Comparison of different analytical methods used for analyzing SPECT scans of patients with unilateral condylar hyperactivity

This study aimed to compare different analytical methods and identify the optimal analysis method to distinguish patients with unilateral condylar hyperactivity (UCH) from those with inactive condyles. Single-photon emission computed tomography (SPECT) scans of patients with progressive and nonprogressive mandibular asymmetry (each group, n = 26), were analyzed using the region of interest technique. Sensitivity, specificity and receiver operating characteristic (ROC) curves were calculated for the different analytic methods. The ROC curve illustrates that UCH can be diagnosed significantly better by determining the percentile bone activity in both condyles. The area under the curve (AUC) of the percentile comparison between the affected and contralateral condyles was 0.93 ± 0.04, that for the condyle/clivus ratio was 0.75 ± 0.07 and for the condyle/cervical spine (CS) ratio 0.57 ± 0.08. Sensitivity for the condyle/clivus ratio was 65% and specificity 61%. Sensitivity for the condyle/CS ratio was 85% and specificity 31%. For the percentile difference of the condyles, sensitivity and specificity were 88%. For UCH patients, direct comparison of bone activity between the affected and contralateral condyle in SPECT scans is the analysis method of choice. Comparison of condylar bone activity to reference bone activity does not have additional value in the diagnosis of UCH.     

SPECT bone scintigraphy in the diagnosis and management of mandibular condylar hyperplasia

Isotope bone scans have been used for a number of years to assess growth activity in the mandibular condyle in patients who present with facial asymmetry. The aim is to distinguish normal bone growth within the condyle from increased activity that may be the cause of the asymmetry. Previous studies have, however, relied only on planar images. SPECT (single photon emission computed tomography) has been used with quantitative assessments of one mandibular condyle to clivus or lumbar spine, but we have compared one condyle with the other, which is more sensitive and accurate in detecting abnormal activity. A relative percentage uptake of 55% or more in the affected mandibular condyle is considered to be abnormal, and this has been validated by comparison with an age-matched control group. We have used SPECT as an aid to diagnosis and treatment in 18 patients with asymmetrical growth and have constructed a therapeutic algorithm to aid the treatment of these patients.     

The potential of hybrid SPECT/CT fusion imaging to improve diagnostic accuracy in the scintigraphic quantitative functional assessment of suspected unilateral mandibular hyperactivity

Background

Mandibular asymmetry is commonly caused by disproportionate mandibular growth due to unilateral condylar hyperactivity. The current standard for mandibular condyle bone scintigraphy uses single photon emission computed tomography (SPECT) imaging after intravenous administration of technetium-99m-labeled diphosphates. To our knowledge, the use of hybrid SPECT integrated with multidetector computed tomography (SPECT/CT) imaging in the scintigraphic quantitative functional assessment of mandibular condyle growth has not yet been described.

Case report

A 22-year-old male with mandibular asymmetry due to suspected unilateral condylar hyperactivity underwent SPECT/CT imaging of the skull and facial bones after intravenous administration of technetium-99m methylene diphosphonate. Using CT to guide anatomical contouring, precise regions of interest were drawn over the mandibular condyles and clivus in adjacent SPECT/CT transaxial slices to calculate the mean radiotracer count ratios. For comparison of quantitative results, conventional SPECT images were obtained from the SPECT/CT data and processed according to conventional methods. Planar images were also obtained for visual assessment of mandibular condyle activity. All three methods, SPECT/CT, conventional SPECT, and planar imaging, found unilateral condylar hyperactivity of the left mandibular condyle. The condyles and clivus were easily and confidently identified on SPECT/CT images.

Discussion

We speculate that SPECT/CT imaging will improve the diagnostic accuracy of unilateral condylar hyperactivity. More studies are necessary to further define its role, obtain baseline reference values, and establish analysis protocols.     

The use of SPECT bone scans to evaluate patients with idiopathic jaw pain

OBJECTIVE: The purpose of this study was to investigate the potential usefulness of single photon emission computed tomography (SPECT) bone scanning with technetium-99m methylene diphosphonate (Tc-99m MDP) in the diagnosis of idiopathic jaw pain. Unlike planar bone scanning, SPECT uses tomographic technology to provide 3-dimensional images, which are more useful in localizing small lesions.Study Design: Twenty patients, each with a diagnosis of chronic idiopathic jaw pain, were compared after SPECT bone scanning with 20 age-matched and gender-matched normal controls. Uptake was identified and compared in sites with previously detected jaw pathoses and jaw pain. RESULTS: Nineteen of 20 patients with jaw pain evaluated with SPECT had positive scans, in contrast with 12 of 20 control subjects (P <.04). Positive scans were correlated with painful sites in 15 of 20 patients, with the remaining 5 patients demonstrating no uptake in painful locations. Patients with jaw pain demonstrated 37 of 80 mouth quadrants with positive scans, in contrast with 21 of 80 mouth quadrants in the controls (P <.01). Nineteen of 24 painful mouth quadrants had uptake in the pain group. Of the 21 quadrants positive in the controls, 17 were correlated with previously detected jaw pathoses. The sensitivity and specificity for detecting painful sites were 0.79 and 0.68, respectively. The sensitivity and specificity for detecting previously identified pathoses in the jaws of normal controls were 0. 80 and 0.93, respectively. CONCLUSION: Patients with idiopathic jaw pain had a significantly greater frequency of positive SPECT bone scans when compared with normal controls. However, the sensitivity and specificity of SPECT bone scans in detecting painful sites were low. These findings suggest that SPECT bone scanning with Tc-99m MDP is not indicated as a routine imaging procedure for the detection of jaw pathoses, but may be considered as a potential research tool in the future study of chronic idiopathic jaw pain.     

Changes in the position of the condyle after bilateral sagittal split ramus osteotomy in patients with mandibular retrusion and protrusion: a new condyle: fossa matching concept

The purpose of this study was to compare the condylar positional changes after bilateral sagittal split ramus osteotomy (BSSRO) in patients with mandibular retrusion and those with mandibular prognathism. We also studied the correlation between the degree of matching of the condyle and fossa, and condylar displacement. Thirty patients with mandibular retrusion (n = 11) or mandibular prognathism (n = 19) who underwent BSSRO were included. The condylar position was assessed from spiral computed tomographic (CT) scans taken preoperatively, during the first postoperative week, and at least 6 months postoperatively. All data were measured by MIMICS 17.0 and analyzed by Student’s t test and Pearson’s correlation analysis. The size of the condyles of patients with mandibular retrusion was significantly less than those of patients with mandibular prognathism (491.5 (172.8) compared with 823.2 (212.0) mm³). The size of the glenoid fossa in those with mandibular retrusion (599.6 (110.4) mm³) and those with prognathism (597.6 (151.6) mm³) did not seem to differ. Postoperatively the condyles moved outwards, backwards, and downwards in both groups of patients. Correlation analysis between the condyle:fossa volume ratio and the condylar positional changes showed that a large condyle:fossa volume ratio correlated with the smaller positional changes in the condyle. The condylar position changed immediately after mandibular advancement and setback, and persisted in the long term. Larger condyles tended to have fewer positional changes.     

The effect of interocclusal appliances on temporomandibular joints as assessed by 3D reconstruction of MRI scans

Magnetic resonance imaging (MRI) enables simultaneous visualization of hard and soft tissues. The aims of the present study were to computer generate three-dimensional (3D) images, reconstructed from MRI scans of normal temporomandibular joints (TMJ), to assess the relative positions of the disc, condyle and articular surface of the temporal bone and to study the effect of two mandibular group function interocclusal appliances (IOAs). Bilateral MRI scans of 2 mm slice thickness were generated for the TMJs of 12 asymptomatic subjects with the image acquisition coils orientated in a corrected oblique sagittal plane. MRI scans were generated for all subjects with 3 mm interincisal distance IOAs, while a subgroup (n = 4) was also scanned with a 5 mm interincisal IOA in situ. An average of 10 slices through each TMJ were generated for the closed mouth and IOA positions. Three-dimensional reconstruction was performed on a 486 IBM compatible computer using a suite of nine programs not commercially available. Three-dimensional images allowed visualization of composite images of joint relationships. Subjective assessment indicated that joint relations in 3D were more informative than multiple separate 2D MRI scans. With the 3 mm IOA in situ, the disc was positioned posteriorly and superiorly to the condyle in three of 12 cases. In four of 12 cases the condyle, and in two of 12 cases both the disc and condyle, were positioned anteriorly and inferiorly. With the 5 mm IOA changes in condyle/disc and condyle/fossa relationships were more variable. It was concluded that 3D images of TMJs enabled the assessment of the positional changes of the condyle/disc and condyle/fossa relationships as altered by IOAs. However, the role of IOAs on the internal arrangements within the TMJ remains variable and is deserving of further study.     

Diagnostic performance of SPECT–CT imaging in unilateral condylar hyperplasia

Nuclear imaging plays an important role in the diagnostic path of patients with unilateral condylar hyperplasia (UCH). The purpose of this study was to determine the performance of single-photon emission computed tomography–computed tomography (SPECT–CT) in a large group of patients with suspected UCH. This study prospectively included 156 patients with a clinical presentation of progressive mandibular asymmetry. All patients underwent ^99 mTc-HDP SPECT–CT and extensive baseline and follow-up documentation. The relative activity of the ipsilateral condyle in relation to the contralateral condyle was calculated for both the mean and maximum count, and the diagnostic accuracy of different cut-off values was determined. The area under the receiver operating characteristic curve of the SPECT–CT scan was 0.892 for the mean count and 0.873 for the maximum count. The optimal cut-off of> 8% (SPECT–CT mean count) resulted in a sensitivity of 87.0% and a specificity of 88.6%. SPECT–CT showed good diagnostic performance in UCH; however the benefit of the CT scan is questionable and the potential disadvantages have to be weighed against the benefits when compared to standard SPECT scanning. When using SPECT–CT in the diagnostic path in UCH, a mean value cut-off of>8% for the relative activity between the condyles is most accurate.     

Association between disk position and degenerative bone changes of the temporomandibular joints: an imaging study in subjects with TMD

The aim of this study was to determine the frequency and relationship between disk position and degenerative bone changes in the temporomandibular joints (TMJ), in subjects with internal derangement (ID). MRI and CT scans of 180 subjects with temporomandibular disorders (TMD) were studied. Different image parameters or characteristics were observed, such as disk position, joint effusion, condyle movement, degenerative bone changes (flattened, cortical erosions and irregularities), osteophytes, subchondral cysts and idiopathic condyle resorption. The present study concluded that there is a significant association between disk displacement without reduction and degenerative bone changes in patients with TMD. The study also found a high probability of degenerative bone changes when disk displacement without reduction is present. No association was found between TMD and condyle range of motion, joint effusion and/or degenerative bone changes. The following were the most frequent morphological changes observed: flattening of the anterior surface of the condyle; followed by erosions and irregularities of the joint surfaces; flattening of the articular surface of the temporal eminence, subchondral cysts, osteophytes; and idiopathic condyle resorption, in decreasing order.     

Craniomandibular bone density in the primate as assessed by computed tomography

Ten normal rhesus monkeys, five juvenile and five adult animals, were analyzed for symmetry in bone density across the cranioskeleton with computed tomography (CT). Fifty contiguous axial CT scans were done using 1.5-mm thick scans between the lower mandibular border and inferior orbital ridge, and 3-mm thick scans from the inferior orbital ridge to the rostral level of insertion of the temporalis muscle. Eleven regions comprising areas of the lower mandibular border, lower ramus, upper ramus with condyle, the coronoid process, the zygomatic arch, and cranial bone were analyzed for symmetry using small regions of interest. Only one region, the condyle, demonstrated a statistically significant difference between the two sides with all other measured sites demonstrating the same bone mineral density bilaterally. Large area analysis of five regions--the lower mandibular border, upper ramus with condyle, the coronoid process, the zygomatic arch, and upper cranium--demonstrated no significant difference in the distribution of CT numbers. This analysis of bilateral distribution of bone density in the primate craniofacial skeleton demonstrates a basic symmetry that can be used to study altered patterns of neuromuscular function and their effects on bone density.     

Quantitative bone SPECT analysis of mandibular condyles in an asymptomatic population: an approach to normal reference values

Bone scintigraphy is an extremely valuable technique in diagnosis and treatment planning for patients with condylar hyperplasia (CH). The main objective of this study was to develop an approach to determine normal activity values in the mandibular condyles, adjusted to age and sex, through quantitative analysis of bone single-photon emission computed tomography (SPECT) on a condyle-by-condyle basis and to compare these values with those of a control group comprising patients with confirmed CH. Technetium 99 m-methylene diphosphonate (^99mTc-MDP) SPECT studies of the mandibular condyles were performed in patients with no mandibular pathology for quantitative analysis. Regions of interest were drawn on slices representing the upper, middle, and inferior thirds of each condyle and on the summation of transaxial slices representing the whole condyle (three-dimensional approach). The clivus was used for internal validation and the condyle to clivus ratios were calculated. These ratios were compared between ‘normal’ and ‘diseased’ condyles. A total 144 condyles in normal patients and 25 in confirmed CH patients were analysed. Differences between the ratios were evaluated through the coefficient of variation. In normal patients, the ratios to the clivus on the summed condyle image showed the lowest variability: range 0.3–1.28 (median 0.74). The quantile regression model showed significant differences with respect to sex, but not to age. The Mann–Whitney test showed significant differences in the ratios to clivus between normal and diseased condyles (P < 0.0001).     

Osteoarthritis and abnormal bone marrow of the mandibular condyle

OBJECTIVE: The purpose of this study was to analyze the relationship between abnormal bone marrow of the mandibular condyle and osteoarthritis. STUDY DESIGN: The relationship between abnormal bone marrow and osteoarthritis of the mandibular condyle was analyzed in magnetic resonance images of the temporomandibular joints of 74 patients. Thirty-seven patients had magnetic resonance evidence of abnormal bone marrow, and 37 control patients had magnetic resonance images with normal bone marrow. RESULTS: Fifteen of 37 patients with magnetic resonance evidence of abnormal bone marrow had no magnetic resonance evidence of osteoarthritis; the other 22 patients had both abnormal bone marrow and osteoarthritis. CONCLUSIONS: Abnormal bone marrow of the mandibular condyle can occur separately from osteoarthritis; nearly one half of the joints with magnetic resonance evidence of abnormal bone marrow did not have any evident osteoarthritis. Abnormal bone marrow may therefore initially represent a separate disease entity. Over time, secondary osteoarthritis probably develops in joints with initial bone marrow abnormalities.     

Cone beam computed tomographic assessment of mandibular condyle in Kennedy class I patients

Objectives

The aim of this study was to assess the dimensional and volumetric changes in the mandibular condyle in Kennedy class I patients versus completely dentate patients by cone beam computed tomography (CBCT) to estimate the effect of loss of posterior teeth on the mandibular condyle.

Patients and methods

This study was performed on one hundred patients requesting CBCT scans: fifty Kennedy class I patients and fifty fully dentate controls. Condyle dimensions mesio-distal, cranio-caudal and antero-posterior as well as condyle volume were measured in both the groups.

Results

Kennedy class I patients showed statistically significant higher mean condyle width but lower mean condyle height than the control group. No statistically significant difference was found between the study group and the control group regarding condyle AP dimension. There was no statistically significant difference between condyle volumes in the two groups.

Conclusion

Loss of posterior teeth is accompanied by significant decrease in condyle height and increase in condyle width with no change in the total condyle volume or antero-posterior dimensions.

     

Condyle position as a predictor of temporomandibular joint internal derangement.

STATEMENT OF PROBLEM: The significance of the position of the mandibular condyle in the glenoid fossa remains a controversial subject. PURPOSE: This study evaluated the relationship between condyle position and disk displacement. MATERIAL AND METHODS: Fifty-two asymptomatic volunteers and 130 symptomatic patients underwent linear tomography and bilateral temporomandibular joint magnetic resonance scans. RESULTS: There was a higher prevalence of distal condyles in symptomatic patients with disk displacement compared with asymptomatic volunteers (P <.05). Distally positioned condyles identified joints with disk displacement with reduction, disk displacement without reduction, or a symptomatic normal joint with a sensitivity of 0.64, 0.56, and 0.33, respectively. Distally positioned condyles identified joints with disk displacement with reduction, disk displacement without reduction, or a symptomatic normal joint with a specificity of 0.56, 0.65, and 0.55, respectively. CONCLUSION: There were more distal condyles in symptomatic subjects with disk displacement, but the reliability of a distal condyle to predict the presence or absence of disk displacement was low.     

Radionuclide skeletal imaging and single photon emission computed tomography in suspected internal derangements of the temporomandibular joint

Fifty one subjects who had pain involving the temporomandibular joint were evaluated using multidirectional tomography, arthrography, conventional nuclear scanning, and single photon emission computed tomography (SPECT) to assess the association of arthritis of the temporomandibular joint with internal derangements related to meniscal dysfunction. Five (56%) of the nine subjects who had normal arthrograms and normal multidirectional tomograms had SPECT scans that were positive for osseous changes. Twenty-two subjects (27 temporomandibular joints) were diagnosed by arthrography to have meniscal displacement with reduction. Multidirectional tomograms of the 27 joints were positive for osseous changes in five (18%) joints, whereas SPECT scans were positive in nine (70%) joints. Twenty subjects (20 temporomandibular joints) had an arthrographic diagnosis of meniscal displacement without reduction. Multidirectional tomograms of the 20 joints were positive for osseous changes in 14 (70%) joints, and SPECT scans were positive in 16 (80%) joints (P less than 0.001 vs control group). Initial observations with SPECT indicate it is a promising imaging method for detecting and staging osseous disease of the TMJ related to meniscal dysfunction.     

Bone scintigraphy as a diagnostic method in unilateral hyperactivity of the mandibular condyles: a review and meta-analysis of the literature

Bone scan analyses and clinical assessment are used to diagnose unilateral condylar hyperactivity (UCH). This review compares the diagnostic accuracy of planar and SPECT bone scans. Studies diagnosing patients with possible UCH using bone scans, published between 1968 and 2008, were included in this review. Of 15 articles that met the inclusion criteria, 7 presented results in sufficient detail to calculate index test characteristics. Three control studies show that the difference in uptake values of the left and right condylar regions in the normal population does not exceed 10%. The pooled sensitivity of the planar bone scan (n = 130) was 0.71 (95% confidence interval: 0.57-0.82), which was significantly lower (p = 0.04) than that of the bone SPECT technique (n = 88), which was 0.90 (0.79-0.97). The pooled specificity of the SPECT scan was 0.95 (0.82-0.99), which did not significantly differ (p = 0.58) from that of the planar scan (0.92 (0.83-0.97)). Future studies should include a diagnostic analysis of the data, including two-by-two contingency tables, so the accuracy of the diagnostic test may be evaluated. Bone scans are best performed using SPECT, conducting a quantitative analysis by calculating the percentile differences between the left and right condylar regions.     

SPECT-CT对成人下颌偏斜患者双侧颞下颌关节代谢及形态对称性研究

目的:利用SPECT-CT骨显像对成人下颌偏斜患者双侧颞下颌关节代谢及形态对称性研究。方法:对36例成人下颌偏斜患者行SPECT骨显像,对髁突、下颌升支、下颌角图像进行冠状面、矢状面、横断面采集进行三维重建,计算出放射性计数比值,并通过CT扫描三维重建后同机融合,根据双侧颞下颌关节解剖关系测量偏斜侧及对侧髁突的高度、内外径、后斜面倾斜角及后斜面长度的差异,进行对比观察。结果:颞下颌关节各区域(髁突、下颌升支、下颌角)放射性计数比值均有所不同,偏斜侧的放射性计数比值均低于对侧,且两侧放射性计数比值有显著差异(P＜0.05);偏斜侧髁突高度及内外径均较之对侧减小(P＜0.01);偏斜侧髁突后斜面长度、后斜面倾斜角较之对侧增大(P＜0.01)。结论:SPECT-CT骨显像对成人下颌偏斜疾病的诊断评估起到了至关重要的作用。     

Study on the reconstruction of a four-dimensional movement model and the envelope surface of the condyle in normal adults

The objective of this study was to reconstruct the envelope surface of the condyle and the four-dimensional trajectory model in mandibular border movement in normal adults. Eleven healthy subjects were selected as volunteers. Cone-beam computed tomographic (CBCT) scanning was performed on the volunteers. The three-dimensional (3D) movement path of the mandible was recorded using a virtual articulator (PN-300), which was based on a 3D model of the mandible. We used Proplan CMF 3.0 (Materialise) software to perform this from the DICOM data generated by CBCT scans. The distance of condylar movement was measured in this model during volunteers’ mouth opening, protrusion, and lateral excursions. The envelope surface of the condyle was reconstructed by merging a functional condylar surface at each recording moment during the movement of the whole border. In the mandibular digital models, the condyle moved downward firstly, and moved upward to the position of maximum mouth opening. The condyle moved forward and downward during protrusion. The working condyle rotated slightly and the non-working condyle moved forward, downward, and inward during lateral excursions. The mean (SD) movement distance of 11 subjects was 19.04 (4.37) mm during mouth opening (including downward and upward) and 9.75 (2.38) mm during protrusion. During lateral excursions the mean (SD) movement distance of the working condyle was 2.87 (1.13) mm, the mean (SD) movement distance of the non-working condyle was 10.85 (3.25) mm. The envelope surface of healthy volunteers showed a double-peak pattern. The envelope surface of the condyle and four-dimensional movement model can be reconstructed by merging the trajectory of the mandible recorded from the novel virtual articulator PN300 and a 3D image of the mandible.     

Reconstruction of the mandibular condyle using the microvascular lateral femoral condyle flap

The lateral femoral condyle (LFC) flap is a new flap first reported in 2015 for the treatment of osteomyelitis in hand surgery. This paper introduces a technique of osteochondral LFC flap harvest for mandibular condyle reconstruction and reports on the use of this flap in temporomandibular joint reconstruction. For condyle resection, a pre-auricular approach saving the temporal artery and vein is performed. A step osteotomy technique is used for condyle resection. LFC harvesting starts with dissection of the popliteal artery and vein. The superior genicular artery and vein are identified and followed along their periosteal branches. An osteochondral flap according to the condyle defect is harvested from the anterior pole of the knee. The flap is banded according to the defect and fixed to the mandibular neck with three miniscrews. Follow-up computed tomography scans should be performed at 1 week, 6 months, and 1 year after surgery. The case of a 58-year-old female patient with osteomyelitis of the left mandibular condyle after multiple preoperative therapies is reported. The LFC flap technique was used for left condyle reconstruction, resulting in good functional and morphological outcomes at the 6-month postoperative follow-up. In conclusion, the osteochondral LFC flap is a new and promising technique for mandibular condyle reconstruction for special indications.     

Evaluation of microvascular bone graft reconstruction of the head and neck with 3-D 99mTc-DPD SPECT scans

OBJECTIVE: We conducted a prospective investigation to evaluate the diagnostic accuracy of computer-aided 3-dimensional (3-D) technetium 99m dicarboxypropane methylene diphosphonate ((99m)Tc-DPD) single photon emission computed tomography (SPECT) reconstruction in the evaluation of microvascular bone flaps used for maxillofacial reconstruction.Study Design: Twenty patients who received 20 autogenous microvascular bone flaps for reconstruction of the mandible and maxilla were evaluated. Forty bone scans with subsequent computer-aided reconstruction were performed. Each graft could be assessed within 48 to 72 hours after surgery. The second bone scan was performed between 12 and 14 days after surgery. RESULTS: Complications were observed in 5 grafts. SPECT investigation performed at the 2 time points after reconstruction showed a significantly higher tracer uptake in grafts with an uncomplicated further course than in those that developed complications. CONCLUSIONS: Computer-aided 3D (99m)Tc-DPD SPECT reconstruction serves as a useful prognostic tool and helps in the very early recognition of complications. This technique adds significantly to the value of planar bone scintigraphy and conventional SPECT images.     

Bone SPECT imaging of patients with internal derangement of temporomandibular joint before and after splint therapy

OBJECTIVE: Temporomandibular joint (TMJ) patients with disc displacement without reduction have a misaligned disc-condyle structural relation. As the condition becomes chronic, painful osteoarthritic changes may occur. For these patients, splint therapy may help to position the condyle to a more structurally compatible and functional position and to decrease the loading force of articular surfaces. The aim of this study was (1). to evaluate osseous reactions and pain relief in patients with disc displacement without reduction after splint therapy and (2). to use single photon emission tomography (SPECT) bone imaging to compare the results with the opposite joint of the patient. STUDY DESIGN: Twelve patients, who presented with pain involving the TMJ and limited mouth opening and were confirmed by soft tissue imaging as having disc displacement without reduction, were included in the study. Each patient underwent bone SPECT imaging, after which semiquantitative evaluation of transaxial images was conducted. The ratios of affected TMJ to nonaffected TMJ, affected TMJ to occipital bone, and nonaffected TMJ to occipital bone were calculated. After 6 months of splint therapy, bone SPECT examinations were repeated. RESULTS: Before splint therapy, the ratios of affected TMJ to nonaffected TMJ and of affected TMJ to occipital bone were found to be significantly higher than the ratios after splint therapy (P < 0.005). CONCLUSION: Six-month splint therapy has a positive effect on the osseous reaction and pain related to internal derangements of TMJs.