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.

Evaluation of dental erosion in patients with gastroesophageal reflux disease.

STATEMENT OF PROBLEM: The cause of dental erosion may be difficult to establish because of its many presentations. Determination of the cause is an important aspect of diagnosis before extensive prosthodontic rehabilitation. PURPOSE: This cross-sectional study evaluated the association between loss of tooth structure as a result of dental erosion and gastroesophageal reflux disease. MATERIAL AND METHODS: Twenty consecutive adult dentate subjects referred to the Division of Gastroenterology for investigation of gastroesophageal tract disease were also evaluated for signs of dental erosion. All subjects underwent a dental evaluation that included a patient history to determine potential etiologic factors responsible for dental erosion. Subjects were examined clinically to quantify loss of tooth structure using a Tooth Wear Index (TWI). Endoscopic examination and 24-hour pH manometry were carried out to determine which subjects met the criteria for gastroesophageal reflux disease (GERD). Scores for maxillary versus mandibular dentition and anterior versus posterior dentition were also compared. Data were analyzed with the Kruskal-Wallis test (P =.004). RESULTS: Ten subjects were diagnosed with GERD and 10 subjects had manometry scores below the level indicating GERD. Overall, subjects diagnosed with GERD had significantly higher TWI scores compared with control subjects (mean difference = 0.6554; P =.004). GERD subjects had higher TWI scores in all quadrants, except in the mandibular anterior region where there was no difference. CONCLUSION: The results indicated that a relationship exists between loss of tooth structure, as measured by the TWI index, and the occurrence of GERD in this group of subjects.

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.

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.

Modeling of jaw biomechanics in the reconstructed mandibulectomy patient.

STATEMENT OF PROBLEM: Biomechanics of occlusal force and indirect calculation of temporomandibular joint loading in patients after surgery for head and neck cancer is poorly understood. PURPOSE: This study compared occlusal force values of 6 mandibulectomy subjects with reconstructed mandibles to 6 noncancer subjects with intact mandibles and reports occlusal force predictions from a developed computer model simulation of both a mandibulectomy subject with a reconstructed mandible and noncancer subject with an intact mandible. MATERIAL AND METHODS: Maximum occlusal force was recorded at the first molar and incisal edge in 6 mandibulectomy subjects who had bony reconstruction of the mandible and 6 noncancer subjects with an intact mandible. Clinical data were then qualitatively compared with occlusal force values generated from an existing computer model simulating an average adult, and a developed model simulating an average mandibulectomy subject who had bony reconstruction of the mandible. The biomechanical parameters modeled also included an estimation of joint force magnitude and direction when biting with maximal force on the first molar. RESULTS: Clinical data revealed no significant differences in occlusal force between the 6 mandibulectomy subjects with bony reconstruction of the mandible and 6 noncancer subjects with an intact mandible; however, average molar and incisal occlusal force values were 22% and 32% less in mandibulectomy subjects with bony reconstruction. Computer simulations of a reconstructed mandibulectomy subject predicted that reconstructed subjects would have 45% less molar occlusal force, 50% less incisal occlusal force, and a higher joint/tooth force ratio compared with a simulated noncancer patient with an intact mandible. CONCLUSIONS: There were no significant differences in first molar or incisal occlusal force between reconstructed mandibulectomy subjects and noncancer subjects with intact mandibles. Trends calculated from computer simulations were consistent with clinical findings.

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.

Failure load of acrylic resin denture teeth bonded to high impact acrylic resins.

STATEMENT OF PROBLEM: Techniques for bonding denture teeth to an acrylic resin denture base remain empirical, with little consensus from the literature, among clinicians, or among dental laboratories. PURPOSE: This study evaluated the failure load of acrylic resin teeth bonded to 2 high impact acrylic resins. METHODS AND MATERIAL: The ridge lap portion on 120 identical denture teeth were modified with 3 variables: (1) placing a diatoric, (2) using monomer to prewet the denture tooth, and (3) breaking the glaze. Variables were combined to form 6 groups of 10 teeth each, and processed with Lucitone 199 (Lucitone) or SR-Ivocap (Ivocap) acrylic resin. Data analysis included the use of a heterogeneous variance linear regression model. RESULTS: Mean (+/- SD) failure load ranged between 10.25 +/- 1.48 Kg to 28.43 +/- 11.05 Kg for the 6 Ivocap groups and 16.63 +/- 5.87 Kg to 28.05 +/- 5.35 Kg for the Lucitone groups. For Lucitone 199 acrylic resin, the highest failure loads resulted when the ridge lap was left with an intact glaze and did not have a diatoric, with no significant influence from the use of monomer. For Ivocap resin, the highest failure loads resulted when the ridge lap had a diatoric but did not have monomer placed, with no significant influence from glaze. CONCLUSION: Failure load of bonding highly cross-linked denture teeth to SR-Ivocap or Lucitone 199 acrylic resin was significantly influenced by modifications to the ridge lap before processing.

Gender difference in jaw pain induced by clenching.

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.

A comparison of masticatory function in patients with or without reconstruction of the mandible.

BACKGROUND: The functional benefits of mandibular reconstruction following a composite resection remain unclear. Although microvascular surgical techniques have dramatically increased the predictability of bone and soft-tissue reconstruction towards presurgical anatomic norms, the specific factors responsible for improved function remain controversial. Objective measures of masticatory function need to be more clearly determined before the predictability and efficacy of reconstructive approaches is established. METHODS: We evaluated objective measures of oral function and patient reports of function in 10 reconstructed mandibulectomy patients, 10 without reconstruction, and 10 controls. Measures of oral function included bite force assessed at the first molar and incisal edge, a measure of tongue and cheek function, and patient reports of food they could eat. RESULTS: Both reconstructed and nonreconstructed patients presented decreased biting force, a more restricted diet, and compromised cheek and tongue function as compared with normals. However, reconstructed patients had significantly better measures of tongue function and ability to eat a varied diet than did nonreconstructed patients. Of the objective measures used to measure masticatory performance, bite force was poorly correlated, whereas measures of tongue function strongly correlated with successful mastication. CONCLUSION: Both reconstructed and nonreconstructed patients presented with a significant functional deficit when compared with normals, with reconstructed patients having better overall function than nonreconstructed patients.

Crevicular fluid analysis around two failing dental implants: a clinical report.

The criteria for monitoring tissue health around endosseous implants remain subjective. Disagreement about which clinical measures of peri-implant health are of diagnostic value continues because of the complexity of the disease process and lack of validated measures of peri-implant health. Crevicular fluid analysis of various inflammatory mediators has been investigated as a means of providing objective criteria of tissue health. In this clinical report, the crevicular fluid levels of interleukin-1 beta (IL-1 beta), an inflammatory cytokine, were used to provide an objective measure of the peri-implant health and the effectiveness of treatment for a patient with two failing implants. The measurement of IL-1 beta may be an important supplement to clinical findings in establishing a diagnosis of peri-implantitis.

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.

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.

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.

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.

Incidence of various classes of removable partial dentures.

The purpose of a classification for removable partial dentures (RPDs) is to simplify identification and enhance its teaching. A classification also allows a longitudinal comparison of various classes of RPDs to determine whether the teaching of RPD design is consistent with the relative frequencies of RPD use. This study surveyed the types of removable partial dentures being fabricated in a regional dental laboratory and compared these findings with data from previous studies. Results indicate that mandibular RPDs are more common than maxillary RPDs and the class I mandibular RPD is the most common type of RPD for either dental arch. A palatal strap was the most frequently used maxillary major connector and a lingual bar was used three times more often than a lingual plate in the mandibular arch. Cast circumferential clasps were used twice as often as RPI clasp designs. The percentage of Kennedy class I RPDs was 40%, class II 33%, class III 18%, and class IV 9%. Comparisons with a previous study indicate the percentage of Kennedy class II has increased, whereas class I, class III and class IV RPDs have not changed significantly. Findings of the study indicate that the frequency of use of the various types of RPDs have changed in the past 30 years.

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)

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.

Purification of PDGF-AB and PDGF-BB from human platelet extracts and identification of all three PDGF dimers in human platelets.

We have developed a panel of monoclonal antibodies to platelet-derived growth factor (PDGF) which have variable specificities for the three dimeric forms of the molecule (AA, AB, and BB). We have used these antibodies to detect and immunoaffinity purify the individual dimers from human platelet rich plasma. Extracts of outdated platelet preparations were initially chromatographed over CM-Sepharose and then passed over the Sepharose-coupled monoclonal antibodies in series in selectively isolate the three dimeric forms of PDGF. The PDGF eluted from the affinity columns was subsequently further purified by reversed-phase HPLC. From 300 units of outdated platelet preparations, we purified 58 micrograms of PDGF-BB and 140 micrograms of PDGF-AB. Using the monoclonal antibodies to develop PDGF dimer-specific ELISAs, it was observed that all three PDGF dimer forms are present in fresh human platelet extracts and that the ratios of the three dimer forms vary depending upon the extraction conditions used. The identification of all three PDGF dimer forms in human platelets point to the need to view PDGF isolated from human platelets by conventional techniques as a mixture of all three forms and not solely as PDGF-AB.