Donald Curtis | UCSF - Academia.edu (original) (raw)

Papers by Donald Curtis

The Journal of Prosthetic Dentistry, 1999

The Journal of Prosthetic Dentistry, 2006

When 1 retainer of a definitive fixed partial denture (FPD) becomes loose, the clinician has the ... more When 1 retainer of a definitive fixed partial denture (FPD) becomes loose, the clinician has the option of either sectioning and removing the FPD or attempting removal of the intact cemented retainer. Excessive force during attempted FPD removal may irreversibly damage dentition. This study evaluated the type and frequency of complications that may accompany the removal of definitive cemented FPDs with a single loose retainer. Participants included 22 patients with a definitive cemented FPD with complete cast crown coverage castings in which 1 retainer became loose and the other retainer remained cemented. Cemented FPD retainers were removed using 1 of 2 attachments supplied with a crown removal system (Dentco). The patient and FPD characteristics, type of attachment, number of attempts before removal, condition of removed FPD, and condition of the abutment teeth were recorded. Descriptive statistics were used to analyze the data. Clinical findings recorded prior to FPD removal showed that 41% of patients were unaware they had a loose FPD retainer and 82% reported no discomfort associated with the loose retainer. Caries were noted on 50% of the teeth with a loose retainer. Damage resulting from attempted removal of the cemented retainer included minor porcelain fracture (9%), minor core chipping (14%), minor incisal edge chipping of tooth preparations (27%), and major damage to the abutment tooth (4%). Retrieval of an intact FPD and recementation was possible 64% of the time.

Journal of Oral Rehabilitation, 1998

Seven normal male and seven normal female volunteers performed three types of biting exercises: a... more Seven normal male and seven normal female volunteers performed three types of biting exercises: an intermittent contraction at maximum voluntary bite force (MVBF) to pain intolerance; a ramp intermittent contraction starting at 10% MVBF and increasing 10% every 10 s; and a sustained biting at 100% MVBF to pain intolerance. The following measurements were made on the first and second days before exercise: a pre- and post-exertional overall jaw pain level; maximum pain-free jaw opening; bilateral masseter pressure pain threshold (PPT) and intolerance (PPI). The results showed that only females presented an increased overall pain level on the second day and a significant decrease in pain-free jaw opening, but no significant decrease of PPT and PPI. These results suggest that females respond differently than males to exertional jaw pain, by increasing their pain response 24 h later.

The Journal of Prosthetic Dentistry, 1993

Three-dimensional condylar movements of 49 symptomatic and asymptomatic volunteers were recorded ... more Three-dimensional condylar movements of 49 symptomatic and asymptomatic volunteers were recorded with a hinge axis tracing system axiograph during maximal opening, protrusion, and mediotrusion. The tracings displayed in sagittal and frontal planes were measured to evaluate biomechanics of the temporomandibular joint. The only differences in condylar tracings between symptomatic and asymptomatic groups were in the right joint, recorded in the sagittal plane during maximal opening, and the Bennett angle. The symptomatic group had a significantly longer condylar path and a smaller Bennett angle compared with the asymptomatic group. The results were interpreted as indications of adaptive morphologic instead of pathologic changes. The alterations in condylar tracings as an indicator of joint pathology should be considered cautiously.

The Journal of Prosthetic Dentistry, 1996

Objective: To investigate the effects of interstitial water within the PDL by replacing with etha... more Objective: To investigate the effects of interstitial water within the PDL by replacing with ethanol. Method: Male Sprague Dawley rats were sacrificed at 12 (n=5) and 20 (n=5) weeks old, and their right maxillae harvested and placed in 0.006% pen-strep tris-buffered-saline solution to maintain in vivo osmolality. The right 2nd molar of each specimen was prepared to evaluate organ biomechanics. The 2nd molar was loaded 3 times, with 1-minute intervals, at 0.2mm/min to a peak load of 5N which represents lower level loading where unbound fluid is displaced out of the PDL-space. Specimens were tested using a mechanical loading device (MT500CT, Deben UK Ltd, Suffolk, UK) after being submerged in TBS, 50%-ethanol, and 100%-ethanol for 24-hours. Changes in organ biomechanics were identified by investigating changes in load-displacement curves for each load-cycle under each condition. Stiffness values were determined from the initial 30% of load-displacement curves. Result: At 12-weeks old,...

Journal of dental education, 2012

Dental student performance on examinations has traditionally been estimated by calculating the pe... more Dental student performance on examinations has traditionally been estimated by calculating the percentage of correct responses rather than by identifying student misconceptions. Although misconceptions can impede student learning and are refractory to change, they are seldom measured in biomedical courses in dental schools. Our purpose was to determine if scaling student confidence and the clinical impact of incorrect answers could be used on multiple-choice questions (MCQs) to identify potential student misconceptions. To provide a measure of student misconception, faculty members indicated the correct answer on twenty clinically relevant MCQs and noted whether the three distracters represented potentially benign, inappropriate, or harmful application of student knowledge to patient treatment. A group of 105 third-year dental students selected what they believed was the most appropriate answer and their level of sureness (1 to 4 representing very unsure, unsure, sure, and very sure...

Our purpose was to compare admissions criteria as predictors of dental school performance in unde... more Our purpose was to compare admissions criteria as predictors of dental school performance in underachieving and normally tracking dental students. Underachieving dental students were identified by selecting ten students with the lowest class grade point average following the first year of dental school from five classes, resulting in a pool of fifty students. Normally track - ing students served as

Tracking student performance in preclinical and clinical courses can be helpful in developing and... more Tracking student performance in preclinical and clinical courses can be helpful in developing and refining a curricu - lum. Our objective was to correlate student performance on three fixed prosthodontic examinations taken by eighty junior dental students. Examinations included a knowledge-based objective structured clinical examination (OSCE), a manual skills exercise completed on a typodont (Typodont), and a competency casting exam

Strain-Guided Biomineralization within the Bone-PDL-Cementum Complex Objective: Pullout forces at... more Strain-Guided Biomineralization within the Bone-PDL-Cementum Complex Objective: Pullout forces at the PDL-bone and PDL-cementum interfaces can be amplified by applying a unidirectional force to the bone-periodontal ligament-cementum complex. We investigated physicochemical properties of biomineral at the strained PDL-bone and PDL-cementum attachment sites. Methods: A unidirectional force of 0.6 N acting mesially was applied on rat molars for two months using an in vivo model (N=5-experimental; N=5-control). Harvested hemimaxillae were investigated using X-ray microscopy, and Raman spectroscopy. Dynamic histomorphometry by injecting fluorescent dyes into a separate set of rats was performed. Results: Histomorphometry illustrated a reversed effect in naturally occurring mesial-bone formation and distal-bone resorption patterns normally observed in controls. Dynamic histomorphometry was positively correlated to TRAP-positive osteoclast localization in experimental groups at the mesial-...

Journal of Biomechanics, 2015

The effects of alveolar bone socket geometry and bone-implant contact on implant biomechanics, an... more The effects of alveolar bone socket geometry and bone-implant contact on implant biomechanics, and resulting strain distributions in bone were investigated. Following extraction of lateral incisors on a cadaver mandible, implants were placed immediately and bone-implant contact area, stability implant biomechanics and bone strain were measured. In situ biomechanical testing coupled with micro X-ray microscopy (µ-XRM) illustrated less stiff bone-implant complexes (701-822N/mm) compared with bone-periodontal ligament (PDL)-tooth complexes (791-913N/mm). X-ray tomograms illustrated that the cause of reduced stiffness was due to limited bone-implant contact. Heterogeneous elemental composition of bone was identified by using energy dispersive X-ray spectroscopy (EDS). The novel aspect of this study was the application of a new experimental mechanics method, that is, digital volume correlation, which allowed mapping of strains in volumes of alveolar bone in contact with a loaded implant. The identified surface and subsurface strain concentrations were a manifestation of load transferred to bone through bone-implant contact based on bone-implant geometry, quality of bone, implant placement, and implant design. 3D strain mapping indicated that strain concentrations are not exclusive to the bone-implant contact regions, but also extend into bone not directly in contact with the implant. The implications of the observed strain concentrations are discussed in the context of mechanobiology. Although a plausible explanation of surgical complications for immediate implant treatment is provided, extrapolation of results is only warranted by future systematic studies on more cadaver specimens and/or in vivo models.

The open pain journal, 2012

This is a longitudinal study of a large US biracial community cohort of 732 young women - 50% Afr... more This is a longitudinal study of a large US biracial community cohort of 732 young women - 50% African-American and 50% Caucasian - specifically investigating incidence, remission, and progression of, as well as factors associated with common chronic pains (back, head, face, chest and abdomen). The results show back, head and abdominal pains were the most common, severe and persistent pains. Facial pain, although less common and severe, was the only pain presenting significant racial differences with Caucasians having higher prevalence, incidence and persistence; incidence per 1000 person-years was 58 for Caucasians and 18 for African-Americans while remission per 1000 person-years was 107 for Caucasians and 247 for African-Americans (p<0.05). Risk factors associated with incidence (I) differed from those associated with persistence(P), perhaps due to the young age and shorter pain duration in this population. Face pain incidence, but not persistence for example, was associated wi...

Today's FDA : official monthly journal of the Florida Dental Association

The clinical signs of dental erosion are initially subtle, yet often progress because the patient... more The clinical signs of dental erosion are initially subtle, yet often progress because the patient remains asymptomatic, unaware and uninformed. Erosion typically works synergistically with abrasion and attrition to cause loss of tooth structure, making diagnosis and management complex. The purpose of this article is to outline clinical examples of patients with dental erosion that highlight the strategy of early identification, patient education and conservative restorative management. Dental erosion is defined as the pathologic chronic loss of dental hard tissues as a result of the chemical influence of exogenous or endogenous acids without bacterial involvement. Like caries or periodontal disease, erosion has a multifactorial etiology and requires a thorough history and examination for diagnosis. It also requires patient understanding and compliance for improved outcomes. Erosion can affect the loss of tooth structure in isolation of other cofactors, but most often works in synerg...

Journal of the California Dental Association, 2011

The clinical signs of dental erosion are initially subtle; yet they often progress because the pa... more The clinical signs of dental erosion are initially subtle; yet they often progress because the patient remains asymptomatic, unaware, and uninformed. Erosion typically works synergistically with abrasion and attrition to cause loss of tooth structure, making diagnosis and management complex. The purpose of this article is to outline clinical examples of patients with dental erosion that highlight the strategy of early identification, patient education, and conservative restorative management.

Accurate self-assessment is an important attribute for practicing dentists and, therefore, an imp... more Accurate self-assessment is an important attribute for practicing dentists and, therefore, an important skill to develop in dental students. Our purpose was to examine the relationship between faculty and student assessments of preclinical prosth- odontic procedures. Seventy-six second-year students completed two consecutive examinations and two self-assessments. The examinations involved setting maxillary denture teeth on a model to simulate the clinical

Journal of the Mechanical Behavior of Biomedical Materials, 2014

Journal of the California Dental Association, 2002

Many variables affect treatment planning, and it is important for clinicians to consider why they... more Many variables affect treatment planning, and it is important for clinicians to consider why they plan certain procedures for patient care. New materials, technologies, and products are constantly being introduced and affect decision making in dentistry. In addition, patients are more informed, have higher esthetic concerns, and want a greater stake in treatment planning decisions than ever before. How dentists treatment plan needs to reflect the many influences on final treatment outcome. The purpose of this paper is to outline how treatment planning has changed in dentistry with the goal of providing the general dentist updated information to develop a cohesive treatment plan.