Maxillofacial prosthetic rehabilitation of a midfacial defect complicated by microstomia: A clinical report
Ansgar C. Cheng, BDS, MSa 1
Alvin G. Wee, BDS, MSb 1
Li Tat-Keung, CDTc 1
Faculty of Dentistry, University of Toronto, and University Health Network-Princess Margaret Hospital, Toronto, Ontario, Canada; College of Dentistry, The Ohio State University, Columbus, Ohio
Abstract
Severe limitation in the oral opening, though an uncommon clinical presentation, makes gaining access to the oral cavity difficult for any dental procedure. This article describes the maxillofacial prosthetic management of a patient with a midfacial defect complicated by postsurgical microstomia. Intraoral and extraoral prostheses restored the patient's speech, dental articulation, mastication, lip support, esthetics, and anterior oral seal. (J Prosthet Dent 2001;85:432-7.)
Effect of adhesive retention of maxillofacial prostheses. Part 2: Time and reapplication effects
Sudarat Kiat-amnuay, DDS, MSa 1
Lawrence Gettleman, DMD, MSDb 1
Zafrulla Khan, DDS, MSc 1
L. Jane Goldsmith, PhDd 1
School of Dentistry, University of Louisville, Louisville, Ky.
Abstract
Statement of problem. The success of most non-implant-retained extraoral prostheses depends on retention derived from skin adhesives. Part 1 of this study found that Skin-Prep Protective Dressing improved the retentive properties of adhesives and that Secure2 Medical Adhesive was stronger than Epithane-3. Part 2 investigates the application of a second layer of adhesive to the prosthesis, which was earlier noted to improve retention at later time periods.
Purpose. This study measured the force needed to remove silicone elastomer strips with Secure2 Medical Adhesive from the skin of human subjects. Testing was performed before and after the removal of the strips and reapplication of the adhesive.
Material and methods. Secure2 Medical Adhesive was painted on silicone rubber strips and placed in a nonsequential random order of the 3 variables to 3 sites on the ventral forearms of 21 human subjects and tested over an 8-hour period. The bond strength was measured at 0, 4, and 8 hours. After a reapplication of adhesive over the existing adhesive, additional bond strength measurements were made at 4 and 8 hours. Testing was at 10 cm/min in an Instron. All subjects had Skin-Prep coating applied before adhesive application.
Results. Bond strengths for both single applications and reapplications of the adhesive were greater at 0 hours and became significantly weaker after the 4- and 8-hour periods. The second application of the adhesive produced the strongest bonds when measured at 4 hours (110 N/m). Bonding was significantly higher at 8 hours if a second application of adhesive was applied at 0 or 4 hours.
Conclusion. The results of this study indicate that the bond strength of silicone elastomer to skin decreased over an 8-hour interval. After removal of the silicone rubber strip and reapplication of Secure2 Medical Adhesive over the existing adhesive, bond strengths increased. (J Prosthet Dent 2001;85:438-41.)
Stress distribution around maxillary implants in anatomic photoelastic models of varying geometry. Part I
Martin D. Gross, BDS, LDS, MSca 1
Joseph Nissan, DMDb 1
Rellu Samuelc 1
The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel
Abstract
Statement of problem. It is unclear which implant inclination and position are most favorable in relation to the supporting anatomy and loading direction in the maxilla.
Purpose. This study was designed to examine stress distribution around implants in a 2-dimensional photoelastic anatomic model.
Material and methods. Two 2-dimensional photoelastic models were prepared with opposing 8-degree cylinder metal implant and molar teeth analogues. A frontal anatomic sectional plate model based on a CT section at the first molar was symmetrically loaded through its long axis. A midfacial rectangular model based on the same section was loaded in a different direction with varying supporting geometries.
Results. Stress distribution around the maxillary implant was highest in the buccal concavity at the apical buccal third and in the lingual concavity on intercuspal loading. No stress concentration occurred at the implant apex under the sinus for axial and nonaxial loading in both anatomic model geometries. On lateral loading, stress concentration was observed at the buccal concavity and at the implant neck. In the midfacial block model, principal stresses were concentrated at the maxillary implant neck on nonaxial loading and at the apex on axial loading.
Conclusion. This 2-dimensional skull model showed different patterns of stress distribution among the maxillary implant, mandibular implant, and teeth. The highest principal stress concentration was seen at the buccal concavity of the maxillary implant; this may play a role in osseointegration with highly angled implants in the posterior maxilla. Differences in stress distribution between anatomic and nonanatomic models showed how the supporting geometry (for example, sinus/nasal anatomy), boundary conditions, and loading direction influence stress distribution. (J Prosthet Dent 2001;85:442-9.)
Stress distribution around maxillary implants in anatomic photoelastic models of varying geometry. Part II
Martin D. Gross, BDS, LDS, MSc,a 1
Joseph Nissan, DMDb 1
The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel
Abstract
Statement of problem. Insufficient buccal bone volume can be a significant problem when loading dental implants in the maxilla. Increased potential for buccal fenestration and dehiscence can result in an exposed implant surface, mucosal irritation, decreased support, and potential implant failure.
Purpose. The objective of this study was to model the stress distribution around maxillary implants by comparing simulated occlusal loading of maxillary implants in a 2-dimensional photoelastic anatomic model and a dry skull model.
Material and methods. Two model systems were used. First, a 2-dimensional photoelastic anatomic frontal skull sectional model was prepared in the first molar region. Left and right maxillary metal cylinder implant analogues inclined at 0 and 25 degrees to the sagittal plane were loaded in simulated intercuspation. Second, a dry skull lined with a photoelastic coating on the buccal aspect over an embedded cylinder implant was prepared in the first molar region. Principal stress concentration was photographed on axial and nonaxial implant loading.
Results. On simulated intercuspal loading, maximum stress concentration occurred at the buccal concavity in both the 2-dimensional anatomic photoelastic and skull models. There was no stress concentration at the apices of the maxillary implants in the 2-dimensional model. On lateral loading of the skull model, stress was distributed along the entire buccal aspect of bone adjacent to the implant, with a higher concentration at the buccal concavity.
Conclusion. Preservation of buccal supporting bone volume is desirable to obtain a physiological modeling response and to enhance the facial plate. Insufficient bone volume may result in buccal fenestration or dehiscence, which can precipitate mucosal irritation, decreased support, and potential implant failure. (J Prosthet Dent 2001;85:450-4.)The influence of intracrevicular crown margins on gingival health: Preliminary findings
Sergio G. Kancyper, DDS, MSa 1
Sreenivas Koka, DDS, MS, PhDb 1
Faculty of Dentistry, National University of Tucuman Argentina, San Miguel de Tucuman, Argentina, and College of Dentistry, University of Nebraska, Lincoln, Neb.
Abstract
Statement of problem. The effect on gingival tissue of various crown materials in combination with different abutment biomaterials should be investigated.
Purpose. This in vivo study determined the gingival health and subgingival levels of periodontal inflammation-associated bacteria adjacent to various crown and abutment material combinations.
Material and methods. Patients in the study received 1 of 5 treatments: an all-ceramic crown luted to a natural tooth, a metal-ceramic (titanium) crown luted to natural tooth, a metal-ceramic (high noble alloy) crown luted to natural tooth, an all-ceramic crown luted to a titanium implant abutment, or a metal-ceramic (high noble alloy) crown luted to a titanium implant abutment. Plaque was collected at least 6 months after luting by paper point from the gingival sulcus of each crown and an adjacent unrestored (control) tooth. DNA probe analysis was performed to determine the levels of Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans. In addition, plaque, gingival redness, swelling, and bleeding scores were recorded with use of the California Dental Association scale. Statistical analysis was used to determine the effect of restoration/abutment type on levels of the bacterial species and clinical parameters pertaining to gingival health.
Results. None of the sulci sampled contained detectable levels of the 3 bacteria. Plaque levels and gingival redness, swelling, and bleeding scores were low. All treatment groups had similar soft tissue response as measured by gingival redness, swelling, and bleeding. Plaque scores from all-ceramic crown/implant abutment sites were higher than plaque scores from all-ceramic crown/natural tooth sites. However, differences between experimental and control sites within the same treatment group were not observed (P>.05) with any of the 4 clinical measures.
Conclusion. In patients with suitable oral hygiene, tooth-supported and implant-supported crowns with intracrevicular margins were not predisposed to unfavorable gingival and microbial responses. (J Prosthet Dent 2001;85:461-5)
Effect of groove placement on the retention/resistance of resin-bonded retainers for maxillary and mandibular second molars
Riyadh Z. Emara, MDentSca 1
Declan Byrne, MScb 1
David L. Hussey, BDS, PhDc 1
Noel Claffey, MDentScd 1
School of Dental Science, Trinity College, Dublin, and School of Clinical Dentistry, Queen's University, Belfast, Ireland
Abstract
Statement of problem. Lack of retention/resistance form in the clinical preparation of teeth for resin-bonded retainers may lead to clinical failure.
Purpose. This study investigated the effect of proximal grooves on the retention/resistance of cast resin-bonded retainers for maxillary and mandibular second molar teeth.
Material and methods. Two ivorine teeth (a maxillary and a mandibular second molar) were prepared for resin-bonded retainers. Twenty metal replicas of the prepared teeth were made (10 for each tooth morphotype). Resin-bonded retainers 0.5 mm thick were made for the 40 replicas and luted with Panavia EX cement. Forces for dislodgment of the retainers were applied along the long axes of the teeth. Forces recorded at the time of dislodgment were analyzed with 2-way analysis of variance and the post hoc Scheffé test.
Results. Grooves resulted in substantial increases in debonding forces for maxillary molars (P<.001). The effect of grooves on mandibular second molars was not significant (P=.13).
Conclusion. Grooves placed in tooth preparations of maxillary molar teeth for resin-bonded retainers had a significant effect on retention/resistance. The effect of grooves on mandibular second molars was less pronounced. (J Prosthet Dent 2001;85:472-8.)Fabrication of imaging and surgical guides for dental implants
Dov M. Almog, DMDa
Eduardo Torrado, DDSb 1
Sean W. Meitner, DDS, MSc 1
University of Rochester Eastman Dental Center, Rochester, N.Y.
Abstract
Research and experience have suggested that the success of dental implants depends on a well-developed and careful treatment plan approach. Historically, implant size and angulation were determined with the use of panoramic radiographs and clinical judgment during surgery. This occasionally resulted in mechanical and esthetic compromise. This article describes the step-by-step fabrication process for 4 different imaging and surgical guides. Set-up disks, which enhance the design and fabrication of guides, also are introduced. These guides are used in conjunction with cross-sectional tomography during the preimplant assessment of surgical sites. (J Prosthet Dent 2001;85:504-8.)
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