Misconceptions amongst dental students: How can they be identified?

AIM: To compare the frequency of misconceptions amongst dental students resulting from assessments in different subject areas using different types of multiple-choice questions (MCQs). We wanted to know whether misconceptions, or strongly held incorrect beliefs, differed by subject area or question type. METHODS: A total of 104 students completed two assessments that included 20 MCQs on endodontics and 20 MCQs on dental implants. On each examination, 10 questions were scenario-type questions requiring interpretation or analysis and 10 questions were factual-based, knowledge questions. Incorrect responses and confidence levels by student and subject were recorded for a comparison of average misconceptions by question type and for correlations between scenario and knowledge question types for misconceptions on both assessments. RESULTS: Students were overly confident on their incorrect responses and misconceptions for both assessments. On the endodontic examination, students held a statistically significant higher number of mean misconceptions on scenario questions than for knowledge questions, but the difference was not statistically significant for the dental implant examination. There was a moderately weak relationship between scenario and knowledge questions for misconceptions on the endodontic (r=.31) and dental implant (r=.20) assessments, suggesting students who have misconceptions on knowledge questions are somewhat more likely to have misconceptions on scenario questions. CONCLUSION: Students had a consistent rate of overconfidence (75%) in their incorrect responses regardless of question type or dental subject. Questions that prompted a higher per cent of incorrect responses were more likely to detect misconceptions, as students were highly confident in their mistakes, for both assessments.

Increased interleukin-1 beta in the crevicular fluid of diseased implants.

Diseased implants can be distinguished from healthy implants by the presence of inflammation in the surrounding tissue. Inflammation correlates with elevated levels of interleukin-1 beta in gingival crevicular fluid. An analysis of interleukin-1 beta levels in diseased implants compared to those in matching healthy implants in 12 patients indicates that the level of interleukin-1 beta was approximately three times that at healthy sites. Interleukin-1 beta levels may provide a means of monitoring the health status of dental implants.

Histologic evaluation of hydroxylapatite-coated versus uncoated titanium blade implants in delayed and immediately loaded applications.

It has been suggested that the long-term success of blade implants could be improved by placing the implants using a two-stage surgical protocol to allow the implant to develop a direct bony interface instead of a fibrous tissue interface. This study compared the implant interfaces of delayed and immediately loaded blade implants in nonhuman primates. A second objective was to compare the effects of hydroxylapatite coating on delayed and immediate loading applications. The delayed loaded uncoated titanium and hydroxylapatite-coated blade implants did osseointegrate. This study also suggests that hydroxylapatite-coated blade implants may form a direct bony interface even when they are loaded immediately after implantation, provided that they are splinted to a firm natural tooth.

Shear bond strength of visible-light-cured resin relative to heat-cured resin.

One promising clinical application of visible-light-cured (VLC) denture resin is for relining complete and partial dentures. Typically, a VLC resin would be used to reline an existing prosthesis fabricated from heat-cured resin (HCR). This study measured the shear bond strength of a VLC resin bonded to HCR specimens by different bonding agents. For comparison, we measured the shear bond strengths of VLC resin bonded to VLC resin specimens and of autopolymerizing resin (APR) to HCR specimens. Cylindrical specimens of HCR (n = 126) and VLC (n = 24) were thermocycled to simulate aging, and the bonding surfaces were prepared by being sanded to approximate clinical roughness. The specimens were divided into seven groups of approximately 20 each, and test materials were bonded by different bonding agents. Statistical analysis by ANOVA and the Student-Newman-Keuls test showed significant differences (p less than 0.05) among all groups except APR to HCR/no bonding agent, VLC to HCR/VLC bonding agent, or VLC to HCR/VLC and HCR bonding agent. The traditional bond of APR to HCR with HCR bonding agent was significantly stronger (p less than 0.05) than the strongest bond of VLC to HCR with HCR and VLC bonding agents.

The relationship between chronic facial pain and a history of trauma and surgery.

OBJECTIVE: Because pain is the most commonly reported symptom of patients presenting to temporomandibular disorders clinics, it is important to identify factors that modify the perception or reality of such pain. The purpose of this study was to investigate the hypothesis that a patient with a history of trauma and/or non-temporomandibular joint surgery might be sensitized to pain and might report increased pain levels if a temporomandibular disorder later developed. STUDY DESIGN: This was a retrospective study of 778 consecutive patients seen over a 1-year period in an Orofacial Pain Clinic. Study parameters included gender, lifetime number of self-reported traumas, lifetime number of non-temporomandibular joint operations, and location, intensity, frequency, and type of temporomandibular disorder-related pain. RESULTS: There were significantly more women than men in the study (609 to 169). There was no relationship between numbers of previous traumas and non-temporomandibular joint operations and types of temporomandibular disorder. However, there were statistically significant relationships between the severity of facial pain and the frequency of facial pain as well as between the severity and frequency of joint pain and the number of traumas. There were also statistically significant associations between the severity and frequency of facial pain and the number of non-temporomandibular joint-related surgical procedures that the patient had undergone. CONCLUSIONS: There is a relationship between a patient's reported history of trauma and/or non-temporomandibular joint-related operations and the severity and frequency of facial and temporomandibular joint pain, should it develop. It is possible that such traumas and operations sensitize the patient in such a way that the pain of subsequent temporomandibular joint disorders is heightened.

Fracture resistance of endodontically treated teeth restored with bonded amalgam and full crowns.

The use of dentin bonding prior to placement of core build-up restorations has been shown to reduce microleakage and reinforce remaining tooth structure. However, information is lacking about the influence a core build-up has on the fracture resistance of crowned teeth. The purpose of this in-vitro study was to compare the influence of three types of core build-ups on the fracture resistance of crowned teeth.

Occlusal considerations for implant restorations in the partially edentulous patient.

The type and frequency of complications associated with dental implants has changed during the past decade. As more-successful rates of osseointegration have resulted from improved surgical protocols and materials, the major complications have become restorative-related rather than surgery-related. Recent studies indicate that restorative complications with implant-retained restorations occur at rates of 10 percent to 77 percent over a three-year period. Many of the restorative complications can be minimized with careful treatment planning and coordination of care. However, because implants lack the stress release associated with a periodontal ligament, impact loading to restorative materials and the crestal bone remains potentially more damaging with implant-supported restorations. This article discusses the biomechanical implications of implant restorations and outlines occlusal considerations designed to decrease restorative complications.

Diagnosis and management of peri-implant disease.

Long-term success of dental implants depends largely on the continued health of peri-implant hard and soft tissues and an appropriate force distribution on the implants. Since dental implants are accepted as viable and, in some cases, ideal restorative options, all members of the dental team are faced with the task of maintaining implant health. This review outlines the current understanding of implant health and disease and presents recommendations for the treatment and management of diseased implants.

A comparison of lateral interocclusal records to pantographic tracings.

Many techniques exist to record patients' lateral jaw movements, but they have not been thoroughly investigated. This study compared recordings of immediate sideshift by using a pantograph and two intraoral registration materials. Pantographs were completed on 20 healthy participants by using chinpoint guidance and a kinematic hinge axis. Three lateral interocclusal records were completed on each participant and averaged for right and left sides. The average immediate sideshift recorded by a pantograph (0.54 mm) was less than that recorded by the two intraoral registration materials. The standard deviations were similar for all materials. An analysis of variance test identified significant statistical differences between a pantograph and one of the intraoral registration materials, but not between the pantograph and the other registration material. Immediate sideshift recorded with one material compared favorably with a pantograph recording when three records using the chinpoint guidance were averaged.

A comparison of protrusive interocclusal records to pantographic tracings.

The rationale for recording protrusive mandibular movement is to accurately adjust an articulator. Techniques to record condylar inclination include radiographic interpretation, extraoral tracings, and intraoral recording materials. This study compared the protrusive settings on an articular adjusted by a pantograph to protrusive settings recorded by two intraoral recording materials, one a polyvinyl siloxane material and one a laminated, metalized wax. Pantographs were completed for 20 patients by using a kinematic hinge axis and conventional pantographic techniques. The patients also had three protrusive interocclusal records made with two intraoral registration materials completed and averaged. The average condylar inclination recorded with a pantograph (29.5 degrees) was greater than the recording by either intraoral registration material. Standard deviations ranged from 4.1 degrees to 6.6 degrees. An analysis of variance showed that the condylar inclination recorded by wax was statistically less than recorded with a pantograph. A comparison between the pantograph and the polyvinyl siloxane displayed no statistically significant difference in recording condylar inclination.

Neurochemical changes in experimental African trypanosomiasis in voles and mice.

Dopamine, norepinephrine, serotonin and related metabolites were measured in the brain of meadow voles and mice after infection with Trypanosoma brucei gambiense with the goal of understanding the neurochemical changes accompanying infection with this parasite. Serotonin and 5-HIAA levels both fell by 26%, and HVA levels rose by 56%, in vole brains during infection. Dopamine, DHPG and norepinephrine levels, however, remained unchanged. In mice, serotonin levels dropped by 17 and 23%, respectively, in the pons-medulla and midbrain regions after infection; 5-HIAA and dopamine levels remained unaffected by infection in mice. The possible causes and the significance of these changes are discussed.

Limitations of semiadjustable articulators. Part I: Straight line articulators without setting for immediate side shift.

The accuracy of two semiadjustable articulators was compared with a fully adjustable articulator. Positive errors in the frontal and horizontal planes were demonstrated at the level of the first molar. Increasing ISS produced more error whereas errors in the sagittal plane were minimal and negative.

Erosion caused by gastroesophageal reflux: diagnostic considerations.

Dental erosion occurs with a high prevalence in the general population, but its impact on prosthodontic care is often unrecognized. The etiology of dental erosion is difficult to establish because it may result from a variety of causes and may have different presentations. Our purpose was to review the literature relevant to dental erosion and to report a patient presentation in which an unusual pattern of severe erosion was the dental manifestation of asymptomatic gastroesophageal reflux disease.

Errors incurred in programming a fully adjustable articulator with a pantograph.

The ability of experienced and inexperienced dentists to follow graphic tracings of known value was compared. The mean differences from known values were low for the settings of condylar inclination, progressive side shift, and immediate side shift. Errors were high in both groups when the parameters of the top wall and rear wall were evaluated. Further work is necessary to determine the clinical significance of these errors.

Vertical dimension increases in the adult rhesus monkey: a pilot study.

Tooth impaction, increased muscle activity, and histologic changes in the bone of the temporomandibular joint have been reported following attempts to increase the vertical dimension of occlusion. The purpose of this research was to study the effects of increases in the vertical dimension of occlusion on bone density at five levels of the mandible in the adult rhesus monkey, and to assess dentoalveolar changes by lateral cephalometric radiographs and mounted diagnostic casts. Mandibular cobalt chromium splints measuring 3 mm in height at the first molar, providing even occlusal contact to the maxillary anterior and posterior teeth, were cemented in place on two monkeys. Five similar monkeys without splints were used as controls. Computed tomograms were completed to evaluate bone density bilaterally at five levels of the mandible after 3 months of splint wear. Pretreatment and posttreatment lateral cephalometric radiographs and mounted diagnostic casts were completed to assess tooth impaction. Periodontal ligament (PDL) thickening and mobility of molars and premolars were evaluated before splint placement and after splint removal. There was no statistically significant difference in the bone density levels of the animals with splints compared with the controls. Minimal dentoalveolar changes were observed.

Adaptability of the adult primate craniofacial complex to asymmetrical lateral forces.

The adaptability of the adult craniofacial skeleton to altered functional relationships has been reported. An experimental quantification of these changes is lacking, however, and the possible underlying mechanisms of the alterations have not been explained. The purpose of this investigation was to evaluate the effect that lateral displacement of the mandible has on the dentoalveolar, craniofacial, and neuromuscular system in the adult rhesus monkey. Ten adult monkeys were studied; five served as controls, three were fitted with bilaterally inclined mandibular splints designed to deviate the mandible toward the left on closure, and two animals had flat splints to provide even occlusal contact. Pretreatment and posttreatment assessment of dentoalveolar and craniofacial change was made from mounted study casts, cephalometric head films, electromyograms and computed tomograms. Axial computed tomographic scans were used to evaluate potential changes in bone density at the lower part of the mandible, the condyle, the coronoid process, the neck of the condyle, and the zygomatic arch by means of a one-way analysis of variance. Changes in the measured variables were not observed in the control animals or in the animals with flat splints. Animals with inclined splints, however, demonstrated attrition and intrusion of maxillary molars and mild proclination of the maxillary incisors. Posttreatment computed tomographic scans in these animals showed significantly increased bone density in the right coronoid process (p less than 0.05) and bilaterally at the necks of the condyles (p less than 0.005). Resting electromyographic activity remained low and was not significantly different among the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

An altered-cast impression technique that eliminates conventional cast dissecting and impression boxing.

An altered-cast impression technique that eliminates conventional cast-dissecting and impression-boxing procedures has been described. The master cast obtained by this method reproduces the teeth in anatomic form and the residual alveolar ridges in functional form.

Axiographic tracings of temporomandibular joint movements.

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.