Aesthetic enhancement of pontic sites for fixed partial dentures

The ridge expansion technique using tapered osteotomes can be used anywhere in the maxilla when a change in external ridge morphology would be advantageous for both aesthetics and/or proper dental implant placement. Usually subsequent to tooth loss, the maxilla is generally somewhat undercut in form. This ridge expansion technique can be used to reduce the undercut by bulging out the base of the facial/buccal plate. This would recreate the illusion of root prominences (Figure 12) or permit implant fixtures to be inserted in a more upright position. The tapered osteotomes can therefore predictably be used to expand the buccal bone to simulate the presence of a root prominence for optimal aesthetics for placement of a fixed partial denture prosthesis (Figure 13).     

Impact of landmark reliability on the planar Procrustes analysis of tooth shape

In a recent study, the ideas of Procrustes analysis were introduced to the study of tooth shape for teeth represented as configurations of 'landmarks' from digital images. This study aimed to establish how well the method could be expected to perform (in its standard form) when used on surfaces from a variety of tooth types and, in particular, how much impact inconsistencies in the positioning of landmarks would have on investigations of shape.Using four different operators' images and landmarks from 10 different surfaces from each of 20 patients, the consequences of location inconsistency are evaluated by calculating its effect on the recorded variation in Procrustes fits, obtained for each set of multiple representations. The proportion of variation in shape attributable to actual differences between patients, rather than other sources of error, ranged from only 36 to 65% for the five buccal-surfaces considered and was no more than 30% for any of the five occlusal surfaces. Further examination of these results indicated that consistent orientation differences before imaging might be a particular source of error in obtaining any occlusal-landmark data, as might location ambiguities around the edges of the teeth. Orientation effects were also suggested for the buccal-surfaces of the molar teeth. In contrast, the relatively flatter buccal-surfaces of the incisors and canines produced the most reliable data.Methods of analysis need to accommodate these problems if landmark data are to be used to describe variations in tooth shape. Different surfaces each present their own particular difficulties and so a variety of solutions may be required.     

Rehabilitation of patients with severely resorbed maxillae by means of implants with or without bone grafts: a 3- to 5-year follow-up clinical report

Forty three patients with severely resorbed maxillae who had been referred for implant treatment were assigned to 1 of 3 treatment options: bone grafting and implant placement (graft group), modified implant placement with no bone grafting (trial group), or optimized complete dentures (no-implant group). Sixteen, 20, and 7 patients, respectively, were assigned to the 3 groups. The patients have been examined annually, and at the time of this report they had been followed for 3 to 5 years after treatment. At the 1-year follow-up, 10% (22 of 221) of the implants had been lost, and at the 2-year follow-up, 18% of the implants had been lost (40 of 221; 25% in the graft and 13% in the trial group); after that time, no further losses occurred. Life table analysis showed cumulative success rates of 82% in the graft group and 96% in the trial group after 1 year, and 74% and 87%, respectively, at the final examination after 3 to 5 years. The failure rate was higher in smokers than in non-smokers. A substantial reduction of the grafted bone, especially of onlay grafts, occurred early after grafting surgery in many patients. Mean marginal peri-implant bone loss was 0.6 mm during the period from prosthesis connection to the 1-year follow-up, and from the 1-year to the 3-year follow-up, average peri-implant bone loss was 0.3 mm in the graft group and 0.5 mm in the trial group. The results corroborated previous findings that patients with severely resorbed maxillae have an increased risk of implant failure in comparison to patients with good bone quantity and quality. However, in this investigation, practically all implant losses occurred during the first 2 years, whereupon a steady state seemed to follow for up to 5 years after loading.     

Reconstruction techniques preparing jaws for fixed dentures placement

Dental implantation is a widespread method of dental arch reconstruction. Alveolar bone quantity in implantation area is crucial for proper implant placement. The paper presents author's experience in alveolar bone reconstruction with mandibular autografts, bone height reconstruction with parietal partial thickness grafts, as well as jaw defects reconstruction with microvascular flaps with subsequent implantation.     

Clinical evaluation of freeze-dried block allografts for alveolar ridge augmentation: a case series

Various grafting materials have been used in guided bone regeneration procedures to augment alveolar ridges deficient in horizontal or vertical dimensions or both. Autogenous block grafts from intraoral and extraoral sites have been used for ridge augmentation with encouraging results. However, the risk of vascular and neurologic injury at the donor site as well as postoperative patient morbidity have been reported following these surgical procedures. The use of a cancellous block allograft could be one alternative to avoid potential donor site complications. Five deficient alveolar ridges in three patients were each grafted with a freeze-dried cancellous block allograft and a resorbable barrier membrane. Ridge measurements taken at baseline, graft placement, and a 6-month reentry surgery demonstrated an increase in alveolar ridge width from 2 to 4 mm. These gains in ridge width compare favorably with other guided bone regeneration studies, suggesting that a freeze-dried cancellous block allograft in conjunction with a resorbable membrane may be an acceptable alternative to the autogenous block graft in the treatment of compromised alveolar ridge deficiencies.     

Anterior iliac bone grafts: techniques and sequelae. Report on 107 cases and review of the literature

The anterior iliac crest is the harvest site preferred by many authors because of the quantity and quality of bone obtainable and the simplicity of harvesting techniques. The purpose of the present paper is to present a review of anterior iliac crest harvesting techniques and to illustrate the most serious sequelae reported in the literature. A clinical series is also presented in order to evaluate what is, in our experience, the degree of morbility connected with this donor site. We have controlled 107 patients who underwent bone harvesting from the anterior iliac crest between 1980 and 2000, investigating minor complications such as walking deficiency (immediate and long-term) the formation of seromas, haematomas, adynamic ileus and more serious complications such as retroperitoneal haemorrhages, abdominal hernias, ileus fractures, nervous lesions (immediate and long-term). From our survey it emerged that, among the major complications, incidentally rarely reported in the international literature, we found only a small percentage of cases involving damage to nervous structures. Minor complications were also limited and the only problem remains difficulty in walking after the operation which resolves fully in almost all cases. We can therefore state that the anterior iliac crest remains, to date, an excellent site for harvesting and there is no significant morbility and the surgeon has numerous techniques available for reducing the incidence of complications to the minimum.     

Mechanical properties and radiopacity of experimental glass-silica-metal hybrid composites.

OBJECTIVES: Experimental glass-silica-metal hybrid composites (polycomposites) were developed and tested mechanically and radiographically in this fundamental pilot study. To determine whether mechanical properties of a glass-silica filled two-paste dental composite based on a Bis-GMA/polyglycol dimethacrylate blend could be improved through the incorporation of titanium (Ti) particles (particle size ranging from 1 to 3 microm) or silver-tin-copper (Ag-Sn-Cu) particles (particle size ranging from 1 to 50 microm) we measured the diametral tensile strength, fracture toughness and radiopacity of five composites.METHODS: The five materials were: I, the original unmodified composite (control group); II, as group I but containing 5% (wt/wt) of Ti particles; III, as group II but with Ti particles treated with 4-methacryloyloxyethyl trimellitate anhydride (4-META) to promote Ti-resin bonding; IV, as group I but containing 5% (wt/wt) of Ag-Sn-Cu particles; and V, as group IV but with the metal particles treated with 4-META. Ten specimens of each group were tested in a standard diametral tensile strength test and a fracture toughness test using a single-edge notched sample design and five specimens of each group were tested using a radiopacity test.RESULTS: The diametral tensile strength increased statistically significantly after incorporation of Ti treated with 4-META, as tested by ANOVA (P=0.004) and Fisher's LSD test. A statistically significant increase of fracture toughness was observed between the control group and groups II, III and V as tested by ANOVA (P=0.003) and Fisher's LSD test. All other groups showed no statistically significant increase in diametral tensile strength and fracture toughness respectively when compared to their control groups. No statistically significant increase in radiopacity was found between the control group and the Ti filled composite, whereas a statistically significant increase in radiopacity was found between the control group and the Ag-Sn-Cu filled composite as tested by ANOVA (P=0.000) and Fisher's LSD procedure.SIGNIFICANCE: The introduction of titanium and silver-tin-copper fillers has potential as added components in composites to provide increased mechanical strength and radiopacity, for example for use in core materials.     

Evaluation of a prototype trilayer membrane (PTLM) for lateral ridge augmentation: an experimental study in the canine mandible

The objective of this animal study was to evaluate a biodegradable/bioresorbable prototype trilayer membrane (PTLM) consisting of two collagen layers and an internal polylactide layer for lateral ridge augmentation in conjunction with two different bone grafting materials: particulate autograft or deproteinized bovine bone mineral (DBBM). In four mongrel dogs, two lateral bone defects per side were created in the mandible. The four defects per dog were randomly subjected to the following grafting treatments 3 months later: 1. PTLM+DBBM, 2. PTLM+particulate autograft, 3. ePTFE membrane+DBBM, 4. ePTFE membrane+particulate autograft. After a healing period of 4 1/2 months, the dogs were sacrificed for histological and histomorphometrical analysis. Percentage calculations for areas showing bone regeneration within the former defect outline were 56.8% for PTLM+DBBM, 85.2% for PTLM+autograft, 52.3% for ePTFE+DBBM, and 96.9% for ePTFE+autograft (differences between autograft and DBBM sites were significant at P<0.01 to P<0.05). Measurements of ridge enlargement (horizontal bone gain) were also significantly better for autograft+ePTFE sites compared to the other three grafting treatments. Histology demonstrated for most PTLM sites a moderate infiltration of lymphocytes and plasma cells adjacent to empty spaces corresponding to polylactide fragments. In addition, these reactions appeared to provoke subsequent resorption of newly formed bone. No such findings were seen in ePTFE sites. The tested prototype membrane cannot be recommended for clinical application.     

Kieferhöhlenuntersuchung nach Sinusbodenelevation kombiniert mit autologer Onlay-Osteoplastik

Background. Complication rates after sinus floor augmentation of up to 10% are mentioned in literature, often when heterologous bone implants are used. The aim of our retrospective study was to determine the complication rate involving the maxillary sinus of patients treated with autologous spongiosa. Patients and methods. In 46 patients with an absolute maxillary atrophy (61% female, 39% male, mean age 49 years), a sinus floor augmentation, if necessary combined with an onlay bone graft of the iliac crest, was performed. Implants (Brånemark) were placed in a two-stage procedure after 3–6 months. Prior to surgery, a panoramic film was made for diagnosis and treatment planning; in addition, a sinus X-ray was taken when disease of the maxillary sinus was suspected. Panoramic radiography was routinely taken after surgery. A clinical and radiological follow-up examination was performed after 6–12 months, and the patients answered a questionnaire. This study also included evaluation of operation reports and case histories. Ultrasound as well as magnetic resonance imaging to prevent radiation exposure were performed additionally. Results. In spite of perforation of the maxillary sinus mucosa in about 25%, removal of the bone graft due to inflammation was not necessary. A transient sinusitis developed in 2%. The implant loss rate (3 out of 154) may be called small. Discussion. Even though alternative heterologous graft materials exist, maxillary sinus floor elevation with autologous bone graft is still a safe option. Changes of the maxillary sinus are detectable in a small percentage, relatively often due to preexisting unrecognized or subclinical diseases of the maxillary sinus. Magnetic resonance imaging is, in spite of the high financial and technical effort required, a serious alternative to computed tomography. The combination of autologous bone graft with calcium phosphate ceramics, platelet-rich plasma, or synthetic bone growth factors should be tested as an alternative treatment method.