Pre-medical assessment of root-canal-filled teeth with asymptomatic apical periodontitis-A multifaceted balancing act.

AIM: Prior to certain medical therapies, dental assessment and treatment of oral foci of infection are recommended. The aim of the present study was to acquire a deeper understanding of the decision-making process regarding the pre-medical management of root-canal-filled teeth with asymptomatic apical periodontitis (AAP). METHODOLOGY: Hospital-affiliated dentists in Sweden were contacted for a semi-structured, in-depth interview. The absolute inclusion criterion was that the dentists had experienced and could recount at least two authentic cases involving root-canal-filled teeth with AAP-one case having resulted in pre-medical treatment, and one having resulted in expectancy. Fourteen interviews, with fourteen informants, were conducted and included in the study. During the interviews, open-ended questions and comments encouraging the informants to elaborate and clarify their experiences were offered. The interviews were digitally recorded, transcribed verbatim and analysed using Qualitative Content Analysis with an inductive approach. RESULTS: A theme describing the latent content was identified through interpretation of the collected data: A multifaceted balancing act characterized by a sometimes-difficult risk-benefit-estimation, where an increased uncertainty entails an increased reliance on external opinions. Three main categories, comprising four sub-categories, describing the manifest content were recognized: The tipping scale, The team effort and The frame of reference. CONCLUSIONS: The current interview study found pre-medical decision-making regarding root-canal-filled teeth with AAP to be a multifactorial and contextual process marked by uncertainty and collaborative measures. Further research, resulting in the development of evidence-based treatment guidelines, is suggested necessary.

Pre-medical dental evaluation and treatment of oral infection - a survey study among hospital-affiliated dentists in Sweden.

OBJECTIVE: To examine how hospital-affiliated dentists assess risk and evaluate oral foci of infection in patients facing certain medical treatments, and whether the nature of upcoming medical treatment affects the choice of dental intervention. MATERIALS AND METHODS: A survey comprising six clinical cases (50 teeth) was sent to hospital-affiliated dentists in Sweden. A treatment option for the affected tooth/teeth in each case was selected whether the patient was facing heart valve surgery, chemotherapy, radiation therapy, intravenous bisphosphonate treatment, solid organ transplantation or was diagnosed with endocarditis. RESULTS: Consensus in choice of dental treatment was high in 62%, moderate in 32% and low in 6% of the assessments. High variability of choice of treatment was seen for eight teeth whereas the remaining 42 teeth often received the same therapy regardless of medical issue. Chemotherapy and radiotherapy were thought to entail the highest risk for oral infectious sequelae with a risk ranging from 1% to 100%. CONCLUSION: Pre-medical dental evaluations and recommended treatments are often uniform with the exception of the management of asymptomatic root canal treated teeth with persisting apical radiolucency and heavily decayed molars. In many instances, dental diagnosis has a greater impact on choice of treatment than the underlying medical issue and associated implications thereof.

Development of criteria for investigation of periapical tissue from root-filled teeth.

OBJECTIVE: To develop and assess a set of criteria to grade inflammation including relative area of inflammation in periapical lesions in endodontically treated teeth. MATERIAL AND METHODS: A set of criteria was developed, encompassing data on: Lymphocytes, denoting chronic inflammation, were graded 0 (occasional) to 4 (heavy/dense inflammation). Polymorphonuclear cells, denoting acute inflammation, were graded 0 (none) to 2 (many). The third parameter, area of inflammation, that is, the relative area of the specimen that was inflamed, was graded 0 (none) to 4 (76-100%). The criteria were tested on 199 consecutive biopsies from 180 patients (aged 31-75 years). Information about symptoms was retrieved from the referrals. Mann-Whitney's U-test was used to calculate possible differences in average values for the histopathological variables in the two groups of patients: symptomatic or asymptomatic. RESULTS: Using the criteria, varying grades of inflammation were seen in the biopsies. The majority showed few or no PMN cells. There was a correlation between symptoms and the extent of infiltration of lymphocytes and plasma cells (p = .001), PMN cells (p < .001) and the area of inflammation (p = .002): biopsies from the asymptomatic patients exhibited less pronounced and relatively smaller areas of inflammation. CONCLUSIONS: Using the criteria on a specific selection of root-filled teeth with persisting apical periodontitis, periapical inflammation was common, but varied in extent and severity. The inflammation was less pronounced and affected a relatively smaller area in asymptomatic teeth, although outliers in both directions were identified.

Crystal structure of the parasite inhibitor chagasin in complex with papain allows identification of structural requirements for broad reactivity and specificity determinants for target proteases.

A complex of chagasin, a protein inhibitor from Trypanosoma cruzi, and papain, a classic family C1 cysteine protease, has been crystallized. Kinetic studies revealed that inactivation of papain by chagasin is very fast (k(on) = 1.5 x 10(6) M(-1) x s(-1)), and results in the formation of a very tight, reversible complex (K(i) = 36 pM), with similar or better rate and equilibrium constants than those for cathepsins L and B. The high-resolution crystal structure shows an inhibitory wedge comprising three loops, which forms a number of contacts responsible for the high-affinity binding. Comparison with the structure of papain in complex with human cystatin B reveals that, despite entirely different folding, the two inhibitors utilize very similar atomic interactions, leading to essentially identical affinities for the enzyme. Comparisons of the chagasin-papain complex with high-resolution structures of chagasin in complexes with cathepsin L, cathepsin B and falcipain allowed the creation of a consensus map of the structural features that are important for efficient inhibition of papain-like enzymes. The comparisons also revealed a number of unique interactions that can be used to design enzyme-specific inhibitors. As papain exhibits high structural similarity to the catalytic domain of the T. cruzi enzyme cruzipain, the present chagasin-papain complex provides a reliable model of chagasin-cruzipain interactions. Such information, coupled with our identification of specificity-conferring interactions, should be important for the development of drugs for treatment of the devastating Chagas disease caused by this parasite.

Displacement of the occluding loop by the parasite protein, chagasin, results in efficient inhibition of human cathepsin B.

Cathepsin B is a papain-like cysteine protease showing both endo- and exopeptidase activity, the latter due to a unique occluding loop that restricts access to the active site cleft. To clarify the mode by which natural protein inhibitors manage to overcome this obstacle, we have analyzed the structure and function of cathepsin B in complexes with the Trypanosoma cruzi inhibitor, chagasin. Kinetic analysis revealed that substitution of His-110e, which anchors the loop in occluding position, results in 3-fold increased chagasin affinity (Ki for H110A cathepsin B, 0.35 nm) due to an improved association rate (kon, 5 x 10(5) m(-1)s(-1)). The structure of chagasin in complex with cathepsin B was solved in two crystal forms (1.8 and 2.67 angstroms resolution), demonstrating that the occluding loop is displaced to allow chagasin binding with its three loops, L4, L2, and L6, spanning the entire active site cleft. The occluding loop is differently displaced in the two structures, indicating a large range of movement and adoption of conformations forced by the inhibitor. The area of contact is slightly larger than in chagasin complexes with the endopeptidase, cathepsin L. However, residues important for high affinity to both enzymes are mainly found in the outer loops L4 and L6 of chagasin. The chagasin-cathepsin B complex provides a structural framework for modeling and design of inhibitors for cruzipain, the parasite cysteine protease and a virulence factor in Chagas disease.

Crystal structure of the parasite protease inhibitor chagasin in complex with a host target cysteine protease.

Chagasin is a protein produced by Trypanosoma cruzi, the parasite that causes Chagas' disease. This small protein belongs to a recently defined family of cysteine protease inhibitors. Although resembling well-known inhibitors like the cystatins in size (110 amino acid residues) and function (they all inhibit papain-like (C1 family) proteases), it has a unique amino acid sequence and structure. We have crystallized and solved the structure of chagasin in complex with the host cysteine protease, cathepsin L, at 1.75 A resolution. An inhibitory wedge composed of three loops (L2, L4, and L6) forms a number of contacts responsible for high-affinity binding (K(i), 39 pM) to the enzyme. All three loops interact with the catalytic groove, with the central loop L2 inserted directly into the catalytic center. Loops L4 and L6 embrace the enzyme molecule from both sides and exhibit distinctly different patterns of protein-protein recognition. Comparison with a 1.7 A structure of uncomplexed chagasin, also determined in this study, demonstrates that a conformational change of the first binding loop (L4) allows extended binding to the non-primed substrate pockets of the enzyme active site cleft, thereby providing a substantial part of the inhibitory surface. The mode of chagasin binding is generally similar, albeit distinctly different in detail, when compared to those displayed by cystatins and the cysteine protease inhibitory p41 fragment of the invariant chain. The chagasin-cathepsin L complex structure provides details of how the parasite protein inhibits a host enzyme of possible importance in host defense. The high level of structural and functional similarity between cathepsin L and the T. cruzi enzyme cruzipain gives clues to how the cysteine protease activity of the parasite can be targeted. This information will aid in the development of synthetic inhibitors for use as potential drugs for the treatment of Chagas disease.