Human temporomandibular joint and myofascial pain biochemical profiles: a case-control study

Neurobiological mechanisms of human musculoskeletal pain are poorly understood. This case-control study tested the hypothesis that biomarkers within temporomandibular muscle and joint disorders (TMJD) subjects' masseter muscles or temporomandibular joint (TMJ) synovial fluid correlate with plasma biomarker concentrations. Fifty subjects were recruited and categorized into TMJD cases (n=23) and pain-free controls (n=27) at the University of Minnesota School of Dentistry. Prior to specimen collection, pain intensity and pressure pain threshold masseter muscles and the TMJs were assessed. We collected venous blood; biopsied masseter muscle; and sampled TMJ synovial fluid on the subjects' side of maximum pain intensity. We assayed these tissues for the presence of nerve growth factor (NGF), bradykinin (BK), leukotreine B(4) (LTB(4) ) and prostaglandin E(2) (PGE(2) ), F(2) -isoprostane (F(2) I) and substance P (SP). The data was analyzed using Spearman Correlation Coefficients. We found that only plasma concentrations of bradykinin statistically correlated with synovial fluid concentrations (ρ=-0·48, P=0·005), but no association was found between pain intensities. The data suggests that biomarkers used to assess TMJD need to be acquired in a site-specific manner. We also discovered that F(2) I concentrations were associated with muscle pain intensity and muscle pressure pain threshold (PTT) (β=0·4, 95%CI: 0·03-0·8) and joint PPT (β=0·4, 95%CI: 0·07-0·8) suggesting that muscle oxidative stress is involved in myofascial pain and that F(2) -I may be a biomarker for myofascial pain.

Randomized effectiveness study of four therapeutic strategies for TMJ closed lock

For individuals with temporomandibular joint (TMJ) disc displacement without reduction with limited mouth opening (closed lock), interventions vary from minimal treatment to surgery. In a single-blind trial, 106 individuals with TMJ closed lock were randomized among medical management, rehabilitation, arthroscopic surgery with post-operative rehabilitation, or arthroplasty with post-operative rehabilitation. Evaluations at baseline, 3, 6, 12, 18, 24, and 60 months used the Craniomandibular Index (CMI) and Symptom Severity Index (SSI) for jaw function and TMJ pain respectively. Using an intention-to-treat analysis, we observed no between-group difference at any follow-up for CMI (p > or = 0.33) or SSI (p > or = 0.08). Both outcomes showed within-group improvement (p < 0.0001) for all groups. The findings of this study suggest that primary treatment for individuals with TMJ closed lock should consist of medical management or rehabilitation. The use of this approach will avoid unnecessary surgical procedures.

Effects of implant healing time on crestal bone loss of a controlled-load dental implant

The universally accepted concept of delay-loaded dental implants has recently been challenged. This study hypothesizes that early loading (decreased implant healing time) leads to increased bone formation and decreased crestal bone loss. We used 17 minipigs to study implants under a controlled load, with non-loaded implants for comparison. Radiographic and histological assessments were made of the osseointegrated bone changes for 3 healing times (between implant insertion and loading), following 5 months of loading. The effect of loading on crestal bone loss depended on the healing time. Early loading preserved the most crestal bone. Delayed loading had significantly more crestal bone loss compared with the non-loaded controls (2.4 mm vs. 0.64 mm; P < 0.05). The histological assessment and biomechanical analyses of the healing bone suggested that loading and bioactivities of osteoblasts exert a synergistic effect on osseointegration that is likely to support the hypothesis that early loading produces more favorable osseointegration.

Effect of intra-articular versus systemic anti-inflammatory drugs in a rabbit model of temporomandibular joint inflammation

PURPOSE

In an attempt to better understand the time course of inflammatory mediator production or release in inflammatory joint disease, a rabbit model of acute temporomandibular joint (TMJ) inflammation was established. This model was used to evaluate the effects of specific anti-inflammatory agents administered either systemically (intraperitoneal, IP) or locally (intra-articular, IA) on the modulation of in vivo tissue levels of two prototypic inflammatory mediators, prostaglandin E2 (PGE2) and bradykinin (BK).

MATERIALS AND METHODS

An experimental model of inflammation was created by administering carrageenan (carra) into one joint and an equivalent volume of saline (control) into the contralateral joint of 42 male New Zealand White rabbits. The development of hyperthermia was assessed by placement of a microthermister probe into the joint space. The inflammatory mediators, immunoreactive PGE2 (iPGE2) and BK (iBK), were recovered with microdialysis probes, and samples were assayed in conjunction with specific pharmacologic interventions. In the first part of the study, the time course for the release or production of iBK and iPGE2 was determined. In the second part, the effects of IP versus IA administration of dexamethasone and a nonsteroidal anti-inflammatory drug, ketorolac tromethamine, were compared. Dexamethasone and ketorolac were administered at 3 hours and 1 hour, respectively, before the peak release of the inflammatory mediators.

RESULTS

The onset of IA hyperthermia, an index of inflammation, was evident by 90 minutes post-carra and reached a maximum of 1.2 degrees C above core temperature by 150 minutes post-carra. Intra-articular levels of iPGE2 and iBK peaked at 240 minutes (3.35+/-1.9 nmol/L) and 270 minutes (0.45+/-0.29 nmol/L), respectively, after the induction of inflammation in the superior joint space. iBK levels within the superior joint space were significantly decreased by dexamethasone and ketorolac. Ketorolac (50 microg) decreased iBK and iPGE2 levels when given IA or IP. With dexamethasone (3 mg), the levels of iBK were significantly reduced, and iPGE2 levels were not changed.

CONCLUSIONS

This study shows that the rabbit model of TMJ inflammation, with concurrent collection of iBK and iPGE2 via microdialysis, is a reproducible and reliable method to investigate the time course of inflammatory mediator release and their modulation by either the local or systemic administration of anti-inflammatory medications.

The use of opioid drugs in management of chronic orofacial pain

The use of opioid analgesics for the management of patients with chronic pain is controversial. However, randomized and double-blind clinical trials have shown that in select groups of patients with chronic pain, the daily administration of oral opioids decreases pain levels and improves quality of life. This article provides a review of the most recent basic and clinical research supporting the rationale for the use of opioids in a select group of patients with chronic orofacial pain. Critical to the employment of this technique are proper patient evaluation and use of comprehensive management strategies. This management scheme should be reserved for patients with chronic pain that is refractory to most nonopioid therapy. The primary reason for the clinician's reluctance to initiate long-term opioid therapy for their patients with chronic pain is the potential risk of developing opioid tolerance, dependence, or addiction. In contrast to these beliefs, studies have shown a nonexistent to low risk of opioid dependence or addiction behavior with administration of scheduled oral opioids in chronic pain patients. It is essential that potential patients for this type of therapy have been carefully screened and have not had a history of drug addiction. The criteria to be evaluated when considering opioid therapy for chronic orofacial pain control include 1) inadequate pain diminution from prior nonopioid therapy, 2) negative history of substance abuse, 3) definitive determination that the pain being treated is of physiologic rather than psychologic origin, 4) a willingness to adhere to an "opioid contract" between the doctor and patient, 5) compliance with a scheduled, rather than "as needed" or "breakthrough," administration of an oral opioid, and 6) close clinical follow-up to evaluate pain relief, return to daily activities, and titration of drug levels. If these criteria are followed, administration of oral opioids may be a successful means of decreasing the patient's debilitating chronic pain to tolerable levels, enabling an improvement in the quality of life and return to function.

Heat generation in hydroxyapatite-coated implants as a result of CO2 laser application

Previous studies have demonstrated that heat may induce bone resorption and minimize the regenerative capacity of bone. This finding is of potential clinical importance because the carbon dioxide laser may often be used to surgically expose dental implants. However, little is known about the actual amount of heat generated at the implant-bone interface. This experiment measured heat generation on the surface of dental implants exposed to the carbon dioxide laser. A total of 90 trials were performed. A complete factorial (3 x 3 x 2) experimental design was used to evaluate the interactions among laser wattage output (4, 8, and 15 watts), duration of exposure time (1, 5, or 15 seconds) and variations in emission conditions (pulsed or continuous laser mode). Linear increases in temperature to temperatures greater than 50 degrees C were observed with increases in wattage output or duration of exposure time. The pulse mode generated significantly less heat. The results of this study suggest that caution should be used when using the carbon dioxide laser for second stage dental implant surgery.

Toxic systemic reactions of bupivacaine and etidocaine

Since the introduction of the long-acting agents, bupivacaine in 1983 and etidocaine in 1985, to the dental local anesthetic armamentarium, their use has increased rapidly. Although an estimated one-half million local anesthetic injections are administered in the United States daily, the actual risks of toxicity from these local anesthetic injections remain unknown. Our review of the literature reveals numerous cases of severe adverse reactions associated with the administration of bupivacaine and etidocaine. This case review includes several fatalities, even after injection of only very small amounts of these long-acting local anesthetics. Results from animal studies have demonstrated increased systemic toxicity associated with bupivacaine and etidocaine as compared with lidocaine, the most extreme of which include severe central nervous system and cardiovascular reactions, eventually leading to hemodynamic instability, cardiovascular collapse, and death. Although many aspects of the side effect profile of bupivacaine and etidocaine are common to all local anesthetics, the physiochemical properties of the long-acting local anesthetics enhance their adverse effects. It is therefore imperative that the dental practitioner who uses these long-acting local anesthetics become familiar with the adverse reactions of these drugs.

Pharmacology of peripheral neuropeptide and inflammatory mediator release

Research conducted in the last 10 years has increased our knowledge on pain mechanisms substantially. Although many local tissue mediators, including neuropeptides, are known to exert pro-inflammatory effects, comparatively little is known about the actual tissue levels of these inflammatory mediators and their pharmacologic regulation. This article describes two new methods, clinical microdialysis and superfusion of dental pulp, which provide data on the pharmacology of peripheral neuropeptide and inflammatory mediator release. Collectively, these methods provide a biochemically based approach toward determining the mechanisms and management of orofacial pain.

Ameloblastic fibro-odontoma of the anterior maxilla. Report of a case

The ameloblastic fibro-odontoma is an infrequently encountered mixed odontogenic tumor. There has been much discussion in the literature regarding its proper classification. It is characteristically slow growing and asymptomatic, and occurs most commonly in the posterior region. It shows a slight predilection for boys with a mean age of roughly 10 years. A case in a 9-month-old boy of an exophytic, rapidly growing ameloblastic fibro-odontoma of the anterior maxilla is reported.

Pentazocine analgesia: is there a niche for Talwin Nx?

Pentazocine can be a useful analgesic agent for the management of acute dental pain. It has both central and peripheral opioid activity. In clinical trials, analgesic compounds containing pentazocine have been shown to effectively relieve moderate-to-severe pain. It is an appropriate analgesic for the codeine-sensitive patient. Because of a change in formulation, the potential for abuse has been minimized. Although there is a possibility that the drug may have a psychotomimetic effect, the incidence is low and should not preclude use. Analgesic compounds containing pentazocine are clinically appropriate for the management of surgically induced dental pain.

Effect of flurbiprofen on tissue levels of immunoreactive bradykinin and acute postoperative pain

This study evaluates whether preoperative administration of flurbiprofen alters the levels of immunoreactive bradykinin (iBK) peripherally released into inflamed tissue. Thirty-six patients were randomly treated on a double-blind basis with either flurbiprofen (100 mg) or placebo before the surgical extraction of impacted third molars. Microdialysis probes were implanted into the surgical site and dialysates, and subjective pain reports were collected every 15 minutes for 4 hours after surgery. Tissue levels of iBK were measured using a radioimmunoassay. Preoperative administration of flurbiprofen significantly reduced patients' reports of pain from 120 to 240 minutes after surgery and blocked the peak increase in tissue levels of iBK (135 to 150 minutes after surgery). Although these results indicate that flurbiprofen has an "antibradykinin" effect, the analgesia both preceded and persisted beyond the inhibition of iBK levels. Accordingly, an antibradykinin effect may only partly contribute to flurbiprofen analgesia. The data are consistent with the hypothesis that prostaglandins contribute to the peak release of iBK owing to the potent inhibition of prostaglandin synthesis by flurbiprofen, but other yet unidentified mediators are also required for the sustained release of this inflammatory mediator into the surgical field.

Skeletal stability following mandibular advancement and rigid fixation

Twenty non-growing subjects underwent sagittal ramus osteotomies and rigid fixation. Cephalograms were analyzed before surgery, immediately after surgery and at least six months following surgery to evaluate skeletal stability. A mean horizontal relapse of 0.42 mm (8%) and a mean vertical increase in lower face height of 0.2 mm were found six months after surgery. Both were statistically insignificant. The mean backward rotation of the mandible of 0.55 degrees found six months after surgery was statistically significant (P less than 0.015), but was considered to be clinically insignificant. The results of this study show that surgical mandibular advancement with rigid fixation is a very reliable and stable procedure.