Fourier-transform infrared study on effects of ageing, oestrogen level and altered dietary loading on rat mandibular condylar cartilage

OBJECTIVE

Mandibular condylar cartilage (MCC) of the rat was examined with the Fourier-transform infrared (FITR) spectroscopic imaging to study the effects of ageing, oestrogen level and altered dietary loading on the structure of MCC.

MATERIALS AND METHODS

The Sprague-Dawley rats (n = 96) aged 5 and 14 months were divided into 12 subgroups according to age, oestrogen status (ovariectomized [OVX], non-ovariectomized [non-OVX)]) and diet (hard, normal, soft). Specimens of the MCC were examined with FTIR spectroscopic imaging to quantify the distribution of collagens and proteoglycans. MCC was divided sagittally into three segments: anterior, most superior and posterior. From each segment, the collagen and proteoglycan contents at different depths of cartilage were statistically compared between the groups using an N-way analysis of variance (ANOVA).

RESULTS

The amount of collagen content was significantly associated with old age in the deep layer of the anterior segment and in the middle layer of the posterior segment of MCC. In the deep layer of the most superior segment, the collagen content also increased with ageing. The amount of proteoglycan content increased significantly when dietary loading increased, and the oestrogen level decreased in the deep layer of the most superior segment of MCC.

CONCLUSION

Ageing, oestrogen level and altered dietary loading have a significant effect on the location and content of collagens and proteoglycans of rat MCC. Ageing significantly increased the amount of collagen content in the superior and posterior segments, being highest in the older soft-diet rats. Decreased oestrogen levels and increased dietary loading increased the amount of proteoglycan content.

Thermographic findings related to facial pain - a survey of 40 subjects

OBJECTIVE

The purpose of this study was to assess how thermography findings relate painful symptoms and signs of temporomandibular disorders (TMD).

METHODS

Thermography, combined with chewing of paraffin wax, was performed on 40 subjects. The results were analyzed according to gender and pain-related TMD symptoms and clinical signs.

RESULTS

The overall temperatures after chewing were higher in TMD patients than in controls. For females, the most significant findings were the thermal increase between the relaxed state and subjects' state after chewing in temporal and temporomandibular joint (TMJ) regions. For males, all calculated parameters demonstrated a poor ability to discriminate TMD from controls.

CONCLUSION

Thermography could be a potential tool in diagnostics of female TMD patients. The results suggest that the thermal information assessed in specific facial areas could help to discriminate TMD patients from non-TMD patients and could be used to quantify the pain associated with TMD.

Association of climacterium with temporomandibular disorders at the age of 46 years – a cross-sectional study

OBJECTIVE

Hormonal factors have been suggested to contribute to female dominance among subjects with temporomandibular disorders (TMD). Aim of the study was to examine the association of climacteric status with TMD amongst female participants in the Northern Finland Birth Cohort (NFBC) 1966 at 46 years of age.

MATERIAL AND METHODS

Among female subjects in NFBC1966, climacteric status was determined based on menstrual anamnesis and measurement of blood follicle-stimulating hormone (FSH) levels. Women with FSH > 25 IU/L and amenorrhoea > 4 months were defined as climacteric (case group, n = 71); women not diagnosed as climacteric were defined as preclimacteric (control group, n = 656). Differences between cases and controls were evaluated on self-reported TMD pain, clinical TMD signs and TMD diagnoses using modified Diagnostic Criteria for TMD (DC/TMD) protocol. Crosstabulation and logistic regression models were used to analyse differences between cases and controls.

RESULTS

Compared to preclimacteric women, climacteric women had significantly more often pain on palpation in temporomandibular joints (TMJs) (OR = 2.64, 95% CI 1.12-6.21, p= .026) and more crepitus in TMJs (OR = 2.92, 95% CI 1.13-7.56, p= .027). Degenerative joint disease diagnoses were more common in climacteric than preclimacteric women (OR = 2.27, 95% CI 1.05-4.91, p= .037). Differences were statistically significant after adjusting for confounding factors (body mass index (BMI), smoking, parity). No statistically significant differences in self-reported TMD pain were noted between groups.

CONCLUSION

Among females at the age of 46 years, climacterium seems associated with TMD by increasing pain on palpation in TMJs, subjective symptoms, and clinical signs indicating degenerative changes in TMJs when using DC/TMD.

Association of temporomandibular disorders with pain sensitivity: A cohort study

BACKGROUND

Pain related to temporomandibular disorders (TMD) can be linked with multiple site pain (MSP), and may associate with increased pain sensitivity, more frequently among women than men. The aim of the study was to examine the associations of pressure pain threshold (PPT) and tolerance (PPTo) with TMD and associated MSP in the Northern Finland Birth Cohort 1966 (NFBC1966) study.

METHODS

Altogether 1961 NFBC1966 subjects attended clinical medical and dental examination at the Institute of Dentistry, University of Oulu in 2012-2013. Clinical examinations were carried out using a modified Diagnostic Criteria for TMD protocol (DC/TMD). MSP was defined based on questions regarding body pain sites. Additionally, PPT and PPTo were assessed using algometer measurements. Mann-Whitney U-test and Tobit regression models were used to analyse associations between TMD sub-diagnoses, MSP, PPT and PPTo, stratified by sex. Further models were adjusted with anxiety and depressive symptoms, which were assessed using Hopkins Symptom Checklist-25 (HSCL-25) and two-way interaction terms.

RESULTS

Among females, lower PPT and PPTo were associated with myalgia and arthralgia. Among males, lower PPT and PPTo were associated with MSP-linked TMD. Tobit regression analysis showed significantly lower PPT and PPTo values in the myalgia and arthralgia subgroups among female TMD subjects. Among females, disc displacement with reduction had an inverse association with PPT and PPTo. Among males, lower PPTo was associated with degenerative joint disease and MSP-linked TMD.

CONCLUSIONS

The pain regulatory mechanisms behind TMD act differently between the genders as local TMD among females and MSP-linked TMD among males were associated with pain sensitivity.

SIGNIFICANCE

The study shows that there are differences in the associations of painful TMD with pressure pain tolerance, pressure pain sensitivity and MSP between male and female subjects.

Association of self-reported bruxism with temporomandibular disorders - Northern Finland Birth Cohort (NFBC) 1966 study

Objective: To investigate the prevalence of self-reported bruxism and its association with temporomandibular disorders (TMD). The hypothesis of the study was that self-reported bruxism is associated with TMD.Methods: The data were gathered from 1962 subjects who participated in a field study in 2012-2013, including a questionnaire concerning bruxism and TMD symptoms as well as clinical sub-diagnoses of TMD using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Statistical method was chi-square test. Bonferroni correction was made, and a p-value of <0.003 was considered as significant.Results: The prevalence of self-reported bruxism was 39.6%: 34.0% in men and 44.5% in women. Those who reported sleep bruxism (SB) or awake bruxism (AB) had significantly more pain-related TMD symptoms and signs compared to those not reporting bruxism.Conclusion: The prevalence of self-reported bruxism is high among middle-aged adults and is associated with TMD pain-related symptoms and signs, as well as TMD diagnoses.

Occlusal characteristics in facial pain cases and controls - 12-year follow-up of the Northern Finland Birth Cohort (NFBC) 1966

Objective: The purpose of this study was to investigate the occlusal characteristics in Finnish adults at 12-year follow-up based on the Northern Finland Birth Cohort 1966 (NFBC1966) subjects.Methods: The occlusal analyses were performed at ages 34 and 46 years of facial pain cases (n = 52) and controls (n = 49) by two different methods.Results: At 12-year follow-up, a significant decrease in upper anterior segment peer assessment rating (PAR) score was found in the controls, indicating improvement in teeth alignment. In facial pain cases, left lateral occlusal relationship and midline asymmetry were significantly decreased. Occlusal asymmetry and overjet were significantly increased. In controls, the left canine showed a more normal occlusal relationship, cuspid asymmetry was changed, and midline asymmetry was significantly decreased.Conclusion: During a 2-year period, occlusal asymmetry and overjet increased significantly in facial pain cases, while occlusal relationship showed more normal characteristics in controls.

The effect of nanodiamonds on candida albicans adhesion and surface characteristics of PMMA denture base material - an in vitro study

Candida albicans is the main causative pathogen of denture stomatitis, which affects many complete denture patients. Objective: To evaluate the effect of different concentrations of nanodiamonds (NDs) added to polymethyl methacrylate (PMMA) denture base material on Candida albicans adhesion as well as on surface roughness and contact angle. Methodology: Acrylic resin specimens sized 10×10×3 mm³ were prepared and divided into four groups (n=30) according to ND concentration (0%, 0.5%, 1%, 1.5% by wt). Surface roughness was measured with a profilometer, and the contact angle with a goniometer. The effect of NDs on Candida albicans adhesion was evaluated using two methods: 1) slide count and 2) direct culture test. Analysis of variance (ANOVA) and Tukey's post hoc test were used in the statistical analyses. Results: Addition of NDs decreased the Candida albicans count significantly more than in the control group (p<0.05), with a lowest of 1% NDs. Addition of NDs also significantly decreased the surface roughness (p<0.05), but the contact angle remained the same. Incorporation of NDs into the PMMA denture base material effectively reduced Candida albicans adhesion and decreased surface roughness. Conclusion: PMMA/NDs composites could be valuable in the prevention of denture stomatitis, which is considered one of the most common clinical problems among removable denture wearers.

Influence of tooth loss on mandibular morphology: A cone-beam computed tomography study

Background

Tooth loss adversely affects patients’ health and psychosocial wellbeing. In addition, it changes mandibular morphology. Objective: To evaluate the effect of tooth loss, age, and gender on mandibular morphology.

Material and Methods

Cone-beam computed tomographic (CBCT) scans of 101 patients were examined to measure the gonial angle (GA), ramus height (RH) and condylar height (CH). Patients’ age, gender, and dental status were recorded. Repeated measures analysis of variance (ANOVA) was used to assess the impact of gender, age, and tooth loss on the GA, RH and CH. The mean measurements of the GA, RH and CH were compared between dentate/edentulous patients after splitting by gender.

Results

The GA was larger in edentulous patients compared to dentate ones, in females than in males, and in older than in younger. RH on the right side was significantly longer than on the left side (P< 0.0001), and also longer in males and younger patients. CH was shorter in younger than in older patients and in dentate than in edentulous patients.

Conclusions

Tooth loss is associated with changes in mandibular morphology and its prevention would avoid these irreversible changes.

Key words:Tooth loss, mandibular morphology, Cone-Beam computed tomography, gender, age.

Association of risk factors with temporomandibular disorders in the Northern Finland Birth Cohort 1966

OBJECTIVE

To investigate the association between risk factors and pain-related symptoms and clinical signs of temporomandibular disorders (TMD) in Northern Finland Birth Cohort (NFBC) 1966.

MATERIAL AND METHODS

A total of 1962 subjects (1050 women, 912 men) attended the follow-up study. The questionnaires included the subjects' background information concerning living conditions and general health, socioeconomic factors, and dental health. The clinical examination was performed using the modified protocol of Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) presented at the International Association for Dental Research (IADR) Conference in 2010. Cross-tabulation, a chi-square test and Fisher's exact test were used to analyze differences between groups.

RESULTS

Female gender showed statistically significant association with symptoms and signs of TMD, while marital status, living conditions, and socioeconomic group showed no association. A strong association was found between self-reported health condition as well as general health problems [i.e. depression, migraine, fibromyalgia (FM), gastrointestinal diseases] and TMD pain-related symptoms and pain on palpation in the masticatory muscles and TMJs.

CONCLUSION

In conclusion, general health problems and female gender had a strong association with pain-related symptoms and clinical signs of TMD. These findings are important to take into account when diagnosing and treating TMD patients. Conversely to earlier presented results, no statistically significant association was shown here between marital status, living conditions or socioeconomic group and pain-related symptoms and clinical signs of TMD.

Flexural and Surface Properties of PMMA Denture Base Material Modified with Thymoquinone as an Antifungal Agent

PURPOSE

To evaluate the effect of addition of different concentrations of thymoquinone (TQ) on the flexural strength, elastic modulus, surface roughness, and hardness of PMMA denture base material.

MATERIALS AND METHODS

A total of 160 rectangular specimens were prepared from heat-polymerized acrylic resin, with dimensions of 65 × 10 × 2.5 mm³ for flexural strength testing and 10 × 20 × 3 mm³ for surface property testing. The specimens were divided into eight groups of 20 specimens: one control group without addition of TQ and seven test groups prepared by adding TQ to acrylic powder in concentrations of 0.5, 1, 1.5, 2, 2.5, 3, and 5 wt%. The polymer was added to the monomer before being mixed, packed, and processed using the conventional water bath method. A universal testing machine was used to measure flexural strength and elastic modulus. A profilometer and a Vickers hardness tester were used to measure surface roughness and hardness, respectively. One-way ANOVA and the Tukey-Kramer multiple-comparison test were used for statistical analysis, with statistical significance at p ≤ 0.05.

RESULTS

Addition of TQ to PMMA denture base material significantly decreased flexural strength and elastic modulus at high concentrations (p < 0.01), while no significant differences were observed at low concentrations (0.5%, 1% TQ) in comparison with the control group. At high TQ concentrations, surface roughness increased while hardness decreased (p < 0.0001), and no significant differences were observed at low concentrations (0.5%, 1% TQ) in comparison with the control group. The most favorable addition values were 0.5% and 1% TQ in all TQ groups.

CONCLUSIONS

Addition of TQ did not affect the flexural and surface properties of PMMA denture base material at low concentrations (0.5%, 1% TQ) and could be incorporated into PMMA denture base material as an antifungal agent.

Changes in Type I and Type II Collagen Expression in Rat Mandibular Condylar Cartilage Associated with Aging and Dietary Loading

AIMS

To evaluate the usefulness of diet board feeding as a model for temporomandibular joint (TMJ) research, characterize dietary loading-related morphometric changes in the mandibular condylar cartilage of aging rats, and investigate changes in type I and type II collagen expression in different age, sex, and diet groups.

METHODS

Material was collected from a study that examined the effects of 1-year and 2-year diet board feeding on rats. In diet board feeding, rats must gnaw wood to reach their food, leading to a higher masticatory workload. The material analyzed was comprised of 150 TMJ samples from 75 Hsd:Sprague Dawley rats grouped according to feeding method (diet board [experimental group] or ad libitum [control group]), sex, and experiment length (1 or 2 years). The rats were sacrificed at the age of 15 or 26 months (15-M rats or 26-M rats). From the TMJ samples, 5-μm-thick sections were cut parallel to the sagittal plane of the mandibular condyle. Histomorphometric analysis of the thickness of the condylar cartilage and the number of cartilage cells was performed after toluidine blue staining. Immunohistochemical staining included type I and type II collagen antigens. Differences in the thickness of the cellular layer and the number of cells in the condylar cartilage were analyzed by means of a repeated-measures analysis of variance (ANOVA) model, and differences in the type of collagen with a one-way random-effects ANOVA model.

RESULTS

Condylar cartilage was significantly thicker in the 15-M diet board-fed rats than in the 15-M control rats and in the 26-M rats than in the 15-M rats. The number of cells was larger in the 26-M female rats than in the 26-M male rats. Type I collagen expression was significantly higher in the 15-M diet board-fed female rats than in the 15-M controls. Type II collagen showed increased expression in older rats compared to younger rats.

CONCLUSION

Condylar cartilage is sensitive to the interplay between loading, aging, and sex of middle-aged and older rats. High loading of condylar cartilage increased the thickness of cartilage in younger rats.

The role of occlusion in temporomandibular disorders (TMD) in the Northern Finland Birth Cohort (NFBC) 1966

OBJECTIVE

To investigate the role of occlusion in temporomandibular disorders (TMDs) in the Northern Finland Birth Cohort 1966 (NFBC 1966).

METHODS

Subjects (n = 1962) participated in clinical medical and dental examinations. The association between TMD signs and diagnoses with occlusal disturbances, i.e. malocclusions and occlusal interferences, was examined. Pearson's chi-square test, as expressed by odds ratios (OR) and 95% confidence intervals (CI) and logistic regression models, were used in the analysis.

RESULTS

A statistically significant association was found between myalgia and lateral scissor bite and also between arthralgia and lateral deviation in the retruded contact position and intercuspal contact position (RCP-ICP) slide. Pain in the masticatory muscles was associated with negative overjet and the amount of RCP-ICP slide.

DISCUSSION

Occlusal factors showed a statistically significant association with TMD. The TMD signs were associated with unstable occlusion, especially the amount and lateral deviation in RCP-ICP slide, as well as negative overjet.

Prevalence of Temporomandibular Disorders in the Northern Finland Birth Cohort 1966

AIMS

To investigate the prevalence of temporomandibular disorders (TMD) in the 46-year-old cohort subjects from the Northern Finland Birth Cohort 1966 (NFBC 1966).

METHODS

Altogether, 1,962 subjects (1,050 women, 912 men) participated in a clinical medical and dental examination and responded to questionnaires in 2012 to 2013. The stomatognathic examination was performed according to a modified protocol of the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Pearson's chi-square test and Fisher's exact test were used to analyze the signs of TMD between genders, and logistic regression models were used to analyze the relationship between self-reported pain associated with TMD and modified DC/TMD protocol (P < .05).

RESULTS

Of the subjects available for analyses, 18.5% responded positively to the self-reported screening question for pain related to TMD. The most common signs of TMD were clicking in the temporomandibular joint (TMJ) (26.2%) and palpation pain in the masticatory muscles (11.2%). Women had signs of TMD more often than men (P < .05). The most common diagnosis was disc displacement with reduction (7.0%). Myalgia, arthralgia, disc displacement with reduction, and degenerative joint disease diagnoses were statistically significantly more common in women than in men (P < .05). The prevalence of TMD signs among the cohort subjects was 34.2%.

CONCLUSION

The most common sign of TMD was clicking in the TMJ and the most common TMD diagnosis was disc displacement with reduction. The prevalence of TMD signs among the examined cohort subjects was 34.2%. TMD was diagnosed in women more often than in men. The results are comparable with other corresponding population-based studies in adults.

Inter-arch digital model vs. manual cast measurements: Accuracy and reliability

OBJECTIVES

The purpose of this study was to evaluate the accuracy and reliability of inter-arch measurements using digital dental models and conventional dental casts.

METHODS

Thirty sets of dental casts with permanent dentition were examined. Manual measurements were done with a digital caliper directly on the dental casts, and digital measurements were made on 3D models by two independent examiners. Intra-class correlation coefficients (ICC), a paired sample t-test or Wilcoxon signed-rank test, and Bland-Altman plots were used to evaluate intra- and inter-examiner error and to determine the accuracy and reliability of the measurements.

RESULTS

The ICC values were generally good for manual and excellent for digital measurements. The Bland-Altman plots of all the measurements showed good agreement between the manual and digital methods and excellent inter-examiner agreement using the digital method.

CONCLUSION

Inter-arch occlusal measurements on digital models are accurate and reliable and are superior to manual measurements.

PMMA denture base material enhancement: a review of fiber, filler, and nanofiller addition

This paper reviews acrylic denture base resin enhancement during the past few decades. Specific attention is given to the effect of fiber, filler, and nanofiller addition on poly(methyl methacrylate) (PMMA) properties. The review is based on scientific reviews, papers, and abstracts, as well as studies concerning the effect of additives, fibers, fillers, and reinforcement materials on PMMA, published between 1974 and 2016. Many studies have reported improvement of PMMA denture base material with the addition of fillers, fibers, nanofiller, and hybrid reinforcement. However, most of the studies were limited to in vitro investigations without bioactivity and clinical implications. Considering the findings of the review, there is no ideal denture base material, but the properties of PMMA could be improved with some modifications, especially with silanized nanoparticle addition and a hybrid reinforcement system.

The 1st Baltic Osseointegration Academy and Lithuanian University of Health Sciences Consensus Conference 2016. Summary and Consensus Statements: Group I - Peri-Implantitis Aetiology, Risk Factors and Pathogenesis

Introduction

The task of Group 1 was to review and update the existing data concerning aetiology, risk factors and pathogenesis of peri-implantitis. Previous history of periodontitis, poor oral hygiene, smoking and presence of general diseases have been considered among the aetiological risk factors for the onset of peri-implant pathologies, while late dental implant failures are commonly associated with peri-implantitis and/or with the application of incorrect biomechanical forces. Special interest was paid to the bone cells dynamics as part of the pathogenesis of peri-implantitis.

Material and Methods

The main areas indagated by this group were as follows: influence of smoking, history of periodontitis and general diseases on peri-implantitis development, bio-mechanics of implant loading and its influence on peri-implant bone and cellular dynamics related to the pathogenesis of peri-implantitis. The systematic reviews and/or meta-analyses were registered in PROSPERO, an international prospective register of systematic reviews: http://www.crd.york.ac.uk/PROSPERO/. The literature in the corresponding areas of interest was screened and reported following the PRISMA (Preferred Reporting Item for Systematic Review and Meta-Analysis) Statement: http://www.prisma-statement.org/. Method of preparation of the systematic reviews, based on comprehensive search strategies, was discussed and standardized. The summary of the materials and methods employed by the authors in preparing the systematic reviews and/or meta-analyses is presented in Preface chapter.

Results

The results and conclusions of the review process are presented in the respective papers. One systematic review with meta-analysis, three systematic reviews and one theoretical analysis were performed. The group′s general commentaries, consensus statements, clinical recommendations and implications for research are presented in this article.

The Prosthetic Influence and Biomechanics on Peri-Implant Strain: a Systematic Literature Review of Finite Element Studies

Objectives

To systematically review risks of mechanical impact on peri-implant strain and prosthetic influence on stability across finite element studies.

Material and Methods

An online literature search was performed on MEDLINE and EMBASE databases published between 2011 and 2016. Following keywords tiered screening and selection of the title, abstract and full-text were performed. Studies of finite element analysis (FEA) were considered for inclusion that were written in English and revealed stress concentrations or strain at peri-implant bone level.

Results

There were included 20 FEA studies in total. Data were organized according to the following topics: bone layers, type of bone, osseointegration level, bone level, design of implant, diameter and length of implant, implant-abutment connection, type of supra-construction, loading axis, measurement units. The stress or strain at implant-bone contact was measured over all studies and numerical values estimated. Risks of overloading were accented as non-axial loading, misfits, cantilevers and the stability of peri-implant bone was related with the usage of platform switch connection of abutment.

Conclusions

Peri-implant area could be affected by non-axial loading, cantilever prosthetic elements, crown/implant ratio, type of implant-abutment connection, misfits, properties of restoration materials and antagonistic tooth. The heterogeneity of finite element analysis studies limits systematization of data. Results of these studies are comparable with other findings of in vitro, in vivo, prospective and retrospective studies.

Veneered zirconia crowns as abutment teeth for partial removable dental prostheses: a clinical 4-year retrospective study

STATEMENT OF PROBLEM

The mechanical properties of zirconia suggest that it might serve as a material for abutment crowns for partial removable dental prostheses (RDPs). Only limited clinical evidence is available for the use of ceramics as abutment crowns.

PURPOSE

The purpose of this retrospective clinical study was to evaluate the outcome of veneered zirconia single crowns in abutment teeth for RPDs in participants treated by predoctoral students.

MATERIAL AND METHODS

Thirty-seven veneered zirconia single crowns in 17 participants (9 men and 8 women; mean age 62.5 years) were prepared as abutment teeth for a clasp-retained RDP with a metal framework: 22 crowns with an occlusal rest seat and 15 crowns with both an occlusal rest seat and retentive clasps. The mean follow-up time was 4.2 years (2.9 to 5.4 years). In a clinical examination, the anatomic form of the crown, marginal fidelity (the border between the crown and the tooth was felt with an explorer), wear of the ceramic surface in the rest seat, and fracture of the veneering porcelain were examined and assessed as good, acceptable, or unacceptable. The retention and stability of the RDPs were recorded as good, moderate, or poor.

RESULTS

The complications found were fracture of the veneering porcelain (11%) and fracture of the occlusal rest seat (3%). Wear of porcelain at the occlusal contact point was found in 24% of the zirconia single crowns. Wear of the ceramic surfaces of the rest seats for the RDPs was not found. The retention was good in all RDPs. The stability was good in 73% and moderate in 23% of the RDPs.

CONCLUSIONS

Veneered zirconia single crowns are suitable in abutment teeth for RDPs with a metal framework. Fracture in the veneering porcelain remains a problem with veneered zirconia, although the zirconia surface in the rest seats for RDPs showed no wear.

Outcome of zirconia single crowns made by predoctoral dental students: a clinical retrospective study after 2 to 6 years of clinical service

STATEMENT OF PROBLEM

Zirconia has established its role as a reliable ceramic material for fixed prostheses.

PURPOSE

The purpose of this retrospective study was to evaluate the outcome of zirconia single crowns made by predoctoral students after 2 to 6 years of clinical service.

MATERIAL AND METHODS

A cohort of 88 patients treated with zirconia single crowns (mean 3 crowns per patient, range 1 to 12 crowns) from 2007 to 2010 by predoctoral dental students was identified. The patients were invited to attend a clinical examination.

RESULTS

Sixty-six participants (75%) took part in the clinical follow-up (30 women and 36 men; mean age 60.4 years, range 19 to 81 years). Altogether, 190 teeth with single crowns were examined, and the mean follow-up time was 3.88 years (1.85 to 6.04 years). The most common complications were chipping of veneering porcelain (4%) and loss of cementation (4%). The success rate of the zirconia single crowns after 2 to 6 years was 80% and the survival rate 89%.

CONCLUSIONS

Zirconia crowns can be successfully used in predoctoral dental education. The success rate of zirconia single crowns after 2 to 6 years was 80% and the survival rate was 89%, in accordance with previous studies.

Early complications and short-term failures of zirconia single crowns and partial fixed dental prostheses

STATEMENT OF PROBLEM

Ceramic single crowns fabricated from newer materials, especially zirconia, have shown relatively high survival rates. However, early reversible complications may increase the risk of an irreversible failure later.

PURPOSE

The purpose of the study was to evaluate the early complications and short-term failures of zirconia single crowns and partial fixed dental prostheses (FDPs) made by predoctoral dental students.

MATERIAL AND METHODS

Data were collected from the patient records. Altogether, 264 zirconia single crowns and 120 FDPs (342 abutments and 190 pontics) were fabricated for 173 patients between 2007 and 2010. Early complications were recorded during the prosthetic treatment phase, and short-term failures were recorded during the first year in use.

RESULTS

The most frequent early complications were localized gingival irritation (1.9% of single crowns and 2.5% of FDP) and postoperative tooth sensitivity (0.4% of single crowns and 3.3% of FDPs). Pulp exposure during preparation was recorded in 3 abutment teeth of the FDPs. The most frequent short-term failure was chipping of the veneering porcelain (0.8% for single crowns, 0.8% for FDPs). One crown lost cementation because of poor retention (0.4%), and 2 FDPs failed because of framework fractures (1.7%).

CONCLUSIONS

The most frequent early complications were localized gingival irritation and postoperative tooth sensitivity, and the most frequent short-term failure was chipping of the veneering porcelain.

Occlusal Characteristics in Subjects with Facial Pain Compared to a Pain-Free Control Group

Facial pain has been considered a common symptom of temporomandibular disorders (TMD) with a multifactorial etiology. There is controversy regarding the role of occlusion in the background of facial pain and TMD. The aim of the study was to compare the occlusal relationships with two definite measurements in subjects with and without facial pain, in a population-based sample of young adults. The study is part of the Northern Finland 1966 Birth Cohort Project. A subsample of the cohort was formed based on a questionnaire and consisted of 104 subjects, including 52 subjects with facial pain and 52 non-pain controls. Analyses of the dental occlusion of the subjects were performed in gypsum casts by following two methods: 1. the Peer assessment rating (PAR), according to Richmond, et al. (Method 1), and 2. the bilateral canine relationship and the dental midline measurement by the method presented by Pirttiniemi, et al. (Method 2). Method 2 showed higher sensitivity in detecting sagittal occlusal discrepancies than Method 1. Assessment of the intermaxillary relationships in terms of the canine relation showed the lower canine to be more mesially located in the facial pain group, compared to the controls, measured by Method 2. It can be concluded that differences in occlusal sagittal relationships, especially mesial canine relation, seem to correlate with facial pain symptoms at population level.

Outcome of treatment of implant-retained overdenture in patients with extreme mandibular bone resorption treated with bone grafts using a modified tent pole technique

PURPOSE

To evaluate the outcome (prosthetic maintenance, survival of implants, patient satisfaction, and quality of life) of prosthetic treatment using an implant-retained overdenture and a modified tent pole procedure for severe mandibular resorption.

MATERIAL AND METHODS

Seventeen edentulous patients (mean age, 68 yr; range, 54 to 77 yr) with severely resorbed mandibles were treated with autogenous bone grafts using a modified tent pole technique and implant overdentures. A bar was used to splint the implants and the final prostheses with implant connection were completed approximately 7 months after surgery. The mean follow-up time was 5 years (1.5 to 7.4 yr). Patients filled out the Oral Health Impact Profile-14 questionnaire concerning their oral health-related quality of life, and then panoramic radiographs were taken during clinical examination.

RESULTS

The stability of the overdenture was good in 58.8% of cases and retention was good in 64.7%. The most usual prosthetic complication was loosening of the attachment component, which occurred in 7 cases (41.2%). The amount of plaque and bleeding was more remarkable on the lingual surface of the implants and less remarkable on the buccal surface. Pocket depth around the implants seemed to correspond to intraoral implantation. The radiographs depicted excellent grafted bone survival. The patients' oral health-related quality of life was found to be good after treatment.

CONCLUSIONS

Implant placement with bone grafting using a modified tent pole technique enables the achievement of a good prosthetic solution and the rehabilitation of occlusion, thereby improving the functionality of the prostheses and quality of life.

Quality of Life of Patients Treated With Implant-Supported Mandibular Overdentures Evaluated With the Oral Health Impact Profile (OHIP-14): a Survey of 58 Patients

Objectives

The purpose of this study was to evaluate the oral health-related quality of life of patients treated with implant-supported mandibular overdentures and to compare the attachment systems used.

Material and Methods

Altogether 112 patients treated with implant-supported mandibular overdentures in 1985 - 2004 were invited to the follow-up; 58 of them attended and replied to the Oral Health Impact Profile (OHIP-14) -questionnaire. There were 48 overdentures with a bar connection and 10 with a ball connection, the total number of implants installed and still in use was 197. The mean follow-up time was 13.7 years. The associations between the OHIP-14 variables and the patient's age, gender as well as the number of implants supporting the overdenture and the type of attachment used were assessed.

Results

The results showed that patients with implant-supported mandibular overdentures were satisfied with their oral health-related quality of life (OHRQoL). Older patients were more satisfied than younger ones in both genders. Neither the implant connection type nor the number of supporting implants seemed to have a significant influence on the OHRQoL.

Conclusions

Especially older patients with mandibular implant-supported overdentures were satisfied with their oral health-related quality of life. Attachment type or the number of supporting implants did not have a significant influence on the oral health-related quality of life.

Effect of mandibular advancement device therapy on the signs and symptoms of temporomandibular disorders

Objectives

Mandibular advancement device therapy is effectively used in the treatment of obstructive sleep apnea, but also several side effects in the masticatory system have been reported. The aim of this study was to evaluate the subjective symptoms and clinical signs of temporomandibular disorders connected to mandibular advancement device therapy.

Material and Methods

The material consisted of 15 patients (9 men and 6 women, mean age 51.1 years, range 21 to 70 years) diagnosed with obstructive sleep apnea (OSA). Subjective symptoms and clinical temporomandibular disorders (TMD) signs were recorded at the beginning of the treatment (baseline) and at 1-month, 3-month, 6-month and 24-month follow-ups. The degree of TMD was assessed using the anamnestic (Ai) and the clinical dysfunction index (Di) of Helkimo. For assessing the effect of TMD the patients were divided in discontinuing and continuing groups.

Results

According to Ai and Di, the severity of TMD remained unchanged during the follow-up in most of the patients. Temporomandibular joint (TMJ) crepitation was found more frequently in discontinuing patients at all follow-ups. The difference was statistically significant (P < 0.05) at the six-month follow-up. Masticatory muscle pain during palpation was a frequent clinical sign at the baseline and during the follow-up period but the difference between discontinuing and continuing patients was not significant.

Conclusions

It seems that signs and symptoms of temporomandibular disorders do not necessarily increase during long-term mandibular advancement device therapy. However, it seems that patients with clinically assessed temporomandibular joint crepitation may discontinue their mandibular advancement device therapy due to temporomandibular disorders.

The comparison of outcomes of surgically treated bilateral temporomandibular joint disorder in different groups: a retrospective study

Objectives: The main purpose of this study was to determine the prognosis and outcomes of the patients with bilateral temporomandibular disorder which underwent bilateral temporomandibular joint surgery in a consecutive number of patients in a retrospective study. Study Design: Sixty five patients with 130 bilateral TMJ were included the study with the selection from consecutive 256 TMJ patients who were treated with open surgery who do not respond to conservative treatment. 65 patients were divided in to 3 main groups according to the clinical diagnosis of bilateral TMJ site. In the first group comprised 29 patients with 48 TMJ, the clinical diagnosis was bilaterally presence of anterior disc displacement with reduction (ADDR). In the second group comprised 19 patients with 26 TMJ, bilateral presence of TMD consisted of anterior disc displacement without reduction (ADDNR) on both site. In the third group comprised 27 patients with 46 TMJ, bilaterally presence of TMD consist of ADDR on one site and ADDNR on another site. The patients in three different groups were operated either high condylectomy alone or high condylectomy with additional surgical procedures. Results: In the evaluation of pain relief, clicking, crepitation, headache, marked improvement was determined in all groups, but it was statistically insignificant in the comparison of 3 groups. Slight increase in maximal mouth opening was determined in the mean values of the 3 groups and also in the comparison of 3 groups it was not statistically significant. Conclusions: These similar succesfull outcomes of bilateral TMD with the respect of TMJ surgical procedures were obtained in 3 main groups although different diagnosis on the patients’ groups waspresent.

Key words:Temporomandibular joint, prognosis, retrospective studies.

Efficacy of stabilisation splint treatment on temporomandibular disorders

The evidence supporting the use of stabilisation splints in the treatment of temporomandibular disorders (TMD) is scarce and a need for well-controlled studies exists. The aim of this randomised, controlled trial study was to assess the efficacy of stabilisation splint treatment on TMD. The sample consisted of 80 consecutive referred patients who were randomly assigned to the splint group (n = 39) and the control group (n = 41). Subjects in the splint group were treated with a stabilisation splint, whereas subjects in the control group did not receive any treatment except counselling and instructions for masticatory muscle exercises which were given also to the subjects in the splint group. Outcomes were visual analogue scale (VAS) on facial pain intensity and clinical findings for TMD which were measured at baseline and after 1-month follow-up. The differences in change between the groups were analysed using regression models. Facial pain decreased and most of the clinical TMD findings resolved in both of the groups. The differences in changes in VAS or clinical TMD findings between the groups were not statistically significant. The findings of this study did not show that stabilisation splint treatment in combination with counselling and masticatory muscle exercises has additional benefit in relieving facial pain and increasing the mobility of the mandible than counselling and masticatory muscle exercises alone in a short time-interval.

Effect of estrogen and dietary loading on condylar cartilage

AIMS

To study the effect of estrogen deficiency and altered temporomandibular joint loading on the histomorphology of condylar cartilage and on the expression of types II and X collagen and matrix metalloproteinase-3 (MMP-3).

METHODS

Thirty-six female rats were divided into four groups: ovariectomized rats on a normal diet, nonovariectomized control rats on a normal diet, ovariectomized rats on a soft diet, and nonovariectomized control rats on a soft diet. Ovariectomy was performed at the age of 60 days. Repeated-measures ANOVA was used to analyze the data.

RESULTS

The condylar cartilage in the ovariectomized normal diet group showed a significantly higher number of cells than in the nonovariectomized control rats (P < .001). The proportional amount of MMP-3 expression was significantly higher in the ovariectomized rats than in the nonovariectomized control rats in both diet groups (P < .001). The area covered by types II and X collagen was significantly higher in the experimental groups than in the control groups (P < .01).

CONCLUSION

Condylar cartilage is sensitive to both estrogen level and dietary loading.

An 18-year retrospective analysis of treatment outcomes with metal-ceramic fixed partial dentures

PURPOSE

The aim of this clinical retrospective study was to evaluate the survival and success rates of metal-ceramic fixed partial dentures (FPDs) made by dental students over an 18-year interval. Biologic and technical complications as well as patient satisfaction were recorded.

MATERIALS AND METHODS

Fifty-seven patients with 82 FPDs from an original group of 104 patients with 128 FPDs attended an approximate clinical 18-year follow-up examination. The mean follow-up period was 17.7 years (range: 17.1 to 21.3 years).

RESULTS

Nine FPDs were lost because of extraction of an abutment tooth, and 1 FPD was removed for esthetic reasons. Technical problems recorded included loss of cementation, fractures in the metal framework, and need for placement of a dowel in an abutment tooth. The most common clinical findings were gingival bleeding on probing and appearance of supragingival crown margins. The survival rate of the FPDs was 78%, and the established success rate was 71%.

CONCLUSION

This 18-year follow-up of metal-ceramic FPDs in just over half of the originally treated patient group was associated with good patient satisfaction and few biologic and technical complications. Int J Prosthodont 2011;24:314-319.

Effect of estrogen and altered diet hardness on the expression of estrogen receptor alpha and matrix metalloproteinase-8 in rat condylar cartilage

AIMS

To examine the effect of decreased estrogen level and altered diet hardness on condylar cartilage morphology of the rat temporomandibular joint (TMJ) and on the expression of condylar cartilage estrogen receptor alpha (ERa) and matrix metalloproteinase-8 (MMP-8).

METHODS

A total of 36 female rats was divided into four groups: ovariectomized rats fed a normal diet, non-ovariectomized controls fed a normal diet, ovariectomized rats fed a soft diet, and non-ovariectomized controls fed a soft diet. Ovariectomy was performed at the age of 60 days. Seven days after the operation, the rats were sacrificed. Repeated measures ANOVA and Duncan's multiple comparison tests were used for statistical analysis.

RESULTS

The ovariectomized rats had thicker cartilage layers than the controls, both in the normal diet and soft diet groups. The thinnest cartilage layers were found in the control rats fed with the soft diet. The thickness of the chondroblastic layer was significantly higher (P < .001) in the normal-diet rats than in the soft-diet rats in both ovariectomized and non-ovariectomized groups. The thickness of the proliferative layer was significantly higher (P < .001) in the ovariectomized soft-diet rats than in the soft-diet control rats. The proportional amount of ERa was statistically significantly higher (P < .001) in the condylar cartilage of the ovariectomized rats than in the non-ovariectomized control rats both in the normal- and soft-diet groups. The proportional amount of ERa was statistically significantly higher (P < .001) in the ovariectomized normal-diet rats than in the ovariectomized soft-diet rats. The proportional number of MMP-8-positive cells was statistically significantly higher (P < .001) in the condylar cartilage of ovariectomized rats fed the soft diet than in non-ovariectomized control rats fed the soft diet. Control rats fed with the normal diet had a higher proportional amount of MMP-8 positive cells than control rats fed with the soft diet (P < .05).

CONCLUSION

The rat TMJ condylar cartilage is sensitive to changes in estrogen levels and altered diet hardness.

Effect of diet hardness on mandibular condylar cartilage metabolism

AIMS

To study the effect of diet hardness on condylar cartilage thickness, extracellular matrix composition, and expression of matrix metalloproteinase (MMP) -3, -8 and tissue inhibitor of metalloproteinase-1 (TIMP-1), by using immunohistochemical and morphometric methods.

METHODS

Seventy-two female Sprague Dawley rats were exposed to different dietary hardness, from soft to hard. MMP -3, -8, and TIMP-1 expression, cartilage thickness, cell count, and expression of type II collagen were studied. Analysis of variance among treatments was carried out followed by Bonferroni's comparisons test.

RESULTS

The ratio of MMP-3 and TIMP-1 immunopositive cartilage cells were similar in all age groups, whereas the number of MMP-8 positive cells decreased with age. A change of diet from soft to hard caused a significant decrease in the number of MMP-3 and MMP-8 and an increase in TIMP-1 positive cells. Cartilage thickness and area of type II collagen-positive staining were significantly affected by diet hardness.

CONCLUSION

The results show that a soft diet during growth increases collagenolytic activity and may increase the vulnerability of condylar cartilage.

Missing posterior teeth and risk of temporomandibular disorders

There is disagreement about the association between missing posterior teeth and the presence of temporomandibular disorders (TMD). Here, the purpose was to investigate whether the number of missing posterior teeth, their distribution, age, and gender are associated with TMD. Seven hundred and forty-one individuals, aged 21-60 years, with missing posterior teeth, 386 with and 355 without TMD, were included. Four variables-gender, age, the number of missing posterior teeth, and the number of dental quadrants with missing posterior teeth-were analyzed with a logistic regression model. All four variables-gender (OR = 1.59, men = 1, women = 2), age (OR = 0.98), the number of missing posterior teeth (OR = 0.51), and the number of dental quadrants with missing posterior teeth (OR = 7.71)-were entered into the logistic model (P < 0.01). The results indicate that individuals who lose posterior teeth, with fewer missing posterior teeth but in more quadrants, have a higher prevalence of TMD, especially young women.

Twenty-year follow-up of metal-ceramic single crowns: a retrospective study

PURPOSE

The aim of this clinical retrospective study was to evaluate the survival and success of single metal-ceramic crowns after 20 years. The biologic and technical complications as well as patient satisfaction were recorded.

MATERIALS AND METHODS

Fifty patients treated with 100 single metal-ceramic crowns attended the clinical 20-year follow-up examination. The mean follow-up time was 18.8 years (17.5 to 20.5 years).

RESULTS

Twenty-one teeth with single crowns were extracted because of root fractures or esthetic or periodontal reasons. Ninety-seven percent of the subjects had no complaints about the esthetics of the crowns. The most common clinical findings were supragingival crown margins caused by gingival recessions, gingival bleeding on probing, and occlusal wear in opposing teeth. The success of the crowns after 20 years was 75%, and the survival was 78%.

CONCLUSION

In the 20-year follow-up of single metal-ceramic crowns, there were few biologic and technical complications, and patients were satisfied with the crowns. Crown removal was in most cases the result of root fractures in single crowns with endodontic posts.

Effect of storage time on the accuracy of casts made from different irreversible hydrocolloids

AIM

Several new irreversible hydrocolloid formulations have recently become available with claims of an improved dimensional stability by the manufacturers. The aim of this study was to evaluate the accuracy of casts made from alginate impression materials poured immediately and after specific storage periods.

METHODS AND MATERIALS

Five alginates were tested: CA 37 (Cavex); Jeltrate (Dentsply Caulk); Jeltrate Plus (Dentsply Latin America); Hydrogum 5 (Zhermack); and Alginoplast (Heraeus Kulzer). A master model was mounted on a special device and used to obtain the impressions. These impressions were stored at 23 degrees C and 100% relative humidity, then poured with gypsum immediately, and again after 24, 72 and 120 hours. The casts were measured and the data were analyzed by one way analysis of variance (ANOVA) and Tukey test at p<0.05.

RESULTS

The dimensional stability of the alginate impressions was both material and time dependent (p<0.05). After 24 hours of storage, only Alginoplast and Hydrogum 5 comply with the master model (p>0.05). After 72 and 120 hours, only Hydrogum 5 was dimensionally stable (p>0.05).

CONCLUSION

The dimensional stability of the alginate impressions is influenced by the selected material and the storage time.

CLINICAL SIGNIFICANCE

Alginate impressions should generally be poured immediately. However, some new types of alginate may have the pouring delayed.

Dietary loading and aggrecanase-1/TIMP-3 expression in rat mandibular condylar cartilage

AIMS

To examine the expression of aggrecanase-1 and a tissue inhibitor of metalloproteinases (TIMP-3) in the condylar cartilage of young rats and to determine their relationship during altered dietary loading at different time points after weaning.

METHODS

One hundred Sprague-Dawley rats were randomly assigned to 1 of 2 groups: the soft-diet group, which served as the control group (n=50), or the hard-diet group, which served as the experimental group (n=50). Ten soft- and 10 hard-diet rats were killed at 6 hours, 12 hours, 24 hours, 48 hours, and 9 days after weaning (i.e., after initiation of diet change for hard-diet rats). The right-side temporomandibular joints (TMJs) were prepared for immunohistochemical staining. The cartilage from the left-side mandibular condyles of all 10 animals in each group was combined for Western blot analysis.

RESULTS

Immunohistochemical analysis revealed strong staining for aggrecanase-1 localized mainly in the chondrocytes of proliferative and upper hypertrophic cartilage zones at all time points in both groups. The immunohistological expression of aggrecanase-1 was significantly higher in the hard-diet group at 12 and 24 hours than in the soft-diet group. Strong staining for TIMP-3 was mainly localized in the chondrocytes of proliferative and upper hypertrophic zones at all time points in both groups. The expression of TIMP-3 in the hard-diet group was at a significantly lower level compared to the soft-diet group at 6 hours. Western blot analysis also showed time-related differences in aggrecanase-1 and TIMP-3, but there was no significant difference between the 2 groups.

CONCLUSION

The temporary change in aggrecanase-1 and TIMP-3 expression reflects the complex interaction of these enzymes in the physiologic range and cartilage response to altered dietary loading.

MMP-3 and -8 expression is found in the condylar surface of temporomandibular joints with internal derangement

BACKGROUND

Internal derangement is one of the most common disorder of the temporomandibular joint (TMJ). The aim of this study was to investigate the associations of matrix metalloproteinase (MMP)-3 and -8 expression in articular condylar surface with different stages of TMJ internal derangement according to Wilkes (Minn Med, 1978; 61: 645-52) and osteoarthrosis (OA) according to Dijkgraaf et al. (J Oral Maxillofac Surg, 1995; 53: 1182-92).

METHODS

The study was based on 54 condylar specimens obtained during TMJ surgery. Immunohistochemistry using antibodies specific to MMP-3 and -8, represented in cartilage destruction, was carried out.

RESULTS

In all tissue specimens, MMP-3 expression was intense in the surface layer but showed less intensive staining in the deeper layers. Some MMP-8 expression was also seen. The severity of TMJ internal derangement, however, did not seem to have a statistically significant correlation (P<0.05) with the expression of these enzymes.

CONCLUSION

The study confirms that distinct expression of MMP-3 and -8 is found in the condylar surface of TMJs with internal derangement.

Renewal of the clinical-phase dental curriculum to promote better learning at the University of Oulu

The degree awarded to a dentist in Finland is Licentiate of Dentistry, and it takes 5 years to achieve it. The old curriculum at the Institute of Dentistry, University of Oulu, Finland, was based on the departmental division, and there was minimal integration between the disciplines. According to student feedback, the old curriculum was overloaded. The amount of contact teaching was up to 40 h per week throughout the academic year. Based on the workload regulation model launched at the University of Oulu, the actual workload of students for three clinical years was found to exceed the confirmed curriculum (40 study weeks per year for 3 years, representing 180 European Credit Transfer System (ECTS) credits) by 68 ECTS credits (representing 45.3 study weeks). Because of the heavy workload, students did not have time actively to deepen their scientific reasoning. To tackle this problem and to maintain the high academic standards, the Institute of Dentistry, University of Oulu, Finland, decided to change the dental curriculum. The properties and qualities of the competent dentist were listed and arranged in the corners of an octagonal to provide the model of the key dental competencies. Based on this, a thorough core analysis of the courses was carried out by the departments. The new curriculum consists of 10 broader integrative entities, so called dental teaching strands (DTSs), wherein the teaching given by the different departments has been combined. The effort was successful. We managed to remove overlap in the substance of the courses to reduce the students' actual workload by about 45 ECTS credits (representing 30 study weeks and 1200 h of studying) and to promote better scientific reasoning and learning results. The authentic learning and comprehensive patient care comprise the core of the clinical practice.

Matrix metalloproteinases in mild and severe temporomandibular joint internal derangement synovial fluid

OBJECTIVES

The first objective of this study was to verify the presence of and identify the molecular forms of matrix metalloproteinases (MMPs), including collagenases (MMP-1, MMP-8, and MMP-13) and gelatinases (MMP-2 and MMP-9), in the synovial fluid (SF) of mild and severe temporomandibular joint internal derangement (TMJ-ID). Another objective was to evaluate whether the SF MMPs are potential diagnostic markers that reflect the stage of intra-articular inflammation in the TMJ.

STUDY DESIGN

The subjects were 44 patients with mild (n = 16) or severe (n = 28) TMJ-ID; they were classified on the basis of subjective symptoms, clinical and radiographic findings, and surgical observations. The patients were surgically treated, and SF samples were collected immediately before the operation. The collagenase activity of SF samples was analyzed by means of a type I collagen degradation assay. The levels and molecular forms of the SF MMPs as well as the tissue inhibitors of MMPs (TIMP-1 and TIMP-2) were analyzed with Western immunoblotting and gelatin zymography.

RESULTS

The SF of both the mild and the severe TMJ-ID patients exhibited free collagenase activity and activity capable of further degrading the (3/4)(alphaA) fragments. Ninety-two-kilodalton proMMP-9 and its 121-kD complex form, as well as 72-kD proMMP-2 were significantly increased in the mild TMJ-ID group (P <.05 in all cases). Both 70- to 80-kD neutrophil type and 45- to 55-kD mesenchymal cell-type MMP-8 (corresponding to the latent and active forms) were observed in mild and severe TMJ-ID SF, but they predominated in mild TMJ-ID. Both MMP-1 and MMP-13 were observed in both groups, and in mild TMJ-ID SF the low-molecular weight forms of MMP-1 indicated activation of the enzyme.

CONCLUSIONS

The degradation of type I collagen in the TMJ is evidently due to the collective action of many collagenolytic MMPs present in the SF of patients with mild and severe TMJ-ID. The elevated levels of MMP-2, MMP-9, and MMP-8 in the SF of patients with mild TMJ-ID eventually reflect the active phase of TMJ destruction. These observations may have considerable diagnostic and therapeutic significance in the management of TMJ disorders.

Clinical and computed tomographic findings in costochondral grafts replacing the mandibular condyle

PURPOSE

The aim of this study was to evaluate by computed tomography (CT) and clinically the structure and function of costochondral grafts (CCG) used to replace the mandibular condyles.

MATERIAL AND METHODS

CT and clinical examination were performed in 11 patients with CCGs (9 female, 2 male; mean age at surgery, 25 years; range, 9 to 44 years) approximately 4.5 years after surgery (range, 5 months to 10.5 years). One mandibular condyle was replaced in six patients and two in five patients.

RESULTS

Facial asymmetry was observed in two cases and palpation tenderness of the TMJs or clicking and crepitation were found in 10 of 16 operated TMJs. In three cases coronal CT scans showed the graft to be situated laterally in the mandibular fossa, and lateral overgrowth of the graft was seen in three cases. In two cases, coronal CT slices showed that a new fossa had developed. In most cases translatory movement of the graft was minimal. The graft was either partially or almost completely mineralized, especially in cases with longer follow-up.

CONCLUSIONS

Most of the patients in this study seemed to have benefitted from replacement of the deformed mandibular condyle with a CCG as estimated by improved range of mandibular movements and decreased symptoms. There were some problems related to unpredictable growth and location of the graft, as well as restricted movement of the replaced condyle. In the future, care should be taken to ensure proper postoperative functional therapy and to examine the role of cartilage thickness on future growth in young patients.

Influence of antineoplastic therapy on function of the masticatory system, tooth development, and cariogenic status: a case report

Antineoplastic therapy causes developmental disturbances in the dental enamel and root if children are treated during tooth development. Increased caries activity has also been reported. The effect of anticancer therapy on the function of the masticatory system (i.e. jaws, dentition, masticatory muscles) is not well known. A case report of a 9-year-old girl with right auricular rhabdomyosarcoma is presented. She received irradiation of 50 Gy to the right auricular area and chemotherapy. A year and a half after cessation of cancer therapy, she was disease free and the clinical stomatognathic examination combined with electromyogram (EMG) registration of the masseter and temporal muscles and magnetic resonance imaging (MRI) examination of the temporomandibular joints (TMJ) revealed a strongly restricted mouth opening capacity, painful right TMJ, and flattened head of the right mandibular condyle. Muscle atrophy in the right masseter muscle was clearly visible but EMG activities of the masseter and temporal muscles, however, were higher on the right than on the left. More severe developmental defects, and worse gingival and cariological health were observed on the right side than on the left side. She developed 12 carious lesions and all the lesions were on the right maxilla or mandible or on anterior teeth. The left side was not affected. Intensive prophylactic dental care after cancer treatment is important in order to prevent caries and gingival inflammation. Stomatognathic treatment (i.e. management of occlusal and dysfunctional problems) may improve the mouth opening capacity and relieve pain.

Relationships of bicondylar position to occlusal asymmetry

Mandibular asymmetry in the frontal plane is a common finding, the left side of the mandible being more often the longer one, and a progressive trend for a more post-normal occlusion on the right side as compared to the left has been reported recently. The aim of the present work was to measure bicondylar asymmetry using computed tomography (CT) and to determine whether this is correlated with certain occlusal characteristics in young adults with no gross malformations. The subjects were 49 adults aged from 15 to 33 years, mean 24.2 years (SD 3.79 years). All of them had a complete or nearly complete dentition. The left condyle was found to be more anteriorly located on average and to be positioned closer to the skull base midline than the right condyle. The joint space between the condyle and the posterior wall of the glenoid fossa was larger on the left side. The asymmetry in bicondylar position correlated with the occlusal asymmetry. Subjects with lateral malocclusions showed a more asymmetric position of the condyles with respect to the posterior wall of the glenoid fossa. This may be of clinical importance and stresses the necessity for early correction of such malocclusions, as complete adaptation does not seem to occur in these cases.

Internal derangement of the temporomandibular joint: a histochemical study

The purpose of this study was to correlate histologic findings in temporomandibular joint (TMJ) condyles and discs with their macroscopic appearance at surgery. The 24 patients with internal derangement of the joint included 20 women and 4 men (mean age, 37 years; range, 18 to 61 years). The tissue lesions varied in degree from mild soft-tissue fraying and bone remodeling to extensive resorption and new cartilage and bone formation with high phosphatase enzyme activities, and even to loss of articular soft tissue and breakdown of cortical bone. Reactions may arise in the hard tissues before they occur in the articular surface layers.