Evolution of Aesthetic Dentistry

One of the main goals of dental treatment is to mimic teeth and design smiles in a most natural and aesthetic manner, based on the individual and specific needs of the patient. Possibilities to reach that goal have significantly improved over the last decade through new and specific treatment modalities, steadily enhanced and more aesthetic dental materials, and novel techniques and technologies. This article gives an overview of the evolution of aesthetic dentistry over the past 100 y from a historical point of view and highlights advances in the development of dental research and clinical interventions that have contributed the science and art of aesthetic dentistry. Among the most noteworthy advancements over the past decade are the establishment of universal aesthetic rules and guidelines based on the assessment of natural aesthetic parameters, anatomy, and physiognomy; the development of tooth whitening and advanced restorative as well as prosthetic materials and techniques, supported by the pioneering discovery of dental adhesion; the significant progress in orthodontics and periodontal as well as oral and maxillofacial surgery; and, most recently, the implementation of digital technologies in the 3-dimensional planning and realization of truly natural, individual, and aesthetic smiles. In the future, artificial intelligence and machine learning will likely lead to automation of aesthetic evaluation, smile design, and treatment-planning processes.

A Comparative Assessment of Implant Site Viability in Humans and Rats

Our long-term objective is to devise methods to improve osteotomy site preparation and, in doing so, facilitate implant osseointegration. As a first step in this process, we developed a standardized oral osteotomy model in ovariectomized rats. There were 2 unique features to this model: first, the rats exhibited an osteopenic phenotype, reminiscent of the bone health that has been reported for the average dental implant patient population. Second, osteotomies were produced in healed tooth extraction sites and therefore represented the placement of most implants in patients. Commercially available drills were then used to produce osteotomies in a patient cohort and in the rat model. Molecular, cellular, and histologic analyses demonstrated a close alignment between the responses of human and rodent alveolar bone to osteotomy site preparation. Most notably in both patients and rats, all drilling tools created a zone of dead and dying osteocytes around the osteotomy. In rat tissues, which could be collected at multiple time points after osteotomy, the fate of the dead alveolar bone was followed. Over the course of a week, osteoclast activity was responsible for resorbing the necrotic bone, which in turn stimulated the deposition of a new bone matrix by osteoblasts. Collectively, these analyses support the use of an ovariectomy surgery rat model to gain insights into the response of human bone to osteotomy site preparation. The data also suggest that reducing the zone of osteocyte death will improve osteotomy site viability, leading to faster new bone formation around implants.

Complications of grafting in the atrophic edentulous or partially edentulous jaw

Complications of ridge reconstruction can delay healing or even cause total failure of the procedure, making implant placement impossible. Most intraoperative complications, such as insufficient material for a graft or inadequate range of a soft tissue flap, are the result of poor treatment planning or execution. Postoperative infection is usually associated with onlay, veneer, and J grafts and dehiscence. Resorption of the graft can range from minor (exposure of the heads of the fixation screws) to total. Retraction of a soft tissue flap is most likely where the vestibule is shallow or the muscle pull is great. It is important to discuss the risks and consequences of all potential complications with the patient before informed consent is obtained. This measure will help prevent another complication, patient dissatisfaction with the results of surgery.

Implant placement in three-dimensional grafts in the anterior jaw

A series of 12 men and 13 women ranging in age from 24 to 71 years underwent two- or three-dimensional reconstruction of type C, D, or E ridges and placement of anterior implants. The mean horizontal augmentation was 6.4 mm (range 2 to 17 mm), and the mean vertical augmentation was 4.22 mm (range 0 to 15 mm). The 67 implants were all loaded, with the time averaging 34.4 months for the maxillary implants and 19 months for the mandibular implants. None of the implants have been lost to date. Two patients had flap retraction within the first 2 weeks that necessitated reapproximation. One patient had total failure of a J graft of iliac crestal bone from the maxillary left central incisor to canine starting 3 weeks after placement as the result of infection. The graft was removed at 6 weeks, and no implants were placed. Two patients suffered partial anterior graft loss, but their implants were successful in location and angulation. Implants and grafts can be combined with acceptable rates of complications and failure.

Efficacy of implant placement after bone grafting for three-dimensional reconstruction of the posterior jaw

A series of 21 men and 41 women received grafts resulting in mean faciolingual augmentation of 5.1 mm and mean vertical augmentation of 3.9 mm. In most patients, bone was obtained from the iliac crest. At the time of implant placement, the bone at the site was restored anatomically to type B in 50 patients and to type C in 12. The patients received from one to ten posterior implants, which were placed simultaneously with (n = 5) or approximately 6 months after grafting. All of the implants were loaded, with the follow-up ranging from 12 to 96 months (mean 37.3 months). Ceramometal restorations were ultimately used in all patients. Five patients suffered partial graft loss at a total of 21 implants, of which five (24%) failed. The total failure rate for implants placed in patients who received sinus + veneer grafts was 4% (9/222). In patients who received sinus and J grafts, the final implant failure rate was 2%. All implants placed in anteroposterior J grafts and mandibular grafts were successful. Overall, including replacement implants, the failure rate was 7% (23/329). Posterior implants can be placed after graft reconstruction with a success rate similar to that obtained without grafting, thereby improving the function and esthetic outcome.

Brånemark system implants in the posterior maxilla: clinical study of 660 implants followed for 5 to 12 years

Originally, osseointegrated implants were used principally in the anterior region of the mandible and maxilla, but use in the posterior segments of both arches is common today. The long-term success of implants placed in the posterior region, an environment of stronger forces and poorer bone quality, has not been thoroughly reviewed. The purpose of the present study was to review a large series of Brånemark System implants placed in posterior maxillae (660 implants in 202 patients) that have been restored with fixed partial ceramometal restorations and followed for as long as 12 years after loading. Thirteen of the implants (2%) failed between placement and loading, 12 implants were lost between loading and the end of the first year, and 10 failed thereafter, 2 as the result of fractures at 3 and 4 years. The cumulative success rate is therefore 94.4% at 5 to 6 years and 93.4% after 10 years. The quality and quantity of bone appeared to have little influence on the success rate. Surgical techniques are particularly important to the success of osseointegrated implants placed in the posterior maxilla. With careful surgical planning and execution, a success rate of approximately 95% at 5 years can be achieved.

A Prospective Multicenter Clinical Trial Comparing One- and Two-Stage Titanium Screw-Shaped Fixtures with One-Stage Plasma-Sprayed Solid-Screw Fixtures

BACKGROUND

Brånemark fixtures were originally placed in two stages, whereas titanium plasma-sprayed (TPS) solid-screws are placed in one stage. Long-term survival rates for both types of implants are excellent. Excellent survival rates have also been reported for machined screw-shaped (MS) titanium implants placed in one stage. A small number of studies have compared different implant systems and methods of implant placement.

PURPOSE

The purpose of this study is to report clinical outcomes from a prospective longitudinal, multicenter study comparing Brånemark MS fixtures (Nobel Biocare, Yorba Linda, California, USA) placed in either one or two stages with a one-stage TPS system (ITI Straumann, Waldenburg, Switzerland).

METHODS

A protocol was designed to compare implant survival rates, changes in crestal bone for titanium MS fixtures placed in one and two stages, and plasma-sprayed solid-screw fixtures placed in one surgical stage. Twenty-nine patients ranging in age from 24 to 82 years received MS fixtures in one stage. The average age for males was 58 years (n = 11), whereas the ages for females (n = 18) ranged from 15 to 84 years (average 58 years). Twenty-nine patients received machined titanium fixtures placed in two stages. There were 20 females ranging in age from 23 to 74 years (average 54 years) and 9 females ranging from 24 to 74 years (average 46 years). Twenty-five patients received TPS fixtures. There were 15 males, ranging in age from 57 to 79 (average 70), and 10 females, ranging in age from 40 to 83 years (average 62 years). Bone quality and quantity were determined from radiographs and during site preparation. Patient age, sex, location of implant placement according to jaw, length of fixtures, and number of lost fixtures were entered onto computer code sheets and continuously entered into a locked computer system. For one- and two-stage MS fixtures, nonstandardized periapical radiographs were taken at abutment connection and follow-up. Solid screws were x-rayed at prostheses connection and follow-up. The average time between implant restoration and radiographic follow-up was 15 months. The x-rays were scanned into a computer, and a program designed to measure radiographs was used to determine changes in crestal bone. Measurements for one- and two-stage MS fixtures were made from the top of the implant shoulder to the first bone to implant contact mesial and distally. Plasma-sprayed screws were measured from the bottom of the implant to the coronal most bone to implant contacts mesial and distally. Mesial-distal radiographic measurements were averaged and changes were compared using the t-test for related samples.

RESULTS

This report presents data from the 2- to 3-year follow-up examinations. Twenty-nine patients received 80 one-stage MS fixtures. Between 0 and 1 year, two fixtures were lost, resulting in a 97.5% cumulative survival rate (CSR). The CSR remained unchanged through the 2- to 3-year follow-up. Twenty-eight patients received 78 two-stage MS fixtures. One implant was lost prior to loading and two were lost between 0- and 1-year follow-up, yielding a 96.2% CSR at the end of 1 year. The CSR remained unchanged through the 2- to 3-year follow-up. Twenty-three patients received 78 solid-screw plasma-sprayed screws. One implant was lost prior to loading and one between the 0- to 1-year follow-up, accounting for a 97.4% CSR at the 2- to 3-year follow-up. Changes in bone crest measurements for one-stage titanium threaded fixtures were insignificant (-0.11 mm, p = .08, maxillary; 0.07 mm, p = .42, mandibular). For two-stage MS fixtures, crestal bone loss was insignificant in maxillae (-0.16 mm, p = .92) and significant in mandibles (-0.43 mm, p = .000). There was significant bone loss for TPS implants in maxillae and mandibles (maxillae, 1.31 mm, p = .04; mandibles, 0.98 mm, p = .000).

CONCLUSIONS

Cumulative survival rates for MS fixtures placed in one and two stages as well as one-stage TPS screws up to the 2- to 3-year follow-up examination were similar, indicating excellent clinical results. Radiographic measurements for changes in crestal bone loss were clinically insignificant for fixtures placed in one stage. For two-stage fixtures, maxillary changes were insignificant, whereas mandibular bone loss was statistically significant but clinically insignificant. Changes in crestal bone loss for TPS implants were statistically significant.

Interrelations of soft and hard tissues for osseointegrated implants

Success in using osseointegrated dental implants-optimal function, esthetics, and phonetics-requires selection of the treatment modality that is optimal for the patient, protection of tissue blood supply, and adherence to a plan based on a thorough analysis of all deviations from the normal anatomy. The options for correction of hard-tissue deficiencies are mechanical modification of the implants and reconstructive surgery. Mechanical approaches reduce the time needed for reconstruction but direct the occlusal forces in unnatural directions. Surgical reconstruction is preferable. Any bone graft must be precisely fitted to the recipient site to facilitate revascularization. Restoration of hard-tissue dimensions usually requires soft-tissue coverage and augmentation. There are two basic options: (1) flaps with or without inlay or onlay grafts and (2) controlled tissue expansion. An onlay graft can help restore soft-tissue height and width. Inlay grafts have greater vascularity than onlay grafts, and the color matching is better. Controlled tissue expansion creates "like" tissue without a secondary defect, and fewer tissue transfers are needed. However, the technique is difficult, and the patient must make multiple visits to the office. For implant placement to be successful, the patient's expectations must be understood, and the benefit-to-risk ratio should be extremely high.

Use of wide implants and double implants in the posterior jaw: a clinical report

As experience with osseointegrated implants has grown, greater use has been made of placement in the posterior jaw. To reduce the risk of implant failure and increase the ability of posterior implants to tolerate the occlusal forces, it is beneficial to create a wider base either by using wider (eg, 5-mm) implants or by placing two or even three standard implants at one site. In the present series, unpaired 5-mm Nobelpharma implants were placed in 38 sites in the mandible and 21 sites in the maxilla. All implants were uncovered and restored with ceramometal crowns, with follow-up ranging from 3 to 26 months (mean 16 months) postloading. Two implants in one patient failed and were replaced successfully at 14 months. At 20 sites, pairs of 5-mm implants were placed and restored, and with a loading period of 3 to 26 months (mean 14 months), all of these implants were successful. At 34 sites, a 5-mm implant was paired with a 3.75-mm or 4-mm implant. With a loading period of 3 to 24 months (mean 13 months), one implant 5 mm wide and 8 mm long failed and was replaced successfully at 13 months, and an implant 4 mm wide and 10 mm long failed and was not replaced. The failure rate for this group of implants therefore was 3%. Double 3.75-mm or 4-mm implants were placed at 149 sites in the mandible and 13 sites in the maxilla. All of these double-root implants were uncovered and restored with ceramomental crowns. With follow-up ranging from 4 to 78 months (means 37 months) postloading, there were five implant failures in four patients, for a failure rate of 1.2%. The failure rate for all 5-mm implants was 2.3%, and that for all double implants was 1.6%. The use of either 5-mm or double implants necessitates changes in surgical technique, and both are highly dependent for their success on proper surgical execution.

Surgical reconstruction--a prerequisite for long-term implant success: a philosophic approach

Loss of teeth results in the loss of other tissues. Without adjunctive reconstruction of the hard and soft tissues, this loss can impair the reconstruction of the dentition using osseointegrated implants. Inadequate treatment planning-based on rules derived from anterior implant use in older edentulous patients or poor execution of the surgical plan, leading to errors in the number, angulation, distribution, and position of implants-can be the foundation for future failure. The learning objective of this article is to review specific reconstructive measures that may be appropriate in patients with special functional, aesthetic, or phonetic demands. The authors suggest that the present definition of failure be expanded to include long-term functional, aesthetic, and phonetic outcomes.

Treatment planning and site development for the implant-assisted periodontal reconstruction

Implants can be used to recreate an edentulous dentition that is esthetic, comfortable, and functional by augmenting the total surface area of load carrying abutments. Traditionally, implants were placed in areas of the mouth where adequate amounts of bone were present. Today, clinicians are strategically planning and developing implant sites to optimize oral health. This article will describe methods of treatment planning and site development for the reconstruction of the implant-assisted periodontal restoration.

New challenges in treatment planning and execution for osseointegrated implant placement

Implant-supported prostheses have become an established treatment for fully or partially edentulous patients. With restoration of function, aesthetics, and phonetics being recognized as essential for a successful implant treatment, the author of this presentation discusses several aspects that might be included in the definition of success and failure. The author also suggests subjecting all mechanical modifications of implants to the same stringent standards as surgical reconstruction before these designs are widely utilized.

Prosthetically formulated natural aesthetics in implant prostheses

The discrepancy in the anatomic dimensions between an endosteal root-form dental implant and the root of a natural tooth can compromise the aesthetic appearance of the final restoration. For the past five years the authors have used an abutment system, the components of which are designed to enable the clinician to achieve a predictable aesthetic result. This article describes and illustrates the anatomic abutment system (AAS). Until recently, the restoration usually began at the gingival line where a cylindrical implant emerged to be restored with a noncylindrical prosthesis. The new system uses components which compensate for the difference between the diameter of the natural tooth root and the endosteal implant. The importance of teamwork is emphasized, and a step-by-step procedure is presented, indicating which steps are performed by the combined team and which are the responsibility of the laboratory or the restorative dentist. The learning objective of this article is to introduce this system to the reader.

Percutaneous exposure to ethyl parathion in a feral Griffon vulture (Gyps fulvus)

A feral Griffon vulture (Gyps fulvus) was found with tremors, weakness, digit and wing flexion, and an inability to fly. A zero blood cholinesterase activity and a favorable response to treatment with pralidoxime hydrochloride indicated exposure to an anticholinergic pesticide. The bird died after 7 d, and traces of the organophosphate insecticide ethyl parathion were found in the liver and from a blue discolored skin area of the neck. Continuous exposure to ethyl parathion through dermal absorption was presumed the cause of death of the vulture.