dimension of interproximal spaces between natural or restored approximating tooth surfaces in 40 human subjects. The midline was frequently found to exhibit the largest space, and the dimension of the spacing was found to be greater in anterior teeth than posterior teeth. The canine-premolar spaces were also relatively large. The magnitude of interproximal tooth spacing was not related to gender or age. Results indicate that the position of teeth is naturally adjusted to maintain interproximal spacing. Interproximal spacing may allow for physiological movement to increase tolerance to trauma and improve tactile sensation.

Gingival crevicular fluid IL-8: correlation with local IL-1 beta levels and patient estrogen status.

Gingival crevicular fluid (GCF) IL-8 and IL-1 beta levels were determined by sandwich enzyme-linked immunosorbent assays. Associations between IL-8 and IL-1 beta GCF levels, and between these cytokines and patient estrogen status were evaluated. IL-8 and IL-1 beta were detected more frequently and in higher amounts/30 s GCF sample in estrogen-deficient patients than in estrogen-sufficient patients. IL-8 and IL-1 beta GCF levels were significantly correlated. These findings suggest that GCF IL-8 levels are associated with patient estrogen status and local IL-1 beta concentrations.

HLA-D and T lymphocyte reactivity to specific periodontal pathogens in type 1 diabetic periodontitis.

Bacterial antigen fragments complexed with class II major histocompatibility molecules (HLA-D) on antigen presenting cells (APCs) stimulate CD4+ T lymphocyte proliferation, presumably to protect the host. This study examined these responses to antigens of two periodontal pathogens in four groups (n = 15) of age- (young adult) and sex-matched Caucasian subjects with or without type 1 diabetes and moderate to severe periodontitis: Group DP = diabetics with periodontitis; Group DnP = diabetics without periodontitis; Group nDP = nondiabetics with periodontitis; and Group nDnP = nondiabetics without periodontitis. HLA-D phenotypes for each subject were determined by lymphocytotoxicity assays. T lymphocytes purified from peripheral blood were stimulated in cell culture with APC pulsed with various concentrations of tetanus toxoid, Porphyromonas gingivalis, and Capnocytophaga sputigena antigens. T lymphocyte reactivity (3H thymidine incorporation) was numerically lower in cultures from diabetics stimulated with unpulsed APC (not significant), and antigen-pulsed cultures showed low proliferation and no significant differences among groups. Stimulation indices in cultures from diabetic patients stimulated with P. gingivalis or C. sputigena, however, were significantly elevated at all antigen concentrations compared to nondiabetic cultures. The occurrence of HLA-DR4 was moderately associated with diabetes (P < 0.05) and highly associated with periodontitis (P < 0.001, log-linear model for categorical variables); and HLA-DR53 and HLA-DQ3 were significantly associated with periodontitis (P < or = 0.02). HLA-DR was crucial to lymphocyte stimulation (anti-HLA-DR blocking experiments), but the low peripheral blood T cell reactivity to antigens of periodontal pathogens could not be linked with HLA-D type or periodontitis susceptibility.(ABSTRACT TRUNCATED AT 250 WORDS)

Mandibular condyle position: comparison of articulator mountings and magnetic resonance imaging.

This study evaluated the reliability of jaw positions, the existence of distinct jaw positions, and condyle-disk-fossa relationships in a symptom-free population by using articulator mountings and magnetic resonance imaging (MRI). The subjects examined included 28 men, 22 to 35 years of age, all having Angle Class I molar relationships and no discernible TMJ dysfunction. Records taken included the following: an axiographic face-bow to locate retruded hinge axis position, an interocclusal registration of retruded position (RE), a series of interocclusal registrations for centric occlusion (CO), a leaf gauge-generated centric relation (CR), a series of interocclusal registrations for CR, and MRI. The mandibular position indicator of the SAM articulator (Great Lakes Orthodontics, Ltd., Tonawanda, N.Y.) was used to determine reliability and existence of distinct jaw positions. Magnetic resonance imaging also evaluated jaw positions and anatomic relationships. The results indicate: (1) The articulator analysis of CO and CR is statistically replicable. (2) A distinct jaw position could be demonstrated for CO that was separate from RE and CR. It was not possible to discriminate between RE and CR. (3) Condylar concentricity was observed in half of the sample and remained consistent in RE, CO, and CR. (4) Of the sample 13% demonstrated anteriorly displaced disks that were not influenced by posterior condyle placement. (5) The clinical concept of treating to CR as a preventive measure to improve disk-to-condyle relationships was not supported by this study.

IL-1 in gingival crevicular fluid following closed root planing and papillary flap debridement.

Interleukin (IL)-1 alpha and beta are cytokines which can mediate inflammatory, bone resorbing, and reparative effects in the periodontium, but few longitudinal data exist exploring their role following periodontal therapy. This study examined gingival crevicular fluid (GCF) concentrations of IL-1 alpha and IL-1 beta at sites with shallow sulci (SS) or inflamed moderate/advanced pockets (M/AP) before and 6 months after treatment with closed scaling/root planing (SC/RP) or papillary flap debridement (PFD), all in the same subject (n = 14 patients). No significant differences were noted in IL-1 alpha or beta concentrations (determined with two-site enzyme-linked immunosorbent assays) between SS and M/AP sites at baseline. While both therapies improved clinical parameters of periodontal disease, IL-1 alpha concentration increased significantly (p < 0.05) in M/AP-PFD sites 6 months after treatment, but were unchanged in other groups. IL-1 beta concentrations were numerically lower after therapy, except for a significant increase (p < 0.05) in M/AP-PFD sites. These data suggest that surgical wound healing in an inflamed, plaque-infected site (M/AP-PFD) results in prolonged production of IL-1, which may be a reflection of the extent of tissue trauma and delayed wound healing. In spite of increased IL-1 levels, these sites demonstrated significant short-term improvement in clinical attachment level (+ 1.8 mm, p < or = 0.001) postoperatively.

Gingival fluid IL-1 and IL-6 levels in refractory periodontitis.

Selected gingival bacteria and cytokine profiles associated with patients who did not respond to conventional periodontal therapy (refractory) were evaluated. 10 subjects with a high incidence of post-active treatment clinical attachment loss (> 2% sites/year lost > or = 3 mm) were compared to 10 age-, race-, and supragingival plaque-matched patients with low post-treatment clinical attachment loss (< 0.5% sites/year) relative to the following parameters at 2 sites/patient with the deepest probing depths: (1) presence of 3 selected periodontal pathogens (Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Eikenella corrodens) in subgingival plaque as determined by selective culturing, and (2) gingival crevicular fluid (GCF) levels of 3 cytokines associated with bone resorption (IL-1 alpha, IL-1 beta, IL-6) as determined by two-site ELISA. Results indicated no significant differences in any clinical measurement (except incidence of clinical attachment loss), in the presence of any bacterial pathogen, or in GCF cytokine levels between refractory subject sites versus stable subject sites. However, when sites producing the greatest total GCF cytokine/patient were compared, sites from refractory patient produced significantly more IL-6 (30.1 +/- 4.0 versus 15.4 +/- 2.8 nM, p < 0.01). The subgingival presence of each of the 3 bacterial pathogens was associated with elevated GCF IL-1 concentrations. These data suggest that gingival IL-1 and IL-6 production is different in response to local and systemic factors associated with periodontitis, and that IL-6 may play a role in the identification and mechanisms of refractory periodontitis.

Vestibular ontogeny: measuring the influence of the dynamic environment.

In comparison to other special senses, we are only meagerly informed about the development of vestibular function and the mechanisms that may operate to control or influence the course of vestibular ontogeny. Perhaps one contributing factor to this disparity is the difficulty of evaluating vestibular sense organs directly and noninvasively. The present report describes a recently developed direct noninvasive vestibular function test that can be used to address many basic questions about the developing vestibular system. More particularly, the test can be used to examine the effects of the dynamic environment (e.g. gravitational field and vibration) on vestibular ontogeny.

Clinical effects of closed root planing compared to papilla reflection and fiber optic augmentation.

Mini-surgical approaches in 4 to 7 mm probing depths have been shown to facilitate improved deposit removal as compared to closed instrumentation. At the same time this treatment is less traumatic than more extensive flap reflection for root planing. The purpose of this study was to compare the clinical effects of closed root planing (C/SCRP) to those of root planing augmented by papilla reflection and fiber optic illumination (PR/SCRP) over a 6-month period. Fourteen patients with moderate/advanced adult periodontitis received each therapy in 2 experimental periodontitis sites (PS = greater than or equal to 5 mm probing depth and greater than 5 mm attachment loss) and one non-periodontitis site (NPS = less than or equal to 3 mm probing depth and no recession). Presence of supragingival plaque, bleeding on probing, probing depths, and clinical attachment levels were measured before treatment and 6, 12, and 24 weeks posttreatment. Mean supragingival plaque levels were high and did not vary significantly over the course of the study, but bleeding on probing was significantly reduced in PS following both C/SCRP and PR/SCRP (P less than or equal to 0.0001). Mean probing depths were significantly reduced after 6 months (P less than or equal to 0.01) in NPS-PR/SCRP from 2.8 +/- 0.1 to 2.0 +/- 0.2 mm, in PS-C/SCRP from 5.5 +/- 0.2 to 4.5 +/- 0.4 mm, and in PS-PR/SCRP from 5.8 +/- 0.2 to 3.2 +/- 0.1 mm. In periodontitis sites, PR/SCRP demonstrated greater probing depth reductions than C/SCRP at all time periods (P less than or equal to 0.004). PS attachment levels also improved following C/SCRP and PR/SCRP at all postoperative times (P less than or equal to 0.01). PR/SCRP appears to provide better short-term mean probing depth reduction (2.6 mm) than C/SCRP (1.0 mm), presumably due to apical positioning of the papillae and periodontal repair following improved access for root planing.

Effects of topical and systemic nicotine on gingival blood flow in dogs.

It has been suggested that due to its vasoconstrictive action, nicotine may have a deleterious effect on the periodontium. This study examined the effects of topical and systemic nicotine administration on gingival blood flow. Eighteen young adult dogs were divided into three groups receiving the following treatments for 28 days; topical nicotine in orabase, systemic nicotine via osmotic mini-pumps, and topical orabase or systemic saline via osmotic mini-pumps. Blood flow to the gingiva was measured (at days 0 and 28) by the radiolabeled microsphere method. Blood flow was consistently increased from day 0 to day 28 in the nicotine-treated animals. Comparison of days 0 and 28 blood-flow values demonstrated a statistically significant change (p less than 0.05) in the anterior regions of the topical-nicotine group as compared with the control group. The increased flow may be a reflection of the mode of nicotine delivery and timing of the blood-flow determination procedures.

Acute-phase protein detection and quantification in gingival crevicular fluid by direct and indirect immunodot.

The development of an assay for markers of active periodontitis, obtained directly from gingival crevicular fluid (GCF) and simply quantified, would be of great importance to the dental practitioner. The purpose of this study was to evaluate direct and indirect immunodot techniques as to their potential in easily quantifying acute-phase proteins within periodontally diseased and healthy site GCF. Indirect immunodots (GCF eluates dotted onto nitrocellulose membrane) using monoclonal antibodies and a radioactive isotope label were used to identify and establish relative amounts of C-reactive protein (CRP) and alpha-2-macroglobulin (A2M) in 2 diseased and 2 healthy sites in 24 periodontitis patients. Periodontally diseased sites were found to contain significantly lower concentrations of A2M than healthy sites (p less than 0.001), but CRP levels did not vary significantly between healthy and diseased locations. Using a direct immunodot assay (GCF absorbed directly into nitrocellulose membrane strips), A2M levels quantified with radioactive isotopes at healthy and diseased sites could be correlated with A2M levels determined by enzyme-linked antibody-colormetric probes at those same sites. Such a direct sampling and quantification system shows promise for future "in-office" diagnostic methodology.

Skeletal maturation and craniofacial growth.

The purpose of this study was to assess the relevance of hand-wrist radiographs to craniofacial growth and clinical orthodontics. Serial annual cephalometric and hand-wrist radiographs and standing height measurements were obtained from a sample of 47 girls (ages 10 through 15 years) and 39 boys (ages 11 through 16 years) from the Bolton-Brush data base. Four skeletal linear measurements showing statistically significant increases were analyzed: SN, GoGn, SGo, and NMe. The hand-wrist radiographs were scored by the Tanner-Whitehouse TW2 RUS method of skeletal maturity assessment. The results of the study indicated that statural height and hand-wrist skeletal maturation in both sexes are significantly related. The children demonstrated a large variety of growth patterns, and growth spurts could not be consistently observed on an individual basis. Because of low statistical correlations, the relationship between acceleration and deceleration in growth of the specific craniofacial dimensions and statural height or skeletal maturity was not deemed clinically significant for prediction. However, it may be used as a factor for consideration in diagnosis and treatment planning of an individual case.