The role of pathophysiological explanations in clinical case representations of dental students and experts

INTRODUCTION

Teaching of biomedical knowledge lays the foundations for the understanding and treatment of diseases. However, the representation of pathophysiological explanations in the management of clinical cases differs for various levels of medical expertise and different theories have been proposed to explain this phenomenon. The present study investigated for the first time how biomedical knowledge is used in clinical reasoning in dental medicine.

MATERIALS AND METHODS

In an experimental study 20 experts in the field of Periodontology and 61 students of different levels of training produced written pathophysiological explanations after having studied three different clinical cases. By comparing the written protocols to a visualised expert-made 'canonical' explanation the concepts used in the pathophysiological explanation were counted and classified as well as the links between concepts.

RESULTS

The statistical analysis by MANOVA showed significant differences between third- and fourth-year students, students of intermediate expertise level (fifth-year) and experts for various parameters qualifying concepts or links of the written pathophysiological explanations. The participants of intermediate expertise level produced a high rate of concepts and links; however, characteristic findings for knowledge encapsulation in the different levels of expertise were not evident. The analysis showed that the design of the clinical cases and of the canonical explanations significantly influenced the outcomes.

CONCLUSION

The present study demonstrated the pathophysiological representations of clinical cases in dental students and experts to be different from other medical disciplines. It could be assumed that this observation is based on different contents for teaching of practical skills and diagnostic procedures in dental compared with medical education.

[The influence of age upon circadian rhythm of human pulp sensibility]

OBJECTIVE

To explore the influence of age on the circadian rhythm of pulp sensibility, guide the diagnosis and treatment of dental and endodontic diseases.

METHODS

The first lower molars of young, middle-aged, and aged volunteers were inspected for the threshold of pulp sensitivity. Each inspection was implemented every 4 hours earlier, totally 7 times during 24 hours. All values of pulp sensibility threshold from each volunteer were analyzed by Halberg methods for cosinor-rhythmometry. The chronobiology characteristics of pulp sensibility were compared among young, middle-aged, and aged.

RESULTS

The pulp sensibility threshold values of the young, middle-aged, and aged indicated to have the circadian rhythm alternation in period of 24 hours, with fitting well to a cosine curve. The trend of rhythm curve was similar to all three age groups. The acrophase and bathyphase appeared at 0:00 and 12:00 separately. The values and amplitudes of pulp threshold sensibility showed to be: young>aged> middle-aged.

CONCLUSION

The circadian rhythm of pulp sensibility changes according with age. The pulp sensibility threshold value is lower in aged people than in the young, and the lowest sensibility threshold is in middle-aged people. Besides, the extent of rhythm fluctuation is the least in middle-aged people.

Ameloblastin fusion protein enhances pulpal healing and dentin formation in porcine teeth

Ameloblastin (Ambn, also named "amelin" or "sheathlin") is a protein participating in enamel formation and mesenchymal-ectodermal interaction during early dentin formation in developing teeth. Experiments have demonstrated an association between Ambn expression and healing of acute pulp wounds. The purpose of this study was to investigate if local application of recombinant fusion Ambn (rAmbn) could influence reparative dentin formation in pulpotomized teeth. In this randomized, double-blinded study, pulpotomy was performed in 28 lower central incisors in 17 adult miniature pigs. Following the surgical procedure, the exposed pulp tissue was covered either with rAmbn or with calcium hydroxide. After 2, 4, or 8 weeks, the teeth were extracted and examined by histomorphometry and immunohistochemistry using antibodies against porcine ameloblastin, collagen type I, and dentin sialoprotein (DSP). In rAmbn-treated teeth, a substantial amount of newly formed reparative dentin was observed at the application site, completely bridging the pulpal wound. Dentin formation was also observed in calcium hydroxide-treated teeth; however, the amount of reparative dentin was significantly smaller (P < 0.001) than after rAmbn treatment. Immunohistochemistry confirmed that the new hard tissue formed was similar to dentin. This is the first time a direct link between ameloblastin and dentin formation has been made in vivo. The results suggest potential for rAmbn as a biologically active pulp-dressing agent for enhanced pulpal wound healing and reparative dentin formation after pulpotomy procedures.

Chitosan monomer promotes tissue regeneration on dental pulp wounds

The present study was undertaken to evaluate the applicability of chitosan monomer (D-glucosamine hydrochloride) as a pulp capping medicament. Both in vitro and in vivo experiments were carried out to study the cell metabolism and wound healing mechanisms following the application of chitomonosaccharide. After 3 days of osteoblast culture, alkaline phosphatase (ALP) activity significantly increased in the chitosan group. Reverse transcription polymerase chain reaction analysis revealed that chitosan induced an increase in the expression of ALP mRNA after 3 days and bone morphogenetic protein-2 mRNA after 7 days of osteoblast incubation. Inflammatory cytokine, interleukin (IL)-8, synthesis in fibroblasts was strongly suppressed in the medium supplemented with chitosan monomer. Histopathological effects were evaluated in rat experiments. After 1 day, inflammatory cell infiltrations were observed to be weak when compared with the application of chitosan polymer. After 3 days, a remarkable proliferation of fibroblasts was seen near the applied chitosan monomer. The inflammatory cell infiltration had almost completely disappeared. After 5 days, the fibroblastic proliferation progressed, and some odontoblastic cells appeared at the periphery of the proliferated fibroblasts. These findings indicate that the present study is the first report that chitosan monomer acts as a biocompatibility stable medicament even at the initial stage of wound healing in comparison with the application of chitosan polymer.

Vitality of the dentin-pulp complex in health and disease: growth factors as key mediators

The vitality of the dentin-pulp complex, both during tissue homeostasis and after injury, is dependent on pulp cell activity and the signalling processes, which regulate the behavior of these cells. Research, particularly over the last ten to fifteen years, has led to a better understanding of the molecular control of cellular behavior. Growth factors play a pivotal role in signalling the events of tissue formation and repair in the dentin-pulp complex. Sequestration of growth factors in the dentin matrix during tissue formation provides a pool of these molecules, which may be released during injury and contribute to signalling of reparative events. Therapeutic intervention with recombinant growth factors also provides possibilities for control of cell activity during repair. Harnessing both endogenous and exogenous sources of growth factors can provide exciting opportunities for novel biological approaches to dental tissue repair and the blueprint for tissue engineering of the tooth. These approaches offer significant potential for improved clinical management of dental disease and maintenance of tooth vitality.

Apoptosis: an introduction for the endodontist

Apoptosis plays an important role in many aspects of endodontics, yet there is a paucity of information in this regard in the endodontic literature. Apoptosis is a single deletion of scattered cells by fragmentation into membrane-bound particles that are phagocytosed by other cells. It is a key process in the embryological development of the tooth, periodontal ligament and supporting oral tissue in the progression of oral disease, bone resorption, immunological response and inflammation, and in wound healing and certain pharmacological effects. The understanding of the ability of clinical materials to induce or inhibit apoptosis and the investigation of apoptosis as it relates to the pathogenesis of pulpal and periradicular pathology may eventually lead to new treatment approaches for the endodontist. The purpose of this review is to familiarize the clinical endodontist with current knowledge on apoptosis as it relates to the pulp and periradicular tissues.

Feline immunodeficiency virus model to study human immunodeficiency virus/acquired immune deficiency syndrome conditions

This study was designed to induce rapid progression of the feline immunodeficiency virus (FIV) infection in cats. Predictably inducing the FIV disease state in the cat would yield an excellent tool to study endodontic disease processes under immunosuppressed conditions. Eight cats were immunosuppressed with steroids before infection with FIV. Another eight cats, age- and sex-matched littermates, served as uninoculated seronegative controls. Complete blood counts were taken for 10 mo in the FIV group, and 10 wk in the control group, including lymphocyte subsets. ELISAs were used to detect FIV infection. Statistical analysis was performed with generalized estimating equation models. All cats were positive at one point in time. The FIV group had significantly lower peripheral blood CD4+ counts compared with the control group. Therefore the FIV model presented gives the desired outcome and simulates what occurs in human immunodeficiency virus infection.

Occlusal considerations in determining treatment prognosis

To function in occlusal harmony, the masticatory apparatus--composed of the teeth and its supporting structures, temporomandibular joints, and associated neuromusculoskeletal structures--must operate in an integrated and dynamic manner. Loss of integrated function, or of homeostasis in response to functional demand, may generate problems in occlusion. In health, adaptive changes occur with the teeth and periodontium in response to functional occlusal forces. With periodontal and endodontic disease, this adaptive capacity diminishes. The ability to foresee how these changes may influence dental treatment is important in the art of determining treatment prognosis.

Intraradicular space: what happens within roots of infected teeth?

The pulpo-dentine complex is normally protected from exogenous substances in the oral cavity by the overlying enamel or cementum. Dental caries, dental trauma, enamel/dentine cracks, and restorative procedures commonly breach the integrity of enamel or cementum and may allow infection of the pulpo-dentine complex to occur, possibly leading to pulp and periapical inflammatory disease. Infection of the intraradicular space is a complex and dynamic process involving interactions between host and microbial factors. An understanding of these factors has led to the development of endodontic techniques that offer predictable success.

Pulpal injury: pathology, diagnosis and periodontal reactions

Diagnosis of pulpal disease can be difficult due to the lack of diagnostic signs and symptoms available to the practitioner. An understanding of the possible underlying pathological processes, combined with an exact assessment of the pain history, and appropriate clinical tests, should aid the practitioner in determining the nature of pulpal inflammation, and differentiating it from dentine sensitivity and cracked teeth. The responses of the pulp to traumatic injury to the periodontal membrane (PDM) require special consideration, particularly with respect to the assessment of pulp vitality, and the determination of cases requiring pulp extirpation in order to avoid inflammatory root resorption. Although the pulp is relatively isolated from the rest of the dentoalveolar complex by a dentine/cementum barrier, it is important to remember that it can communicate with the PDM through apical and lateral foramina, and areas of damaged cementum. Hence, it is a priority to both preserve the integrity of the cemental layer in cases of traumatic injury and periodontal disease, and to prevent the inflammation and resorption associated with periapical lesions by accurate diagnosis of irreversible pulpitis and pulp necrosis, followed by appropriate endodontic debridement procedures.

Pulp survival and hard tissue formation subsequent to dental trauma. A clinical and histological study of uncomplicated crown fractures and luxation injuries

Traumatic injuries in children and adolescents are a common problem, and the prevalence of such injuries has increased over the last 10-20 years. The purpose of the present investigation was to evaluate long-term results following uncomplicated crown fractures and luxations involving subsequent pulp canal obliteration. A total of 198 patients with 488 injured permanent teeth were available for clinical examination (15 year follow-up), of which 102 also answered a questionnaire and were interviewed before oral examination. Further, 82 permanent incisors presenting with pulp canal obliteration (PCO) were followed for a period of 7 to 22 yr. (mean 16 yr.). The histological evaluation of luxation injuries was performed on 123 primary teeth from 98 patients. In the experimental study (crown fractures), 64 monkey permanent maxillary and mandibular central incisors and canines were subjected to different treatment alternatives at the time of fracture. The findings in the follow-up study showed very little pulpal response to crown fracture and subsequent restorative procedures as long as there was no concomitant periodontal injury. Approximately every fourth resin composite restoration was rated unacceptable at the clinical examination. The interview showed that half of the individuals were dissatisfied with the color and/or anatomic form of the composite restoration. PCO was found in all luxation categories, and according to the survival curve, the 20-year pulp survival rate diagnosed with X-ray was 84%. Although the risk for pulp necrosis (PN) increased with time, routine endodontic intervention of teeth with ongoing PCO of the root canal did not seem justified. The histological study showed that changes in dentin were represented by occlusion of the dentinal tubules and deposition of tertiary dentin. The tertiary dentin were classified as either dentin-like, bone-like or fibrotic. In the experimental study, few changes were observed in the pulp 3 months after crown fractures, irrespective of treatment alternative.

The endodontic-periodontal continuum revisited: new insights into etiology, diagnosis and treatment

For many decades, investigators have conducted studies of the interrelationship between endodontics and periodontics. This review article examines previously held concepts regarding the endodontic-periodontal continuum in light of new research and explores promising advances in understanding etiology and in diagnosis and treatment.

Endodontic pathogens in periodontal disease augmentation

Periapical pathology indicating endodontic infection, when present in periodontitis-affected teeth, has recently been shown to be correlated to marginal periodontal breakdown. This has been associated with patency of dentinal tubules in the tooth cervix, an area normally devoid of cementum following periodontal therapy. These studies are, however hampered by that only circumstantial evidence such as presence of periapical destruction have been applied as criteria of endodontic infection. The aim of the present investigation was to assess the effects of endodontic pathogens on marginal periodontal wound healing on root surfaces devoid of cementum but surrounded by healthy periodontal membrane. Significant differences between infected and non-infected teeth were found with respect to pathological pocket and connective tissue: The experimental defects were covered by approximately 20% more pocket epithelium in infected teeth while defects in non-infected teeth showed approximately 10% more connective tissue coverage. It was concluded, that an intra-canal infection of endodontic pathogens stimulates epithelial downgrowth along denuded dentin surfaces with marginal communication. Extrapolated to the clinical situation, endodontic infections in periodontitis-prone patients may augment periodontitis propagation.

The flare-up index: a quantitative method to describe the phenomenon

Acute exacerbation of symptoms during the inter-appointment time interval of endodontic treatment is a well-known complication. The phenomenon is termed "flare-up" by most researchers and clinicians, although the exact definition of it differs from one author to another, making it difficult to compare the results of the studies. The suggested flare-up index may be the way to build a common language that will enable the dental community to measure and study more of this phenomenon.

Periodontal healing in teeth with periapical lesions. A clinical retrospective study

The purpose of the present investigation was to compare clinical periodontal healing in periodontally involved teeth with and without pulpal pathosis. The investigation was conducted as a retrospective study on a consecutive referral population. The periapical conditions in endodontically involved single-rooted teeth from a selected patient sample were evaluated and correlated with their periodontal healing pattern. Multiple regression analysis of the registered variables showed that initial mean pocket depth and time elapsed after treatment significantly influenced change in pocket-depth. Non-surgical treatment of periodontal pockets exceeding 2.5 mm in teeth with horizontal marginal defects, over the observation period, showed significantly reduced mean pocket depth reduction in teeth with periapical pathology compared to teeth without periapical pathology. It was, furthermore, evident that proximal restorations, abutments for fixed bridges and root fillings with and without dowels did not significantly influence pocket depth reduction in the present material. It was concluded, based on the present results, that a root-canal infection, evident as a periapical radiolucency, if left untreated may in the long term perspective result in retarded or impaired periodontal healing following periodontal therapy and, consequently, should be given appropriate consideration when coordinating endodontic therapy and periodontal treatment.

Relationship between periapical and periodontal status. A clinical retrospective study

The purpose of the present investigation was to explore possible relationships between clinical periodontal status in periodontally involved teeth with and without endodontic infection. The investigation was conducted as a retrospective study on a consecutive referral population. The periapical conditions in endodontically-involved single-rooted teeth from a selected patient sample were evaluated and correlated to their periodontal status. There was a significant correlation between periapical pathology and vertical bony destructions. An intra-individual comparison between pocket depth in teeth with and without periapical pathology showed that periapical pathology was significantly correlated to an increased pocket depth in the absence of a vertical bony destruction. It was concluded that an endodontic infection, evident as a periapical radiolucency, promotes periodontal pocket-formation on an instrumented marginal root surface and, consequently, should be regarded as a risk factor in periodontitis progression and be given appropriate consideration in periodontal treatment planning.

Endodontic infection and calcium hydroxide-treatment. Effects on periodontal healing in mature and immature replanted monkey teeth

Large experimental defects with marginal communication, and small isolated experimental defects were created on the root surfaces of extracted monkey lateral incisors with either open or closed apices. The pulp tissue was either infected or removed, and calcium hydroxide placed in the root canal. The teeth were then replanted and the healing pattern evaluated histomorphometrically after 20 weeks. From the results, it was concluded that (1) an intrapulpal infection promotes marginal epithelial down-growth on a denuded dentin surface irrespective of tooth developmental stage, and that (2) the periodontal healing potential after calcium hydroxide-treatment appears to be higher in teeth with open apices compared with teeth with closed apices, where ankylosis was promoted as opposed to teeth with open apices where significantly more reparative cementum was found.

[Endo-periodontal relations. Microbiological and clinical aspects]

Periodontics and endodontics share common objectives and common field of interest. Both disciplines treat lesions of the periodontal tissues; in their marginal aspect the first, in the periapical aspect the latter. These relationships have not been well understood for a long time. This article is a review of the literature on the topic aimed at clarifying the anatomic, microbiological, pathogenetic relationship in the periodontal and endodontic lesions.

[Furcation lesions in deciduous teeth]

The area of furcation of temporary molars constitutes a zone of exchanges and rearrangements relating to the evolution of the sub-adjacent permanent tooth. It is subjected to the eruption of the latter and to the physiological modifications of the temporary tooth. Moreover, this area is the site of above-mentioned inflammatory or infections conditions, maintained or aggravated by anatomical factors (accessory canals, thin pulpar floor, with little calcified dentine and broad tubuli), physiological factors (multiplication of accessory canals, decrease in the floor and migration of the epithelial attachment), endodontic factors (pulpal involvement and its complications) and periodontal factors (septum syndrome). The pathology of furcation is an evolving lesion. When discovered early it can be treated by endodontic therapy, while, in a later phase, it will require the extraction of the tooth. The assessment is made on the basis of a X-Ray examination which permits the temporary tooth to be situated in its stable or labile phase, the condition of the pulpal floor to be evaluated and the stage of sub-adjacent germ mineralisation to be estimated. A periodontal arrangement, by coronal reconstitution, conditions the reliability of the endodontic therapies.

Prevalence of dental abscess in a population of children with vitamin D-resistant rickets

A population of patients with vitamin D-resistant rickets whose present ages range from 4 to 22 years was examined to determine the prevalence of dental abscess associated with that condition. For those patients affected with abscesses in the primary dentition, four associated factors were examined: 1) the age at onset of the first abscess; 2) the tooth/teeth most commonly involved; 3) whether or not other teeth were involved over time; and 4) the order of occurrence of multiple abscesses. Six of 24 patients (25%) were affected with abscesses of the primary dentition; all had multiple abscesses. Males were more commonly involved than females. The sequence of involvement generally followed the pattern of tooth eruption; however, dental treatment in susceptible individuals shortened the time between eruption and abscess. Medication dose and measurement of radiographs were not reliable predictors of the occurrence of abscesses in this population; however, the results indicate that one abscess is a predictor of future abscesses for that patient.

Perspectives, controversies and directives on pulpal-periodontal relationships

While established clinical, radiographic and histologic criteria exist to explain the intimate relationship of the pulp and periodontium during pathological states, the recognition, diagnosis and treatment of this perplexing interplay remains a challenge for the practitioner. This dynamic interrelationship is investigated with a focus on simplicity and succinctness to enhance diagnostic probabilities, clarify treatment modalities and provide realistic prognoses in management.

[Pathogenesis of periapical inflammatory processes]

The Authors, after a short description of the anatomy of the root canal, deal with the aetiological factors of the periapical pathology, acute and chronic. They examine the pathogenetic mechanisms of acute flogistic process of the periapical tissue and consider the principal mediators involved in the tissue lesion.

Why teeth associated with inflammatory periapical lesions can have a vital response

It is a general conception that teeth having an inflammatory periapical lesion are nonvital and the associated periapical lesions are not innervated. However, structurally intact and functioning nerve fibers have been shown to be present in the periapical lesion and/or the associated pulp. Therefore, when a patient presents with an endodontically involved tooth associated with a periapical lesion and experiences pain during canal instrumentation, the need for local anesthesia is apparent.

[Development of plasma extravasation in the dental pulp]

Recent studies suggest an active participation of postcapillary venules in inflammatory plasma extravasation. Intravital microscopic studies of rats' incisors show that Evans blue allows the demonstration of plasma extravasation in the dental pulp. This process takes place in the postcapillary venules, as can be seen from the staining of the interstice. Rather than depending on hydrodynamic pressure mechanisms, inflammatory plasma extravasation seems to be subjected to a direct regulation of vascular permeability.

Isolated extramedullary relapse of acute myelogenous leukemia in a tooth

We report a case of isolated extramedullary relapse of acute myelogenous leukemia in a tooth following bone marrow transplantation. The patient was a 4-yr-old child who developed gingival swelling and bleeding while in bone marrow remission. Crush artifact prevented definitive diagnosis of leukemic relapse in a biopsy of the gingival soft tissue, but decalcification of the tooth showed an unequivocal leukemic infiltrate in the dental pulp. Decalcification and sectioning of extracted teeth are recommended when equivocal findings are present in the gingival soft tissue or when there is a history of lymphoreticular malignancy.

Influence of pulpal treatments on cell and tissue reactions in the marginal periodontium

The effects of pulpal infection and intrapulpal application of calcium hydroxide and antibiotics were evaluated with special reference to cell and tissue reactions in the marginal hard/soft tissue interface in monkeys. Results indicate the pulpal conditions and endodontic dressings influence marginal healing and repair, provided an endodontic-periodontic pathway such as patent dentin tubules is present. These results suggest that permanent endodontic treatment, with an inert material, should be performed before the protective cementum layer is removed. Pulpally aggravated periodontal lesions should therefore not be overlooked in periodontal diagnosis and treatment.

Classification and diagnosis of pulpal pathoses

The purpose of this article has been to review some concepts regarding the histophysiology and histopathology of the pulpodentinal complex and the "language of classification." Although there may not be agreement on the "language" presented here, there can be no disagreement that from a clinical perspective, knowledge and appreciation of the ideas presented can be helpful in determining pathologic presence. In reaching the ultimate clinical decision, the following questions must be answered: Are we dealing with a pulpal disease that is potentially reversible? If treatment is necessary do we treat the pulp or the pulp canal?

A radiographic survey of apical root resorption in pulpless permanent teeth

A radiographic statistical study was performed in order to determine the presence and type of external resorption found in pulpless permanent teeth. Of 1,372 roots evaluated, 49.6% showed resorption. The degree of apical external resorption was significantly related to the presence and size of the periapical lesions in all roots. Much more resorption was found in the roots without root canal filling than in those that were filled.