'Adaptable condylectomy' for acquired facial asymmetry and malocclusion caused by temporomandibular joint condylar hyperplasia.

This article describes the 'adaptable condylectomy' and highlights two innovative treatment protocols for the variety of acquired facial asymmetry and associated malocclusion caused by condylar hyperplasia, as illustrated by the cases of seven patients presenting different manifestations of condylar hyperplasia. Protocol I (three cases) is applied for condylar hyperplasia with a normal occlusion and involves a high condylectomy, with the goal of guiding the mandible back to the original occlusion. Protocol II (four cases) is applied for condylar hyperplasia with diverse acquired malocclusions and involves condylectomy at a level adapted to the malocclusion, allowing the mandible to be guided back to the occlusion that pre-existed the active change caused by the condylar hyperplasia, or to a position as close to the midline as possible. Both protocols are followed by gradual self-correction of the acquired facial asymmetry. These protocols often obviate the need for further surgical intervention and, if further correction is needed, it is much simpler.

Limited mouth opening of unknown cause cured by diagnostic coronoidectomy: a new clinical entity?

Limited mouth opening is a constant annoyance and can be life-threatening should intubation be needed. The causes are numerous and are categorised as intra-articular or extra-articular, which are often difficult to distinguish. We present what we regard as a new clinical entity - long-standing limited mouth opening of unknown cause - and describe our treatment. Four female patients presented with limited mouth opening and lateral and protrusive movements within normal limits, which were typical of restriction of extra-articular origin. However, the radiological findings were within normal limits, with no visible cause of the restriction. All four were treated by bilateral coronoidectomy that resulted in the immediate return of mouth opening to within normal limits that was preserved over subsequent years. Histopathological examination showed atrophy and degenerative changes in the temporalis band that had been attached to the coronoid, which accounts for the stiffness of the temporalis muscle but does not explain the pathogenesis. In the light of this "diagnostic coronoidectomy" further studies are required to document the underlying pathological changes and to develop more accurate imaging that will enable correct diagnosis in future.

Injection of vascular endothelial growth factor into knee joints induces osteoarthritis in mice.

UNLABELLED: Osteoarthritis (OA) is a common joint disorder affecting circa 2% of the population. OBJECTIVES: It has been suggested that secretion of vascular endothelial growth factor (VEGF) could play a role in the chain of events leading to OA. METHODS: In the present study, healthy mice were injected intra-articularly with VEGF. RESULTS: Shortly after the administration of VEGF, synovial hyperplasia, increased calcification of the articular cartilage and bone sclerosis were observed. Consequently, cartilage degradation characteristic of OA was found. These changes were seen to a lesser degree in the opposite knees of VEGF-injected mice and did not occur in the control mice. CONCLUSIONS: The findings suggest an active role of VEGF in the pathogenesis of OA and render support to a possible role for subchondral bone sclerosis in the pathogenesis of cartilage degradation.

2-Butoxyethanol model of haemolysis and disseminated thrombosis in female rats: a preliminary study of the vascular mechanism of osteoarthritis in the temporomandibular joint.

Female rats develop haemolytic anaemia and disseminated thrombosis and infarction in multiple organs, including bone, when exposed to 2-butoxyethanol (BE). There is growing evidence that vascular occlusion of the subchondral bone may play a part in some cases of osteoarthritis. The subchondral bone is the main weight bearer as well as the source of the blood supply to the mandibular articular cartilage. Vascular occlusion is thought to be linked to sclerosis of the subchondral bone associated with disintegration of the articular cartilage. The aim of this study was to find out whether this model of haemolysis and disseminated thrombosis supports the vascular hypothesis of osteoarthritis. Six female rats were given BE orally for 4 consecutive days and the two control rats were given tap water alone. The rats were killed 26 days after the final dose. The mandibular condyles showed histological and radiological features consistent with osteoarthritis in three of the four experimental rats and in neither of the control rats. These results may support the need to explore the vascular mechanism of osteoarthritis further.

'Friction and adhesive forces'--possible underlying causes for temporomandibular joint internal derangement.

Since normal temporomandibular joint (TMJ) movements depend primarily on the disc freely sliding down the slope of the eminence, understanding how aberrations in the lubrication system contribute to TMJ dysfunction is clearly critically important. It provides a possible explanation for the genesis of disc displacement and helps make us familiar with the clinical appearance and ways of treating limited mouth opening caused by the anchored disc phenomenon (ADP) versus disc displacement without reduction, TMJ open lock versus dislocation and osteoarthritis. This understanding clarifies the efficiency of procedures such as joint hydraulic pump, arthrocentesis and arthroscopic lavage and lysis particularly in ADP, open lock and osteoarthritis.

Changes in the reducing power of synovial fluid from temporomandibular joints with "anchored disc phenomenon".

PURPOSE: In this study, we examined the hypothesis that uncontrolled oxidative stress causes collapse of the lubrication system, which is considered a major initiator of temporomandibular joint (TMJ) dysfunction. The oxidative stress was evaluated by measuring the overall antioxidant capacity of the low-molecular-weight antioxidants in the TMJ, using cyclic voltammetry (CV), in synovial fluid from normal and anchored disc phenomenon (ADP) TMJs. MATERIALS AND METHODS: Synovial fluids samples were taken from 13 normally functioning and 33 ADP TMJs. The samples were frozen initially on collection and analyzed in CV to measure their overall reducing power. RESULTS: CV measurements of the fluids collected from 90% of the healthy joints showed an anodic waves at peak potential [Ep(a)1/2] of 290 +/- 30 mV. Of the samples 56% showed another wave at 650 +/- 100 mV. These waves were generally absent in the fluid collected from ADP TMJs, but 2 new waves at 465 +/- 90 mV and greater than 750 mV were detected in 68% and 87% of the patients, respectively. CONCLUSIONS: The results show more anodic waves, most of which of higher potentials (greater than 750 mV) in ADP TMJs, indicating that the capacity to cope with oxidative stress is lower in these joints. It is not clear whether this is due to absence of low-molecular-weight antioxidants or their consumption by uncontrolled production of reactive oxygen species, which might be the initial step in the collapse of the lubrication system.

Adhesive force: the underlying cause of the disc anchorage to the fossa and/or eminence in the temporomandibular joint--a new concept.

The commonly held cause for using the closed lock technique is the prevention of disc sliding by using the non-reducible disc. The purpose of this study was to re-evaluate the pathogenesis of sudden and persistent severely limited mouth opening associated with a total lack of disc sliding in view of the fact that it is promptly released by lavage of the upper compartment of the temporomandibular joint (TMJ). The proposed pathogenesis is based upon earlier clinical and laboratory findings of the first author coupled with pertinent information culled from the literature. It is suggested that sliding of the disc in the TMJ is enabled due to the presence of phospholipids protected by hyaluronic acid (HA) that constitute an efficient lubrication system. Joint overloading may be associated with uncontrolled production of reactive oxygen species (ROS) that causes degradation of the HA, followed by the exposure of the phospholipids to lysis by phospholipase A2 (PLA2). The denuded, smooth and elastic articular surfaces that possess high surface energy become strongly adherent when placed in direct physical contact with each other. The presence of an extremely thin film of fluid (sub-boundary lubrication) between the mating surfaces may cause even higher adhesion. These adhesive forces are probably responsible for the flexible disc anchorage to the fossa and/or eminence. They also explain the immediate release of the disc and rehabilitation of its sliding following arthrocentesis. Since it is uncommon for two opposing surfaces to be stripped bare and to become adherent, the likelihood of anchored disc phenomenon (ADP) occurring and recurring is very low.

Electron microscope and biochemical observations of the surface active phospholipids on the articular surfaces and in the synovial fluid of the temporomandibular joint: a preliminary investigation.

PURPOSE: The goal of this article is to investigate the surface-active phospholipids located on the articular surfaces and in the temporomandibular joint (TMJ) synovial fluid (SF) by means of electron microscopy and biochemical analysis. MATERIALS AND METHODS: Synovial fluids and articular cartilage samples taken from 6 normally functioning TMJs were studied. The osmiophilic lining of human TMJ articular surfaces has been studied by using special nondestructive fixation procedures. To study the SF, negative staining technique has been used. In addition, thin-layer chromatography has been used to identify the phospholipids extracted from synovial fluid of human TMJs. RESULTS: In the SF, granular bodies were identified with diameter of between 170 and 280 nm. Their diameter decreased dramatically when exposed to phospholipase-A(2). The amorphous and highly osmophilic material on the articular surface include membrane-bound vesicles (270 nm in diameter) with lamellated pattern surrounding the amorphous-dense core. Biochemical extraction revealed phosphatidylcholine as the major component of the polar lipids. CONCLUSIONS: This preliminary study presents findings that suggest that phospholipids present in the TMJ may provide an efficient boundary lubrication that enables the disc to slide down the slope of the eminence on joint function.

The use of arthrocentesis for the treatment of osteoarthritic temporomandibular joints.

PURPOSE: The purpose of this retrospective study was to determine the efficacy of arthrocentesis in restoring the functional capacity of osteoarthritic temporomandibular joints (TMJ). PATIENTS AND METHODS: This study involved 36 patients (29 females, 7 males; age range, 16 to 54 years, mean, 37.36 +/- 14.60 years) presenting with 38 dysfunctional joints that had not responded to conservative treatment. The postarthrocentesis status (follow-up period 6 to 62 months, mean 20.7 +/- 20.5 months) of the TMJs was determined by patient self-evaluation using visual analog scales and clinical examination. RESULTS: Of the 38 TMJs treated with arthrocentesis, 26 joints reacted favorably to the treatment; pain and dysfunction scores were reduced from 9.86 +/- 0.73 to 3.39 +/- 0.76 and from 11.34 +/- 0.66 to 3.4 +/- 0.69, respectively (P <.001). Self-assessed general improvement/deterioration was +4.90 +/- 2.10 (on a scale of -7 to +7). Maximal mouth opening increased from 24.40 +/- 2.70 mm to 43.20 +/- 3.10 mm (P <.001). Lateral and protrusive jaw movements also increased in magnitude. In 14 patients in whom no improvement was noted, arthrocentesis acted as a diagnostic tool before surgical treatment. CONCLUSIONS: Arthrocentesis is a safe and rapid procedure that in many instances results in the osteoarthritic TMJs returning to a healthy functional state. Failure of arthrocentesis suggests that the painful limitation is most probably caused by changes such as fibrous adhesions or osteophytes that require surgical intervention for their removal.

The role of hyaluronic acid in protecting surface-active phospholipids from lysis by exogenous phospholipase A(2).

BACKGROUND: This in vitro study aimed to elucidate the extent and kind of involvement of hyaluronic acid (HA) in the currently accepted view of synovial joint lubrication, in which surface-active phospholipids (SAPL) constitute the main boundary lubricant. The integrity of SAPL is apparently threatened by the lysing activity of phospholipase A(2) (PLA(2)). METHODS: The effects of increasing concentrations of HA degraded by free radicals and non-degraded HA on the lysing activity of PLA(2) were examined in vitro. Liposomes (lipid model membrane) containing phosphatidylcholine (PC) were used as the substrate, on the assumption that they are appropriate representatives of SAPL. RESULTS: HA adhered to the phospholipid membrane (liposomes), inhibiting their lysis by PLA(2). However, in its degraded form, HA not only failed to inhibit PLA(2)-lysing activity, but accelerated it. CONCLUSIONS: It is reasonable to assume that HA plays an important indirect role in the steady state of the boundary lubrication process of joints by protecting SAPL from being lysed by PLA(2). However, as excessive loading generates free radicals within the joint (among other effects), the HA that is degraded in this way is incapable of protecting SAPL from lysis by PLA(2). When the rate of degradation exceeds that of synthesis, there will be insufficient replacement of HA and/or SAPL, resulting in denudation of the articular surfaces. These are then exposed to increasing friction, and hence increased danger of degenerative joint changes.

The process of lubrication impairment and its involvement in temporomandibular joint disc displacement: a theoretical concept.

PURPOSE: This article re-evaluates the chain of events leading to temporomandibular joint (TMJ) disc displacement. The joint lubrication system and the process of its breakdown are clarified and an attempt is made to evaluate the possible effect of increased friction between the disc and fossa on the anterior displacement of the disc. MATERIALS AND METHODS: The study is based on the author's accumulated clinical data and results obtained from laboratory investigations regarding TMJ lubrication and its possible breakdown, coupled with pertinent information culled from the literature. RESULTS: Translation of the disc in the TMJ is enabled due to the presence of phospholipids and hyaluronic acid, which constitute an efficient lubrication system. This system may break down in the presence of uncontrolled free radicals. In the absence of lubricants, the articular surfaces are smooth, elastic in texture, and possess strong surface energy. Such opposing planes, especially in the presence of a thin fluid film (sub-boundary lubrication) tend to generate high friction while the disc is sliding against the fossa. Such friction is probably the prime mover in loosening the disc attachments to the condyle, with subsequent disc displacement. CONCLUSIONS: Increased friction of the contiguous parts may well be a major causative factor in displacement of the articular disc. This should be taken into account in considering the appropriate treatment approach. It also raises some doubts regarding the validity of using repositioning techniques.

Surgical management of temporomandibular joint ankylosis type III by retaining the displaced condyle and disc.

PURPOSE: This article proposes a hypothesis regarding the value of saving the fractured condyle and disc in their displaced position in ankylosis type III for optimal temporomandibular joint (TMJ) function and growth, and describes four cases treated in this manner. PATIENTS AND METHODS: Four patients (three females and one male, 9 to 48 years old) with TMJ ankylosis type III of 3 to 8 years' duration, a maximal mouth opening of 15 to 19 mm, and severely limited lateral and protrusive movements were treated. The ankylosed sites were resected, leaving the displaced condyle and disc in their medial position. RESULTS: Fifteen to 60 months after surgery, the patients had a maximal mouth opening of 44 to 50 mm, as well as better contralateral and protrusive movements. In addition, two young patients (9 and 11 years old) showed an improved facial symmetry. CONCLUSIONS: Treatment of patients with type III TMJ ankylosis should involve retention rather than removal of the displaced condyle and disc. The condyle and disc are left untouched in their precarious medial position so as to provide normal function and growth.

Salivary gland transplantation: a canine model.

Impaired salivary function with resultant severe dryness of the mouth, or xerostomia, may occur in association with a variety of systemic disorders or therapies. No adequate treatment exists for this debilitating condition, which impedes normal oral function, in particular alimentation and phonation. This study explores the feasibility of salivary gland autotransplantation, using a canine model. A salivary gland with its duct and surrounding blood vessels still attached was excised and reimplanted in the dog's thigh by anastomosing the graft's blood vessels to the femoral artery and vein. The duct was sutured to an artificial orifice cut in the thigh's skin, from which the saliva was collected. Salivary secretion was induced by a single intravenous bolus of pilocarpine (5 mg). Preoperative (normal) salivation was measured by collecting saliva from the gland in situ. Periodic functional studies showed normal saliva production during the first month after grafting, after which the salivary flow was reduced by 35% over the next 2 months. This reduction was interpreted as a sign of disuse atrophy resulting from the lack of autonomic innervation. To overcome this impediment, oral pilocarpine (5 mg/day) was administered to the recipient dog, after which normal levels of saliva were excreted through the graft during the 3-month follow-up period. The quality of the graft saliva was assessed by its protein and electrolyte levels, which showed close to normal values.

The "anchored disc phenomenon": a proposed etiology for sudden-onset, severe, and persistent closed lock of the temporomandibular joint.

This article establishes a rationale for a particular type of sudden and severely restricted mouth opening caused by anchoring of the disc to the fossa termed anchored disc phenomenon, describes the possible pathogenesis of this disorder, and recommends appropriate treatment. The clinical characteristics supporting the proposed pathogenesis, and treatment of the disorder are based on data published in the literature and clinical experience with the diagnosis and treatment of this disorder.

Long-term outcome of arthrocentesis for sudden-onset, persistent, severe closed lock of the temporomandibular joint.

PURPOSE: This study analyzed the long-term effect of arthrocentesis for severe closed lock of the temporomandibular joint (TMJ) and reevaluated the pathogenesis of this condition based on the data obtained. PATIENTS AND METHODS: Thirty-nine patients (40 joints) who had experienced sudden-onset, persistent limited mouth opening were the subjects of this study. After unsuccessful noninvasive treatment, arthrocentesis of the upper compartment of the affected TMJ was performed using saline. The follow-up, which consisted of patient self-assessment and clinical examination, ranged from 6 to 37 months (mean, 16.6 +/- 12.0 months). Visual analog scales were used for preoperative and postoperative self-evaluation of pain and dysfunction on forced mouth opening and for assessment of overall change in these parameters postarthrocentesis. Maximal mouth opening (MMO), contralateral movement (CLM) and protrusive movement of the jaw, and presence of joint noises were noted preoperatively and at clinical follow-up examinations. RESULTS: At 6 to 37 months postarthrocentesis, MMO and CLM had increased significantly (from a mean of 23.10 +/- 5.15 mm to 44.25 +/- 4.96 mm, and from a mean of 4.81 +/- 2.36 mm to 8.20 +/- 1.90 mm, respectively; P < .001). Functional improvement was associated with a significant reduction in pain and dysfunction levels (from a mean of 9.24 +/- 2.90 to 1.45 +/- 1.74, and from a mean of 9.26 +/- 2.82 to 2.68 +/- 2.80, respectively, on a scale of 0 to 15; P < .001). The overall improvement, as expressed in pain and dysfunction levels, was about 95%, with no recurrence of severe closed lock. CONCLUSIONS: Arthrocentesis for sudden-onset closed lock provided sustained normal joint function and marked pain relief. Because the available literature shows that arthrocentesis changes neither disc position nor disc shape, it places in doubt the concept of a displaced and deformed disc limiting joint function. Rather, the efficacy of lavage in resolving closed lock suggests that the condition is the result of sudden adherence of the normally shaped disc to the fossa, rendering it incapable of sliding. The characteristic features of sudden-onset, limited mouth opening warrants classification of this disorder as an independent entity within the realm of TMJ disturbances.

H2O2 renders cells accessible to lysis by exogenous phospholipase A2: a novel mechanism for cell damage in inflammatory processes.

Phospholipase A2 (PLA2) and H2O2, secreted from activated inflammatory cells, play a central role in the tissue damage occurring in inflammatory processes. However, while exogenous PLA2 alone does not cause cell lysis, it readily does so when acting with H2O2. We have found that H2O2 degrades cell surface proteoglycans, thus rendering the membrane PL accessible to hydrolysis by exogenous PLA2. This novel mechanism introduces a role for cell surface proteoglycans in protection of cells from damage by pro-inflammatory agents, and may assign a central role for the combined action of H2O2 and PLA2 in inflammatory and bacteriocidal processes.

Intraarticular pressure in the functioning human temporomandibular joint and its alteration by uniform elevation of the occlusal plane.

Intraarticular pressure (IAP) was measured at the posterior slope of the eminence in the upper compartment of the temporomandibular joint (TMJ) of 35 individuals (28 females and 7 males) under local anesthesia. Pressure measurements were obtained with the jaw in rest position, during maximal mouth opening (MMO), and while clenching. During MMO, IAP decreased to levels ranging between -130 and -5 mm Hg (mean, -53.82 +/- 34.40 mm Hg), whereas during clenching the pressure was always positive (range, +8 to +200 mm Hg; mean, 63.90 +/- 52.25 mm Hg). The significance of the fluctuating pressures with respect to the joint's maintenance and performance, as well as the potentially harmful effect of the positive pressure, especially when it is high and prolonged, are discussed. Females generated significantly higher pressures than males (73.70 +/- 61.06 mm Hg vs 31.42 +/- 11.47 mm Hg, P = .017). This gender difference regarding IAP may help elucidate the enigma of the considerably higher proportion of women with TMJ problems. In 22 of the patients IAP also was measured while clenching on a specifically constructed interocclusal appliance (IOA), which uniformly elevated the occlusal plane so as to reduce the force directed toward the TMJ. During clenching without the IOA, pressures ranged from 20 to 200 mm Hg (mean, 68.8 +/- 49.1), decreasing by 81.2% to IAP levels ranging from 0 to 40 mm Hg (mean, 7.9 +/- 10.9; P < .001) with the appliance in place. The use of an IOA as a palliative treatment for symptomatic TMJs is discussed.

Pathoses of coronoid process as a cause of mouth-opening restrictions.

The mandible coronoid process is another site subject to various pathoses that may result in limited jaw movement. Six different pathoses that prevented the free rotation of the coronoid are presented. Differential diagnosis and treatment approach are emphasized.