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Biomedical subjects

J F Bowley

Publications and source records attributed to J F Bowley.

16 recordsLinked to original sources
PubMed2001

Masticatory muscle activity assessment and reliability of a portable electromyographic instrument.

STATEMENT OF PROBLEM: Masticatory muscle hyperactivity is thought to produce muscle pain and tension headaches and can cause excessive wear or breakage of restorative dental materials used in the treatment of prosthodontic patients. The quantification and identification of this type of activity is an important consideration in the preoperative diagnosis and treatment planning phase of prosthodontic care. PURPOSE: This study investigated the quantification process in complete denture/overdenture patients with natural mandibular tooth abutments and explored the reliability of instrumentation used to assess this parafunctional activity. MATERIAL AND METHODS: The nocturnal EMG activity in asymptomatic complete denture/overdenture subjects was assessed with and without prostheses worn during sleep. Because of the large variance within and between subjects, the investigators evaluated the reliability of the 3 instruments used to test nocturnal EMG activity in the sample. RESULTS: Electromyographic activity data of denture/overdenture subjects revealed no differences between prostheses worn versus not worn during sleep but demonstrated a very large variance factor. Further investigation of the instrumentation demonstrated a consistent in vitro as well as in vivo reliability in controlled laboratory studies. CONCLUSION: The portable EMG instrumentation used in this study revealed a large, uncontrollable variance factor within and between subjects that greatly complicated the diagnosis of parafunctional activity in prosthodontic patients.

Analysis of Variance↗
PubMed2001

Occlusal plane discrepancies generated by transverse horizontal axis deviations.

STATEMENT OF PROBLEM: Any deviation from the patient's rotational axis of the mandible during closure and the arc of closure on an articulator has been reported to produce occlusal discrepancies. These discrepancies can affect diagnostic planning procedures and the occlusal relationships of restorations. PURPOSE: This study investigated the magnitude and types of occlusal errors produced by deviations between the patient's transverse horizontal axis and the axle on the articulator. MATERIAL AND METHODS: A simplified monoplane model was diagrammatically analyzed for deviations from the model's true transverse horizontal axis. Axis deviations of 5 mm were used in 8 different directions from the true transverse horizontal axis of the model. Changes in the orientation of the mandibular plane to the maxillary plane were illustrated diagrammatically. These changes were quantified by geometric and trigonometric assessments. RESULTS: All axis deviations produced mandibular plane orientation errors with angular plane malalignment to the maxillary plane on complete closure. These axis deviations also produced anterior-posterior shifting of the mandibular plane relative to the maxillary plane. CONCLUSION: Several different types of planar shifting and angular discrepancies were demonstrated from deviations away from the true transverse horizontal axis.

Computer Simulation↗
PubMed1999

Reliability of an ear-bow arbitrary face-bow transfer instrument.

STATEMENT OF PROBLEM: Accuracy of techniques for recording the orientation of the maxillary arch to the articulation of the temporomandibular joints has been reported. The variability contributed by the dentist and the equipment within a technique may also contribute to technical error. PURPOSE: This study investigated the variability of a group of dentists who used an arbitrary ear-face-bow instrument to mount a maxillary cast. MATERIAL AND METHODS: The same maxillary cast on a single experimental subject was mounted on an articulator with a common arbitrary ear-face-bow instrument. This cast was equipped with 4 reference points for the measurement of changes of spatial orientation of the cast, which were determined through coordinate measurements with a machinist's microscope. A repeated measures analysis of variance was used to determine statistically significant changes in spatial orientation with a Wilks' Lambda test to compare mean values. RESULTS: A confidence interval of 95% demonstrated that any dentist might expect a range of +/-1.2 mm error in using this instrument/articulator combination. The 3 dentists did not demonstrate any significant differences in the spatial orientation of their mountings in the vertical or horizontal directions. However, there were significant differences in their mountings in linear distance changes of the patient's posterior right side. CONCLUSION: A range of inherent error attributable to the operator using this instrument was recorded.

Analysis of Variance↗
PubMed1998

Intrusion phenomenon in combination tooth-implant restorations: a review of the literature.

STATEMENT OF PROBLEM: Controversy regarding the connection of implants to natural teeth in fixed partial dentures has emerged in response to clinical reports of intrusion of the natural teeth. Although theories have been proposed to explain this phenomenon, the cause of the intrusion remains unknown. Numerous longitudinal studies have demonstrated that teeth can be successfully connected to implants. The use of rigid connectors, or nonrigid connectors with the keyway on the implant, are described as mechanisms to prevent intrusion of the natural tooth. PURPOSE: This article reviews the literature that pertains to this subject and includes treatment modalities that may be helpful in preventing intrusion.

Animals↗
PubMed1998

Management of the gingival sulcus in fixed prosthodontics: a literature review and treatment protocol.

This review of the fixed prosthodontics and periodontology literature illustrates the influence of various factors on the health of the periodontium during and after fixed prosthodontic treatment. This article describes four categories of marginal finish lines for fixed prosthodontic restorations relative to the gingival margin and the epithelial attachment. The management of each category from both the periodontal and prosthodontic prespectives is also discussed.

Denture, Partial, Fixed↗
PubMed1997

An evaluation of operator preference of diamond burs in coronal tooth preparation.

Three postgraduate prosthodontic students served as clinicians/evaluators in a study rating their preferences for three different diamond cutting instruments from three manufacturers. Each evaluator prepared the axial walls of complete veneer crowns on extracted molar teeth and then ranked their preference of the instruments. To prepare nine teeth, each of the three instruments was used in random order and without knowledge of the specific manufacturer. The methodology for analyzing the evaluators' preferences and the results are discussed.

Analysis of Variance↗
PubMed1993

Reliability and validity of instrumentation used to record nocturnal clenching and/or grinding.

Nocturnal clenching and grinding can be recorded with a portable electromyograph unit and a standard cassette tape recorder, which registers the clenching episodes on a cassette tape. The information can then be coded by a new instrument, called a Pulse Identifier, that subsequently transfers the data to a polygraph chart recorder. This study evaluated the reliability and validity of the Pulse Identifier when interfaced with other instruments that measure nocturnal clenching/grinding. A known number of clenching incidents over a baseline period of time were evaluated by three "blind" scores. The results demonstrated an interscorer reliability coefficient of 0.99 and a validity coefficient of 0.99.

Analysis of Variance↗
PubMed1992

Reliability of a facebow transfer procedure.

The three-dimensional orientation of a maxillary cast mounting from a simulated-kinematic facebow transfer was evaluated in multiple trials among three operators on a single subject. The anterior and posterior anatomic facial reference points were marked on the subject. Each operator performed a separate series of trials to reset the anterior facebow component, the two posterior facebow components, and a control series with no resetting of any facebow components relative to the subject. The x, y, and z coordinates of three reference points on the maxillary cast were determined with a machinist microscope relative to a fixed reference after each facebow transfer. A range of differences between mountings of the maxillary cast were found between trials with all three methods used. These mounting errors were due to setting of the instrument and would be expected in routine clinical use of this instrument.

Analysis of Variance↗
PubMed1992

Evaluation of the accuracy of cast reorientation to a surveyor by prosthodontic residents.

This study investigated the accuracy of a group of evaluators in reestablishing the orientation of a tripoded master cast to a surveyor instrument. Three prosthodontic residents served as evaluators to reestablish the tilt of a previously tripoded cast with three known reference coordinates. The distance from the known to the reference point was recorded for the three points in four trials by a judge with a machinist height gauge. Analysis of variance revealed a significant difference between the evaluator cast position and the known reference position. The investigation demonstrated +/- 0.2 mm errors at each of the three locations; 0.3-degree angulation errors occurred in reestablishing the tilt of the master cast in relation to the surveyor.

Analysis of Variance↗
PubMed1992

Evaluation of variables associated with the transverse horizontal axis.

The effect of transverse horizontal axis deviations on the vertical and horizontal orientation of maxillary and mandibular members was investigated on a laboratory articulator model. Twelve axis deviations (+30, +25, +20, +15, +10, +5, -5, -10, -15, -20, -25, and -30 mm groups) within a 55 mm dimension model were evaluated. Three trials at each transverse horizontal axis deviation demonstrated significant changes in maxillomandibular orientation after mounting the mandibular member with a standardized intermember mounting record. A linear regression analysis produced an equation for predictive interpolation of anterior-posterior shift as a result of axis deviations from +30 to -30 mm.

Analysis of Variance↗
PubMed1992

A preliminary diagnostic and treatment protocol.

The objectives of the preliminary diagnostic and treatment protocol are 1. To reveal retention or resistance form deficiencies. 2. To reveal need for augmentive periodontal crown-lengthening surgical procedures. 3. To evaluate pontic form for the existing space. 4. To preplan occlusal plane deficiencies and methods of corrective treatment to establish Curve of Spee. 5. To preplan occlusal scheme, i.e., canine guidance, group function, mutually protected occlusion, and cross-bite conditions. 6. To aid in preplanning sequence of treatment and method of preservation of occlusal vertical dimension. 7. To serve as a visual aid for discussion of treatment recommendations with patient prior to actual treatment. 8. To act as a medicolegal record to document the clinician's pretreatment planning in complex treatment situations for possible use in peer review or litigation. 9. To aid in fabrication of an elastomer reduction guide for use during crown preparation. 10. To aid in fabrication of a vacuum-formed template for provisional restoration of crown and abutment teeth after preparation.

Clinical Protocols↗
PubMed1992

Clinical decision analysis in fixed prosthodontics.

Structured clinical decision analysis in dentistry in fixed prosthodontics, as in any branch of dentistry, allows the practitioner to think through more clearly the problems at hand based on the clinical data and extenuating factors presented by the patient. This discipline of decision making is intended to complement the experience level and educational background of the clinician in assisting him or her through the decision process. Additionally, CDA helps the clinician define not only the pre-existing condition of the patient prior to irreversible therapy, but also which treatment strategies may best be suited for that individual over an extended period. The systematic nature of decision analysis stimulates the focusing of one's attention on those factors considered to be germane to the overall complexity of the case and, at the same time, excluding those factors having little or no influence on its final outcome. With further implementation of computerized databases and procedural outcome probabilities based on clinical and laboratory studies as well as the clinical experience of those choosing to use it, the future for structured, formalized clinical decision analysis seems quite promising.

Decision Support Techniques↗
PubMed1990

Reliability and validity of a transverse horizontal axis location instrument.

Previous studies have demonstrated a relatively accurate location of the transverse horizontal axis (THA) with several different instrument systems. This study statistically evaluated the reliability and validity of an instrument used to locate a known THA on a mannequin. Three experienced prosthodontists were the subjects. Each operator used 15 mm of interincisal arc to locate the THA. The mandibular stylus was aligned by the investigator with the known horizontal axis. The vertical microdot flags were positioned so the stylus was over a known coordinate and were repositioned so the operator could attempt to locate the axis. The known coordinates were varied with each of four trials. Subjects No. 1 and 3 demonstrated the best coefficient of reliability, 0.25. The 95% confidence interval for linear deviation from the known was 0.44 +/- 0.10 mm on the right side and 0.97 +/- 0.10 mm on the left side. These confidence intervals did not include zero. A statistically better result was achieved on the right side compared with the left side (F1,3 = 131.24, p = 0.0014). The results of this study indicate that a random error factor of 0.3 to 1.2 mm can be expected when this instrument system is used clinically.

Analysis of Variance↗
PubMed1987

Experimental masticatory muscle pain.

Ten female subjects with no history of temporomandibular disorders performed five exercises designed to induce masticatory muscle pain. Three of the exercises were replications of Christensen's tooth-clenching (1970) and tooth-grinding (1971) studies and Scott and Lundeen's mandibular protrusion (1980) study. The other two exercises were designed to induce specific unilateral masticatory muscle pain. The amount of muscle pain as well as the time of onset and the duration were assessed by a clinical palpation exam and a pain questionnaire. These five pain-inducing methods did not consistently produce masticatory muscle pain in non-pain subjects. However, certain individuals appeared to be very susceptible to developing pain during or after most of the exercises. These susceptible individuals demonstrated a bilateral muscle pain pattern after the unilaterally stressful exercises. None of the five exercises produced a statistically significant amount of site-specific masticatory muscle pain as determined by either the palpation examination or the pain questionnaire, even when the exercise was intended to produce such specificity. The fact that some subjects did develop masticatory muscle pain is indicative that muscle exercise and fatigue may lead to TMD-like symptoms.

Adolescent↗
PubMedDate not supplied

Prevalence of temporomandibular disorders (TMD) in children based on physical signs.

Temporomandibular disorders (TMD) are related to the function and integrity of the masticatory system with restricted jaw movement and/or joint clicking or crepitus, for example, dominating the clinical signs of these disorders. The prevalence of TMD signs was examined in non-patient children ages six to twelve (1994 n = 185, 1995 n = 237) by four examiners using standardized techniques. Of significance was the finding that 7.3 percent of the 1994 children had audible joint sounds, while the 1995 examination reported 3 percent. Statistically significant relationships (p < 0.05) between the ages of the subjects and measurements of overbite (p < 0.0001), overjet (p < 0.01), and clicking (p < 0.005) were calculated from the 1994 data, while significant correlations for overbite (p < 0.001) and overjet (p < 0.01), but not clicking were found in the 1995 examination. One study of four- to six-year-old nonpatients reported a higher occurrence of joint sounds (48 percent). This disparity indicates a possible need for standardization of examination techniques specifically targeting joint sounds and their role in TM disorders.

Analysis of Variance↗