Clinical evaluation of patients with temporomandibular joint implants

PURPOSE: An undetermined number of patients with temporomandibular joint (TMJ) symptoms have been treated with intra-articular disc implants composed of Teflon ethylene/propylene or Teflon polytetrafluoroethylene and aluminum oxide (Proplast-Teflon; Vitek, Houston, TX). These implants have shown the potential to fragment in situ resulting in nonbiodegradable particles that stimulate a giant cell reaction and lead to degeneration of local structures, pain, and limitation of mandibular opening. We examined the possible relationship between TMJ implants and persistent pain, responses to sensory stimuli, quality of life, and systemic immune dysfunction. PATIENTS AND METHODS: This case series (32 patients) were referred from university-based orofacial pain centers and private practices from across the United States. Laboratory and clinical assessments evaluated orofacial pain symptoms, neurologic function, clinical signs and symptoms of rheumatologic disease, physical function, systemic measures of immune function, and behavioral measures. RESULTS: We found that TMJ implant patients appeared to have altered sensitivity to sensory stimuli, a higher number of tender points with a diagnosis of fibromyalgia, increased self-report of chemical sensitivity, higher psychologic distress and significantly lower functional ability. Systemic illness or autoimmune disease was not evident in this series of TMJ implant patients. CONCLUSIONS: Significant problems were noted on clinical assessment of TMJ implant patients. This is a US government work. There are no restrictions on its use.     

How to increase the durability of resin-dentin bonds

Resin-dentin bonds are not as durable as was previously thought. Microtensile bond strengths often fall 30% to 40% in 6 to 12 months. The cause of this poor durability is a combination of the activation of matrix metalloproteinases (MMPs) by weak acids such as lactic acid released by caries-producing bacteria, and acid-etchants used in adhesive bonding systems. These acids uncover and activate matrix-bound MMPs. The other contributing factor is incomplete resin infiltration. If all exposed collagen fibrils were enveloped by resin, the MMPs would not have free access to water, an obligatory requirement of these enzymes. Recently, several inhibitors of MMPs have been added to adhesive primers. Examples include chlorhexidine (CHX), benzalkonium chloride (BAC), and MDPB, an antibacterial monomer used in a two-step self-etching primer adhesive. The advantage of MDPB over CHX and BAC is that it polymerizes with adhesive resins and cannot leach from the hybrid layer. This is an example of what can be termed a "therapeutic adhesive system" that provides anti-MMP activity along with antibacterial qualities.     

Bruxism-induced parotitis: A retrospective case series analysis

ABSTRACT

Objective: A group of patients with recurrent parotitis had clinical symptoms suggesting an obstruction of the glandular duct system, though without any signs of sialoliths or other ductal pathologies.

Methods: Clinical and radiological data of five patients with recurrent obstructive parotitis and long-standing definite bruxism were reviewed retrospectively. Ultrasonography, MRI, and sialendoscopy were performed for evaluation of ductal pathologies as the cause of glandular obstruction. Electromyography was used to evaluate the activity of masticatory muscles in all patients. The parotitis was treated with injection of botulinum toxin into the buccinator muscle.

Results: Dilatation of the Stensen’s duct proximal to the area of the buccinator muscle was shown in radiological examination with no evidence of ductal strictures. Electromyography revealed an abnormal activity of the ipsilateral buccinator muscle. All patients were free of disease after treatment of the buccinator muscle.

Discussion: Bruxism should be considered as a possible cause of recurrent parotitis.     

Does occlusal splint affect posture? A randomized controlled trial

ABSTRACT

Objective

The aim of this study was to evaluate the effect of an occlusal splint on body posture of intra-articular temporomandibular joint (TMJ) disorders patients.     

Mechanical properties of computer-aided design/computer-aided manufacturing resin composites assuming perfect silane coupling using in silico homogenization of cryo-electron microscopy images

Purpose

The aim of this study was to determine the mechanical properties of computer-aided design/computer-aided manufacturing (CAD/CAM) resin composites for dental restoration assuming perfect silane coupling by in silico homogenization analysis using a three-dimensional model constructed from cryo-electron microscopy (cryo-EM) images.

Influence of novel resin monomer on viability of L-929 mouse fibroblasts in vitro

We have previously synthesized a novel acrylic resin monomer, methacryloyloxyethyl methyl succinate (TA). The aim of this in vitro study, therefore, was to examine its influence on cell viability using L-929 mouse fibroblasts and then compare the results with MMA, EMA, and LMA. Medium containing each monomer was changed every 15 minutes as some monomers were volatile. After one hour of exposure, these mediums were replaced with a normal medium and cells were further incubated for 72 hours. IC50 value for each monomer was determined, and chronological cell viability and cytomorphologic observation were evaluated. Viability was impaired in a dose-dependent manner. All monomers, except TA, tended to correlate between molecular weight and cell viability. On the other hand, TA showed excellent viability and did not impair growth abruptly. These results thus demonstrated that cellular damage by TA was much lower than that by other monomers.     

GABA(A) receptors in the nucleus accumbens core modulate turning behavior induced by dopamine receptor stimulation

The role of GABA(A) and GABA(B) receptors in the core of the nucleus accumbens in turning behavior of rats was investigated. Unilateral injections into the core of the nucleus accumbens of the GABA(A) receptor agonist (muscimol, 50 ng) and antagonist (bicuculline, 200 ng), and the GABA(B) receptor agonist (baclofen, 100 ng) and antagonist (2-hydroxysaclofen, 2 microg) did not produce turning behavior. In rats pretreated with unilateral injections of the dopamine D1-like/D2-like receptor antagonist, cis(Z)-flupentixol (10 microg), into the ventrolateral striatum and saline into the nucleus accumbens core of contralateral side, systemic injection of a mixture of dopamine D1-like (SKF 38393, 3 mg/kg) and D2-like (quinpirole, 1 mg/kg) receptor agonists has been found to elicit contraversive pivoting, namely pivoting away from the side of the core injection. This dopamine D1-like/D2-like receptor-mediated pivoting was significantly inhibited by injections into the core of the nucleus accumbens of muscimol (50 ng), but not bicuculline (200 ng). In contrast, the dopamine D1-like/D2-like receptor-mediated pivoting was suppressed by either baclofen (100 ng) or 2-hydroxysaclofen (2 microg) injected into the nucleus accumbens core. It is therefore concluded that neither GABA(A) nor GABA(B) receptor stimulation in the core of the nucleus accumbens produces turning behavior, and that GABA(A), but not GABA(B), receptors in the nucleus accumbens core may modulate dopamine D1-like/D2-like receptor-mediated pivoting.