Critical bending moment of four implant-abutment interface designs.

PURPOSE: Critical bending moment (CBM), defined as the bending moment at which the external nonaxial load applied overcomes screw joint preload and causes loss of contact between the mating surfaces of the implant screw joint components, was measured for four different implants and their single-tooth replacement abutments. MATERIALS AND METHODS: CBM at the implant-abutment screw joint for four implant-abutment test groups was measured in vitro at 80%, 100%, and 120% of the manufacturers' recommended torque levels. Regular-platform implants with their corresponding single-tooth abutments were used. Microstrain was measured while known loads were applied to the abutment at known distances from the implant-abutment interface. Strain instrumentation was used to record the strain data dynamically to determine the point of gap opening. All torque applications and strain measurements were repeated five times for the five samples in each group. RESULTS: For the Branemark/CeraOne assemblies, the mean CBMs were 72.14 Ncm, 102.21 Ncm, and 119.13 Ncm, respectively, at 80%, 100%, and 120% of the manufacturer's recommended torque. For the Replace/Easy assemblies, mean CBMs were 86.20 Ncm, 109.92 Ncm, and 120.93 Ncm; for the Biomet 3i/STA assemblies, they were 67.97 Ncm, 83.14 Ncm, and 91.81 Ncm; and for the Lifecore/COC assemblies, they were 58.32 Ncm, 76.79 Ncm, and 78.93 Ncm. Two-way analysis of variance revealed significant effects for the test groups and torque levels. Subsequent tests confirmed that significant differences existed between test groups and torque levels. CONCLUSION: The results appear to confirm the primary role of the compressive preload imparted by the abutment screw in maintaining screw joint integrity. CBM was found to differ among implant systems and torque levels. Torque levels recommended by the manufacturer should be followed to ensure screw joint integrity.

Load fatigue performance of implant-ceramic abutment combinations.

PURPOSE: The mechanical properties and functional load performance of implant restorations coupled with metal abutments have been studied widely. However, the fatigue performance of the newly introduced ceramic implant abutments has not been reported. This study investigated the load fatigue performance of four implant systems and their corresponding zirconia ceramic abutments at the manufacturers' recommended torque levels. MATERIALS AND METHODS: Three different diameters (narrow, regular, and wide) of the Replace Select and Branemark systems and two different diameters (4.1 mm and 5.0 mm) of the Osseotite NT and Osseotite NT Certain systems provided 10 implant-abutment test groups. The abutments tested were Procera zirconia, Zireal posts, and Certain ZiReal posts. Each group had a sample size of five. A rotational load fatigue machine applied a 21-N load to the specimens at an angle of 45 degrees to produce an effective bending moment of 35 Ncm at a test frequency of 10 Hz. The number of cycles to failure was recorded. RESULTS: Twenty-nine of the 50 implant-abutment combinations tested failed. Eighteen abutments fractured. Seven implant fractures and 16 abutment screw fractures were seen, along with some damage to the implant platform in some specimens. No significant difference was seen between the implant systems, but significant differences were observed between the implant diameters. A subsequent one-way analysis of variance revealed statistically significant differences between the 10 implant-abutment test groups. CONCLUSIONS: Rotational load fatigue testing performance of zirconia abutments is dependent on the abutment diameter. Failure modes varied according to system design characteristics.

Load fatigue performance of four implant-abutment interface designs: effect of torque level and implant system.

PURPOSE: Biomechanical load-fatigue performance data on single-tooth implant systems with different implant-abutment interface designs is lacking in the literature. This study evaluated the load fatigue performance of 4 implant-abutment interface designs (Brånemark-CeraOne; 3i Osseotite-STA abutment; Replace Select-Easy abutment; and Lifecore Stage-1-COC abutment system). The number of load cycles to fatigue failure of 4 implant-abutment designs was tested with a custom rotational load fatigue machine. The effect of increasing and decreasing the tightening torque by 20% respectively on the load fatigue performance was also investigated. MATERIALS AND METHODS: Three different tightening torque levels (recommended torque, -20% recommended torque, +20% recommended torque) were applied to the 4 implant systems. There were 12 test groups with 5 samples in each group. The rotational load fatigue machine subjected specimens to a sinusoidally applied 35 Ncm bending moment at a test frequency of 14 Hz. The number of cycles to failure was recorded. A cutoff of 5 x 10(6) cycles was applied as an upper limit. RESULTS: There were 2 implant failures and 1 abutment screw failure in the Brånemark group. Five abutment screw failures and 4 implant failures was recorded for the 3i system. The Replace Select system had 1 implant failure. Five cone screw failures were noted for the Lifecore system. Analysis of variance revealed no statistically significant difference in load cycles to failure for the 4 different implant-abutment systems torqued at recommended torque level. A statistically significant difference was found between the -20% torque group and the +20% torque group (P < .05) for the 3i system. CONCLUSIONS: Load fatigue performance and failure location is system specific and related to the design characteristics of the implant-abutment combination. It appeared that if the implant-abutment interface was maintained, load fatigue failure would occur at the weakest point of the implant. It is important to use the torque level recommended by the manufacturer.

Influence of osseointegration degree and pattern on resonance frequency in the assessment of dental implant stability using finite element analysis.

PURPOSE: Resonance frequency analysis (RFA) has been widely used to predict dental implant stability by assessing conditions surrounding the implant. The aim of this study was to investigate the influence of osseointegration degree and pattern on the resonance frequency of implant-bone structure by means of finite element analysis (FEA). MATERIALS AND METHODS: A basic FEA model was created to represent a titanium implant in a portion of the maxillary bone at the left first premolar region. This model was then used to compute the vibration behaviors for 5 osseointegration degrees and 8 osseointegration pattern models using modal and harmonic analysis. RESULTS: In the arbitrarily set osseointegration pattern models, a significant influence of osseointegration degree on the resonance frequency (P < .001) could be expressed as the linear function R2 = 0.99. No significant influence from the osseointegration pattern could be observed (P = .89). While the coronal-osseointegration model had a slightly higher resonance frequency than others and the apical-osseointegration model had the lowest, the difference between the highest and lowest value was within 5% (P = .51). In the randomly set osseointegration models, the osseointegration degree had a statistically significant influence on the resonance frequency (P < .001); the pattern of random osseointegration for a certain osseointegration degree had little influence. CONCLUSION: It seems that RFA can detect implant-stability changes related to the increase in osseointegration degree. However, careful consideration should be given to its use in predicting the stability in vivo of loss of osseointegration at the marginal bone.

Three-Dimensional Accuracy of Digital Implant Impressions: Effects of Different Scanners and Implant Level.

PURPOSE: To compare the three-dimensional (3D) accuracy of conventional direct implant impressions with digital implant impressions from three intraoral scanners, as well as different implant levels-bone level (BL) and tissue level (TL). MATERIALS AND METHODS: Two-implant master models were used to simulate a threeunit implant-supported fixed dental prosthesis. Conventional test models were made with direct impression copings and polyether impressions. Scan bodies were hand-tightened onto master models and scanned with the three scanners. This was done for the TL and BL test groups, for a total of eight test groups (n = 5 each). A coordinate measuring machine measured linear distortions (dx, dy, dz), global linear distortion (dR), angular distortions (dθy, dθx), and absolute angular distortions (Absdθy, Absdθx) between the master models, test models, and .stl files of the digital scans. RESULTS: The mean dR ranged from 35 to 66 µm; mean dθy angular distortions ranged from -0.186 to 0.315 degrees; and mean dθx angular distortions ranged from -0.206 to 0.164 degrees. Two-way analysis of variance showed that the impression type had a significant effect on dx, dz, and Absdθy, and the implant level had a significant effect on dx and Absdθx (P < .05). Among the BL groups, the mean dR of the conventional group was lower than and significantly different from the digital test groups (P = .010), while among the TL groups, there was no statistically significant difference (P = .572). CONCLUSION: The 3D accuracy of implant impressions varied according to the impression technique and implant level. For BL test groups, the conventional impression group had significantly lower distortion than the digital impression groups. Among the digital test groups, the TR system had comparable mean linear and absolute angular distortions to the other two systems but exhibited the smallest standard deviations.

In Vitro Three-Dimensional Accuracy of Digital Implant Impressions: The Effect of Implant Angulation.

PURPOSE: To compare the three-dimensional (3D) accuracy of conventional impressions (CIs) with digital scans (DSs) using an intraoral scanner (IOS) with intraoral scan bodies (SBs) and varying buccolingual interimplant angulations. A secondary aim was to measure the SB machining tolerance and height with and without application of torque. MATERIALS AND METHODS: Three master models (MMs) with two implants simulating an implant-supported three-unit fixed partial denture for bone-level implants were used. The implants had buccolingual interimplant angulations of 0, 10, and 20 degrees. Test models for the CI test groups were made with impression copings and polyether impressions. SBs were attached to the MMs, tightened to 15-Ncm torque, and scanned by an IOS for the DS test groups (six test groups, n = 5). A coordinate measuring machine measured linear distortions (dx, dy, dz), 3D distortions (dR), angular distortions (dθx, dθy), and absolute angular distortions (Absdθx, Absdθy) of the physical CI test models and STL files of the DS virtual models relative to the MMs. Metrology software allowed both physical and virtual measurement of geometric targets that were comparable and allowed computation of relative displacements of implant centroids and axes. RESULTS: Mean dR ranged from 31 ± 14.2 to 45 ± 3.4 µm for DS and 18 ± 8.4 to 36 ± 6.5 µm for the CI test groups. Mean Absdθx ranged from 0.041 ± 0.0318 to 0.794 ± 0.2739 degrees for DS and 0.073 ± 0.0618 to 0.545 ± 0.0615 degrees for the CI test groups. Mean Absdθy ranged from 0.075 ± 0.0615 to 0.111 ± 0.0639 degrees for DS and 0.106 ± 0.0773 to 0.195 ± 0.1317 degrees for the CI test groups. Two-way analysis of variance showed that the impression technique (P = .012) and implant angulations (P = .007) had a significant effect on dR. Distortions were mostly in the negative direction for DS test groups. Perfect coaxiality of the SB with the implant was never achieved. For SB to implant machining tolerances, the mean absolute horizontal displacement ranged from 4 ± 1.2 to 7 ± 2.3 µm. The SB dz was -5 ± 3.2 µm, which increased in the negative direction to -11 ± 4.9 µm with torque application (P = .002). CONCLUSION: Distortions were found for both DS and CI test groups. The best accuracy was obtained with CIs for parallel implants. With angulated implants, conventional and DSs were not significantly different. Excessive torque application that causes negative dz for SB fit would position the virtual implant at a deeper location compared with reality, resulting in possible framework misfit.

Load fatigue performance of a single-tooth implant abutment system: effect of diameter.

PURPOSE: This study investigated the load fatigue performance of narrow-, regular-, and wide-diameter CeraOne (Nobel Biocare) single-tooth implants and abutments. MATERIALS AND METHODS: Five samples of each implant-abutment combination in 3 different widths were tested at 3 applied screw torque levels (recommended torque, recommended torque +20%, and recommended torque -20%). A rotational load fatigue machine was used to apply a 21-N load, at an angle of 45 degrees to the long axis of the specimens. This loading produced an effective bending moment of 35 Ncm at the abutment-implant interface. An upper cyclic limit was set at 5 x 10(6) load cycles for all specimens. RESULTS: Two-way analysis of variance revealed a significant difference between narrow-diameter and wide-diameter implant test groups but no significant difference between the 3 torque levels for each implant diameter. In the narrow-diameter group, 6 of the 15 specimens failed (5 abutment screw failures and 1 implant failure). In the regular-diameter group, 3 of the 15 specimens failed (2 implant failures and 1 abutment screw failure). There were no failures in the wide-diameter group. DISCUSSION: The results of this study indicate that the abutment screw is not the only potential failure location. The possibility of implant fracture clinically has been previously reported for prostheses supported by both single- and multiple-implant prostheses. CONCLUSION: The wide-diameter CeraOne single-tooth implant system demonstrated superior load fatigue performance. For clinical situations with significant functional loading, the narrow-diameter implants would be at a greater risk of fatigue failure.

Relationships between depression/somatization and self-reports of pain and disability.

AIMS: To examine the relationship between depression and somatization and pain during muscle and joint palpation as well as limitations related to mandibular functioning (LRMF) in patients with temporomandibular disorders. METHODS: The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) data for Axes I and II for 196 consecutive patients (56 men and 140 women) with a history of facial pain were obtained. The mean age of the predominantly Chinese patient population (83.2%) was 33.4 years (range 18 to 55 years). A computerized diagnostic system was used to collect the RDC/TMD history data. The Symptom Check List (SCL-90) depression and somatization scales were generated on-line and archived. The mean muscle pain (MP), joint pain (JP), and LRMF scores were computed with depression and somatization as main effects. Data were subjected to analysis of variance (Scheffé test) and Pearson's correlation at a significance level of .05. RESULTS: Depression scores ranged from 4.03 to 8.16 (MP), from 0.67 to 1.03 (JP), and from 0.30 to 0.38 (LRMF); somatization scores ranged from 2.64 to 7.75 (MP), from 0.58 to 1.00 (JP), and from 0.30 to 0.41 (LRMF). Interaction effects between depression and somatization were not significant. Patients with severe depression had significantly higher MP scores than normal patients or patients with moderate depression. Patients with moderate and severe somatization had significantly higher MP scores than normal patients. LRMF scores of patients with severe somatization were significantly greater than those who were normal or suffered from moderate somatization. No significant difference in JP scores was observed for depression and somatization scales. Correlations between depression/somatization and MP, JP, and LRMF scores were significant and positive but weak; coefficients ranged from 0.15 to 0.41. CONCLUSION: The results suggest that depression and somatization are related to the self-report of MP. In addition, severe somatization may be associated with an increase in jaw disability.

Prevalence of temporomandibular disorder subtypes, psychologic distress, and psychosocial dysfunction in Asian patients.

AIMS: To use the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) to investigate the physical diagnoses, psychologic distress, and psychosocial dysfunction in Asian TMD patients. The RDC/TMD Axis I and II findings were compared to those of Swedish and American TMD patients. METHODS: One hundred ninety-one patients (53 male and 138 female) referred to 2 institutionalized TMD clinics in Singapore were enrolled in the study. The mean age of the predominantly Chinese population (83.2%) was 33.6 +/- 9.3 years. Data from a RDC/TMD history questionnaire and clinical examination were fed directly by patients and clinicians into a computerized diagnostic system (NUS TMDv1.1). Axis I and II findings were generated on-line, based on RDC/TMD rule engines. Data were automatically exported to SPSS for statistical analysis. RESULTS: Group I (muscle) disorders were found in 31.4% of the patients; Group II (disc displacement) disorders were found in 15.1% and 15.7% of the patients in the left and right temporomandibular joints, respectively; and Group III (arthralgia, arthritis, and arthrosis) disorders were found in 12.6% and 13.0% of the patients in the left and right joints, respectively. Axis II assessment of psychologic status showed that 39.8% of patients experienced moderate to severe depression and 47.6% had moderate to severe nonspecific physical symptom scores. Psychosocial dysfunction was observed in only 4.2% of patients based on graded chronic pain scores. CONCLUSION: Axis I and II findings of Asian TMD patients were generally similar to their Swedish and American cohorts. In all 3 populations, women of child-bearing age represented the majority of patients. Muscle disorders were the most prevalent type of TMD. A substantial portion of TMD patients were depressed and experienced moderate to severe somatization.

The effect of 3 torque delivery systems on gold screw preload at the gold cylinder-abutment screw joint.

PURPOSE: This study measured the gold screw preload at the gold cylinder-abutment screw joint interface obtained by 3 torque delivery systems. MATERIALS AND METHODS: Using a precalibrated, strain-gauged standard abutment as the load cell, 3 torque delivery systems tested were shown to have significant differences in gold screw preload when a gold cylinder was attached. RESULTS: Mean preloads measured were 291.2 N for hand torque drivers set at 10 Ncm, 340.3 N for electronic torque controllers at low setting/10 Ncm, 384.4 N for electronic torque controllers at high setting/10 Ncm; and 140.8 N for hand-tightening with a prosthetic slot screwdriver. Significant differences in screw preload were also found between operators using a hand torque driver. DISCUSSION: Hand-tightening delivered insufficient preload and cannot be recommended for final gold screw tightening. Different electronic torque controller units set at 10 Ncm induced mean gold screw preloads that ranged from 264.1 N to as high as 501.2 N. CONCLUSION: Electronic torque controllers should be regularly recalibrated to ensure optimal output.

Critical bending moment of implant-abutment screw joint interfaces: effect of torque levels and implant diameter.

PURPOSE: Critical bending moment (CBM), the moment at which the external nonaxial load applied overcomes screw joint preload and causes loss of contact between the mating surfaces of the implant screw joint components, was measured with 2 types of implants and 2 types of abutments. MATERIALS AND METHODS: Using 4 test groups of 5 implant-abutment pairs, CBM at the implant-abutment screw joint was measured at 25%, 50%, 75%, and 100% of the manufacturer's recommended torque levels. Regular Platform (RP) Nobel Biocare implants (3.75 mm diameter), Wide Platform (WP) Nobel Biocare implants (5.0 mm diameter), CeraOne abutments, and Multiunit abutments were used. Microstrain was measured as loads were applied to the abutment at various distances from the implant-abutment interface. Strain instrumentation logged the strain data dynamically to determine the point of gap opening. All torque applications and strain measurements were repeated 5 times. RESULTS: For the CeraOne-RP group, the mean CBMs were 17.09 Ncm, 35.35 Ncm, 45.63 Ncm, and 62.64 Ncm at 25%, 50%, 75%, and 100% of the recommended torque level, respectively. For the CeraOne-WP group, mean CBMs were 28.29 Ncm, 62.97 Ncm, 92.20 Ncm, and 127.41 Ncm; for the Multiunit-RP group, 16.08 Ncm, 21.55 Ncm, 34.12 Ncm, and 39.46 Ncm; and for the Multiunit-WP group, 15.90 Ncm, 32.86 Ncm, 43.29 Ncm, and 61.55 Ncm at the 4 different torque levels. Two-way analysis of variance (ANOVA) (P < .001) revealed significant effects for the test groups (F = 2738.2) and torque levels (F = 2969.0). DISCUSSION: The methodology developed in this study allows confirmation of the gap opening of the screw joint for the test groups and determination of CBM at different torque levels. CONCLUSION: CBM was found to differ among abutment systems, implant diameters, and torque levels. The torque levels recommended by the manufacturer should followed to ensure screw joint integrity.

Three-dimensional accuracy of plastic transfer impression copings for three implant systems.

PURPOSE: The purpose of this study was to compare the three-dimensional accuracy of indirect plastic impression copings and direct implant-level impression copings from three implant systems (Nobel Biocare [NB], Biomet 3i [3i], and Straumann [STR]) at three interimplant buccolingual angulations (0, 8, and 15 degrees). MATERIALS AND METHODS: Two-implant master models were used to simulate a three-unit implant fixed partial denture. Test models were made from Impregum impressions using direct implant-level impression copings (DR). Abutments were then connected to the master models for impressions using the plastic impression copings (INDR) at three different angulations for a total of 18 test groups (n = 5 in each group). A coordinate measuring machine was used to measure linear distortions, three-dimensional (3D) distortions, angular distortions, and absolute angular distortions between the master and test models. RESULTS: Three-way analysis of variance showed that the implant system had a significant effect on 3D distortions and absolute angular distortions in the x- and y-axes. Interimplant angulation had a significant effect on 3D distortions and absolute angular distortions in the y-axis. Impression technique had a significant effect on absolute angular distortions in the y-axis. With DR, the NB and 3i systems were not significantly different. With INDR, 3i appeared to have less distortion than the other systems. Interimplant angulations did not significantly affect the accuracy of NBDR, 3iINDR, and STRINDR. The accuracy of INDR and DR was comparable at all interimplant angulations for 3i and STR. For NB, INDR was comparable to DR at 0 and 8 degrees but was less accurate at 15 degrees. CONCLUSIONS: Three-dimensional accuracy of implant impressions varied with implant system, interimplant angulation, and impression technique.

Three-dimensional accuracy of a digitally coded healing abutment implant impression system.

PURPOSE: This study examined the three-dimensional (3D) accuracy of the Encode Impression System (EN) in transferring the locations of two implants from master models to test models and compared this to the direct impression (DI) technique. The effect of interimplant angulation on the 3D accuracy of both impression techniques was also evaluated. MATERIALS AND METHODS: Seven sectional polymethyl methacrylate mandibular arch master models were fabricated with implants in the first premolar and first molar positions. The implants were placed parallel to each other or angulated mesiodistally or buccolingually with total divergent angles of 10, 20, or 30 degrees. Each master model was secured onto an aluminum block containing a gauge block, which defined the local coordinate references. Encode healing abutments were attached to the implants before impressions were made for the EN test models; pickup impression copings were attached for the DI test models. For the seven test groups of each impression technique, a total of 70 test models were fabricated (n = 5). The EN test models were sent to Biomet 3i for implant analog placement. The centroid of each implant or implant analog and the angular orientation of the long axis relative to the x- and y-axes were measured with a coordinate measuring machine. Statistical analyses were performed. RESULTS: Impression technique had a significant effect on y distortion, global linear distortion, and absolute xz and yz angular distortions. Interimplant angulation had significant effects on x and y distortions. However, neither impression technique nor interimplant angulation had a significant effect on z distortion. CONCLUSIONS: Distortions were observed with both impression techniques. However, the results suggest that EN was less accurate than DI.

Load fatigue performance of conical implant-abutment connections.

PURPOSE: Conical implant-abutment connections for platform switching have been recently introduced in implant systems. This study investigated the load fatigue performance of three conical abutment systems and their corresponding titanium and zirconia abutments. MATERIALS AND METHODS: Regular-diameter implants of the Ankylos (AK), PrimaConnex (PC), and Straumann (ST) systems were tested with their corresponding titanium (Ti) and zirconia (Zr) abutments tightened to the recommended torque (n = 5 implant-abutment assemblies per group). A rotational load fatigue machine applied a sinusoidally varying tensile-compressive 21 N load to specimens at a 45-degree angle, producing an effective bending moment of 35 Ncm at a frequency of 10 Hz. The number of cycles to failure was recorded, with the upper limit set at 5 million cycles. Results were evaluated through analyses of variance. RESULTS: Except for the ST Zr group, which showed no failures in four samples and one failure just below the screw head, and the AK Ti group, in which one sample was preserved without fracture, all groups experienced failure of at least one of the components, whether the abutment screw only, the abutment, and/or the implant neck. There were significant differences between systems. There was no difference between systems for the Ti abutments, and the ST group was significantly different from the AK and PC groups for the Zr abutments. CONCLUSIONS: Ti conical abutments appear to have poorer load fatigue performance compared with earlier studies of external-hexagon connections. The load fatigue performance of Zr conical abutments varied and seemed to be highly system dependent. Many of the fractures in both the Ti and Zr abutment groups occurred within the implant, and retrieval would pose a significant clinical challenge. The clinician should weigh the mechanical, biologic, and esthetic considerations before selection of any implant system, connection type, or abutment material.

Depression and somatization in patients with temporomandibular disorders.

STATEMENT OF PROBLEM: Psychological and behavioral traits may be important for the diagnosis and management of orofacial pain. PURPOSE: This study compared the levels of depression and somatization in patients in single and multiple research diagnostic criteria for temporomandibular disorders (RDC/TMD) diagnostic groups. MATERIAL AND METHODS: The RDC/TMD was established to allow standardization and replication of research into the most common forms of muscle- and joint-related research and is divided into 2 axes: axis I, clinical TMD, and axis II, pain-related disability and psychological status. One hundred seventeen patients (28 male and 89 female; mean age, 33.3 +/- 10.3 years) with RDC/TMD-defined clinical TMD were selected. The RDC/TMD history questionnaire and examination forms were input directly into computers with the use of a software program developed at the National University of Singapore (NUS TMDv1.1 software). Axis I and II variables were generated online and automatically archived for statistical analysis. Patients were subsequently classified into 7 groups based on the presence of the various RDC/TMD axis I diagnostic groups: group A, myofascial pain only (group I); group B, disk displacement only (group II); group C, other joint conditions such as arthralgia, osteoarthritis, and osteoarthrosis only (group III); group D, myofascial pain and disk displacement (groups I and II); group E, myofascial pain and other joint conditions (groups I and III); group F, disk displacement and other joint conditions (groups II and III); and group G, myofascial pain, disk displacement, and other joint conditions (groups I, II, and III). Differences in mean Symptom Checklist-90 scores between groups were compared by analysis of variance/Scheffé tests to contrast depression and somatization levels between the various axis I diagnostic groups (alpha=.05). RESULTS: The frequencies of the different groups were as follows: group A, 26.5%; group B, 29.9%; group C, 12.8%; group D, 6.0%; group E, 13.7%; group F, 4.3%; and group G, 6.8%. Approximately 39% of patients were clinically depressed, and 55% had moderate to severe somatization. Differences in mean depression and somatization with pain item scores were significant between groups (P<.05). CONCLUSION: Within the limitations of this study, patients diagnosed with myofascial pain and other joint conditions (group E) had significantly higher levels of depression (P=.03) and somatization (P=.03) than patients diagnosed with only disk displacements (group B).

Depressive symptoms in Asian TMD patients and their association with non-specific physical symptoms reporting.

BACKGROUND: The expression of depression in Asian temporomandibular disorder (TMD) patients may differ from that of their Caucasian counterparts. This study examined the prevalence of depressive symptoms and their association with non-specific physical symptoms (NPSs) reporting in Asian patients. METHODS: Two hundred and fifty-five Asian TMD patients (68 males; 187 females) with a mean age of 33.0 years were selected for this study. Research diagnostic criteria (RDC)/TMD history questionnaire was input directly into computers by patients using the NUS TMDv.1.1 software. Symptom Checklist 90 (SCL-90) depression and NPS scales were generated online and automatically archived for statistical analysis. Data were subjected to ANOVA/Scheffe's test and Pearson's correlation at significance level 0.05 and 0.01, respectively. RESULTS: 43.1 and 50.6% of the patients scored moderate-to-severe on the depression and NPS scales, respectively. The percentage of patients with diffuse physical symptoms remained high (45.5%), even after pain items were excluded from the computation. NPS scores ranged from 0.34 to 1.64, while depression scores ranged from 0.27 to 1.21. A significant and positive correlation (r = 0.74) was observed between depression and NPS scores. CONCLUSIONS: The prevalence of depressive symptoms and NPSs was lower in Asian TMD patients. Psychological distress experienced by female Asian TMD patients was comparable to their male counterparts. Results also suggest that depressive symptomatology is associated with the reporting of multiple NPSs.

Multiple pains and psychosocial functioning/psychologic distress in TMD patients.

PURPOSE: This study assessed multiple pain conditions and their association with psychosocial functioning, psychologic distress, and somatization in patients with temporomandibular disorders (TMD) based on RDC/TMD Axis II findings. Nonspecific pain items examined included headaches, heart/chest pain, lower back pain, nausea/abdominal pain, and muscle pain. MATERIALS AND METHODS: In this study, 202 TMD patients (58 men and 144 women) referred to two TMD clinics participated. The mean age of the predominantly Chinese patient population (82%) was 32.6 years (range 13 to 65). The RDC/TMD history questionnaire was input directly into computers by patients. Graded chronic pain and SCL-90 scales were generated online and automatically archived for statistical analysis. Data were subjected to Spearman's rank-order correlation and Kruskal-Wallis and Mann-Whitney tests at a significance level of .05. RESULTS: Of the patients, 43% were moderately to extremely distressed by headaches. The percentage of patients who were distressed by heart/chest pain (7%), lower back pain (26%), nausea/abdominal pain (17%) and soreness of muscles (22%) was lower. Of the TMD patients, 16% experienced more than three pain items. Significant and positive correlations were observed between number of pain items experienced and graded chronic pain severity, depression, and somatization. Correlation coefficients ranged from .27 to .65 for graded chronic pain scales and somatization (without pain items) scores, respectively. CONCLUSION: Results suggest that the number of nonspecific pain conditions reported may be a predictor of psychosocial dysfunction, depression, and somatization.