Purpose: The aim was to describe early and a few recent methods to evaluate masticatory function in patients before and after implant treatment.
Study selection: Three Swedish doctoral theses from the early era of osseointegration and a recent Swedish doctoral thesis studying oral function in implant patients are reviewed. Furthermore, a PubMed search was conducted to identify studies published during the last 3 years related to masticatory function in implant patients.
Results: The first studies used questionnaires and methods for assessing bite force and chewing efficiency before and after implant treatment. Subsequent studies included methods evaluating dietary selection, psychological problems, occlusal perception, oral stereognosis, oral motor ability and phonetics. The results demonstrated overwhelming improvement, both subjectively and objectively, of oral functions, and in the patients’ lives, after implant treatment. The methods employed appear to have been adequate and they have continued to be utilized, only slightly modified, in a number of subsequent and recent studies. New methods using custom-made equipment to monitor changes in bite force, jaw movements and muscle activity during various tasks demonstrated the important role of periodontal mechanoreceptors in biting and chewing. These methods promise to be valuable in ongoing and future prosthodontic research.
Conclusions: The early methods used for assessment of masticatory function appear to have been adequate and they have, with only slight modifications, continued to be utilized. New methods monitoring bite force, jaw movements and muscle activity have deepened the knowledge of masticatory functions and promise to be valuable in future prosthodontic research.

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Purpose: The aim of this study was to evaluate creep and viscoelastic properties of dental impression materials after different storage times.
Methods: Six commercially available impression materials (one polyether and five silicones) were tested after being stored for 30 min to 2 weeks under both static and dynamic testing. Shear and Young's moduli, dynamic viscosity, loss tangent and other viscoelastic parameters were calculated. Four of the materials were tested 1 h after setting under creep for three hours and recovery was recorder for 50 h.
Results: The tested materials showed differences among them, while storage time had significant influence on their properties. Young's modulus E ranged from 1.81 to 12.99 MPa with the polyether material being the stiffest. All of the materials showed linear viscoelastic behavior exhibiting permanent deformation after 50 h of creep recovery.
Conclusion: As storage time affects the materials’ properties, pouring time should be limited in the first 48 h after impression.

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Purpose: The aim of this in vitro study was to evaluate the implant–abutment assembly of Astra Tech (AST), Bego (BEG), Camlog (CAM), Friadent (FRI), Nobel Biocare (NOB) and Straumann (STR) with respect to yield force before and after cyclic fatigue, using a static overload test with a test set-up according to ISO 14801.
Methods: Ten specimens of each type were split into two homogenous groups: one half was tested for static yield force without any further treatment (control), whereas the other one underwent one million cycles of mechanical loading with 100 N as the upper load limit. For load-to-failure testing, specimens were then placed in a stainless steel jig and loaded in a universal testing machine under an angle of 30° with respect to the implant axis until failure. Load–displacement curves were analyzed and the yield forces at which non-linear behaviour set in (Fp) were recorded. Statistical analysis was performed using one-way ANOVA and t-test, respectively, with the level of significance set at 0.05.
Results: Statistical analysis revealed that the type of implant–abutment connection has a significant influence on Fp (p < 0.001). Furthermore, dynamic loading proved to significantly influence Fp of BEG and CAM (p < 0.001).
Conclusion: None of the implant–abutment types tested would be expected to fail under clinically relevant forces, but the type of implant–abutment connection significantly influences the yield force Fp.

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Purpose: A digital image correlation (DIC) method for full-field surface strain measurement was used to analyze the effect of two veneering materials for implant supported crowns on the strain distribution within the surrounding bone.
Methods: An epoxy resin model of a bone block was made by housing acrylic resin replicas of a mandibular first premolar and second molar together with threaded implants replacing the second premolar and first molar. Porcelain-veneered (G1 and G3) and resin-veneered (G2 and G4) screw-retained splinted crowns were fabricated and loaded with (G1 and G2) and without (G3 and G4) the presence of the second molar replica. A 2-dimensional DIC measuring system was used to record surface deformation of the bone block model at a frequency of 1.0 Hz during application of a 250-N load.
Results: Maximum compressive strains (ε_XX, %) were found for the following regions: between molars, G1 (−0.21), G2 (−0.18), G3 (−0.26), and G4 (−0.25); between implants, G1 (−0.19), G2 (−0.13), G3 (−0.19), and G4 (−0.14). The magnitude of strains in the simulated bone block with the resin-veneered crowns was lower than that with porcelain-veneered crowns, irrespective of the presence or absence of the second molar.
Conclusions: The softer resin veneer helped to spread the load more evenly amongst the supporting teeth and implants, thus reducing the strains in the simulant bone block. Conversely, using the harder porcelain veneer resulted in the load being concentrated within one or two teeth or implants, thus leading to higher strain values in the bone block.

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Purpose: The use of implants to treat edentulous jaws has become a well-established and accepted contemporary clinical method. The aim of this study was to analyze information about the implants used, patients, denture modality, and complications after denture insertion in partially and fully edentulous patients with implant overdentures placed.
Methods: A survey was performed about patients rehabilitated using implant dentures at the Tsurumi University Dental Hospital during 8 years. A total of 201 implants were placed: 112 in the maxilla and 89 in the mandible. Descriptive statistics were used for each patient, such as the implant positions and numbers, retainer designs, denture modalities, implant survival rate and prosthetic complications.
Results: The positions of implant placement were: incisor (44%); canine (26%); premolar (18%); and molar (12%). Approximately 70% of the retainers were bar attachments and magnet attachments. The majority of the prostheses were metal-based dentures (84%) compared to only 10 acrylic dentures (16%). Fully edentulous, fourteen (12 maxillary, 2 mandibular) of 171 implants failed. Partially edentulous, three (3 maxillary, 0 mandibular) of 30 implants failed. The denture complications observed during maintenance were denture fracture, retainer breakage and artificial tooth fracture.
Conclusion: Although the mandibular implant dentures placed were exceedingly reliable for rehabilitation with a high survival rate, the maxillary implant dentures exhibited a low survival rate and more frequent complications. Significantly higher implant failures and prosthetic complications were observed in the initial period after placement than in the following years.

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Purpose: The purpose of this study was to clarify the day-to-day variations of salivary cortisol to discuss the appropriate timing for collecting saliva in a day for stress evaluation.
Materials and methods: Saliva samples from twelve healthy adults were collected by means of Salivette^® (SARSTEDT Co.) three times per day, immediately after awakening (Time1), 6:00 PM (Time2) and 30 min before going to bed (Time3), on 5 nonconsecutive days. Cortisol concentration was measured using a radioimmunoassay.
Results: Salivary cortisol concentration showed the larger value at Time1 than that at Time2. The mean value of %CV for day-to-day variation showed the smallest value at Time1 (mean: 43.1%) and the largest value at Time3 (mean: 100.3%). There were significant differences in %CV value between Time1 and Time3, Time2 (mean: 64.1%) and Time3.
Conclusions: There are considerable day-to-day variations in salivary cortisol concentration measurements. From the viewpoint of day-to-day variation, collecting saliva immediately after awakening in the morning is thought to be more advantageous for evaluating cortisol concentration.

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Patient: A 66-year-old woman, who had a bilateral free-end edentulous mandible and no experience with dentures, was examined for the chief complaint of masticatory dysfunction on left side of dental arch. A unilateral distal extension removable partial denture (RPD) replacing lower-left molars was selected. Tomographic images were obtained using Fluorine-18 NaF positron emission computerized tomography (NaF-PET)/computed tomography (CT) before the RPD use and at 1, 6, and 13 weeks after the RPD use to observe the metabolic changes in residual bone caused by the RPD use. PET standardized uptake values (SUVs) and CT values were calculated for lower-left edentulous site (test side) and lower-right edentulous site (control side). As a result, SUVs on the control side remained static after the RPD use, whereas those on the test side increased at 1 and 6 weeks after the RPD use and then decreased. However, CT images showed no obvious changes in the bone shape and structure beneath RPD, and CT values both on the control and test sides did not change either.
Discussion: This report shows that NaF-PET could detect bone metabolic changes soon after the RPD use, which cannot be detected by clinical X-rays. The SUV changes may be a mechanobiological reaction to the pressure due to the RPD use, and wearing of the RPD may increase the bone turnover beneath denture.
Conclusion: This report demonstrates that wearing of an RPD increases bone turnover beneath denture immediately after the RPD use without clinically detectable changes in bone structure or volume.

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Patient: A 67-year-old female with root fracture of the maxillary central incisor underwent implant placement immediately after extraction, with the goal of shortening the treatment period. The superstructure was placed on the implant after a 4-month healing period. Review 5 years after implant loading revealed no clinical problems.
Discussion and conclusion: The treatment time was shortened effectively by the flapless immediate post-extraction placement procedure. Immediate post-extraction implant placement based on proper examination and diagnosis would reduce the patient burden.

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Purpose: Assessment of swallowing dysfunction, particularly the risk of aspiration, is extremely important to clinicians because it provides crucial information for preventing morbidity and mortality from dysphagia. The purpose of this study was to describe a magneto-impedance sensor-aided screening system (MISS) for assessing swallowing function and clarify its effectiveness with the repetitive saliva-swallowing test (RSST).
Methods: An MI sensor attached to the skin over the sternum detected the distance from a magnet attached to the skin over the thyroid cartilage during swallowing as the change of magnetic fields. The MISS was validated by videofluoroscopic and videoendoscopic observations. Further, the swallowing behavior of 93 individuals was assessed by using the MISS and then analyzed with the RSST.Swallowing behavior can be recorded and investigated objectively by signal inspection in the MISS compared with the conventional methods. The MISS is a simple and straightforward method for recording and safe because of dry swallow.The MISS system was validated by using simultaneous recordings with videofluoroscopic or videoendoscopic examinations, and compared with the conventional RSST method.
Conclusions: The MISS combined with the RSST is an effective screening test for swallowing function.

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Purpose: The aim of the present study was to evaluate commercially pure titanium (CP Ti) casting quality when a specific to titanium and a conventional phosphate bonded investments were used under different mold temperatures. For this, the evaluated parameters were surface roughness, bending strength, Vickers microhardness, casting quality by radiographies and microstructure of CP Ti.
Methods: Wax patterns (28 mm × 3 mm × 1 mm) were invested using two phosphate bonded investments: Rematitan Plus (REM), specific to titanium, and Castorit Super C (CAS), a conventional investment, fired and cooled until reaching two mold temperatures: 430 °C (430) and room temperature (RT). Specimens were cast from CP Ti by plasma. After casting, specimens were radiographically examined and submitted to Vickers microhardness, roughness and bending strength evaluation. Microstructure was analyzed in the center and at the surface of specimen.
Results: Qualitative analysis of radiographs showed that specimens which were cast using CAS-RT presented more casting porosities while the specimens which were cast with REM-430 did not present any casting porosity. No significant difference was noted among the groups in the surface roughness and Vickers microhardness data, but the bending strength of the specimens cast using CAS was greater than REM groups. The microstructure of the specimens of the different groups was similar, presenting a feather-like aspect.
Conclusion: Casting porosities found in the specimens cast using conventional investments (CAS) and lower mold temperatures would limit their use, even mechanical properties were similar than in specimens cast using specific to titanium investment (REM) at temperatures recommended by the manufacturer.

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Purpose: This article describes a method to express implant positions in the dental arch as well as the type and extent of superstructures.
Methods: Basic signs, a (circle) and a (dot), which denote an implant and a single standing implant, respectively, are utilized to construct the Panoramic Implant Notation System (PIN System), which allows graphical representation of implants and implant-supported prostheses. The use of the PIN System is described by means of its application to common dental implant situations. While the Universal Numbering System is applied principally, examples of use of FDI Two-Digit Notation and Palmer Notation are also illustrated.
Conclusion: By employing the PIN System, implant positions as well as information pertaining to the type and extent of implant prosthodontics can be easily visualized, and, therefore, practically described, which leads to the avoidance of misunderstanding and ambiguity in communication.

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