Contemporary evaluation of dental cements.

Today, the clinician has numerous dental cements available for luting of restorations to prepared teeth. Compared to traditional cements, many of the newer cements have improved physical properties. In this article, we analyze available cements in terms of these physical properties based on scientific data and attempts to determine their effect on long-term clinical performance. We conclude that these improved physical properties do not necessarily result in improved clinical performance. We also conclude that although these newer cements have specific clinical applications, they should not be routinely used for the cementation of metal castings because they are clearly more technique-sensitive than traditional luting agents. Zinc-phosphate cement remains the cement of choice for cementing cast gold and metal-ceramic restorations.

Soft tissue management with metal-ceramic and all-ceramic restorations.

Many advances have been made in recent years to the science and the art of metal-ceramic and all-ceramic restorations. However, no matter how natural and lifelike such restorations may be, the final esthetic result is most dependent upon the health and level of the surrounding gingival tissues. The key to success is effective soft tissue management, and the goal of this soft tissue management has been to provide healthy gingival tissues covering sound, smooth restorative margins.

The versatile and esthetic metal-ceramic crown.

The predictability, many advantages and remarkable adaptability of metal-ceramic crowns account for their frequent use. Metal-ceramic crowns will continue to be one of the most widely used dental restorations.

Materials for conservative posterior restorations.

Advantages and disadvantages of amalgam and cast gold restorations are compared to those of new tooth-colored restorations. Success can be achieved using many different types, but the benefits of traditional restorations should not be forgotten.

An alternative altered cast technique for a distal extension removable partial denture.

The use of a removable partial denture to restore the posterior edentulous space continues to be a viable treatment option for patients who are not candidates for cantilevered fixed prostheses or dental implants because of the nature of the remaining teeth and bony support, the anatomy of the residual ridges, or financial constraints. The purpose of this paper is to introduce an alternative technique for the fabrication of a well-fitting distal extension RPD that will take maximum advantage of the dual nature of the support provided by the teeth and the resilient tissues of the residual ridge.

Rational use of contemporary all-ceramic crown systems.

There are a host of contemporary all-ceramic systems available today, as well as improved techniques for metal-ceramic restorations. Perhaps the most important factor in achieving predictable success with these restorations is excellent soft tissue management. Metal-ceramic restorations provide the most predictable service in terms of clinical longevity, versatility and prevention of wear to the opposing dentition.

Clinical experiences with bonded porcelain laminate veneers.

Bonded porcelain veneers can provide successful esthetic and functional long-term service for patients. The purpose of this article is to describe the authors' clinical experiences with veneers over the past decade and to outline the procedures required to achieve predictable success with this conservative esthetic restorative modality. It is hoped that the authors' experiences and those of others will encourage practitioners to consider more routine use of this type of restoration in many of their more complex reconstructive cases.

Restoration of an anterior edentulous space.

Removable partial dentures are often overlooked as a restorative option for an anterior edentulous space. This article will focus on the advantages and disadvantages of removable prostheses for the restoration of the anterior edentulous space in specific clinical situations.

Urbanization of the Malays since independence: evidence from West Malaysia, 1957 and 1970.

PIP: The authors attempt to evaluate the Malaysian policy for promoting urbanization of Malays by comparing their geographical location in 1957 and 1970. Data are taken primarily from the 1970 census.^ieng

Efficient soldering index materials for fixed partial dentures and implant substructures.

Multiple-unit fixed partial dentures routinely require an intraoral index to ensure accurate fit. One of the most commonly used materials is Duralay acrylic resin, which has yielded satisfactory clinical results, but one disadvantage has been a prolonged setting time. This study compared the setting times of two autopolymerizing resins, Duralay and G. C. Pattern resin. The dimensional accuracy of these materials was also compared with one light-cured resin, G.C. Unifast light-cure resin. All three materials were suitable to relate castings with clinically acceptable outcomes, and chairside time could be saved with the use of recently introduced indexing materials.

Custom characterization of the provisional restoration.

The fabrication of esthetic custom provisional restorations that provide optimum esthetics and function accomplished with minimal chairside time is described. The effects of mamelons, translucency, and incisal haloes are reproduced to mimic natural dentition. The technique is based on a provisional shell that is made in the laboratory and relined intraorally for a more precise fit. In addition, it can be characterized chairside to better satisfy the esthetic demands of the patient. The laboratory-processed shell allows us to attain optimal physical characteristics with auto-polymerizing methylmethacrylate resin.

A rationale for not connecting implants to natural teeth.

When restoring partially edentulous arches with implants, there are some practitioners who believe it is occasionally beneficial to connect implants to natural teeth. This connection is performed to gain shared support from the natural tooth and implant, prevent rotation of the restoration, or sometimes merely to retain the natural tooth. A discussion and review of the literature concerning this connection is presented, and a patient treatment is shown to illustrate potential complications.

Diagnostic provisional restorations in restorative dentistry: the blueprint for success.

There is no question that patients today demand a sophisticated level of restorative dentistry, in terms of both esthetics and function. No elective restorative dentistry should be undertaken without a clear understanding of the patient's expectations and the limitations of restorative therapy. The dentist should have a clear picture in mind of the final results before initiating irreversible therapy. The use of mounted diagnostic casts, diagnostic wax-ups and provisional restorations permits patient acceptance to be obtained before the definitive phase is initiated. Too often the dentist does not take advantage of this important restorative option, with disastrous results when definitive restorations are viewed by the patient for the first time. By following the plan of treatment outlined in this article, such disasters can be avoided.

Replicating soft tissue contours on working casts for implant restorations.

Restoration of partially edentulous arches is often aided by the use of dental implants. When anterior edentulous spaces are restored, the clinician is challenged to provide an esthetic and functional restoration. The soft tissue that surrounds the implant restoration and the soft tissue at the base of the pontics are important factors in achieving an esthetic result. A technique is presented that will allow soft tissue morphology of both peri-implant and pontic bearing soft tissue to be incorporated into the working cast utilizing a provisional restoration. This allows the fabrication of a restoration that will harmonize with the soft tissue form of the patient.

An in vitro comparison of 5 techniques for impressing dowel space preparations.

PURPOSE: This in vitro study compared 5 different dowel space impression techniques using polyvinyl siloxane impression material to determine which method produced fewer voids in the dowel space impression. MATERIALS AND METHODS: Five techniques were used to make impressions of a prepared dowel space in a simulated endodontically treated tooth. Technique I used a 25-gauge anesthetic needle to act as a vent at the apex of the preparation to reduce voids produced during the expression of light body impression material. The anesthetic needle was removed after the impression material was injected, and an impression post was then inserted to the depth of the preparation. Twenty impressions made using this technique were compared with other techniques that used the vent without a post, no vent with a post, no vent without a post, and a lentulo spiral with a post (Techniques II through V, respectively). The percentage of impressions with voids from each group was compared to determine which technique consistently produced a void-free impression of the complete preparation length. If voids were observed in the impression, the specimen was considered inadequate. RESULTS: The percents of void-free impressions using Techniques I through V were 100%, 70%, 40%, 60%, and 20%, respectively. CONCLUSIONS: Using a 25-gauge needle as a vent while expressing impression material into the dowel space followed by placing the impression post consistently produced void-free dowel space impressions.

Time-domain transillumination of biological tissues with terahertz pulses.

We present time-domain transmission imaging of an opaque structure in pork-fat tissue obtained with a terahertz (THz) field sampling technique. Compared with imaging with near-infrared pulses, the terahertz sampling technique shows significantly enhanced contrast, as a result of low scattering. For enhanced spatial resolution, we show mid-infrared THz imaging of onion cells. Water absorption of THz pulse in muscle tissues is discussed.

Progress in treatment of thoracoabdominal and abdominal aortic aneurysms involving celiac, superior mesenteric, and renal arteries.

This is a report of surgical treatment of thoracoabdominal aortic aneurysms and aneurysms of the abdominal aorta from which the visceral vessels arise during the 18 year period from April 5, 1960, to April 20, 1978. The extent of aneurysm is divided into five groups. Group I (10 patients) involved most of the thoracic and abdominal aorta down to celiac axis. Group II (22 patients) involved most of the thoracic and abdominal aorta distal to left subclavian artery. Group III (20 patients) were those with lesser involvement of the thoracic aorta and most of the abdominal aorta. Group IV (18 patients) with involvement of the entire abdominal aorta and Group V (12 patients) with involvement of lower abdominal aorta and renal arteries. Treatment in the majority of these cases was by graft inclusion technique with visceral vessel reattachment by direct suture of orifice to openings made in the graft. Intercostal and/or lumbar arteries were also reattached in some with the more extensive lesions. Aortic and renal artery occlusion times varied from 15 to 155 minutes. Paraplegia developed in five patients with the more extensive lesions but was reduced to one-third and made less severe by reattaching intercostal and lumbar arteries. Renal dysfunction was mild in four patients and severe in three patients after operation. All these were transient except one who died while recovering from renal failure. The latter cases were those difficult to reattach or were not initially successful and required reoperation. Of the 82 patients, 77 (94%) survived operation and long-term followup was obtained in 95% of cases, 23 performed over five years ago. Actuarial curves were constructed and compared to survival curves following simple infrarenal abdominal aortic resection. The survival rate both immediately and at six years, were the same.

Tensile bond strength of polyvinyl siloxane impressions bonded to a custom tray as a function of drying time: Part I.

Time-dependent bond strength studies of two polyvinyl siloxane impression materials to acrylic resin disks with their respective adhesives were studied to determine the optimal time for maximum bond strength. Six groups were tested with varying adhesive dry times of 0, 7, 15, and 60 minutes and 8 and 24 hours before testing. The results indicated that the bond strength of the adhesive increased at least twofold from time zero to 7 minutes adhesive dry time and peaked at 60 minutes for one of the materials and at 8 hours for the other. Bond strengths increased rapidly to the 15-minute test interval and then seemed to plateau. Both materials exhibited decreased adhesive bond strengths at 24 hours.