Determination of bone quality of 372 implant recipient sites using Hounsfield unit from computerized tomography: a clinical study

BACKGROUND

The type and architecture of bone are very important factors in the successful implant treatment, and it is manifested that higher implant failure is more likely in the poorer quality of bone. Conventional bone classifications have recently been questioned because they are subjective and retrospective.

PURPOSE

This clinical study aimed to determine the variations of the bone density in dental implant recipient sites using computerized tomography (CT).

MATERIALS AND METHODS

The study group comprised of randomly selected 140 patients with 372 implant sites. Recipient sites for implant placement were determined based on CT data using implant planning StentCad software (Media Lab Software, La Spezia, Italy). The mean bone density values in Hounsfield unit (HU) of the simulated implant areas were recorded using the StentCad software.

RESULTS

The HU values ranged from 68 to 1,603 HU. It was found that mean bone density values were 927 +/- 237, 721 +/- 291, 708 +/- 277, and 505 +/- 274 HU in the anterior mandible, posterior mandible, anterior maxilla, and posterior maxilla, respectively.

CONCLUSION

Preoperative CT examination may be a useful method for determining the bone density of recipient areas before implant placement, and this valuable information about bone quality helps clinicians to make better treatment planning regarding the implant positions.

An investigation of tooth/implant-supported fixed prosthesis designs with two different stress analysis methods: an in vitro study

PURPOSE

Tooth/implant-supported fixed prostheses (TIFPs) present biomechanical design problems, because the implant is rigidly anchored within the alveolus, and the tooth is attached by the periodontal ligament that allows movement. While TIFP designs with rigid connectors (RCs) are preferred by many clinicians, the designs containing non-rigid connectors (NRCs) are suggested as a method to compensate for these mobility differences. However, studies have failed to show the advantage of one design over the other. This study examined stresses formed around the implant and natural tooth abutments under occlusal forces, using two dimensional finite element (2D-FEM) and photoelastic stress analysis methods (PSAM).

MATERIALS AND METHODS

Connection of TIFP designs were investigated in distal extension situations using stress analysis interpreted with the 2D-FEM and PSAM. Three TIFP (screw type implant, 3.75 mm x 13 mm) models with various connection designs (i.e., rigidly connected to an abutment tooth, connected to an abutment tooth with an NRC, connected to an abutment implant with an NRC) were studied. The stress values of the three models loaded with vertical forces (250 N) were analyzed.

RESULTS

The highest level of stresses around the implant abutment was noted on the TIFPs with the RC. On the other hand, NRCs incorporated into prostheses at the site of the implant abutment reduced the level of stresses in bone.

CONCLUSION

It could be suggested that if tooth and implant abutments are to be used together as fixed prostheses supports, NRCs should be placed on the implant abutment-supported site.

Temporomandibular joint clicking noises caused by a multilocular bone cyst: a case report

When diagnosing patients with temporomandibular disorder (TMD) symptoms, the possibility of unusual causes must be considered, including neoplastic disorders, as well as infections and inflammatory disease. Therefore, radiologic examination may prove to be invaluable in the differential diagnosis of TMDs. This article describes a patient whose temporomandibular joint (TMJ) noise was initially diagnosed by another dental clinic as a TMJ anterior disc displacement with reciprocal clicking. Occlusal splint therapy was used for nearly three to four months but did not improve the TMJ noise condition. When the patient was examined clinically and imaged with magnetic resonance imaging (MRI) and computed tomography (CT), a multilocular bone cyst (MBC) was suspected. The cyst could cause surface irregularities in the posterior part of the left eminence of the temporal bone, which could be the source of the clicking noise.

Implant-Supported Prosthetic Applications Upon Development of Children and Adolescents: A Pilot Study in Pigs

PURPOSE

The purpose of this study is the investigation of the application of implant-supported prosthetic restorations using 2 implants supporting a fixed prosthesis during the physical growth and the development period of growing pigs.

MATERIALS AND METHODS

This study was carried out on 6 male farm pigs (1 as a control). The effect of the 2 screw-type endosseous implants inserted into the premolar area on the left mandibular arches of 5 farm pigs upon the jaw was investigated during a 3.5-8-month growth period using cephalometric radiographs. The cephalographs were taken with a specially standardized cephalostat, and a significant test of differences between 2 partners was used to evaluate them.

RESULTS

The study suggested that the implants showed alveolar elevation by bone growth but could not keep pace with the natural teeth eruptions and the bone growth in the region.

CONCLUSION

Although the sagittal and transverse developments of the neighboring bone region are greater than the implant-inserted region, the difference in this growth can be tolerated by corrections or modifications of implant-supported superstructures.

[Conservative applications on treatment of teeth with esthetic problem]

Today with the development of new restorative materials, the esthetic problems of the anterior teeth because of hypoplazies, fluorizes, fractures shape, form or color irregularities can be treated with conservative preventive and esthetic techniques such as bleaching, surface coating, cosmetic contouring and composite laminate veneering. These procedures are usefull adjuncts and economic alternatives to more extensive procedures such as crown applications. In this study, the young patients who have esthetic and psychologic problems due to color, form, shape, surface texture abnormalities and fractures of their anterior teeth were treated with bleaching, composite laminate veneer and cosmetic contouring techniques.

[Clinical and histopathological investigation of pontic-mucosa relation on bridge prosthesis]

The studies carried upon the pontic-mucosa relation, show that inflammatory changes take place in the adjacent soft tissue. It was also reported that inflammatory reactions were observed in the 95% of the cases following the removal of the prosthesis. In this study the clinical and histopathological data of the cases showing pontic designing complaining about their prosthesis, were evaluated. Clinically in almost all the bridges there was a question of collapsing and pressure upon the mucosa, particularly at posterior group bridges. The histopathological examinations of the sections taken from the underpontic mucosa having hyperemic appearance, showed bleeding regions, degeneration and descuamation in epithelium, and chronic inflammatory cell infiltration at the surface regions under epithelium. These findings prove the chronic inflammatory process in the mucosa under the bridge pontic.

[Alloys of fixed partial dentures]

The metals used in the prosthetic restorations, addition to pure gold are the alloys that can be easily melted with conventional casting techniques, have sufficient physical properties, adequate marginal fit, resistance to corrosion and tarnish. Also they are economic. In the result of introducing of metal-ceramic restorations to the prosthetic dentistry, also the physical and chemical compatibility with ceramic have been joined to those properties. The investigations that are concerning to find the unique alloy are still continuing and compared to the precious alloys that have unique properties about marginal fit, castability, manipulation, corrosion and tarnish resistance, nonprecious are found to be insufficient yet.