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Statement of Problem: The pain commonly suffered by denture wearers during mastication is not documented in the objective biomechanical criteria for the pressure pain threshold., Purpose: The purpose of this finite element analysis study was to determine whether the pressures developed beneath a removable mandibular complete denture during mastication would exceed the average pressure pain threshold in patients for whom the denture foundation had an acceptable load-bearing capacity., Material and Methods: A patient with an acceptable load-bearing denture foundation was modeled with finite element analysis. The denture/mucosa interface was modeled as a sliding or detaching interface. A convex mandibular residual ridge, resilient mucosa, and denture were modeled in computer-aided design (CAD) software using curves and cross sections. A unilateral vertical occlusal load of 100 N was assumed only for model verification, and an oblique mastication load of 141 N was assumed for simulated mastication with balanced articulation. The nonworking-side occlusal contact was simulated in 2 situations: prompt nonworking-side occlusal contact and delayed nonworking-side occlusal contact by setting an initial distance of 0.1 mm or 1 mm between the denture and a flat solid above the nonworking side., Results: The denture was held to the mucosa under vertical force and a maximum pressure of 203 kPa. The denture was tilted under an oblique mastication load and achieved stability through nonworking-side occlusal contact. This means that the denture was supported not only by the denture foundation but also by the nonworking-side occlusal contact and had a downwardly directed stabilizing reaction force. The denture was weakly supported on the delayed nonworking-side occlusal contact compared with the prompt nonworking-side occlusal contact and weakly supported on the denture foundation. In delayed nonworking-side occlusal contact, the pressure beneath the denture was 783 kPa (>pressure pain threshold) compared with 484 kPa (

Statement of Problem: Implants in posterior regions of the jaw require short dental implants with long crown heights, leading to increased crown-to-implant ratios and mechanical stress. This can lead to fracture and screw loosening., Purpose: The purpose of this study was to investigate the dynamic nature and behavior of prosthetic components and preimplant bone and evaluate the effect of increased crown height space (CHS) and crown-to-implant ratio on stress concentrations under external oblique forces., Material and Methods: The severely resorbed bone of a posterior mandible site was modeled with Mimics and Catia software. A second mandibular premolar tooth was modeled with CHS values of 8.8, 11.2, 13.6, and 16 mm. A Straumann implant (4.1×8 mm), a directly attached crown, and an abutment screw were modeled with geometric data and designed by using SolidWorks software. Abaqus software was used for the dynamic simulation of screw tightening and the application of an external load to the buccal cusp at a 75.8-degree angle with the occlusal plane. The distribution of screw load and member load at each step was compared, and the stress values were calculated within the dental implant complex and surrounding bone., Results: During tightening, the magnitude and distribution of the preload and clamp load were uniform and equal at the cross section of all CHSs. Under an external load, the screw load decreased and member load increased. An increase in the CHS caused the corresponding distribution to become more nonuniform and increased the maximum compressive and tensile stresses in the preimplant bone. Additionally, the von Mises stress decreased at the abutment screw and increased at the abutment and fixture., Conclusions: Under nonaxial forces, increased CHS does not influence the decrease in screw load or increase in member load. However, it contributes to screw loosening and fatigue fracture by skewing the stress distribution to the transverse section of the implant., (Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: Patients with myofascial pain experience impaired mastication, which might also interfere with their sleep quality., Purpose: The purpose of this study was to evaluate the jaw motion and sleep quality of patients with myofascial pain and the impact of a stabilization device therapy on both parameters., Material and Methods: Fifty women diagnosed with myofascial pain by the Research Diagnostic Criteria were enrolled. Pain levels (visual analog scale), jaw movements (kinesiography), and sleep quality (Epworth Sleepiness Scale; Pittsburgh Sleep Quality Index) were evaluated before (control) and after stabilization device use. Range of motion (maximum opening, right and left excursions, and protrusion) and masticatory movements during Optosil mastication (opening, closing, and total cycle time; opening and closing angles; and maximum velocity) also were evaluated. Repeated-measures analysis of variance in a generalized linear mixed models procedure was used for statistical analysis (α=.05)., Results: At baseline, participants with myofascial pain showed a reduced range of jaw motion and poorer sleep quality. Treatment with a stabilization device reduced pain (P<.001) and increased both mouth opening (P<.001) and anteroposterior movement (P=.01). Also, after treatment, the maximum opening (P<.001) and closing (P=.04) velocities during mastication increased, and improvements in sleep scores for the Pittsburgh Sleep Quality Index (P<.001) and Epworth Sleepiness Scale (P=.04) were found., Conclusion: Myofascial pain impairs jaw motion and quality of sleep; the reduction of pain after the use of a stabilization device improves the range of motion and sleep parameters., (Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: When implants are incorporated into an existing partial removable dental prosthesis, the acrylic resin base can fracture. It is therefore essential to study the mechanical behavior of partial removable dental prostheses by using stress and deformation analysis., Purpose: The purpose of this study was to analyze the effect of the occlusal rest position on the implant-assisted partial removable dental prosthesis by finite element analysis., Material and Methods: A Faro Arm scan was used to extract the geometrical data of a human partially edentulous mandible. A standard plus regular neck (4.8×12 mm) implant and titanium matrix, tooth roots, and periodontal ligaments were modeled by using a combination of reverse engineering in Rapidform XOR2 and solid modeling with the Solid Works CAD program. The model incorporated a partial removable dental prosthesis and was loaded with standard bilateral forces. A uniform pressure was applied on the occlusal surface so as to generate an equivalent net force of 120 N for both the left and right prosthesis. The finite element analysis program ANSYS Workbench was used to analyze the stress and strain distributions in the implant-assisted partial removable dental prosthesis., Results: Maximum stresses were significantly high for the metal framework compared to the acrylic resin surface, and these stresses were different for the mesial and distal arm designs. The maximum stress in the metal framework for the mesial arm design was 614.9 MPa, and it was 796.4 MPa for the distal arm design. The corresponding stresses in the acrylic resin surface were 10.6 and 8.6 MPa., Conclusions: Within the limitation of this study, it was found that moving the position of the occlusal rest from the mesial to distal side of the abutment teeth improved the stress distribution in the metal framework and acrylic resin denture base structures., (Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: The design of a mandibular fixed complete denture can influence periimplant bone loss. However, the design that transfers the greatest stress to the periimplant bone is not well documented., Purpose: The purpose of this study was to assess the stress distribution associated with splinted and nonsplinted implant-supported mandibular fixed complete denture designs., Material and Methods: Three-dimensional finite element models simulating 6 osseointegrated implants were created in the mandible to support a cobalt-chromium alloy and feldspathic porcelain veneering framework. One model simulated a 1-piece framework, and the other models simulated 2-piece and 3-piece frameworks. Axial and oblique loads were applied to the frameworks., Results: For all the models, the greatest stress values were recorded in the periimplant bone of posterior implants, with differences between the left and right sides. The axial load transferred greater stress values to the periimplant bone than did the oblique load. The lowest periimplant bone stress values were observed in the 3-piece framework model at all implant locations, with the exception of implants placed in the canine region., Conclusions: A framework separated into 3 pieces transfers the least stress to the periimplant bone., (Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: The human mandible flexes during different jaw movements. Mandibular flexure is known to be restricted when natural dentition is restored with long-span fixed prostheses, but its effect on implant-supported fixed prostheses is unknown. Restriction of mandibular movement by implant-supported fixed prostheses may lead to excess strain accumulation, which could affect the outcome of implant treatment., Purpose: The purpose of this study was to investigate the influence of mandibular flexure on the implant bone interface by measuring the strain distribution in the body of the mandible at the periimplant level and at the implant framework level during the unilateral loading of a long-span implant-supported fixed prosthesis., Material and Methods: A partially edentulous mandible model with the mandibular left premolars and molars missing was fabricated in epoxy resin. Two implants were placed in the edentulous area, one in the position of the first premolar and one in the position of the second molar. Strain gauges were cemented at the implant bone interface parallel to each implant on the body of the mandible and on the framework. Three screw-retained, 3 × 3-mm bar-shaped frameworks were cast from cobalt-chromium alloy. The fit of these frameworks was deemed clinically acceptable with a routine clinical assessment technique. The mandible model was suspended by elastic cords to a universal testing machine. A 50-N load cell was placed on the occlusal surface of the right first molar. The mandible model was then loaded to 50 N on the working side first without any framework and then a second time with the framework in place. Information from the strain gauges were collected with a computer for analysis., Results: When the mandible model was loaded without the implant framework, the buccal aspect of the body of the mandible experienced mainly compression, whereas the lingual aspect was mainly in tension on the working side under unilateral loading. At the implant-bone interface, compression strain was detected on the mesial aspect of the mesial implant. When frameworks were placed and a unilateral load applied, compression was detected on the mesial and buccal aspect of the mesial implant with all 3 frameworks. The amount of strain recorded was higher than that recorded without any framework in place., Conclusions: Mandibular flexure occurred during unilateral loading. The amount of strain transmitted to the implants increased with the screw-retained fixed-implant frameworks in place. The amount of strain introduced by mandibular flexure under unilateral loading may not be enough to stimulate bone remodeling; however, the accumulative strain generated by mandibular flexure under cyclic loading and its relationship with bone remodeling is unclear., (Copyright © 2014 The Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: Some patients may opt for a prosthetic rehabilitation without replacing all missing teeth, finishing treatment with a reduced dental arch. This choice may be due to biologic reasons or financial restrictions. It is unclear if a reduced dental arch functions as well as a complete dental arch., Purpose: The purpose of this study was to analyze whether shortened dental arches could result in tooth displacement., Material and Methods: Four different 3-dimensional maxillary and mandibular arches with different levels of arch length reduction were created. In all models, anatomic structures that represent the temporomandibular joint, cortical and cancellous bone, enamel, dentin, and periodontal ligament were modeled. Mechanical properties were attributed to each anatomic component, and a total occlusal load of 100 N on masseter, temporal, and medial pterygoid muscles was simulated for each model. The MSC. Patran software was used for the preprocessing and postprocessing of the biomechanical analysis of the models. One complete dental arch was used as the control., Results: The simulations showed that shortened dental arches presented greater tooth displacements than those found in a complete dental arch. The changes in mandibular tooth position were greater than those observed in the maxillary arches. In finite element models 1 and 2, the largest maxillary displacements were found for posterior teeth., Conclusions: Decreasing numbers of occlusal units resulted in increasing amounts of displacements of the remaining teeth, which may compromise dental stability in patients with shortened dental arches., (Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: Strain levels in periimplant bone are affected by implant dimensions, bone quality, and implant insertion depth, resulting in different bone maintenance characteristics., Purpose: The purpose of this study was to evaluate the biomechanical response of the jaw bone to a wide-diameter, short (WDS) implant, and a narrow-diameter, long (NDL) implant for various simulated clinical scenarios., Material and Methods: The finite element method was used to evaluate periimplant bone strain distribution for 5 × 6-mm (WDS) and 3.5 × 10.7-mm (NDL) implants. A 3-dimensional segment of the mandible was constructed from a computerized tomography image of the premolar region. Occlusal force was simulated by applying a 100-N oblique load on the abutment. Bone strain distributions for 5 different implant insertion depths and 2 different levels of alveolar bone quality were evaluated., Results: For an NDL implant, approximately 60% to 80% of the bone volume surrounding the implant was subjected to 200-1000 μstrain (μɛ), and 15% to 35% was subjected to 1000-3000 μɛ, regardless of the alveolar bone quality. For a WDS implant, the bone volume subjected to 1000-3000 μɛ increased, and the bone volume subjected to 200-1000 μɛ decreased in lower quality alveolar bone. For both implant types, bone volume experiencing strain levels less than 200 μɛ, and/or greater than 3000 μɛ, was predicted to be relatively small., Conclusions: In general, the thread design promoted relatively high strain around the thread tips, and the bone inside grooves was less strained. A more even and higher strain distribution in the periimplant bone was generated by the WDS implant as compared to the NDL implant. Regardless of the implant dimensions and simulated clinical scenarios, the development of high strain in the alveolar region was inevitable. Strain levels in periimplant bone were reduced as the insertion depth of the implant was increased., (Copyright © 2010 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.)

Statement of Problem: Composite mandibular resection resulting in mandibular discontinuity can alter jaw motion, occlusal forces, and mastication, whether or not the jaw is reconstructed. The biomechanical events associated with these changes are difficult to assess clinically and, therefore, are not well documented or researched., Purpose: The purpose of this study was to model movements of a mandible with a discontinuity defect, and to compare them to movements of a mandible with its continuity restored by alloplastic reconstruction., Material and Methods: Computational models were created with a novel simulation platform. The variables designed into the models included gravity, external forces, and jaw muscle activity. Each jaw was observed at rest, when opened by external force or by muscle drive, and during the generation of unilateral occlusal force on the nonoperated side. Scarring was simulated with springlike forces. Outputs included individual muscle forces and torques, as well as mandibular incisor and condylar motions., Results: Both models displayed plausible resting postures, and jaw opening with deviation toward the defect side when scarring was simulated. Opening caused by downward force on the incisors differed from that due to muscle activation. Jaw rotations during unilateral molar contact on the unaffected side were muscle specific and influenced by mandibular discontinuity., Conclusions: Plausible jaw movements after hemimandibulectomy and/or alloplastic reconstruction could be predicted by dynamic modeling. The effect of soft tissue forces on jaw posture and movements varied with the condylar support available. In both models, different opening trajectories were produced by external force on the jaw and by jaw muscle activation. Mandibular rotation during unilateral molar contact depended on which muscles were activated, and the availability of bilateral condylar support., (Copyright © 2010 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.)

Statement of Problem: There is confusion in the literature about how physical properties of bone vary between maxillary and mandibular regions and which physical properties affect initial implant stability., Purpose: The purpose of this study was to determine correlations between physical properties of bone and initial implant stability, and to determine how physical properties and initial stability vary among regions of jawbone., Material and Methods: Four pairs of edentulous maxillae and mandibles were retrieved from fresh human cadavers. Six implants per pair were placed in different anatomical regions (maxillary anterior, right and left maxillary posterior, mandibular anterior, right and left mandibular posterior). Immediately after surgery, initial implant stability was measured with a resonance frequency device and a tapping device. Implant surgeries and initial stability measurements were performed within 72 hours of death. Elastic modulus (EM) and hardness were measured using nano-indentation. Composite apparent density (cAD) was measured using Archimedes' principle. Bone-implant contact percentage and cortical bone thickness were recorded histomorphometrically. Mixed linear models and univariate-correlation analyses were used (alpha=.05)., Results: Generally, mandibular bone had higher initial implant stability and physical properties than maxillary bone. Initial implant stability was higher in the anterior region than in the posterior. EM was higher in the posterior region than in the anterior; the reverse was true for cAD., Conclusions: Of the properties evaluated, cAD had the highest correlation with initial implant stability (r=0.82). Both physical properties of bone and initial implant stability differed between regions of jawbone.

Statement of Problem: The osseointegration or fibrous encapsulation of immediately loaded dental implants depends largely on the extent of implant micromovement. The impact of acrylic resin or metal-reinforced acrylic resin provisional restorations on this movement is currently unknown., Purpose: The purpose of this study was to isolate and measure the effect of provisional restoration type on the vertical displacement of adjacent implants under load at 2 locations., Material and Methods: Vertical loads ranging from 10-200 N were applied to polymethyl methacrylate resin (n=56) or metal-reinforced acrylic resin provisional restorations (n=56) supported by 4 implants inserted into homogenous artificial bone in a "u-shaped" alignment. Provisional restorations were first loaded in the anterior segment where the provisional restoration was supported by a mesial and distal implant, followed by loading on an extension 8 mm distal to the last implant. Vertical displacement of the 2 implants nearest the load application was measured and recorded using an optical image correlation technique based on photogrammetric principles. Data were subjected to a nonparametric multivariate analysis (generalized Wilcoxon test) and a Mann-Whitney test with a 2-tailed P value (alpha=.05)., Results: There was no significant difference in the vertical implant displacement of the 2 provisional restoration groups when they were loaded in the anterior segment. However, when loads were applied to the distal cantilever, metal reinforcement resulted in less vertical displacement of the next-to-last implant. The mean vertical displacement of the next-to-last implant when supporting an acrylic resin provisional restoration increased from 20 microm +/-3 microm (pooled loads of 10-50 N) to 130 microm +/-21 microm (pooled loads of 160-200 N), while the vertical displacement of the implant when retaining a metal-reinforced acrylic resin provisional restoration increased from 10 microm +/-2 microm to 69 microm +/-13 microm under the same loads (P

This article describes the fabrication of an occlusal splint for a patient with limited mouth opening due to temporomandibular disorder. A face-bow fork is used as a tray to obtain an accurate dual-arch impression and occlusal registration.

Statement of Problem: Masticatory forces acting on dental implants can result in undesirable stress in adjacent bone, which in turn can cause bone defects and the eventual failure of implants., Purpose: A mathematical simulation of stress distribution around implants was used to determine which length and diameter of implants would be best to dissipate stress., Material and Methods: Computations of stress arising in the implant bed were made with finite element analysis, using 3-dimensional computer models. The models simulated implants placed in vertical positions in the molar region of the mandible. A model simulating an implant with a diameter of 3.6 mm and lengths of 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, 17 mm, and 18 mm was developed to investigate the influence of the length factor. The influence of different diameters was modeled using implants with a length of 12 mm and diameters of 2.9 mm, 3.6 mm, 4.2 mm, 5.0 mm, 5.5 mm, 6.0 mm, and 6.5 mm. The masticatory load was simulated using an average masticatory force in a natural direction, oblique to the occlusal plane. Values of von Mises equivalent stress at the implant-bone interface were computed using the finite element analysis for all variations. Values for the 3 most stressed elements of each variation were averaged and expressed in percent of values computed for reference (100%), which was the stress magnitude for the implant with a length of 12 mm and diameter of 3.6 mm., Results: Maximum stress areas were located around the implant neck. The decrease in stress was the greatest (31.5%) for implants with a diameter ranging from of 3.6 mm to 4.2 mm. Further stress reduction for the 5.0-mm implant was only 16.4%. An increase in the implant length also led to a decrease in the maximum von Mises equivalent stress values; the influence of implant length, however, was not as pronounced as that of implant diameter., Conclusions: Within the limitations of this study, an increase in the implant diameter decreased the maximum von Mises equivalent stress around the implant neck more than an increase in the implant length, as a result of a more favorable distribution of the simulated masticatory forces applied in this study.

Statement of Problem: Edentulous patients treated with implant-supported prostheses have shown increased passive tactile sensibility compared with those using conventional complete dentures. This is thought to be due to the close mechanical coupling between the implant and bone via the osseointegrated interface, yet the phenomenon has received little attention., Purpose: The purpose of this study was to measure passive tactile sensibility in a group of edentulous subjects treated with dental implants, and to relate the measured sensibility to a range of factors thought to be of possible relevance, namely, patient age, gender, time since implant placement, implant length, and implant separation., Material and Methods: Twenty edentulous subjects successfully treated with 2 or more Nobel Biocare dental implants in the anterior mandible were studied. The inclusion criteria were : (1) age of less than 50 years, (2) a period of at least 12 months since implant placement, (3) implant length of at least 10 mm and of standard diameter (excluding narrow and wide platform designs), and (4) implant separation of at least 18 mm. Using a computer-controlled custom-made device, pushing forces (2.1, 2.4, 2.7, and 3.0 N/s) were applied directly and perpendicular to the long axes of the implant abutments until the subjects felt the first sensation of pressure. The magnitude of these forces was measured with an integral transducer. The applied force had a ramped staircase pattern, and force application rates were varied between 2.1 and 3.0 N/s. Multilevel modeling was used to analyze the collected data (alpha=.05)., Results: The threshold values of passive tactile sensibility ranged between 3.1 and 15.7 N (mean 10.9; SD 3.9). Analysis failed to show any significant association between passive tactile sensibility and the variables studied., Conclusion: Within the limitations of this study, which included a small sample size, no relationship was found between passive tactile sensibility associated with long-standing implants and any of the variables studied (age, gender, time since implant placement, implant length, and implant separation).

Statement of Problem: It is unclear whether patients with temporomandibular disorders (TMD) who report high levels of bruxism have more severe signs and symptoms of TMD and more advanced tooth wear than patients with TMD who report lower levels of bruxism., Purpose: The purpose of this study was to determine whether there was a significant association between tooth wear, the parafunctional oral habit of bruxism, temporomandibular joint (TMJ) pain, and muscle pain severity in a TMD population., Material and Methods: A total of 84 subjects previously diagnosed with TMD, according to the Research Diagnostic Criteria for TMD (RDC/TMD) and who met 10 specific inclusion/exclusion criteria underwent a thorough multiaxial examination and classification recommended by the National Institute of Dental and Craniofacial Research (NIDCR). Measurement of tooth wear facets by use of a 4-point scale were graded in 10 zones on mandibular casts. One calibrated examiner performed all scoring. Bruxism was assessed in a standardized pretreatment questionnaire and in the dental history and interview (RDC/TMD) to indicate how frequently (0 = never to 3 = very often) subjects performed a list of oral habits, which included bruxism. The Kappa reliability coefficient (range from: -1.0 to 1.0) was used to correct for chance agreement, and was computed for each of the 10 study sites designated for rating. Subjects were also compared for muscle and joint pain. Muscle pain was a summed measure derived from the dental examination findings (range 0 to 20), calculated from the presence or absence of pain induced by palpation of 20 predetermined muscle sites. Similarly, joint pain was a summed measure of the presence or absence of pain in the TMJs induced by palpation of the joints on the outer surface and in the external auditory canal in 5 different positions of the mandible. A Pearson product-moment correlation was used to compute the summed severity of tooth wear and the subjects' age. Analysis of covariance was used to determine whether the number of wear facets was significantly higher in patients with TMD who reported a history of bruxism, compared with patients with TMD who reported no or minimal bruxism, after controlling for the effect of age. Multivariate analysis of variance was used to determine whether the number of painful muscles of mastication and joint sites on standardized examination were significantly higher in patients with TMD with a history of bruxism (alpha=.05)., Results: In the population tested, tooth wear was modestly correlated with age (r =.40, P<.001). Of the 84 subjects studied, 11.9% reported no bruxing activity, 32.1% reported some or occasional bruxing activity, and 47.6% had frequent bruxism activity; the remaining 8.4% were eliminated from analysis because they provided inconsistent responses. Bruxism activity was not correlated with muscle pain on palpation and was inversely associated with TMJ pain on palpation. Tooth wear was not significantly correlated with bruxism, TMJ pain, or muscle pain., Conclusions: In this TMD population, tooth wear factors did not differentiate patients with bruxism from those without. The amount of bruxism activity was not associated with more severe muscle pain and was associated with less pain in the TMJ on palpation.

Statement of Problem: There is some question about whether implant abutment selection affects the transfer of load between connected implants and natural teeth., Purpose: The purpose of this study was to compare stress transfer patterns with either 1 or 2 posterior implants connected to a single anteriorly located simulated natural tooth with either 1 or 2 segmented and nonsegmented implant abutments under relevant functional loads by use of the photoelastic stress analysis technique., Material and Methods: A model of a human left mandible, edentulous posterior to the first premolar, with two 3.75-mm x 13-mm screw-type implants embedded within the edentulous area, was fabricated from photoelastic materials. The implants were in the first and second molar positions. Two fixed partial denture prosthetic restorations were fabricated with either segmented conical abutments or nonsegmented UCLA abutments. Vertical occlusal loads were applied at fixed locations on the restorations. The photoelastic stress fringes that developed in the supporting mandible were monitored visually and recorded photographically. The stress intensity (number of fringes), stress concentrations (closeness of fringes), and their locations were subjectively compared., Results: Loading on the restoration over the simulated tooth generated apical stresses of similar intensity (fringe order) at the tooth and the first molar implant for both abutment types. Low-level stress was transferred to the second molar implant. Loading directed on the implant-supported region of the restoration demonstrated low transfer of stress to the simulated tooth. Nonvertical stress transfer with slightly higher intensity was observed for the nonsegmented abutment., Conclusion: Within the limitations of this simulation study, stress distribution and intensity for the 2 implant conditions was similar for segmented and nonsegmented abutment designs. Magnitude of stresses observed for both abutment designs was similar for the single implant condition. Vertical loading produced more nonaxial stresses away from the force applied for the 1 implant condition with the nonsegmented abutment. Direct loading results were similar for both abutment designs. Specific recommendations for selection of implant abutment and application should be based on clinical criteria.

Statement of Problem: Temporomandibular joint (TMJ) sound recordings could be analyzed to assess the state of TMJ internal derangements., Purpose: The aim of the study was to assess the value of sound analysis in the diagnosis of the type of the TMJ internal derangements., Material and Methods: After clinical and radiologic examinations, phonographic sound recordings on mandibular excursions were obtained in 52 patients with TMJ internal derangements and 12 control individuals. Sound correlations were made on the basis of opening-closing, protrusive-retrusive, and lateral excursions of the mandible., Results: Clicking was a consistent finding of anterior disc displacement with reduction, whereas crepitation was found in varying degrees in anterior disc displacement and osteodegenerative arthritis. Silent TMJs were the feature of normal TMJs, except for the situations of acute lock. Although in 29 TMJs opening click was followed by a closing click (reciprocal clicking), 46 TMJs with opening click also had clicking on protrusion. On the other hand, 19 TMJs with opening click also had clicking on ipsilateral motion, and 40 TMJs with opening click had clicking on contralateral motion of the mandible. The sound patterns were found to be similar in opening-protrusive clicks and opening-contralateral clicks. The lack of protrusive clicking in the presence of opening click was considered an indication of late disc reduction on opening. Crepitation was observed in advanced cases of TMJ internal derangements., Conclusion: Within the limitations of this study, the results suggest that TMJ sound analysis on mandibular excursions was indicative for diagnosis and establishment of severity of TMJ internal derangements. Clicking and crepitation may be looked on as signs of abnormal joint disorder, clicking indicating anterior disc displacement with reduction, and crepitation, indicating progression from anterior disc displacement without reduction to osteodegenerative arthritis.

Statement of Problem: Patients who have lost moderate posterior tooth support may also lose clenching force as a result of sensitivity to increased loading to the remaining teeth and possibly a loss of muscle strength, because clenching forces are limited to avoid stress to the remaining teeth. Few studies have correlated moderate posterior tooth loss with maximum clenching force., Purpose: The purpose of this pilot study was to test the hypothesis that moderate loss of posterior tooth support will have a significant effect on maximum clenching force., Material and Methods: The maximum clenching force of 44 adults, ages 28 to 76 (mean 46), with posterior tooth loss was compared with the maximum clenching force of a control group of 20 healthy full dentition adults, ages 18 to 55 (mean 30), by use of a bilateral strain-gauged transducer. The transducer consisted of 2 stainless steel plates separated by a steel sphere that balanced occlusal forces between right and left sides. Acrylic resin pads were fabricated for each patient to protect the cusps of the teeth. The overall accuracy was found to be within 2.3% of full scale over a range of 0 to 4000 N (0 to 900 lbs). The calibration reliability of the system was checked frequently by use of a dead weight of 222 N (50 lbs). Clenching forces were supported by first and second molars and second premolars when possible. The instrumentation, methods, and operator were the same for both groups. A 2-tailed Student t test (alpha=0.01) and a pooled estimate of the mean were used to determine possible statistical significance. To test for possible correlations between clenching force and lost tooth support and between clenching force and age, a linear regression correlation coefficient R was calculated., Results: For the 44 subjects with posterior tooth loss, the mean clenching force was 462 N (104 lbs), with a range of 98 to 1031 N (22 to 232 lbs). This compares with a mean of 720 N (162 lbs) with a range of 244 to 1243 N (55 to 280 lbs) for the full-dentition subjects. A 2-tailed t test showed that the average difference of 258 N (58 lbs) between the 2 groups was significant (P< or =.01). There was only a moderate negative association between clenching strength and loss of mandibular tooth support (R = -0.35). Clenching force was not well correlated with age as indicated by low R values (R = 0.21, missing tooth group and R = -0.03, full dentition group)., Conclusion: Within the limitations of this study the maximum clenching force was less (P< or =.01), by 258 N (58 lbs) on average, in subjects with moderate loss of posterior tooth support. Loss of maximum clenching force was associated with a modest negative correlation to the number of missing teeth in the mandibular arch (R = -0.35). The range of clenching force was surprisingly large for both the missing tooth (98 to 1031 N) and full dentition (244 to 1243 N) groups.

The American Dental Association has approved several devices as aids in the diagnosis of temporomandibular disorders. Concerns remain, however, about their safety and effectiveness. This article reviews the validity and use of several instruments that claim to serve as aids in the detection of masticatory muscle pain, trismus, joint noises, and limitation of jaw motion. A review of data from 62 published articles indicated that, although commercial devices that measure jaw muscle tenderness, muscle activity levels, joint noises, and jaw motion are safe and can document these phenomena, cost-benefit analyses of these devices have not yet been conducted. Moreover, these devices have not been shown to have stand-alone diagnostic value and, when tested, they have demonstrated unacceptable sensitivity and specificity levels. None of the instruments reviewed in this article can be said to provide more than ancillary documentation.

Statement of Problem: Understanding is needed regarding the effect that occlusal interferences have on the teeth, periodontium, and especially on jaw function., Purpose: This article summarizes research in which experimental occlusal interferences have been placed on the teeth of animals and human volunteers., Material and Methods: Data from 18 human and 10 animals studies were reviewed. Experimental occlusal interferences were grouped into those that alter intercuspal position and those contacting on lateral jaw movement only. The outcome of these interferences were analyzed according to their local pulpal-periodontal, jaw function, or bruxism effects., Results: Experimental occlusal interferences in maximum intercuspation had a deleterious effect on periodontal and pulpal tissues of the affected tooth; sometimes this produces a disruption of smooth jaw function and occasionally jaw muscle pain and clicking. Experimental occlusal interferences that contact only in a lateral jaw movement are infrequently harmful to jaw function. Furthermore, no reliable evidence demonstrates that occlusal interferences can cause nocturnal bruxism, or stop it., Conclusion: Transient local tooth pain, loosening of the tooth, a slight change in postural muscle tension levels, chewing stroke patterns, and sometimes a clicking joint can be induced by an experimental occlusal interference. Because such findings are present in relatively asymptomatic patients, these data do not prove that occlusal interferences are causally related to a chronic jaw muscle pain or temporomandibular joint dysfunction problems.

Statement of Problem: Osseointegrated implants used in the mandible post resection and reconstruction for cancer represents a treatment option with the potential for functional improvement and enhanced quality of life. Unfortunately, protocols for their use in this patient population have been empirical and technique-driven with the assumption that they will overcome most, if not all, functional deficits encountered., Purpose: The article reviews the salient oral physiologic factors for this group of patients and presents a rational approach and functional criteria for patient selection and implant placement. Other considerations discussed include: timing of implant placement, irradiated and compromised tissues, patient motivation, and tumor prognosis., Conclusion: These principles, if followed, may enhance realistic functional outcomes for this patient population.

Statement of Problem: There are discrepancies among researchers concerning the reliability and use of temporomandibular joint sounds., Purpose: This study examined the reliability of mandibular movements and sounds and determined the correlation between movements and sounds., Material and Methods: The mandibular movements of 35 subjects diagnosed with temporomandibular disorders were recorded with 2 CCD cameras, and sounds were recorded bilaterally with Panasonic electret condenser microphones in the ear canal. Subjects performed 3 movements, each repeated 5 times., Results: Reliability of maximum movements across the 5 trials was good to excellent, with Intraclass Correlation Coefficients (ICC) between 0.76 and 0.91 for all movements except protrusion. Temporomandibular sound event counts were reliable for most movements, including vertical opening, protrusion, and right and left laterotrusion (ICCs between 0.41 and 0.81). Most subjects produced sound events either in 100% or in none of the trials. Reliability for sound events was better during protrusion (ICCs between 0.56 and 0.81) than vertical opening (ICCs 0.41 to 0.64). Subjects with sound events during vertical opening (followed by closing) were significantly more likely to have sound events during protrusion (followed immediately by vertical opening and closing) (P <.01)., Conclusion: Temporomandibular sound events are generally reliable and warrant study regarding their use in classifying and diagnosing patients with temporomandibular disorders. Condylar translation, which occurs during both vertical opening and protrusion, appears to have a strong influence on the production of temporomandibular sound events.

Statement of Problem: Patients with temporomandibular disorders may have a cluster of joint and muscle disorders characterized primarily by pain, joint sounds, and irregular or deviating jaw function., Purpose: This study evaluated changes in local cross-sectional dimensions of muscles of the head and neck associated with short-term application of "splint therapy" using the diagnostic approach of high resolution gray-scale ultrasonography., Material and Methods: The study included 15 subjects with signs and symptoms of temporomandibular disorders, 10 in the internal derangement type (IDT) III-a group, and 5 in the myalgia type I (MT I) and myalgia type II (MT II) group. Ultrasonographic investigation was performed with a linear (B-scan) 7.5 MHz small-part transducer to visualize the anterior temporalis, anterior and deep masseter, anterior and posterior digastric, and sternocleidomastoid muscles. The absolute asymmetry index was used to assess local muscle asymmetry patterns and to evaluate the respective effect of occluding splints, with the mean maximum muscle diameter of the respective right and left sides calculated from 3 consecutive measurements before and after splint therapy., Results: A comparison of pretreatment with 2-month follow-up values revealed a slight decrease in the overall mean local cross-sectional dimensions in the internal derangement type III-a group (0.3 mm) and a moderate decrease in the myalgia type I/II group (3.3 mm). With an overall mean pretreatment absolute asymmetry index of 1.3% for the internal derangement type III-a group and 0.5% for the myalgia type I/II groups, the 2-month follow-up showed the internal derangement type III-a group to be associated with a moderate (1.2%) and the myalgia type I/II groups with a slight (0.1%) decrease in the respective overall mean pretreatment absolute asymmetry indices., Conclusion: This study suggests that stabilization-type splints are effective in the reduction of local muscle thicknesses and asymmetries. Further studies are necessary to evaluate muscle-site specific effects in patient and nonpatient groups and to relate these effects to variables such as bite force, preferred chewing side, facial structure, and occlusion.

Statement of Problem: A significant number of patients exist who are in need of prosthodontic rehabilitation and who at the same time report musculoskeletal pain in the facial area., Purpose: This article, which is based on an assessment of both the past and the most recent basic science and clinical literature, evaluates the effect of musculoskeletal facial pain on two static (physiologic rest position and centric relation) and two dynamic (protrusive border and lateral border movements) maxillomandibular relationships., Material and Methods: To find the relevant studies addressing the association between musculoskeletal facial pain and maxillomandibular relationships, a MEDLINE search was conducted, which was complemented by a hand search in selected journals., Results and Conclusions: Musculoskeletal facial pain seems to variably affect the aforementioned positions and movements. Hence, the validity of maxillomandibular registrations in patients with existing facial pain is questioned. In those patients with facial pain who simultaneously are in need of a prosthodontic rehabilitation, clinicians should be cautious with regard to the timing of the restorative procedures.

Purpose: The purpose of this retrospective study was to evaluate the effect of maxillary full-coverage occlusal splint (stabilization splint) therapy for specific temporomandibular disorders and their symptoms/signs., Material and Methods: This study assessed the outcome of 232 patients who were suffering from chronic pain on movements, joint noise except reciprocal clicking, and difficulty of mouth opening. All were treated with the stabilization splint alone., Results: The total remission rate was 41% and, including those reporting some improvement, the rate was 84%. The presence of displaced disk significantly decreased the success rate. However, the presence or absence of radiographic changes in the temporomandibular joint did not influence the treatment outcome., Conclusion: From this study, it is suggested that the stabilization splint therapy may be a useful treatment modality in treatment of temporomandibular disorders, especially for the patients without clinical evidence of displaced disk.

The elastic limit of bone surrounding implants may be surpassed and thus produce microfractures in bone. The purpose of this study was to use computer simulations to examine clinical situations with IMZ implants in edentulous mandibles and to identify loading conditions that could lead to bone microfractures. Three-dimensional finite element analysis models were used to examine effects of: (1) types of edentulous mandibles, (2) veneering materials, (3) the absence of cortical bone, (4) different intramobile elements, (5) loading directions, and (6) loading levels. Stress distribution patterns were compared and interfacial stresses were monitored specifically at four heights along the bone-implant interface. Stresses were concentrated toward cortical bone (0.8 to 15.0 MPa). There were no differences between types of veneering materials and the absence of cortical bone increased interfacial stresses. The use of a titanium intramobile element decreased stresses. Minor stress increases were associated with smaller mandibles. Oblique loads increased stresses 15 times, and 200 N loads increased stresses 10 times. Conditions for bone microfracturing were associated with oblique loads, high occlusal stress magnitudes, and the absence of cortical bone.

Temporomandibular joint alterations have been associated with abnormal mandibular movements in the open/close cycles and in the laterotrusive border movements. The quantitative analysis of these movements could allow a better or earlier diagnosis for patients and offer some insight into the pathophysiology of the disorder. Maximum opening and mandibular laterotrusive border movements were studied and measured in a group of 165 patients with a considerable lateral deviation (equal to or greater than 5mm) in maximum opening. Movements were directly performed by the patients and recorded with a mandibular kinesiography. The slope of the lateral guidance (frontal plane projection) was measured in the first millimeters of motion and started from the maximum intercuspal position. On average, slopes were significantly flatter on the same side with the opening deviation. These slopes were significantly flatter than previously published physiologic ranges, whereas contralateral slopes were similar to normal references. The results may be explained by a correlation between the insufficient lateral protection and a temporomandibular mandibular joint dysfunction (ipsilateral low mobility).

This study simultaneously examined the load transfer and stress distribution by an implant-supported fixed partial denture. A mandibular implant framework with implants connected to the abutments was embedded in a three-dimensional photoelastic model of a mandible. Strain gauges were attached on the superior surface of the framework, and a vertical load of 7.5 kg was applied to seven points on the framework. The measurements derived from this simulation revealed that (1) there was a direct proportion between the stress distribution in the metal framework and stresses created in the supporting structure around the implants; (2) the mode of load transfer and stress distribution was directly proportional to the distance of the components from the loading point; and (3) when the cantilever was loaded, the major part of the stress was distributed within the cantilever in the connection to the distal abutment. In this simulation, stress was distributed over the two, or maximum three, closest implants with the distal implant the most stressed.

The results of a temporomandibular joint survey sent to 167 members of the Greater New York Academy of Prosthodontics indicated a great variation in the diagnosis and treatment of patients with temporomandibular joint dysfunction. Although most indicated that their background in temporomandibular joint disorders was from clinical experience and/or textbooks and the dental literature, only 59% treated patients for these disorders. The most common diagnostic procedures were occlusal evaluation; joint evaluation for tenderness, crepitus, and click; evaluation of range of motion of the mandible; and a muscular evaluation. Only 35% used a formal temporomandibular joint dysfunction questionnaire. The percentage of complete denture patients with these symptoms was 5% or less. Thirty-three percent of clinicians sometimes treated asymptomatic patients who were without pain but had a click. Two thirds of the respondents believed that surgery was sometimes indicated for disk degeneration and displacement. More recent graduates are more likely to treat patients who have temporomandibular joint dysfunction than are older more experienced practitioners.

This article discusses the occlusal concepts when making implant-supported and implant-retained mandibular overdentures. The dentate or edentulous condition of the maxilla plays a significant role in this respect. If the maxilla is edentulous, balanced occlusion is indicated. In a maxillary Kennedy class I or II situation, either group function or balanced occlusion is advocated depending on the characteristics of the opposing dentition. When a complete dentition is present in the maxilla or in the case of a Kennedy class III or IV situation, mutually protected occlusion or group function is recommended depending on the length, position, and number of implants. It is stressed that detailed preimplant placement diagnosis and treatment planning are essential to obtain a high standard of treatment with overdentures supported and retained by implants.

A procedure is described for the final impression of the severely atrophied mandible. The final impression is developed by use of open- and closed-mouth procedures. The objective is to develop a physiologic impression with maximum support of both hard and soft tissues.

From a pool of 89 patients, 49 patients were classified as having chronic myofascial pain dysfunction syndrome (MPDS), and 40 were classified as asymptomatic or non-MPDS patients designated as the control group for the study. To achieve balanced sample size in both groups, 40 patients were arbitrarily selected from the MPDS group. All patients from each of the two primary groups were then categorized and assigned to one or more subgroups according to the following criteria: (1) jaw classification, (2) open occlusion, (3) previous orthodontic therapy, or (4) no previous orthodontic therapy. A fifth subgroup composed of only MPDS patients and equally divided into those who had or had not experienced orthodontic therapy was established to determine whether mean disclusion time differences occur between orthodontic and nonorthodontic MPDS patients. All 80 patients were evaluated for disclusion time of their right and left mandibular excursions to determine statistical population comparisons. Statistical assessment of right and left disclusion times for women and men in the MPDS and non-MPDS groups was performed separately for each of the five subgroups. Analysis of the comparisons revealed that in all except two of the subgroups, mean disclusion time was significantly longer in the MPDS patient group than in the non-MPDS group. The two subgroups in which this was not apparent were those with open occlusion and orthodontic patients compared with nonorthodontic patients. These findings suggest that lengthy posterior disclusion time may be of diagnostic importance when the differing etiologic factors of chronic MPDS patients are evaluated.

Two imaging methods are useful in diagnosing internal derangements of the temporomandibular joint: arthrography and magnetic resonance imaging (MRI). Clinical and pseudodynamic MRI findings of 200 temporomandibular joints in 100 patients were evaluated and compared. In 66.5% of the joints, there was a positive correlation between both diagnostic methods. MRI showed the possibility to correct the clinical diagnosis in more than half of the remaining joints. The other half of the joints are a source of discussion and suggest that MRI has some difficulties in detecting the exact disk position, especially in joints with an anterior disk displacement with early reduction. MRI revealed degenerative changes in 43.5% of the joints. They were often seen in joints with a disk displacement without reduction, even in young patients. Pseudodynamic MRI is especially useful in the differential diagnosis of a "closed lock" and should certainly be done when disk surgery is planned.

Six of seven women were recalled after 1 year to remeasure their right- and left-side working disclusion times. Before the occlusal adjustment technique known as immediate complete anterior guidance development (ICAGD), these patients presented lengthy mean disclusion times (> 1.0 second) and multiple chronic myofascial pain dysfunction syndrome (MPDS) symptoms. After ICAGD, these patients presented with short mean disclusion times (< 0.7 second) and no chronic MPDS symptoms were observed. At 1-year follow-up, there was no statistical difference between present measurements of disclusion time and those of 1 year earlier. In addition, all six posttreatment patients demonstrated no observed chronic MPDS symptoms. However, the symptom of nocturnal bruxism appeared to recur with some chronic regularity. These results suggest that, for this population, disclusion time was stable over the 1-year period of observation, and the short disclusion time appears to allow normal daily muscle function with significantly lessened appearance of chronic myofacial pain dysfunction symptoms.

The purpose of this continuing longitudinal investigation was to study the changes on the craniofacial complex in complete denture wearers; herein are reported the 20-year findings. At the onset of the study complete dentures were made for 64 persons. Two dentures techniques were employed: a complex method of construction and a simplified method. At the start of the project the patients' ages ranged from 30 to 60 years (average age 53 years) and all had been edentulous for at least 1 year (range 1 to 30 years). Lateral cephalometric radiographs were made immediately after initial placement of the dentures and during subsequent years (1, 2, 3, 4, 5, 7, 10, 15, and 20). The same cephalostat was used throughout and all films were exposed with the teeth in centric occlusion. Thirty-four subjects presented for the 20-year follow-up. Of this number, the radiographs of 24 subjects (14 women and 10 men; average age 65.5 years [range 50-83 years]) (12 complex denture wearers; 12 simplified technique denture wearers) were used in this report (10 had denture alterations over the 20-year period that excluded them). The 20-year observations corroborate earlier findings. There is a loss of the vertical dimension of occlusion as viewed from the right profile, and the mandible rotates in a counterclockwise fashion resulting in an increase in relative prognathism. The maxillary alveolus was stable, the mandibular alveolus resorbed, and the dentures rotated counterclockwise and shifted slightly forward. The observed changes were not significantly affected by the sex of the patient or by the denture technique employed.

Temporomandibular joint (TMJ) function in patients who experienced lateral cranial base tumor surgery was evaluated by a comparison of recordings of condylar movement in right and left parasagittal planes during opening and protrusive movements. The characteristic tracing and measurements of mandibular movements at the condyle of six patients after surgery were compared with a nonsurgical asymptomatic control group consisting of 16 subjects. Of the six surgical patients, three patients had the condyles disarticulated and rearticulated, and three patients had condyles surgically resected. The data gathered through computerized axiographic tracings of horizontal condylar inclinations at different intervals showed significant interaction effects among right and left sides within the groups (p 0.001). Medical histories and clinical examinations were used to diagnose or rule out the presence of TMJ disorders. Magnetic resonance imaging (MRI) and three-dimensional computerized tomograms (CT) imaging of the TMJs of these patients were investigated. MRI and CT scans illustrated the static detail and morphology of the TMJs. Computerized axiography revealed the dynamic detail and function of the TMJs in the various mandibular movements. The study of condylar pathways during opening and protrusive movements showed variations of mandibular deviation among patients having cranial base surgery. Increased mandibular deviation was found in patients who experienced resected condyles.

Fifty-one patients with craniomandibular disorders were divided into two groups. One group underwent mock occlusal adjustment, the other was treated with adjustments to remove significant slides and nonworking-side interferences. Both groups received identical counseling. Kinesiographic and electromyographic assessment showed no significant difference between the two groups.

Fifty-one patients with craniomandibular disorders were divided in two groups. One group underwent mock occlusal adjustment, the other was treated with adjustments to remove significant slides and non-working side interferences. Both groups received identical counseling. The results show that there was no significant difference in the improvements on the signs and symptoms obtained by real or mock adjustments after the first treatment session.

The stress distribution around dental implants was investigated by use of a two-dimensional model of the mandible with two implants. A vertical load of 100 N was imposed on abutments or the bar connection. The stress was calculated for a number of superstructures under different loading conditions with the help of the finite element method. The length of the implants and the height of the mandible were also varied. A model with solitary abutments showed a more uniform distribution of the stress when compared with a model with connected abutments. The largest compressive stress was also less in the model without the bar. Using shorter implants did not have a large influence on the stress around the implants. When the height of the mandible was reduced, a substantially larger stress was found in the bone around the implants because of a larger overall deformation of the lower jaw.

Surgical resection of a segment or loss of mandibular continuity can adversely affect most of the structures essential for maximum occlusal force. Five subjects who had partial mandibular resections for treatment of squamous cell carcinoma were studied. Occlusal force was recorded before and after cancer treatment and following prosthetic rehabilitation. A gnathodynamometer was used to record anterior occlusal force. Five edentulous and five dentate cancer-free subjects matched for age were studied to establish comparable normative data. The null hypothesis that partial mandibular resection would not affect maximum occlusal force was rejected (p = 0.0101). Mandibular resection did alter maximum occlusal force. The impact of the decrease in maximum occlusal force on masticatory function is yet to be determined.

The association between clinical signs of craniomandibular disorders (CMD) and occlusal interferences was studied longitudinally in two cohorts of children, 5 and 10 years of age at baseline, representing the nonpatient population. They were followed up for 5 years. The range of active participants was 96 to 106 in the younger group, and 64 to 74 in the older group. The subjects were seen annually for registration of signs of CMD and for the presence of interferences, and for a real or placebo occlusal adjustment. The double-blind study design was applied. Baseline data showed no association between the variables studied; parts of data from second and third examinations disclosed significant associations; and fourth, fifth and sixth examinations disclosed a consistent pattern of significant associations.

The form of the anterior mandible in 45 patients was assessed before, immediately after, and 1 year after genioplasty. A specific, consistent pattern of bone apposition and resorption was observed after advancement genioplasty. A consistent but inverse apposition-resorption pattern was observed after reduction genioplasty. In view of the observed pattern of bony change, it is recommended that fixation devices for genioplasty be placed in areas of future bone deposition.

The method used to apply hydroxyapatite to implant surfaces may affect the thickness and ultimately the physical properties of the coating. This study investigated and compared the healing rates of bone around commercially pure titanium implants and titanium implants sputter-coated from a hydroxyapatite target. Forty-five sputter-coated implants and an equal number of noncoated titanium implants were placed into 15 partially edentulated dog mandibles. The implants were removed at three time periods and were evaluated mechanically and histologically. A multiple analysis of variance indicated that the interface bond strength was statistically greater (p less than 0.01) for the sputter-coated implants. Histologic analysis of the bone-implant interface demonstrated that coated implants had nearly twice the percentage of direct bone contact compared with noncoated implants. The results indicate that implants sputter-coated from a hydroxyapatite target will accelerate the healing of bone at the implant interface.

Tooth contact patterns in laterotrusion, protrusion of the mandible, and in the retruded position were recorded in young men with varying types of occlusion. The tooth contacts were recorded clinically with alginate (irreversible hydrocolloid) indices. In addition, the functional state of the masticatory system was evaluated by the recording of signs and symptoms of mandibular dysfunction and of the abrasion of the teeth. On protrusion, most subjects had contacts only on anterior teeth. Protrusive contacts only on posterior teeth were rare. On laterotrusion, most subjects had group function on the functional side. Contact on the nonfunctional side was found in half of the subjects in a 1.5 mm laterotrusive position and in one third of them in a 3 mm laterotrusive position. No correlation between the types of tooth contacts and mandibular dysfunction was found.

Anterior disk displacement without reduction, called "closed locking," is a serious stage of the internal derangement of the temporomandibular joint. Many types of conservative and surgical treatments have been applied to this problem. A new manipulation technique to release "closed locking" of the temporomandibular joint and the clinical results on 35 patients are reported in this study. Voluntary maximal mouth opening of the patients were measured as interincisal distance before and after the application of the manipulation technique. The voluntary maximal mouth opening of 14 of 17 patients (82%) who were younger than 30 years was improved to more than 40 mm after the application of the manipulation technique. Contrariwise, the voluntary maximal mouth opening of only 5 of 18 patients (28%) who were older than 30 years was improved to more than 40 mm.

Each patient with a small mandible presents an occlusal pattern that differs from most of the criteria established for a class I occlusion. The components of a class II occlusion are unlike other occlusions. The anterior teeth do not provide the protection and guidance normally provided by horizontal and vertical overlap. The posterior teeth bear the full force of occlusion. Protrusive movement is the dominant and the most used movement. The posterior teeth must function from centric relation forward to an anterior separation. Most of the posterior teeth exhibit balancing contacts. This occlusion is a type of bilateral balanced occlusion. Greater interocclusal clearance must be provided and tested for adequacy of space during speech and function. A class II occlusion is a most exacting occlusion. The controlling factors are the posterior determinants of occlusion.