The condyle-fossa relationship in temporomandibular disorders. Considerations on the pathogenetic role of the disc

AIM

The purpose of this study is to evaluate the condylar position and its variation in patients with temporomandibular joint (TMJ) disorders before and after therapy with occlusal gnathologic devices.

METHODS

Twenty-five TMJ of 25 patients with temporomandibular joint disorder were examined by linear measurement of the anterior, posterior and superior joint space between the condyle and glenoid fossa through cephalometric analysis on X-ray tomography of the TMJ and by calculating the condylar position with the Pullinger and Hollender method.

RESULTS

The average condylar position in the TMJ with DTM was posterior with a mean value of 22.2% and a range from 14.3% to 36%. The condylar position of 25 TMJs was: anterior 0(0%); centric 8(32%) and posterior 17(68%). After therapy with occlusal gnathologic devices the average condylar position was centric with a mean value of 0.6% and a range from 5.3% to 6.6%. The condylar position of 25 TMJs was: anterior 2(8%); centric 22(88%) and posterior 1 (14%).

CONCLUSIONS

The hypothesis can be advanced that joint pathology is the consequence of the alteration of the condyle position and therefore of the mandibular movement and vice versa. Therapy with occlusal devices makes it possible to modify the condylar position by increasing the condylar capability to recapture the joint disc.

Long term follow-up of patients affected by temporomandibular joint dysfunction treated with orthodontic and/or prosthetic occlusal therapy

AIM

Clinical evidences about therapeutic effectiveness of splint therapy and modern concept concerning the etiopathogenesis of temporomandibular disorders (TMD) lead to a review of the therapeutic approach accepted until the middle 90s for the solution of this derangement of the stomathognatic system. Aim of this study is to produce a long term follow-up of a sample of TMD patients, to estimate the validity and utility of the present therapeutic procedures.

METHODS

After diagnostical classification of the patients observed, they have been included in a therapeutic protocol. The outcomes obtained (46 patients at the 1st control in 1994 and 38 patients at the last control in 2001) are re-examined with an average follow-up of 10 years.

RESULTS

The results obtained showed the efficacy of the therapeutic procedures carried out (36 healed, 9 improved and 1 worsened at the 1994 check-up: on the whole, a successful result in 98% of cases; 17 healed, 21 improved and 8 lost at the 2001 check-up: on the whole, a successful result in 100% of cases), but at present their application has to be reviewed according to a more conservative and careful therapeutic approach, based on the evaluation of some fundamental parameters.

CONCLUSION

The rehabilitative occlusal therapy, in its various aspects, is successful in the long term treatment of TDMs, as long as it is used only when it is possible to determine a correct indication.

[Posterior vertical dimension and condylo-discal non-coordination of the temporomandibular joint. Hypothesis on correlation]

BACKGROUND

On the basis of clinical evidence, an analytic study has been carried out to verify the hypothetic correlation between reduction of the posterior vertical overlap and internal derangements.

METHODS

58 patients with temporomandibular disorders have been observed; they presented clinically a reduction of the posterior vertical dimension (RPVD) due either to the loss of molar teeth or to the molar occlusal surface abrasion or to a wrong prosthetic rehabilitation. A cephalometric exam showed a significative correspondence between the RPVD and the retruded condylar position in the glenoidae fossa with a reduction of posterior joint space in comparison with the standard values purposed by Farrar.

RESULTS

The results obtained showed a possible relation between occlusal alterations and the TMJ pathology.

CONCLUSIONS

The conclusion is drawn that the clinical evaluation brings to consider occlusal factors, and in particular the reduction of posterior vertical dimension may be considered as possible etiologic factors of TMJ disorders.

Intramolecular backfolding of the carboxyl-terminal end of MxA protein is a prerequisite for its oligomerization

Mx proteins are large GTPases, which play a pivotal role in the interferon type I-mediated response against viral infections. The human MxA inhibits the replication of several RNA viruses and is organized in oligomeric structures. Using two different experimental approaches, the mammalian two-hybrid system and an interaction dependent nuclear translocation approach, three domains in the carboxyl-terminal moiety were identified that are involved in the oligomerization of MxA. The first consists of a carboxyl-terminal amphipathic helix (LZ1), which binds to a more proximal part of the same molecule. This intramolecular backfolding is a prerequisite for the formation of an intermolecular complex. This intermolecular interaction is mediated by two domains, a poorly defined region generated by the intramolecular interaction and a domain located between amino acids 363 and 415. Co-expression of wild-type MxA with various mutant fragments thereof revealed that the presence of the carboxyl-terminal region comprising the amphipathic helices LZ1 and LZ2 is necessary and sufficient to exert a dominant negative effect. This finding suggests that the functional interference of the carboxyl-terminal region is due to competition for binding of an as yet unidentified cellular or viral target molecules.

Human MxA protein protects mice lacking a functional alpha/beta interferon system against La crosse virus and other lethal viral infections

The human MxA protein is part of the antiviral state induced by alpha/beta interferon (IFN-alpha/beta). MxA inhibits the multiplication of several RNA viruses in cell culture. However, its antiviral potential in vivo has not yet been fully explored. We have generated MxA-transgenic mice that lack a functional IFN system by crossing MxA-transgenic mice constitutively expressing MxA with genetically targeted (knockout) mice lacking the beta subunit of the IFN-alpha/beta receptor (IFNAR-1(-/-) mice). These mice are an ideal animal model to investigate the unique antiviral activity of human MxA in vivo, because they are unable to express other IFN-induced proteins. Here, we show that MxA confers resistance to Thogoto virus, La Crosse virus, and Semliki Forest virus. No Thogoto virus progeny was detectable in MxA-transgenic mice, indicating an efficient block of virus replication at the primary site of infection. In the case of La Crosse virus, MxA restricted invasion of the central nervous system. In contrast, Semliki Forest virus multiplication in the brain was detectable in both MxA-expressing and nonexpressing IFNAR-1(-/-) mice. However, viral titers were clearly reduced in MxA-transgenic mice. Our results demonstrate that MxA does not need the help of other IFN-induced proteins for activity but is a powerful antiviral agent on its own. Moreover, the results suggest that MxA may protect humans from potential fatal infections by La Crosse virus and other viral pathogens.

Condylar fractures during growth: follow-up of 16 patients

Fractures of the mandibular condyle represent 20% to 35% of all mandibular fractures. There are several clinical variants of this type of fracture that give rise to different problems in relation to their classification and treatment. A sample of 16 patients (of a total of 280 patients examined and treated from 1985 through 1995) with mono- and bilateral, displaced and decomposed, condylar fractures that occurred during growth were examined by the authors, who assessed, by a 2-year follow-up, the relevant clinical, functional, and instrumental parameters. On the basis of the data gathered by this study, a plan was drawn up for treating these patients that takes into account the different situations, such as either a nonsurgical or surgical treatment (by the use of condylectomy or external rigid fixation), and points out the advantages and disadvantages of each method.

[Retrospective study on the application of occlusal splints in 312 patients with temporomandibular disorders]

BACKGROUND

Temporo-mandibular disorders are classified into disorders involving TMJ components (articular disk displacement, deviation in form) and masticatory muscle disorders.

METHODS

In this study the authors describe their experience of the non-surgical treatment of these pathologies. They review a total of 312 patients suffering from TMJ disorders treated with occlusal splint therapy applied for any TMJ dysfunction. The sample was monitored before and after occlusal therapy with an average follow-up of 30 months.

RESULTS AND CONCLUSIONS

The results were evaluated by comparing the authors' method of assessment with the parameters put forward by Levitt in 1993. Both methods of evaluation gave comparable results with a percentage of long-term success in excess of 87%.

Human MxA protein confers resistance to Semliki Forest virus and inhibits the amplification of a Semliki Forest virus-based replicon in the absence of viral structural proteins

Mx proteins form a small family of interferon (IFN)-induced GTPases with potent antiviral activity against various negative-strand RNA viruses. To examine the antiviral spectrum of human MxA in homologous cells, we stably transfected HEp-2 cells with a plasmid directing the expression of MxA cDNA. HEp-2 cells are permissive for many viruses and are unable to express endogenous MxA in response to IFN. Experimental infection with various RNA and DNA viruses revealed that MxA-expressing HEp-2 cells were protected not only against influenza virus and vesicular stomatitis virus (VSV) but also against Semliki Forest virus (SFV), a togavirus with a single-stranded RNA genome of positive polarity. In MxA-transfected cells, viral yields were reduced up to 1,700-fold, and the degree of inhibition correlated well with the expression level of MxA. Furthermore, expression of MxA prevented the accumulation of 49S RNA and 26S RNA, indicating that SFV was inhibited early in its replication cycle. Very similar results were obtained with MxA-transfected cells of the human monocytic cell line U937. The results demonstrate that the antiviral spectrum of MxA is not restricted to negative-strand RNA viruses but also includes SFV, which contains an RNA genome of positive polarity. To test whether MxA protein exerts its inhibitory activity against SFV in the absence of viral structural proteins, we took advantage of a recombinant vector based on the SFV replicon. The vector contains only the coding sequence for the viral nonstructural proteins and the bacterial LacZ gene, which was cloned in place of the viral structural genes. Upon transfection of vector-derived recombinant RNA, expression of the beta-galactosidase reporter gene was strongly reduced in the presence of MxA. This finding indicates that viral components other than the structural proteins are the target of MxA action.

[A longitudinal analysis of dysfunctional TMJ pathology: an assessment of a sample of patients undergoing nonsurgical therapy]

One the different interpretation of the pathological and clinical evolution of TMJ dysfunctions, the most-common of these pathologies is the condyle-disk uncoordination. This study analyzes the evolution of the treatment on the sample of patients affected by TMJ dysfunction and examined at the maxillo-facial department of the University of Rome "La Sapienza". After the TMJ dysfunction has been diagnosed the patients were informed of the individual therapeutic program which consisted of a temporary and definitive occlusal therapy. The aim of this scientific work is to control the efficiency within this therapeutic program in relation to the uncoordination of TMJ. In order to validate this approach the study was compared with another that considered the evolution of TMJ pathology in patients examined at the first diagnostic, visit but who had not undergone any treatment.

[A longitudinal analysis of dysfunctional pathology of the TMJ: an assessment of a sample of patients not undergoing therapy]

Concerning the different interpretation on the pathological and clinical evolution of the TMJ dysfunctions, the most common of these pathology is the condyle-disk incoordination. This study analyzed the evolution of TMJ dysfunctions examined at the maxillo-facial department of the University of Rome "La Sapienza". The non therapeutic approach does not consider an addition al control-sample of the non treated being itself a control-sample of a parallel work whose aim was to analyze patients who had undergone a complete therapeutic cycle.

[The diagnosis and surgical therapy of maxillofacial malformations. The statistical considerations]

In this report the authors develop a thorough statistic analysis upon the past 12-year activity (1980-1991) of the University of Rome, Department of Maxillo-Facial Surgery, in the field of the diagnosis and treatment of congenital or acquired maxillofacial malformations. They point out, in particular, the high frequency rate of bimaxillary osteotomy use in the surgical treatment of dentoskeletal malformations, that are the most frequent malformations in maxillofacial clinical practice. They also point out how wide the use of the rigid internal fixation technique in this surgical field has become.

[Neuromuscular assessment and postural examination in patients with TMJ condylo-meniscal incoordination]

The neuromuscular system plays a primary role in the development of a myofascial syndrome of the temporomandibular joint. Patients suffering from this disease very often show changes in muscular functions. In biomechanical clinical pictures of temporomandibular myofascial syndrome the motor apparatus is involved only in the second stage. In order to determine the efficiency of the motor apparatus and to schedule a physiotherapeutic treatment program to improve condylar-meniscus coordination of the joint, an analysis of muscular function associated with postural examination has been performed, and this with a view to evidence possible skeletal changes, with particular regard to the spine. The study has been carried out in a group of healthy individuals in front of an other group of patients affected by the pathology mentioned.

[A statistical evaluation of the surgical therapy of TMJ condyle-disk incoordination]

Biomechanical pathology of the TMJ occurs most frequently in 4 clinical variants: anterior dislocation of the jaw, reciprocal click, closed lock, osteoarthrotic degeneration. The aim of this study was to evaluate the efficacy of TMJ surgery, using statistical comparative analysis, in resolving condylo-meniscal incoordination. Eighty-one patients were included in the study who had been treated surgically for various symptoms of condylo-discal incoordination from 1982 to 1989, assessing a series of objective and subjective parameters and making a statistical comparison of results.

[Electrognathographic imaging of the articular click]

The study of TMJ phisiopathology by means of computerizing devices is necessary in order to make a correct diagnosis and verify the therapeutic programme. In this study the Authors analyse articular click that is one of the first and characteristic symptom of the internal derangement. The Authors show by means of elettrognatography, chewing cicles and mandibular border movements of patients affected with this particular pathology. Trascing of 135 patients suffering from tmj reciprocal click have been examined in the department of maxillary-facial of Roma "La Sapienza", surgery during the period 1987-88.

[Maxillo-mandibular fracture outcome. Therapeutic program]

The ill-consolidated outcomes of the maxillo and jaw fractures often show ill-positions of the mandible and/or of the jaw in the three space-levels. In order to program a suitable surgical correction of such pathologic pictures it is necessary to make a cephalometric test and a gnathologic one. The result of these tests will guide the therapeutical choise which will be either the re-opening of the surgical treatment to be effected through the usual osteotomy of the mandible.

[Prosthetic rehabilitation in the sequelae of labiopalatoschisis]

Labiopalatoschisis patients present functional and aesthetic alterations in the maxillomandibular area that often require prosthetic correction. Given the features of these malformations therapy and rehabilitation should be programmed as soon as possible after birth and the plastic surgeon should be informed of the factors that cause the malformations and influence the growth of such patients. The present paper briefly outlines the pathogenesis of L.P.S. and proposes a classification system for L.P.S. since both are considered essential for the understanding and assessment of its sequelae. The prosthetic-reconstructive problems in cases of cheilognathopalatoschisis subjected to orthodontic and surgical treatment are described since this is considered the most difficult form of rehabilitation the prosthesis is faced with.

Five-year follow-up of Le Fort I osteotomies

The outcome of a five-year radiographic follow-up study of 150 patients with maxillo-mandibular malformations who had undergone Le Fort I osteotomy of the maxilla is reported. A superimposition technique made possible an exact evaluation of the adjustments effected. The results confirm the validity of a study conducted in 1977 and the five-year stability of the maxilla. The importance of the relationship between the Frankfort plane, occlusal plane and the osteotomy line is emphasized. In operations in which Le Fort I osteotomy of the maxilla is combined with a sagittal osteotomy of the mandible the maxilla undergoes minute displacements in the weeks following surgery, which can easily be predicted and allowed for at the planning stage. The long-term stability of the maxilla is assured.