Emet D. Schneiderman

Osseous regeneration in the presence of four common hemostatic agents

The iliac crest is a common site for bone procurement in oral and maxillofacial surgery. The goal of this study was to evaluate the potential for bone regeneration in the presence of four common hemostatic agents in a manner that parallels iliac bone procurement in humans. The agents evaluated were 1) Avitene (microfibrillar collagen; Medchem Products, Inc, Woburn, MA); 2) bone wax (beeswax with isopropyl palmitate; Ethicon, Inc, Somerville, NJ); 3) Gelfoam (absorbable gelatin sponge; The Upjohn Company, Kalamazoo, MI); and 4) Surgicel (oxidized regenerated cellulose; Johnson & Johnson Products, Inc, Patient Care Division, New Brunswick, NJ). Five surgical defects in each of four dogs were created for placement of the four materials; one defect served as an empty control site. The dogs were then allowed to heal over a 2-month period. Radiographic and histologic examination showed new bone formation in the presence of Avitene, Surgicel, and Gelfoam. Residual material incorporated in bone, without foreign-body response, was noted in the Avitene and Gelfoam sites. Bone wax, however, showed an intense foreign-body reaction, characterized by giant cells, plasma cells, fibrous granulation tissue, and lack of bone reformation. On the basis of these initial findings, it was concluded that Surgicel, Avitene, and Gelfoam may be adequate hemostatic agents for use in iliac bone procurement, whereas the use of bone wax appears to be contraindicated.

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.

Twenty-Year Follow-up Study on a Patient-Fitted Temporomandibular Joint Prosthesis: The Techmedica/TMJ Concepts Device

PURPOSE To evaluate subjective and objective outcomes of patients receiving Techmedica (currently TMJ Concepts) patient-fitted temporomandibular joint (TMJ) total joint replacement (TJR) devices after 19 to 24 years of service. PATIENTS AND METHODS This prospective cohort study evaluated 111 patients operated on by 2 surgeons using Techmedica (Camarillo, CA) patient-fitted TMJ TJR devices from November 1989 to July 1993. Patients were evaluated before surgery and at least 19 years after surgery. Subjective evaluations used standard forms and questions with a Likert scale for 1) TMJ pain (0, no pain; 10, worst pain imaginable), 2) jaw function (0, normal function; 10, no movement), 3) diet (0, no restriction; 10, liquid only), and 4) quality of life (QoL; improved, the same, or worse). Objective assessment measured maximum incisal opening (MIO). Comparison analysis of presurgical and longest follow-up data used nonparametric Mann-Whitney and Wilcoxon signed rank tests. Spearman correlations evaluated the number of prior surgeries in relation to objective and subjective variables. RESULTS Of the 111 patients, 56 (50.5%) could be contacted and had adequate records for inclusion in the study. Median follow-up was 21 years (interquartile range [IQR], 20 to 22 yr). Mean age at surgery was 38.6 years (standard deviation, 10 yr). Median number of previous TMJ surgeries was 3 (IQR, 4). Presurgical and longest follow-up data comparison showed statistically significant improvement (P < .001) for MIO, TMJ pain, jaw function, and diet. At longest follow-up, 48 patients reported improved QoL, 6 patients reported the same QoL, and 2 patients reported worse QoL. Spearman correlations showed that an increased number of previous surgeries resulted in lower levels of improvement for TMJ pain and MIO. CONCLUSIONS At a median of 21 years after surgery, the Techmedica/TMJ Concepts TJR continued to function well. More previous TMJ surgeries indicated a lesser degree of improvement. No devices were removed owing to material wear.

Comparison of Vibringe, EndoActivator, and Needle Irrigation on Sealer Penetration in Extracted Human Teeth

INTRODUCTION Vibringe is a new device that allows continuous sonic irrigation of the canal system during endodontic treatment. The aim of this study was to compare the effect of different irrigation systems on sealer penetration into dentinal tubules of extracted single-rooted teeth. METHODS Fifty single-rooted human teeth were instrumented and randomly divided into 4 groups: group 1 (control), saline; group 2 (conventional irrigation), 17% EDTA followed by 6% NaOCl; group 3 (EndoActivator), same irrigants as group 2; group 4 (Vibringe), same irrigants as group 2. Obturation of all teeth was done with gutta-percha and SimpliSeal labeled with fluorescent dye. Transverse sections at 1 mm and 5 mm from the root apex were examined by using confocal laser scanning microscopy. Percentage and maximum depth of sealer penetration were measured by using NIS-Elements Br 3.0 imaging software. RESULTS Groups 3 and 4 had a significantly greater percentage of the canal wall penetrated by sealer at the 5-mm level than group 1 (P < .0125), but not group 2. No other differences were found between the groups at either section level for both the percentage of sealer penetration and maximum depth. The 5-mm sections in each experimental group had a significantly higher percentage and maximum depth of sealer penetration than did the 1-mm sections (P < .0125). CONCLUSIONS The use of sonic activation with either the EndoActivator or Vibringe did not significantly improve the sealer penetration when compared with conventional irrigation.

Tracking: Concepts, Methods and Tools

Tracking can be defined as the tendency of an individual, or a collection of individuals, to maintain a particular course of growth over time relative to other individuals. A measure of tracking based on Cohens kappa statistic and the tracking indices proposed by Foulkes-Davis and McMahan are considered. Applications, including significance testing, are made to a study of the growth of Guatemalan school children whose stature was measured longitudinally malan school children whose stature was measured longitudinally from 7 to 12 years of age. User-friendly programs for computing these indices are described and made available to interested readers.

Biomechanical properties of small bone screws.

PURPOSE To evaluate systematically the biomechanical properties of 13 popular screw designs, ranging from 0.8 to 2.0 mm in diameter. METHODS Screws were characterized in terms of external, core, and drill diameter; cutting flute and head design; material; pitch, thread depth; and height of shank (unthreaded portion) and shank with plate. They were tested in standardized bone specimens (2 x 2.5cm slabs of fresh bovine femur) 1, 2, 3, and 4-mm thick. For each screw-bone thickness combination, 10 trials were conducted to determine push-out force (POF) and another 10 trials to determine insertion (IT) and maximum torque (MT) yielding a total of 1,040 tests. RESULTS Among the 13 different screws, in 1-mm thick bone, both the lowest (108.5 N) and highest (294.9 N) POF were created by 2-mm screws (P < .001); that with the lowest POF had a long unthreaded shank and pitch, that with highest POF had a short unthreaded shank and pitch. Screws with 0.8- to 1.5-mm diameters showed no differences in POF. The 2-mm screw with the lowest POF also had the lowest MT in 1-mm thick bone compared with the other 2-mm screws (P < .001). In thicker bones (> 2 mm), two 2-mm screws showed 30% to 50% lower MT than the other same size screws (P < .001) because their head slots stripped easily. When all screws were considered together for a particular bone thickness, torque was strongly predicted by screw diameter (MT: r = .94, P < .001; IT: r = 0.92, P < .001). Screws with the same diameters varied significantly in IT because of differences in self-tapping cutting flute design. CONCLUSION External diameter, unthreaded shank height, head slot, and self-tapping cutting flute design had the greatest impact on screw strength and efficiency in thin cortical bone. Thread depth, core diameter, and metal type did not affect performance significantly. Under these highly standardized in vitro conditions, the ideal 2-mm screw has an unthreaded shank that is as short as possible, and the pitch is about 0.8 mm. Additional aspects of a clinical situation beside holding strength must, however, be considered when choosing a screw.

Measuring persistent temporomandibular joint nociception in rats and two mice strains.

Temporomandibular joint (TMJ) pain has been reported to last for prolonged periods in humans. In rodents a variety of methods have been used to measure TMJ nociception, but for most of these methods the period of measurement has been minutes to a couple of hours. In addition, most measurement protocols required restraint or training of the animal. Previous studies from our laboratory demonstrated that feeding behavior, particularly meal duration, was an indicator of TMJ nociception in unrestrained and untrained male and female Sprague-Dawley rats for up to two days. In this study, we first found that injection of complete Freunds adjuvant (CFA) into the TMJ of rats significantly lengthened meal duration for 19 days and also decreased meal frequency for 42 days. Interestingly, the meal duration varied significantly from day to day within the 19 day period. TMJ interleukin-1 beta (IL-1 beta) and calcitonin gene-related peptide (CGRP) were significantly elevated in the TMJ tissues of CFA-injected animals and the level of these markers was attenuated as the meal duration decreased with time. Control animals injected with saline into the TMJ or CFA into the knee did not show a significant lengthening in meal duration but did show a decrease in meal frequency. In a second study, DBA/1LacJ mice given TMJ CFA injections showed a significantly lengthened meal duration on four of the seven days measured using end-of-the meal definition of 5 or 10 min. No other meal pattern changed significantly. Two days post-CFA injection, the DBA/1LacJ mice showed significantly elevated interleukin-6 (IL-6), but not elevated IL-1 beta. Seven days post-injection, both IL-6 and IL-1 beta were significantly elevated. No change in CGRP was detected. In this study C57Bl/6 mice also received TMJ CFA injections, but they did not show a lengthening in any meal pattern or significant increases in IL-1 beta, IL-6 or CGRP. Our data show, for the first time, that meal duration can be used to measure CFA-induced nociception in the TMJ over the course of several weeks in unrestrained rats and for up to seven days in the DBA/1LacJ mouse strain. In addition, C57Bl/6 mice are resistant to CFA-induced TMJ nociception at the same dose used in the DBA/1LacJ mice.

A GAUSS program for computing an index of tracking from longitudinal observations

Tracking can be defined as the tendency of individuals or collections of individuals to stay within a particular course of growth over time relative to other individuals. Thus, tracking describes stability in growth patterns. This paper outlines a statistical procedure for examining tracking in a single sample of measurements made on humans or other animals. This nonparametric procedure, based on Cohens (1960) kappa statistic, is suitable for equally or unequally spaced serial data that is complete and is appropriate for questions concerning growth as well as other time‐dependent phenomena. It is a conceptually simple longitudinal method that affords insight regarding the predictability of growth within a population. For example, by tracking, one can ask if young children who are in the lowest height for age category are likely to end up in that category at an older age. A user‐friendly GAUSS program is provided that generates overall as well as individual and track‐specific statistics. High‐resolution graphic representations of the data are also generated by the program. Examples are presented, including a tracking analysis of Guatemalan Indian children using quartiles.

Characterization of the maxillary complex in unilateral cleft lip and palate using cone-beam computed tomography: a preliminary study.

Deficiencies in maxillary growth have often been implicated in suboptimal results of cleft lip and palate therapy. Cone-beam computed tomography provides an opportunity to look at the dimensions of the maxillary complex in three dimensions in a way that is not possible with lateral cephalograms or dental models. The purposes of this preliminary study were to outline a new set of 18 cone-beam computed tomographic measurements, apply them to 6 patients with unilateral cleft lip and palate (UCLP), and contrast them to a comparable sample of 7 normal young adults. The patients with UCLP were treated with a single protocol by a single surgeon and orthodontist. The 18 measurements had a mean intrarater reliability of 0.95 and ranged from 0.40 to 2.23 for the individual measurements. The mean interrater reliability was 1.01 and ranged from 0.40 to 2.45 for the individual measurements. Significant differences between the patients with UCLP and control subjects (combined sex samples) were found in palate length, anterior palate thickness, overall sagittal maxillary length, and premaxillary height (Mann-Whitney U tests, P ≤ 0.037). The body of the maxilla and its heights appear less affected. These methods and preliminary findings lay the groundwork for larger scale and prospective studies that evaluate such dimensional data in conjunction with positional data and other vital outcomes of cleft lip and palate therapy such as speech and occlusion.

PC program for analyzing one-sample longitudinal data sets which satisfy the two-stage polynomial growth curve model

The two‐stage polynomial growth curve model is described and a GAUSS program to perform the associated computations is documented and made available to interested readers. The two‐stage model is similar to that considered by us earlier (Schneiderman and Kowalski: American Journal of Physical Anthropology 67:323–333, 1985; American Journal of Human Biology 1:31–42, 1989), i.e., it is appropriate for the analysis of one‐sample longitudinal data collected at either equal or unequal time intervals. Here, however, the covariance matrix, Σ, instead of being considered arbitrary, is now assumed to have the special structure Σ = W A W′ + σ2I. We show the conditions under which this special structure may be expected to arise and how it may be exploited to produce sharper results in certain situations. The method and the program are illustrated and the results are contrasted to those obtained when Σ is arbitrary. It is suggested that the two‐stage model is more efficient when the same degree polynomial is adequate to model the data in the two situations, but that, should a higher degree be necessary for the two‐stage model, confidence intervals and/or bands may be wider than those corresponding to Σ arbitrary.