Biomedical subjects

C L Lavelle

Publications and source records attributed to C L Lavelle.

At least 19 recordsLinked to original sources

PubMed1999

The role of direct intraoral sensors in the provision of endodontic services.

The recent commercial success of intraoral sensor systems largely reflects the quest to improve the quality assurances for endodontic services. The many advantages of these systems include reduced radiation exposures, real-time images, resolution improvements after initial image capture and archival benefits, although their diagnostic benefits over conventional film based radiographs remain a concern. For instance, the images from either charge-coupled device or storage phosphor sensors have yet to exceed the potential 50 microns spatial and 12-bit contrast resolutions obtained from the 1.75-6.40 microns silver grain emulsions of conventional films or the potential improvements derived from smaller (1 micron) grains. Intraoral sensor systems alone are therefore unlikely to improve the quality assurances for endodontic services.

Endodontics↗

PubMed1998

Are posts mandatory for the restoration of endodontically treated teeth?

In this era of fiscal and professional accountability, variations in the utilization of posts to improve the retention of crowns or other restorations on endodontically treated teeth are no longer acceptable. This practice ignores not only the potential for root perforations during post space preparations, but also the adhesive properties of modern resin-based materials. Since the retention of restorations hinges on many other factors, the placement of posts does not necessarily assure service quality and may even lead to deleterious changes. The need to reappraise the utilization of posts in the restoration of endodontically treated teeth cannot be overstated.

Crowns↗

PubMed1996

Is antibiotic prophylaxis required for endodontic treatment?

The stable prevalence of infective endocarditis since the advent of antibiotic prophylaxis for patients at-risk reflects the increasing polymicrobial etiology of such infections not associated with dental procedures. In addition to concerns for the growing crisis for antibiotic-resistant bacteria, the need for controlled clinical trials to determine the continued efficacy of prophylactic regimens for endodontic and other dental procedures cannot be overstated.

Antibiotic Prophylaxis↗

PubMed1995

Digital radiographic images will benefit endodontic services.

Future assurances for endodontic services and assessments of traumatized teeth will depend in part on significant improvements to the quality of dental radiographs. Whereas digital images offer many potential sensor, display and archival advantages over film-based radiographs, the marginal image improvements from intraoral sensors primarily benefit patient education. Precisely digitized conventional radiographs are more likely to yield quantum image resolution improvements, although neither dentists nor patients will benefit until cost-effective digitizing systems have been developed for the dental office.

Alveolar Bone Loss↗

PubMed1994

When will excellent radiographic images be available to the general dental office?

Dental radiography is a highly regarded diagnostic practice. More than 25% of all radiographs are taken for dental purposes, so their improvement will benefit many patients. Although recent advances in materials and processing have contributed to incremental improvements in film-based diagnoses, computer-based enhancement of digitized conventional radiographic images is likely to yield more significant benefits. However, until cost-effective digitizing systems have been developed for the general dental office, the benefits derived from precise radiographic diagnoses and associated improvements in the standards of care will continue to elude both dentist and public.

Humans↗

PubMed1994

In search for excellence: an effective strategy for dentistry.

Traditional market strategies no longer stimulate sufficient dental service demands to maintain full employment for all members of the profession. However, the dental needs of adults, particularly older adults, continue to escalate. A more effective strategy should be focused on the provision of services that consistently exceed the expectations of patients.

Adult↗

PubMed1993

Acyclovir: is it an effective virostatic agent for orofacial infections?

Oral and intravenous acyclovir formulations provide effective virostasis against many herpes viruses infections, especially severe herpes simplex or varicella-zoster infections in ambulatory and immunocompromised patients. The therapeutic virostatic efficacy of topical acyclovir formulations requires further development, however, especially for orolabial herpetic infections.

Acyclovir↗

PubMed1993

Dental fees.

Traditional economic theories impact on the viability of a practice. Yet the relationships between revenues generated and dental service fees are more complex than traditionally envisaged. Whereas long-term fee strategies and short term tactics may be instituted to stimulate service demands, the significance of non-fee determinants (e.g. professional skills) cannot be underestimated.

Fees, Dental↗

PubMed1993

Biomechanical considerations of prosthodontic therapy: the urgency of research into alveolar bone responses.

The prognosis of natural and implant abutments depends in part on the complementary and/or antagonistic biomechanic and calcium homeostatic functions of the adjacent alveolar bone. Whereas bone morphology is determined by peak strains, strain rates, and strain distributions, infrequent error strains on abutments have a greater impact on the adjacent alveolar bone than those generated during "normal" activity. Alveolar responses depend on the immediate prevailing systemic and local demands, although unexpected abutment failures will continue until such influences have been investigated further.

Alveolar Process↗

PubMed1992

Diagnosis of skeletal form on the lateral cephalogram with a finite element-based expert system.

Orthodontic diagnosis depends largely on the current methods of cephalometric analysis and categorization. It is therefore unfortunate that such analyses tend to use inappropriate metrical systems that lack a rigorous scientific basis. As a consequence, the resultant data have questionable validity, as well as being subject to observer bias. In this study, an alternative, more rigorous, approach is described. A random sample of 126 pretreatment lateral cephalograms were analyzed with the finite element method. These data were then classified to form a training set or reference data base for the subsequent objective diagnosis of new, previously unclassified cases. This new case-classification system was based on matching the new cases to similar cases within the existing training set. The degree of concordance between such computer-matched cases was then evaluated by their subsequent conventional cephalometric analyses.

Adolescent↗

PubMed1992

A preliminary study of craniofacial classification.

Cephalographic evaluations often hinge on univariate statistical analyses of their component dimensions. These analyses generally depict a progressive increase in cephalometric form with age. Such analyses are, however, complicated by the varied inter-dimensional correlations. But when the cephalometric dimensions were combined together in cluster analysis, complex associations between various age groups were noted in the 1-18 year range. Such multivariate analyses revealed far more complex craniofacial age changes than traditionally envisaged. These data therefore indicated the need for further investigation of such "normocephalic gold standards" before their value in craniofacial evaluation can be established.

Age Factors↗

PubMed1990

Potential of finite element analysis for cephalometric investigation.

In view of concerns relating to the validity of traditional cephalometric appraisals, we undertook this study to use a potentially powerful method, finite element analysis, to compare cephalometric changes between two samples (subjects with and without orthodontic treatment). The derived data show varying sample contrasts depending on the particular finite element array included in the analysis. Thus, although finite element analysis facilitates rigorous morphometric analysis, further investigation is required before it can be applied universally in cephalometric studies.

Adolescent↗

PubMed1989

An evaluation of the changes in soft-tissue profile form induced by orthodontic therapy.

In view of the growing concensus that traditional cephalometric appraisals yield data of dubious scientific value, the changes in soft-tissue profile forms were evaluated by an alternative technique. This involved dividing the soft-tissue profile form into a series of triangular finite elements spanning homologous datum points. With the use of techniques derived from continuum mechanics, the changes in soft-tissue profile form were evaluated by computing the degree of distortion in each triangle after treatment (target element) compared with the triangle before treatment (reference element) in terms of specific size and shape parameters. In a comparison of samples of patients with Class I and II malocclusion, varying patterns of facial profile change were noted, depending on the parameters analyzed. The results, therefore, showed that although such techniques offer rigorous cephalometric potential, further investigation is required to identify more appropriate datum points.

Cephalometry↗

PubMed1989

The role of cluster analysis on traditional cephalometric dimensions.

In order to categorize (classify) craniofacial forms, varying linear dimensional arrays from a series of pretreatment cephalographs ('A' records) were subjected to cluster analysis. The derived subgroups (clusters) not only showed inconsistencies in their component patients, but also their 'nearest neighbors', i.e. cases identified as being most similar to one another. This study, therefore, emphasized the need to devise more appropriate cephalometric appraisal techniques for patient categorization (diagnosis).

Adolescent↗

PubMed1989

An evaluation of conventional cephalometric appraisals.

Although lateral cephalographic diagnosis is central to craniofacial skeletal assessment, their classification (categorization) remains largely empiric. In this study, pre- and post-treatment lateral cephalographic dimensional arrays were subjected to the classic numerical taxonomic technique of cluster analysis. The resultant patient groupings (clusters) were not only inconsistent with respect to their Angle malocclusion categories, but also the composition of each cluster group varies depending upon the dimensional arrays analyzed. These findings demonstrate that lateral cephalometric categorization remains largely subjective.

Adolescent↗

PubMed1989

Statistical methodology applied to facial studies.

The majority of cephalometric studies of anomalous craniofacial taxonomy and evaluation is based upon either isolated cases or methods that cannot withstand rigorous scientific scrutiny. A number of techniques have been devised to resolve such deficiencies, although the image quality of lateral cephalographs limits the precision of their measurement. Thus, further advances in the statistical evaluation of anomalous craniofacial forms hinge upon the acquisition of more precise images.

Cephalometry↗

PubMed1988

Detection of three-walled infrabony defects by subtraction radiography.

An in vitro investigation was undertaken to establish the sensitivity of subtraction radiography for three-walled infrabony defect detection. After the creation of defects of controlled sizes in the interproximal regions of a dried mandible, subsequent radiographs were taken with the help of an occlusal stent. The radiographs were then digitized, and the images were enhanced by frame summation and averaging to reduce electronic noise. Further standardization was facilitated by the use of a step wedge on each radiograph and a computer program to correct variations in processing and exposure. The results show that defect resolution depended not only on the diameter of the defect but also on the mass of the adjacent bone. The smallest detectable lesion was 0.5 mm in diameter in the interproximal region of the premolars. In addition, a change in depth of 1 mm could be detected at the base of three-walled infrabony defects.

Alveolar Process↗

PubMed1988

An analysis of craniofacial form in cleft palate patients.

Lateral cephalometric form was compared between age-sex matched cleft palate and normocephalic (control) samples aged 6-12 years. Analogous arrays of 3 cephalometric datum points were subjected to finite element analysis, a rigorous geometric technique. The results showed that normocephalic craniofacial size changes were greater than those of the cleft palate sample, although the degree of contrast varied depending upon the particular finite element included in the analysis. More complex lateral cephalometric shape changes were denoted by this technique, however, again depending upon the specific finite element included in the analysis. These data therefore suggested that the differences in craniofacial size and shape changes between normocephalic and cleft palate patients were far more complex than traditionally envisaged.

Cephalometry↗