Retentive strength and marginal discrepancies of a ceramic-reinforced calcium phosphate luting agent: An in vitro pilot study

Journal of Prosthetic Dentistry · 2018-06-29 · 5 citations

Effect of Cast Modification on Denture Base Adaptation Following Maxillary Complete Denture Processing

Journal of Prosthodontics · 2017-01-19 · 10 citations

PURPOSE: To investigate the effect of cast modifications on denture base adaptation in coronal and sagittal projections following maxillary complete denture processing. MATERIALS AND METHODS: A total of 60 edentulous maxillary casts (n = 10) were distributed among six groups. Group 1 was the control group with no modification, groups 2 through 6 included a butterfly postdam preparation, groups 3 and 4 also included a 10-mm wide/4-mm deep box with addition of four round holes in group 4, and groups 5 and 6 also included a 20-mm wide/4-mm deep box with addition of four round holes in group 6. The boxes were prepared at the mid-heel area of the casts. Two layers of baseplate wax (1 mm each) were used to standardize denture base thickness across the groups. A standard technique was used to replicate the denture tooth set-up, and standardized processing was done for all the groups. Following deflasking, casts with the dentures were sectioned in the coronal and sagittal directions. Microscopic pictures were taken at preselected points. Data were organized in tables, and statistical analyses were performed using repeated measure ANOVA, Tukey post hoc tests, and post hoc comparison tests set at 5% level of significance. RESULTS: Maximum gaps were measured at the mid-palatal area followed by nearby areas and the areas near ridge crests in both coronal and sagittal projections. The analyses revealed significant differences between the groups in coronal projection (1/2, 3/4, 5/6) and sagittal projection (1, 2, 3/4, 5/6) without significant differences within the pairs. The groups were ranked from the highest group 1 to the lowest group 6 relative to the gap means. Post hoc comparisons showed that points 1C and 2A had the highest gap means across the study groups. CONCLUSIONS: Within the limitations of this study, it can be extrapolated that the denture base adaptation can be effectively increased with the box preparation at the mid-heel aspect of the casts. Significant reduction of gaps was seen when the box size increased from 10 to 20 mm in coronal and sagittal projections; however, the addition of four holes had no significant effect on gap size alterations.

Peri-Implant Strain in an In Vitro Model

Journal of Oral Implantology · 2013-10-11 · 12 citations

An in vitro experimental model was designed and tested to determine the influence that peri-implant strain may have on the overall crestal bone. Strain gages were attached to polymethylmethacrylate (PMMA) models containing a screw-type root form implant at sites 1 mm from the resin-implant interface. Three different types of crown superstructures (cemented, 1-screw [UCLA] and 2-screw abutment types) were tested. Loading (1 Hz, 200 N load) was performed using a MTS Mechanical Test System. The strain gage data were stored and organized in a computer for statistical treatment. Strains for all abutment types did not exceed the physiological range for modeling and remodeling of cancellous bone, 200-2500 με (microstrain). For approximately one-quarter of the trials, the strain values were less than 200 με the zone for bone atrophy. The mean microstrain obtained was 517.7 με. In conclusion, the peri-implant strain in this in vitro model did not exceed the physiologic range of bone remodeling under axial occlusal loading.

The Effects of Loading on the Preload and Dimensions of the Abutment Screw for a 3-Unit Cantilever-Fixed Prosthesis Design

Implant Dentistry · 2013-07-10 · 8 citations

OBJECTIVE: The purpose of this study was to use an in vitro model system to compare the effects on the screw torque and screw dimensions within 2 commercially available implant systems from occlusal loading on a cantilevered-fixed partial denture. MATERIALS AND METHODS: Cantilevered implant-supported 3-unit prostheses with 2 premolar abutments and 1 premolar pontic (7.3 mm in length) were made on resin casts containing 2 implant analogs for 2 implant systems: BioLok Silhouette Tapered Implant System (Birmingham, AL) and Zimmer Tapered Screw-Vent Implant System (Carlsbad, CA) with 10 samples in each group. Each sample was loaded with either of 2 protocols: (1) a load of 50 N on the cantilevered pontic unit and (2) a loading of 150 N on all 3 units. The outcome measures were (1) changes in residual torque of the abutment screws and (2) changes in screw dimension. RESULTS: The BioLok Silhouette Tapered Implant group demonstrated slight but statistically significant torque loss 18.8% to 28.5% in both abutment screws for both protocols, P ≤ 0.05, without any changes in screw dimension. In the Zimmer Tapered Screw-Vent Implant group, there was a significant elongation of the abutment screws and a markedly significant 44.4%, (P ≤ 0.01) loss in torque in the mesial screw and a 28.5%, (P ≤ 0.05) loss in torque in the distal screw when the cantilever alone was loaded. CONCLUSIONS: Differences in screw design influence the maintenance of preload and distortion of the shank. The influence of the interface design, namely an internal hex of 1 mm versus an external hex did not influence the preload. Cantilevered prostheses can cause loss of torque and dimensional changes in abutment screws.

The Effects of Laser Microtextured Collars Upon Crestal Bone Levels of Dental Implants

Implant Dentistry · 2008-06-01 · 74 citations

PURPOSE: The purpose of this study was to examine the crestal bone, connective tissue, and epithelial cell response to a laser microtextured collar compared with a machined collar, in the dog model. MATERIALS: Six mongrel dogs had mandibular premolars and first molars extracted and after healing replaced with BioLok implants 4 x 8 mm. Each dog had 3 control implants placed on one side of the mandible and 3 experimental, laser microtextured, implants placed contralaterally. After 3 months, 1 dog was killed. Bridges were placed on the implants of 4 of the dogs. The sixth dog served as a negative control for the duration of the experiment. Two of the dogs were killed 3 months after loading, of the dogs were killed 6 months after loading as was the negative (unloaded) control. Histology, electron microscopy, and histomorpho-metric analysis was done on histologic sections obtained from block sections of the mandible containing the implants. RESULTS: Initially the experimental implants showed greater bone attachment along the collar. With time the bone heights along the control and experimental collars were equivalent. However, the controls had more soft tissue downgrowth, greater osteoclastic activity, and increased saucerization compared with sites adjacent to experimental implants. There was closer adaptation of the bone to the laser microtextured collars. CONCLUSION: Use of tissue-engineered collars with microgrooving seems to promote bone and soft tissue attachment along the collar and facilitate development of a biological width.

Effects of load and indicator type upon occlusal contact markings

Journal of Biomedical Materials Research Part B Applied Biomaterials · 2007-07-06 · 91 citations

STATEMENT OF PROBLEM: Clinicians use occlusal indicators to identify tooth contacts. However, the reliability of these indicators has been questioned. At times occlusal contacts are not identified or false positive occlusal contacts are observed. PURPOSE OF STUDY: This study was designed to compare the number and size of occlusal indicator marks from both thick and thin occlusal indicator materials with different loads. MATERIALS AND METHODS: Ivorine casts were articulated and mounted on an Hana Mate nonadjustable articulator. Loads of 100N, 150N, and 200N were applied with Accufim (25 microm thick, Parkell, Farmingdale, NY) and Articulating Paper (60 microm thick, G.E. Rudischauer Dental Articulating Paper, Brooklyn, NY) as the occlusal indicators. A fresh piece of indicator was used for each trial. Comparisons were made of the number and size of the contacts for both the thick and thin occlusal indicators at the different loads. RESULTS: Observation of the marks recorded with the thicker occlusal indicator demonstrated both a greater number marks and a larger size to the marks when compared to the thinner Accufilm, p < or = 0.02-0.0001. However, there was no significant increase in the number or size of the marks with an increased load for either material.

Long-term effects of storage and thermal cycling on the marginal adaptation of provisional resin crowns: A pilot study

Journal of Prosthetic Dentistry · 2006-03-01 · 56 citations

Sensory responses from loading of implants: a pilot study.

PubMed · 2004-03-16 · 33 citations

PURPOSE: Osseointegrated implants lack a periodontal ligament. Nevertheless, masticatory function in subjects with implant-supported restorations appears similar to function in those with natural dentition. It is not clear how the neurophysiologic mechanisms that modulate jaw movement are associated with osseointegrated implants. This study examined the output from the inferior alveolar nerve during implant loading. MATERIALS AND METHODS: In 3 dogs, 3 premolars were extracted in the mandible and 2 endosseous titanium implants were placed, allowed to osseointegrate for 3 months, and loaded with vibration force at the threshold response for tooth vibration, at 2x threshold, and at 3x threshold. Neurophysiologic recordings were made from the inferior alveolar nerve during loading of both implants and the adjacent molar and canine. The response magnitude in action potentials in the 50- ms poststimulus period and latency of inferior alveolar afferents in milliseconds were compared following implant loading. RESULTS: Detectable inferior alveolar nerve responses were recorded following loading from both the implants and the teeth at 2x and 3x threshold. However, the response magnitude of teeth (canine, 2.38 +/- 0.18 at 2x, 2.78 +/- 0.2 at 3x; molar, 2.2 +/- 0.16 at 2x, 2.5 +/- 0.21 at 3x) was twice that of the implants (anterior, 1.3 +/- 0.12 at 2x, 1.68 +/- 0.13 at 3x; posterior, 0.8 +/- 0.1 at 2x, 1.53 +/- 0.15 at 3x). The differences in response magnitude between the teeth and implants were significant (P < .05). The latency of response was similar. DISCUSSION: Management of the occlusion for implant-supported restorations has been empirically developed. An underlying assumption has been that implant-guided jaw function lacks significant proprioception to modulate mastication and related jaw movements. This animal study provides preliminary evidence that force application to implants does elicit a proprioceptive response. CONCLUSION: Loading of implants does elicit a sensory response that can be observed in the inferior alveolar nerve. The implications are that during occlusal function, information from regions associated with the implant can provide knowledge that could potentially modulate jaw activity in a manner similar to natural teeth.

Bone response after one‐piece, non‐submerged, single‐stage implant placement

Journal of Prosthodontics · 2002-12-01

Radiographic guides are essential for optimal implant positioning.Surgical guides permit implant placement in pre-selected positions and at proper angulations.A technique is presented for combining the functions of radiographic and surgical guides in a single device.The radiographic component is easily separated from the surgical component after the necessary radiographs have been made.Once radiographs have been secured, the guide can be easily modified to aid the surgical procedure.This procedure requires less paraphernalia and reduces costs since only one basic guide with an add-on component is fabricated.

Effect of an antirotation resistance form on screw loosening for single implant-supported crowns

Journal of Prosthetic Dentistry · 2000-04-01 · 57 citations