Platform switching and abutment emergence profile modification on peri-implant soft tissue.

Although the peri-implant hard tissue advantages of platform switching abutments have been well documented by many authors, the peri-implant soft tissue advantages of platform switching abutments has had limited mention. This article illustrates how the amount of peri-implant soft tissue volume is influenced by the dimensional extent of platform switching and the degree that an abutment's sulcular emergence profile has been modified. This article also introduces the term "abutment sulcular emergence profile enhancement" (ASEPE) to describe the combined effect of platform switching and abutment emergence profile modification. Three unrecognized clinical advantages of ASEPE are described by different clinical cases. First, elimination of excessive abutment impingement on gingival tissue adjacent to implants is achieved. Second, allowance for sufficient interproximal space between implant and adjacent tooth/implant for the entry of interproximal toothbrush is made possible. Third, excessive soft tissue blanching during abutment seating at prosthesis delivery is eliminated. Together, the combined application of platform switching and abutment emergence profile modification represents the opening of a new realm for managing soft tissue around implants to resolve dimensional problems.

Quantitative evaluation of bone density using the Hounsfield index.

PURPOSE: The primary aims of this retrospective study were to: (1) evaluate bone quality in different segments of the edentulous jaw and correlate it with demographic data and (2) establish a quantitative and objective assessment of bone quality based on the Hounsfield scale. MATERIALS AND METHODS: One hundred one randomly selected computerized tomographic (CT) scans were used for the analysis. Edentulous segments ranging from 10 to 30 mm were selected for evaluation, and the findings were analyzed and correlated to demographics. Implant recipient sites were evaluated visually for bone classification by 2 independent examiners. The same sites were subsequently evaluated digitally using the Hounsfield scale, and the results were correlated with the visual classification. RESULTS: The 4 quadrants of the mouth displayed Hounsfield unit (HU) values ranging from -240 HU to 1,159 HU. The highest unit/mean density value (559 +/- 208 HU) was found in the anterior mandible, followed by 517 +/- 177 HU for the anterior maxilla, 333 +/- 199 HU for the posterior maxilla, and 321 +/- 132 HU for the posterior mandible. There was no association between the Hounsfield value and density and age or gender. When subjective bone quality was correlated to Hounsfield index findings, only the relationship between HU and type 4 bone was found to be significant. CONCLUSIONS: Knowledge of the Hounsfield value as a quantitative measurement of bone density can be helpful as a diagnostic tool. It can provide the implant surgeon with an objective assessment of bone density, which could result in modification of surgical techniques or extended healing time, especially in situations where poor bone quality is suspected.

Clinical significance of the structural integrity of the superior aspect of the mandibular canal.

BACKGROUND: Sparse data can be found regarding the structural integrity of the superior aspect of the mandibular canal. In many cases, the mandibular canal must be carefully evaluated prior to defining patient treatment. METHODS: In this case report, a 54-year-old patient presented with a periapical infection involving the mesial root of the mandibular right second molar (#31). Radiographic evaluation revealed that the periapical lesion extended from the apex of the tooth to the superior aspect of the mandibular canal. Upon surgical removal of the tooth, an apical communication between the extraction socket and mandibular nerve was located. A guided bone regeneration procedure was performed to protect the nerve from subsequent damage and to prepare the site for future implant placement. Implants were placed in the area approximately 5 months following the regenerative procedure. RESULTS: After implant placement, the patient experienced normal function and no mandibular symptomatology. Implants have been in function for the past 4 years. CONCLUSIONS: Many factors, both pathologic and developmental, can lead to a discontinuity of the superior aspect of the mandibular canal. Normally, a thin cortical plate of bone protects the nerve. When a lack of structural integrity of the canal roof is discovered, enucleation of a periapical infection or subsequent implant placement can lead to potential disruption of the nerve. Limited information is available regarding the integrity of this protective cover. This case report underscores the importance of proper clinical diagnosis before implant placement in the posterior mandible.