Photometric assessment of tooth color using commonly available software.

It would be expedient to develop a simple digital procedure for matching shade guides to teeth for dental restorations. It was hypothesized that precise and objective L*a*b* measurements could be performed on photographic images of teeth and shade guides using commonly available photo software. Tooth shade guide tabs, shaped like computer-generated posterior crowns, were used for color matching.

Effects of 5 manipulative variables on the color of ceramics used for computer-generated restorations.

Objective: Monochromatic ceramic blocks used for computer-generated posterior restorations require color modification to achieve acceptable shade matches. However, it is not known whether manipulative variables affect the final color of these restorations. This study aimed to determine the effects of ceramic type, thickness, extrinsic colorants, glazing, and luting agent on the final color of monochromatic computer-generated ceramics.

A photographic method to measure the colour characteristics of healthy gingiva.

Background: Colour of healthy gingiva is mostly determined by subjective visual observation. The introduction of digital imaging and diagnostic tools to evaluate colour makes it feasible to measure gingival colour more objectively.

Methods: A study was designed to obtain reproducible photographs of anterior maxillary gingiva of a study group of 26 dental hygienist students with a professional attitude for healthy gingiva.

On the use of 1H and 13C 1D NMR spectra as QSPR descriptors.

Recently, 1D NMR and IR spectra have been proposed as descriptors containing 3D information. And, as such, said to be suitable for making QSAR and QSPR models where 3D molecular geometries matter, for example, in binding affinities. This paper presents a study on the predictive power of 1D NMR spectra-based QSPR models using simulated proton and carbon 1D NMR spectra.

Porcelain-veneered computer-generated partial crowns.

Objective: It would be advantageous to be able to use computer-aided design and manufacturing to fabricate a restoration that can be layered with a conventional porcelain veneer in the occlusal region, thus optimizing esthetics, function, and strength. This case study reports the laboratory technique and the clinical performance of 38 partial crowns fabricated with computer technology and veneered with porcelain.

Method And Materials: Twenty-one mandibular and 17 maxillary molars in 27 patients were prepared for partial crowns.

[Reproducible marginal gap measurements of partial ceramic crowns].

Aim of this research was to test the hypothesis that marginal gap measurements by a digital microscopic image processing computer are reproducible. Light microscopic images of the margins of Artglass partial crowns on stone dies were obtained with a 3CCD color video camera, digitized and processed. Ten measuring points were painted on a 0.

[CAD/CAM-copings for partial coverage].

Aim of the study was to evaluate the Computer Integrated Ceramic Reconstruction (CICERO)-system and the Ceramic Reconstruction (CEREC)-system for the production of all ceramic copings for partial coverage. Posterior teeth were prepared and the stone dies were made. Accuracy analyses were performed on ceramic restorations made by means of the CICERO and by means of the CEREC technique.

Computer copings for partial coverage.

Partial coverage posterior tooth preparations are very complex surfaces for computer surface digitization, computer design, and manufacture of ceramic copings. The aim of this study was therefore to determine whether the Computer Integrated Crown Reconstruction (Cicero) system was compatible with a proposed partial coverage preparation design and capable of producing ceramic copings. Posterior teeth were prepared for partial coverage copings with deep gingival chamfers in the proximal boxes and around the functional cusps (buccal of mandibular and lingual of maxillary posterior teeth).

Marginal fit and short-term clinical performance of porcelain-veneered CICERO, CEREC, and Procera onlays.

Statement Of Problem: Onlay preparations are very complex surfaces for computer surface digitization, CAD, and CAM of all-ceramic onlay cores.

Purpose: This study tested the hypothesis that onlays can be fabricated with CICERO, CEREC, and Procera core technologies.

Material And Methods: Fifteen mandibular and 10 maxillary molars were prepared for onlays in 17 patients (11 women and 6 men).

Alveolar bone response to submerged bisphosphonate-complexed hydroxyapatite implants.

Background: In most studies using submerged hydroxyapatite implants, maintenance of alveolar bone after tooth extraction was attempted with plain hydroxyapatite materials. However, clinical results have shown that hydroxyapatite may require biological modification with a bone resorption-inhibiting agent which may be beneficial for maintenance of alveolar bone. We conducted experimental and clinical studies to evaluate the effect of highly bisphosphonate-complexed hydroxyapatite implants on osteoconduction and repair in alveolar bone.

Normal osteoconduction and repair in and around submerged highly bisphosphonate-complexed hydroxyapatite implants in rat tibiae.

Background: Ceramic hydroxyapatite implants have been used in dentistry for their unique compatibility with alveolar bone. Recently it was reported that bisphosphonates may be beneficial in preventing alveolar bone destruction associated with natural and experimental periodontal disease. Furthermore, bisphosphonate does prevent resorption of alveolar bone following mucoperiosteal flap surgery.

Measurement of the margins of partial-coverage tooth preparations for CAD/CAM.

Purpose: This study tested the hypothesis that a scanning laser 3-dimensional digitizer is a precise and accurate instrument to measure chamfered and beveled margins of partial coverage tooth preparations for computer-aided design/computer-aided manufacturing (CAD/CAM).

Materials And Methods: The margins were measured by the digitizer on stone dies and calculated by triangulation into a 3-D representation. Instrument precision was defined as the ability to reproduce the same margin in repeated measurements and expressed as the coefficient of variation as a percentage.

Assessing mineral density in small trephined jawbone biopsy specimens.

This study reports the test of the hypothesis that mineral density can be precisely assessed in small trephined jawbone biopsy specimens. Mineral density was measured by dual-energy X-ray absorptiometry (DEXA) and peripheral quantitative computed tomography (pQCT). Ten fresh and ten histologically processed specimens, which were not the same, were measured.

Degradable bisphosphonate-alkaline phosphatase-complexed hydroxyapatite implants in vitro.

Degradable hydroxyapatite (HA) implants complexed with the resorption inhibiting agent bisphosphonate (PCP) and the mineralizing agent alkaline phosphatase (ALP) can theoretically maintain alveolar bone mass directly after extraction of teeth. The present in vitro study investigated the surface properties of PCP-ALP-complexed HA implants in relation to the requirements of implant behavior and action. Adsorbed PCP (pH 3.

Net-shaped hydroxyapatite implants for release of agents modulating periodontal-like tissues.

Periodontal-like tissues and, in particular, alveolar bone- and root cementum-like material can theoretically be modulated by release of biochemical agents such as bisphosphonate (PCP), growth hormone (GH) and alkaline phosphatase (ALP) from the implant surface. The present research focused on porous ceramic hydroxyapatite (PCHA) implants. In the past the PCHA implants were machined on a lathe out of simple blocks of PCHA ceramic.

Dual-energy X-ray absorptiometry for histologic bone sections.

In fundamental osteoporosis research precise and accurate assessment of the mineral quantity in histological bone sections is of particular importance when studying the local effects of implants releasing bone modulating agents. A potentially useful technique to estimate the bone mineral density (BMD) is dual-energy X-ray absorptiometry (DXA). A highly collimated (0.

Dual X-ray absorptiometry for alveolar bone: precision of peri-implant mineral measurements ex vivo.

The precision of measurements of minor mineral changes in alveolar bone mineral content (ABMC) and alveolar bone mineral density (ABMD) on implant surfaces was determined in small regions (0.03 +/- 0.005 cm2) using dual X-ray absorptiometry (DXA).

Behavior of calcium phosphate coatings with different chemistries in bone.

Calcium phosphate ceramic coatings with a hydroxyapatite chemistry applied on the surface of dental implants eliminate the need for initial mechanical retention and decrease the time necessary for bonding the implants to the bone. Hydroxyapatite-coated implants retrieved from patients were found to be compatible and to have bonded strongly to the bone, but the coatings showed thinning because of partial or total loss of coating material. This study compared the behavior in bone of newly developed fluorapatite and heat-treated hydroxyapatite coatings, with the clinically used hydroxyapatite coatings used as controls in experimental studies in dogs.

Use of implants for prosthetic rehabilitation after cancer treatment: clinical experiences.

Treatment of patients with head and neck cancer may result in extensive intra- or extra-oral defects. Prosthetic rehabilitation often will be limited by insufficient retention and an atrophic mucosa or skin. In such cases, osseointegrated implants may offer substantially improved retention for the often complex prosthetic constructions.

Ceramic hydroxyapatite implants for the release of bisphosphonate.

Maintaining bone mass after extraction of teeth is a major problem in the prevention of oral disease. Maintenance theoretically could be enhanced by immediate implantation of submerged ceramic hydroxyapatite (HA) implants releasing the bone resorption-inhibiting agent bisphosphonate (P-C-P). Four different types of ceramic HA implants were designed as release systems for an in vitro study and assayed in saline at a temperature of 37 degrees C during 3 months.

Preventive goals in oral implantology.

Preventive dentistry is mainly concerned with caries and periodontal disease and little or no attention is paid to the prevention of alveolar bone loss. An overdenture contributes to the preservation of alveolar bone and offers a number of advantages in comparison to a conventional complete denture. After tooth extraction the atrophy of edentulous lower jaws can be prevented or delayed by using implants supporting an overdenture or a fixed mandibular prosthesis.

Occlusion for maxillary dentures opposing osseointegrated mandibular prostheses.

This paper presents a combination of several occlusal concepts designed to contribute to the successful use of maxillary dentures in opposition to osseointegrated mandibular prostheses. To ensure a positive outcome when designing such an occlusion, three factors must be considered: patient satisfaction, maxillary anterior bone preservation, and mandibular arch shortening. It is recommended that for centric occlusion the molars have a lingual contact occlusion, the premolars have a buccal contact occlusion, and the anterior teeth have an open occlusal relationship.

Five-year study of all-porcelain veneer fixed partial dentures.

Improvements in enamel-dentinal bonding systems combined with the introduction of new ceramics have encouraged replacement of missing anterior teeth in specific patients with porcelain veneer fixed partial dentures. Metal substructures are not needed, and more natural tooth structure can be preserved because the preparation of abutments is conservative. Twelve porcelain veneer fixed partial dentures were monitored for 5 years, and fractures attributed to degradation of the gingival margins occurred in the veneer surface of the fixed partial dentures.

Anatomic consideration for preventive implantation.

The aim of preventive implant therapy is to prevent or delay loss of alveolar ridge bone mass. For use in an anatomic study of 60 mandibles, resorption of the alveolar ridge was classified into four preventive stages: (1) after extraction of teeth; (2) after initial resorption; (3) when the ridge has atrophied to a knife-edge shape; and (4) when only basal bone remains. Implantation in stage 3 necessitates removal of the knife-edge ridge to create space for cylindrical implants.

Preparation-induced stability of bioactive apatite coatings.

The stability of the bioactive surface is a major concern in the chemical and physical design of apatite ceramic coatings. In clinical studies, no sintered-hydroxyapatite bulk coating material was present in the surrounding bone tissue after loading periods up to 11 years. In in vitro studies, hydroxyapatite plasma-sprayed coatings dissolved considerably, possibly because of loss of crystallinity during the plasma-spraying procedure.