Retrospective comparative ten-year study of cumulative survival rates of remaining teeth in large edentulism treated with implant-supported fixed partial dentures or removable partial dentures

PURPOSE

This study aimed to compare the survival rates of remaining teeth between implant-supported fixed dentures (IFDs) and removable partial dentures (RPDs) in patients with large edentulous cases. The second goal was to assess the risk factors for remaining tooth loss.

MATERIALS AND METHODS

The study subjects were selected among those who received prosthodontic treatment at Okayama University Dental Hospital for their edentulous space exceeding at least four continuous missing teeth. Twenty-one patients were included in the IFD group and 82 patients were included in the RPD group. Survival rates of remaining teeth were calculated in three subcategories: (1) whole remaining teeth, (2) adjacent teeth to intended edentulous space, and (3) opposing teeth to intended edentulous space.

RESULTS

The ten-year cumulative survival rate of the whole remaining teeth was significantly higher in the IFD group (40.0%) than in the RPD group (24.4%). On the other hand, there was no significant difference between two groups in the survival rate of teeth adjacent or opposing to intended edentulous space. A Cox proportional hazard analysis revealed that RPD restoration and gender (male) were the significant risk factors for remaining tooth loss (whole remaining teeth).

CONCLUSIONS

These results suggest that IFD treatment can reduce the incidence of remaining tooth loss in large edentulous cases.

A problem-based learning tutorial for dental students regarding elderly residents in a nursing home in Japan

This educational trial was an eight-day problem-based learning (PBL) course for fourth-year predoctoral students at Okayama University's dental school who interviewed elderly residents living in a nursing home. The purpose of this PBL course was to introduce geriatric dentistry to the students by allowing them, independently, to discover the clinical problems of elderly patients as well as the solutions. The sixty-five students were divided into nine small groups and received patient information (age, gender, degree of care needed, medical history, food type, medications, and oral condition) in datasheets before visiting the nursing home. Each group of students directly interviewed one patient and the caregivers and identified the patient's medical, psychological, and social problems. After the interview, the students participated in a PBL tutorial to delineate a management approach for the patient's problems. To measure the efficacy of this program, the students completed a questionnaire before and after the course regarding their level of understanding of and attitudes toward geriatric dentistry, clinical research, and self-study. The results showed that student's perceptions of their knowledge about and attitudes toward oral health care for the elderly significantly increased after the PBL course, which suggests that such tutorials should be an option for dental curricula.

Matrix metalloproteinase-8 is the major potential collagenase in active peri-implantitis

PURPOSE

Current clinical procedures to control or regenerate bone loss due to peri-implantitis are not predictable neither accomplish complete resolution. Therefore, early detection of the onset and the active periods of bone loss are crucial for prevention of extensive peri-implant bone resorption. This study aimed to determine a possible association between the presence of collagenases (MMP-1, MMP-8 and MMP-13) in peri-implant sulcular fluid (PISF) and active periods of bone loss by annually adjusted vertical bone loss (AVBL) measurements.

METHODS

Intended sample consisted of 76 consecutive patients who received oral implant treatment at the Fixed Prosthodontic Clinic of Okayama University Hospital from 1990 to 2000. Twelve subjects were lost to follow-up or refused to participate. Consequently, the actual sample consisted of 64 patients who were followed-up for at least one year. Those patients with AVBL>0.6mm were included in the severe peri-implantitis group, and randomly selected, age-, gender- and implantation site-matched healthy patients (AVBL<0.3mm) comprised the control group. PISF samples were collected from both groups and further analyzed by western blot for detection of collagenases.

RESULTS

Four patients presented severe peri-implantitis. MMP-8 was the only collagenase detected in peri-implant sites with ongoing bone loss. PISF samples from control group showed no positive reactions to any collagenase.

CONCLUSION

This study showed MMP-8 as a possible marker for progressive bone loss in peri-implantitis.

Occlusal dysesthesia: a qualitative systematic review of the epidemiology, aetiology and management

Occlusal dysesthesia refers to a persistent complaint of uncomfortable bite sensation with no obvious occlusal discrepancy. This systematic review aimed to draw a picture of such patients, to present an agreement of previously reported diagnostic criteria and to analyse the evidence level of the recommended management approaches. An electronic search for all relevant reports on occlusal dysesthesia was thoroughly performed based on previous nomenclatures (e.g. phantom bite, occlusal hyperawareness) in PubMed and The Cochrane Library in July, 2011. A total of 84 reports were matched, among which only 11 studies were included after a two-step (abstract and detailed full-text revision) screening process. Additionally, a thorough manual review of reference lists of the included reports enabled the inclusion of two additional studies. Data analysis revealed that 37 occlusal dysesthesia patients presented a mean age of 51.7 ± 10.6 years and were predominantly women (male/female: 1/5.1) with symptom duration of more than 6 years (average: 6.3 ± 7.5 years) and with concomitant psychological disturbances (e.g. mood disorders, somatoform disorders, personality disorders). Only four authors presented diagnostic criteria for occlusal dysesthesia, which served as the basis for an agreement in the diagnostic criteria. Treatment approaches included psychotherapy, cognitive/behaviour therapy, splint therapy and prescription of anti-depressants or anti-anxiety drugs. Classification of evidence level of management approaches, however, revealed that most of them were expert opinions with single- or multiple-case report(s). Future studies are necessary for a deeper understanding of the mechanisms behind the occlusal dysesthesia symptoms, and consequently, for improvements in evidence-based management approaches.

Intradermal injection of Botulinum toxin type A alleviates infraorbital nerve constriction-induced thermal hyperalgesia in an operant assay

Recent studies have shown that infraorbital nerve constriction (IoNC)-induced mechanical allodynia has been attenuated by administration of highly purified 150-kDa Botulinum neurotoxin type A (BoNT/A). Here, we extend these studies to determine whether BoNT/A could attenuate IoNC-induced symptoms of thermal hyperalgesia. Instead of testing head withdrawal thresholds, a thermal operant assay was used to evaluate cortical processing of sensory input following IoNC. In this assay, a fasted rat's desire to obtain a food reward (sweetened condensed milk) is coupled to its ability to tolerate facial contact with a warm (45 °C) thermode. Bilateral IoNC decreased the ratio of thermode contact duration/event, which is an indicative of thermal hyperalgesia. BoNT/A injection intradermally in the area of infraorbital nerve (IoN) innervation 7 days after IoNC resulted in decreased number of facial contacts and increased the ratio of contact duration/event (measured at 14 days after IoNC). The BoNT/A (2-200 pg) effects were dose dependent and statistically significant at 100 and 200 pg (P < 0·05). Complete reversal of thermal hyperalgesia symptoms was obtained with a 200-pg dose, without affecting sham rat behaviour. Off-site (neck) injection of BoNT/A did not relieve thermal hyperalgesia, while co-injection of BoNT/A with a neutralising antibody in the area of IoN innervation prevented relief of thermal hyperalgesia. Neither IoNC nor BoNT/A injection affected operant assay parameters with a 24 °C thermode, indicating selectivity of thermal hyperalgesia measurements. These results strongly suggest that intradermal injection of BoNT/A in the area of IoN innervation alleviates IoNC-induced thermal hyperalgesia in an operant assay.

Guidelines and recommendations for assessment of somatosensory function in oro-facial pain conditions--a taskforce report

The goals of an international taskforce on somatosensory testing established by the Special Interest Group of Oro-facial Pain (SIG-OFP) under the International Association for the Study of Pain (IASP) were to (i) review the literature concerning assessment of somatosensory function in the oro-facial region in terms of techniques and test performance, (ii) provide guidelines for comprehensive and screening examination procedures, and (iii) give recommendations for future development of somatosensory testing specifically in the oro-facial region. Numerous qualitative and quantitative psychophysical techniques have been proposed and used in the description of oro-facial somatosensory function. The selection of technique includes time considerations because the most reliable and accurate methods require multiple repetitions of stimuli. Multiple-stimulus modalities (mechanical, thermal, electrical, chemical) have been applied to study oro-facial somatosensory function. A battery of different test stimuli is needed to obtain comprehensive information about the functional integrity of the various types of afferent nerve fibres. Based on the available literature, the German Neuropathic Pain Network test battery appears suitable for the study of somatosensory function within the oro-facial area as it is based on a wide variety of both qualitative and quantitative assessments of all cutaneous somatosensory modalities. Furthermore, these protocols have been thoroughly described and tested on multiple sites including the facial skin and intra-oral mucosa. Standardisation of both comprehensive and screening examination techniques is likely to improve the diagnostic accuracy and facilitate the understanding of neural mechanisms and somatosensory changes in different oro-facial pain conditions and may help to guide management.

A 15-year clinical comparative study of the cumulative survival rate of cast metal core and resin core restorations luted with adhesive resin cement

PURPOSE

The aim of this study was to compare the core survival rates (CSRs) of cast metal versus resin core restorations luted with adhesive resin cement, as well as to determine the risk factors for core failure.

MATERIALS AND METHODS

Nine hundred ninety-one patients (2,124 cores) who received either cast metal or resin cores luted with adhesive resin cement at the Fixed Prosthodontic Clinic of Okayama University Dental Hospital between April 1988 and December 1991 and whose structured clinical core record was filled appropriately comprised the study subjects. The clinical core record included information regarding patient age, sex, core restoration type, tooth location, tooth type, remaining coronal dentin, and root canal form. CSRs, as well as causes for failure, were analyzed 15 years postinsertion. Since 381 patients lacked data regarding predictors for core failure, a subsample of 610 patients (1,053 cores) was used for the subsequent risk factor analysis.

RESULTS

The cumulative CSR of resin cores (78.7%) was significantly higher than that of cast metal cores (55.4%; log-rank test, P < .0001). The Cox proportional hazards test revealed that sex (male, P < .0001), absence of remaining coronal dentin (P = .0057), core restoration type (cast metal, P = .0186), and higher age at core insertion (P = .0380) were significant predictors for core failure. The incidence of complications, such as core loosening (P = .0016) and tooth extraction (P < .0001), was significantly higher in cast metal cores.

CONCLUSIONS

Cast metal cores were associated with a significantly lower CSR than resin cores, and significant risk factors for core failure were sex (male), absence of remaining coronal dentin, core restoration type (cast metal), and higher age at core insertion.

The relationship between temporomandibular joint pathosis and muscle tenderness in the orofacial and neck/shoulder region

OBJECTIVE

The objective of this study was to investigate the association between TMJ pain/disk pathosis and the muscle tenderness pattern in the orofacial and neck/shoulder region.

STUDY DESIGN

One hundred seventy-one TMD patients were divided into 4 groups, including group 1: patients with painful unilateral TMJ disk displacement (DD); group 2: patients with painless unilateral TMJ DD; group 3: patients with painless bilateral TMJ DD; and group 4: patients with a bilateral normal TMJ disk position (n = 41). Each subject underwent muscle palpation and the side-by-side number of muscle tenderness points was combined as the number of muscle tenderness points on each side. Within each group, DD with and without reduction subjects were separated into subgroups and then were analyzed.

RESULTS

In group 1, the median muscle tenderness points on the side with painful TMJ DD without reduction was significantly higher than on the normal side (P = .019), whereas the palpation scores for painless DD patients showed no significant difference between the DD and normal sides.

CONCLUSIONS

These results indicated painful disk displacement to possibly be correlated with ipsilateral muscle tenderness.

Increased peripheral nerve excitability and local NaV1.8 mRNA up-regulation in painful neuropathy

BACKGROUND

Neuropathic pain caused by peripheral nerve injury is a chronic disorder that represents a significant clinical challenge because the pathological mechanisms have not been fully elucidated. Several studies have suggested the involvement of various sodium channels, including tetrodotoxin-resistant NaV1.8, in affected dorsal root ganglion (DRG) neurons. We have hypothesized that altered local expression of NaV1.8 in the peripheral axons of DRG neurons could facilitate nociceptive signal generation and propagation after neuropathic injury.

RESULTS

After unilateral sciatic nerve entrapment injury in rats, compound action potential amplitudes were increased in both myelinated and unmyelinated fibers of the ipsilateral sciatic nerve. Tetrodotoxin resistance of both fiber populations and sciatic nerve NaV1.8 immunoreactivity were also increased. Further analysis of NaV1.8 distribution revealed that immunoreactivity and mRNA levels were decreased and unaffected, respectively, in the ipsilateral L4 and L5 DRG; however sciatic nerve NaV1.8 mRNA showed nearly an 11-fold ipsilateral increase. Nav1.8 mRNA observed in the sciatic nerve was likely of axonal origin since it was not detected in non-neuronal cells cultured from nerve tissue. Absence of changes in NaV1.8 mRNA polyadenylation suggests that increased mRNA stability was not responsible for the selective peripheral mRNA increase. Furthermore, mRNA levels of NaV1.3, NaV1.5, NaV1.6, NaV1.7, and NaV1.9 were not significantly different between ipsilateral and contralateral nerves. We therefore propose that selective NaV1.8 mRNA axonal transport and local up-regulation could contribute to the hyperexcitability of peripheral nerves in some neuropathic pain states.

CONCLUSION

Cuff entrapment injury resulted in significantly elevated axonal excitability and increased NaV1.8 immunoreactivity in rat sciatic nerves. The concomitant axonal accumulation of NaV1.8 mRNA may play a role in the pathogenesis of this model of neuropathic pain.

Altered ATP release and metabolism in dorsal root ganglia of neuropathic rats

Background

Adenosine 5'-triphosphate (ATP) has a ubiquitous role in metabolism and a major role in pain responses after tissue injury. We investigated the changes in basal and KCl-evoked ATP release from rat dorsal root ganglia (DRG) after peripheral neuropathy induction by unilateral sciatic nerve entrapment (SNE).

Results

After SNE, rats develop long-lasting decreases in ipsilateral hindpaw withdrawal thresholds to mechanical and thermal stimulation. At 15–21 days after neuropathy induction, excised ipsilateral L4-L5 DRG display significantly elevated basal extracellular ATP levels compared to contralateral or control (naive) DRG. However, KCl-evoked ATP release is no longer observed in ipsilateral DRG. We hypothesized that the differential SNE effects on basal and evoked ATP release could result from the conversion of extracellular ATP to adenosine with subsequent activation of adenosine A1 receptors (A1Rs) on DRG neurons. Adding the selective A1R agonist, 2-chloro-N⁶-cyclopentyladenosine (100 nM) significantly decreased basal and evoked ATP release in DRG from naïve rats, indicating functional A1R activation. In DRG ipsilateral to SNE, adding a selective A1R antagonist, 8-cyclopentyl-1,3-dipropylxanthine (30 nM), further increased basal ATP levels and relieved the blockade of KCl-evoked ATP release suggesting that increased A1R activation attenuates evoked ATP release in neurons ipsilateral to SNE. To determine if altered ATP release was a consequence of altered DRG metabolism we compared O₂ consumption between control and neuropathic DRG. DRG ipsilateral to SNE consumed O₂ at a higher rate than control or contralateral DRG.

Conclusion

These data suggest that peripheral nerve entrapment increases DRG metabolism and ATP release, which in turn is modulated by increased A1R activation.

Bidirectional alterations of hippocampal cannabinoid 1 receptors and their endogenous ligands in a rat model of alcohol withdrawal and dependence

BACKGROUND

The hippocampus is strongly implicated in memory processes and contains high concentrations of both cannabinoid receptors and their endogenous ligands. Chronic alcohol consumption impairs a variety of cognitive and performance tasks, including memory and learning. As the activation of cannabinoid receptors by their endogenous ligands modulates hippocampal neurotransmission, we hypothesized that the impaired memory and learning in alcoholism may be due to alterations in the hippocampal endocannabinoid system.

METHODS

We used the rat chronic intermittent ethanol (CIE) model for alcohol withdrawal and dependence which involves intermittent episodes of ethanol intoxication (60 doses) and withdrawal (approximating binge drinking episodes in humans). We measured the levels of cannabinoid 1 receptor (CB1R) protein (Western blot using a C-terminal-directed antibody), CB1R mRNA (real-time RT-PCR), CB1R localization (immunocytochemistry), tissue levels of the endocannabinoids N-arachidonoylethanolamine/anandamide (AEA) and 2-arachidonoylglycerol (2-AG), and function (patch-clamp recordings of depolarization-induced suppression of inhibition (DSI), as well as effects of CB1R agonist WIN 55,212-2 on inhibitory currents) in the hippocampus of CIE rats and their saline-treated controls.

RESULTS

Results were obtained in saline and CIE-treated rats after 2 and 40 days of withdrawal (DW) from their respective treatments. In 2 DW CIE rats, CB1R mRNA and protein levels were decreased by 27% (p<0.05) compared with saline controls. Surprisingly, in 40 DW CIE rats, CB1R mRNA increased by 100% and protein increased by 21%, confirmed by immunohistochemistry. Hippocampal [2-AG] increased in both 2 and 40 DW CIE rats; [AEA] increased only at 40 DW. Hippocampal DSI of CIE rats was significantly reduced at 2 DW but not at 40 DW. The CB1R agonist WIN 55,212-2 (0.5 microM) produced a significantly greater decrease in the frequency of spontaneous inhibitory currents from saline-treated rats compared with CIE rats at 2 DW, but not at 40 DW.

CONCLUSIONS

These data demonstrate that CIE treatment and withdrawal transiently down-regulates hippocampal CB1 Rs followed by a long-term up-regulation, including increased levels of endogenous cannabinoids. These findings are consistent with our hypothesis and suggest that long-term up-regulation of hippocampal CB1Rs may contribute to the long-term cognitive impairments in alcoholism. The data further suggest that the effectiveness of CB1R blockade in decreasing alcohol consumption may be greater after protracted abstinence from alcohol.

Comparison of inter-twin concordance in symptoms of temporomandibular disorders: a preliminary investigation in an adolescent twin population

There is controversy as to the genetic contribution to the pathogenesis of temporo-mandibular disorders (TMD). Several reports reveal a marked familial aggregation in the signs and symptoms of TMD, while others do not. Therefore, our goal was to investigate the hypothesis using a sophisticated research design, which was a well-known genetic survey inter-twin concordance assessment in the symptoms of TMD. This study is the first step to survey TMD symptoms of a twin group in junior and high schools as a preliminary trial. The 63 twins were asked to participate in this study in junior and senior high schools affiliated with the University of Tokyo, Japan, schools which kept ten twins in each grade for the purpose of several genetic survey programs. After excluding incomplete filling out of questionnaire sheets and data from male-female pairs, 43 monozygotic (MZ) (15.3+/-1.7 yrs, male/female = 17/26 pairs) and nine dyzygotic (DZ) (15.2+/-1.8 yrs, male/female = 6/3 pairs) twins were studied. Outcomes consisted of a prevalidated 14-item self-administered questionnaire, which assessed proband- and pair-wise concordance levels in the MZ and DZ twins. These results demonstrated that the MZ twins had a higher tendency of inter-twin concordance than DZ twins in terms of jaw pain in wide mouth opening (proband-wise concordance = 66.7% in MZ, 0% in DZ), difficulty in mouth opening (20% in MZ, 0% in DZ) and difficulty in mouth closing (50.0% in MZ, 33.3% in DZ), while there was no significant difference between the MZ and DZ concordance levels in other general health-related and behavior-related items, except toothache. However, the pair-wise concordance rates of jaw pain in wide mouth opening and difficulty in mouth opening in the MZ twins were not significantly higher compared to the DZ rate. Possibly, a genetic factor contributed to the pathogenesis of TMD in an adolescent population. The sample size needs to be increased, and there are plans to survey the next sample in the same schools.

Responses of the hypothalamic-pituitary-adrenal axis and pain threshold changes in the orofacial region upon cold pressor stimulation in normal volunteers

AIM

This study focused on the relationship between the HPA axis function and the heat pain threshold in the orofacial region upon cold pressor (CP) stimulation.

METHODS

Ten healthy male individuals participated in this study. CP stimulation was applied to each participant, and their peripheral blood was collected 5 min before, during and 5, 15, 30, 45, 60 min after receiving CP. In addition, 5 of those 10 participants were selected at random and they experienced a mock CP trial on different days. The heat pain thresholds on the facial skin about 10mm anterior to the right external auditory canal (trigeminal V2 region) in each subject were simultaneously recorded 5 min before and 5, 30, 60 min after CP stimulation. The blood pressure and heart rate were continuously monitored throughout the course of the CP and mock trials using an electric blood pressure meter.

RESULTS

Significant increases in the plasma concentration of cortisol, beta-endorphin and ACTH were induced by CP stimulation, while no significant increases were observed under the mock trial conditions. The blood pressure and heart rate showed concomitant increases during CP stimulation. In addition, the heat pain threshold in the orofacial region significantly increased after receiving CP stimulation. These results suggest that CP stimulation activated the HPA axis thereby increasing the heat pain threshold in the orofacial region in healthy individuals.

CONCLUSIONS

This observed pain threshold increase might be due to the activation of an endogenous opioid system, such as increase in the circulating beta-endorphin levels.

Two types of neurotransmitter release patterns in isolectin B4-positive and negative trigeminal ganglion neurons

Mammalian nociceptors have been classified into subclasses based on differential neurotrophin sensitivity and binding of the plant isolectin B4 (IB4). Most of the nerve growth factor-responsive IB4-negative (IB4 (-)) nociceptors contain neuropeptides such as substance P and calcitonin gene-related peptide, whereas the glial-derived neurotrophic factor-responsive IB4-positive (IB4 (+)) neurons predominantly lack such neuropeptides. We hypothesized that the differences in neuropeptide content between IB4 (+) and (-) neurons might be reflected in differences in stimulated exocytosis and/or endocytosis. To address this, we monitored the secretory activity of acutely dissociated neurons from adult rat trigeminal ganglia (TRG) using cell membrane capacitance (Cm) measurements and the fluorescent membrane-uptake marker N-(3-triethylammoniumpropyl)-4-(6-(4-(diethylamino)phenyl)hexatrienyl)pyridinium dibromide (FM4-64). Cm measurements were performed under whole-cell voltage clamp and neurons were depolarized from -75 mV to +10 mV to elicit exocytosis. Both types of TRG neurons showed similarly-sized, calcium-dependent increases in Cm, demonstrating that both IB4 (+) and (-) TRG neurons are capable of stimulated exocytosis. However, the peak Cm of IB4 (+) neurons decayed faster toward baseline than that of IB4 (-) neurons. Also, IB4 (+) neurons had stable Cm responses to repeated stimuli whereas IB4 (-) neurons loss their secretory response during repeated stimulation. These data suggested that the IB4 (+) neurons possess a faster rate of endocytosis and vesicle replenishment than IB4 (-) neurons. To test this, we measured vesicle trafficking with the fluorescent membrane dye FM4-64. FM4-64 staining showed that IB4 (-) neurons exhibit a larger pool of endocytosed vesicles than IB4 (+) neurons because the peak fluorescence increases in IB4 (-) neurons were larger but slower than in IB4 (+) neurons. However, the recycled vesicles were released faster in IB4 (+) compared with IB4 (-) neurons. Taken together these data suggest that the IB4 (+) TRG neurons have faster exocytosis and endocytosis than the IB4 (-) neurons.

Site-specific increases in peripheral cannabinoid receptors and their endogenous ligands in a model of neuropathic pain

Selective activation of the peripheral cannabinoid receptor 1 (CB1R) has been shown to suppress neuropathic pain symptoms in rodents. However, relatively little is known about changes in CB1R and its endogenous ligands during development or maintenance of neuropathic pain. Using immunohistochemistry, Western blot, real-time reverse transcription polymerase chain reaction, as well as liquid chromatography/mass spectrometry, we studied the changes in CB1Rs and endocannabinoids N-arachidonoylethanolamine/anandamide (AEA) and 2-arachidonoylglycerol (2-AG) in rat lumbar (L4 and L5) dorsal root ganglia (DRG) after neuropathic pain induction (L5 spinal nerve ligation: SNL). Immunohistochemistry revealed that in control rats, CB1R is expressed in the majority (76-83%) of nociceptive neurons as indicated by co-labeling with isolectin B4 (IB4) or antibodies recognizing transient receptor potential vanilloid (TRPV1), calcitonin gene related peptide (CGRP), and the NR2C/2D subunits of the N-methyl-D-aspartate receptor. After L5 SNL, CB1R mRNA and protein increases in the ipsilateral uninjured L4 DRG whereas the percentages of CB1R immunoreactive (CB1R-ir) neurons remain unchanged in L4 and L5 DRG. However, for these CB1R-ir neurons, we observe significant increases in percentage of TRPV1-ir cells in ipsilateral L4 DRG, and decreases in percentage of IB4- and CGRP-co-labeled cells in ipsilateral L5 DRG. Levels of both AEA and 2-AG increase significantly only in the ipsilateral L5 DRG. These results are consistent with the preserved analgesic effects of cannabinoids in neuropathic pain and provide a rational framework for the development of peripherally acting endocannabinoid-based therapeutic interventions for neuropathic pain.

HSV-1-mediated NGF delivery delays nociceptive deficits in a genetic model of diabetic neuropathy

A previous phase III clinical trial failed to show significant therapeutic benefit of repeated subcutaneous nerve growth factor (NGF) administration in the treatment of diabetic neuropathy. Animal studies have since shown that site-specific viral-mediated expression of NGF in the lumbar dorsal root ganglia prevents peripheral nerve dysfunction associated with chemically induced neuropathy. Using a Herpes simplex virus expression vector, we have investigated the effect of localized NGF expression in a genetic mouse model of progressive diabetic neuropathy, the +/+ Leprdb mouse. We found that site-specific delivery of NGF initially delayed the appearance of hypoalgesia, assessed by the Hargreaves test, by 1 month and effectively attenuated this deficit for 2 months over the approximately 10 months normal life-span of these animals. Once the disease progressed into its more severe stages, NGF, although still capable of altering the electrophysiological profile of the sensory A- and C-fibers and influencing the expression of p75 and substance P in the dorsal root ganglia, could no longer maintain normal nociception. These data suggest that maximal therapeutic benefit in future NGF-based gene therapy trials will be gained from early applications of such viral-mediated neurotrophin delivery.

Characterization of Patients With Disc Displacement Without Reduction Unresponsive to Nonsurgical Treatment: A Preliminary Study

PURPOSE

Arthrocentesis and arthroscopic lysis and lavage have been described as effective treatment modalities for temporomandibular joint (TMJ) disc displacement without reduction (DDw/oR). More commonly, nonsurgical intervention is offered as the desired first-line treatment; however, a certain group of DDw/oR patients receiving nonsurgical treatment may remain unresponsive, thereby prolonging suffering and treatment dissatisfaction. The purpose of this study is to characterize these nonresponders by evaluating the characteristic pretreatment findings peculiar to this group.

PATIENTS AND METHODS

This retrospective study was based on the review of pretreatment clinical and magnetic resonance imaging (MRI) findings of 52 DDw/oR patients who were treated with stabilization appliance, jaw-stretching exercise, and nonsteroidal anti-inflammatory medication. On the last treatment visit, each patient was classified as either a responder (R) or nonresponder (NR) based on the satisfaction or dissatisfaction with the treatment received, respectively. Pretreatment data were then examined and analyzed by logistic regression to identify which clinical and MRI findings were specifically related to the NR group.

RESULTS

Logistic regressions indicated that NR had significantly higher odds ratio for pretreatment pain-free mouth opening of less than 30 mm (odds ratio [OR] = 7.385), "stuck" disc (OR = 4.521), and unchanged disc shape during mouth opening (OR = 4.050). Multiple logistic regression analyses revealed that these factors combined gave the highest likelihood ratio of 15.90 ( P = .001), indicating a strong possibility that these factors are associated with the NR group.

CONCLUSIONS

Nonresponders can be characterized by their pretreatment pain-free mouth opening (<30 mm) in combination with MRI confirmation of "stuck" disc and unchanged disc shapes during mouth opening.