Photoluminescence and optical absorption of Cs2NaScF6:Cr3+.

The main objective of this paper is the characterization of the spectroscopic properties of new materials that are prospective laser media. This approach allows for the comparison of the properties of the Cr3+ in different environments. Here, we have studied the photoluminescence and optical absorption of Cs2NaScF6:Cr3+ single crystals. On the basis of near-infrared luminescence measurements at 2, 77, and 300 K the observed lines originated from the Cr3+-centres were associated with the 4T2(4F) --> 4A2(4F) transition and the lifetimes were obtained. In spite of the quenching observed as a function of temperature at least 10% of the 2 K emission intensity for Cs2NaScF6 doped with 1% of Cr3+ remains at room temperature. Besides, the 2 K emission broad band could be well described in terms of normal modes of the octahedral complex [CrF6]3-, and the Racah and crystal-field parameters calculated.

Maxillary sagittal and vertical displacement induced by surgically assisted rapid palatal expansion.

The purpose of this study was to investigate the sagittal and vertical effects on the maxilla induced by surgically assisted rapid palatal expansion. Twenty patients (average age, 25.6 years) who required a surgically assisted rapid palatal expansion procedure were available for this study. Each patient was banded with a Haas-type palatal expander, maxillary surgery was performed, and the expander was activated. Presurgical and postexpansion lateral cephalograms were taken for each patient. The measurements of SNA, Frankfort horizontal-nasion-A point, sella-nasion-palatal plane, A-point-nasion-perpendicular (in millimeters), 1-nasion-A-point, 1-sella-nasion, 1-nasion-perpendicular (in millimeters) were made on each cephalogram, and the presurgical and postexpansion tracings were superimposed on the cranial base to determine the changes in the anterior nasal spine and posterior nasal spine positions. Results showed that from the presurgical cephalogram to the postexpansion cephalogram SNA, Frankfort horizontal-nasion-A point and A-point-nasion-perpendicular had a mean increase of 0.60 degrees (P <.05), 0.65 degrees (P <.05), and 0.55 mm (P <.05), respectively; 1-nasion-A-point decreased 2.18 degrees (P <.05) and 1-sella-nasion decreased 1.53 degrees (P <.05). No significant maxillary vertical displacement was noted from the first cephalogram to the second. In conclusion, surgically assisted RPE did not significantly affect the maxilla vertically; however, it did induce a slight forward movement of the maxilla and a slight retroclination of the maxillary incisors sagittally (P <.05).

Preprosthetic surgery for the edentulous patients.

Preprosthetic surgery is a rapidly changing area of dentistry. A knowledge of the range, capabilities, and limitations of the commonly used surgical procedures is a must for anyone treating a patient who will receive a complete denture prosthesis. It cannot be overemphasized that the establishment of a clear treatment plan and close coordination of all parties involved in the reconstructive effort are essential to achieve the best overall result.

Diagnosis and treatment of transverse maxillary deficiency.

Treatment of skeletally mature patients is often complicated by inadequately treated or undiagnosed transverse skeletal discrepancy. This report emphasizes diagnosis of transverse maxillo-mandibular discrepancy and describes recommendations for treatment. Proper treatment strategy must consider the type and magnitude of transverse deficiency, patient's growth status, dentofacial esthetics, stability factors, and periodontal tissue health. Indications for surgically assisted maxillary expansion are listed, and the recommended surgical technique to improve frontal dentofacial esthetics, provide better stability, and enhance long-term periodontal health is described. Specific modifications in surgical technique to help prevent postoperative complications are included. New recommendations for sequencing, timing, and correction of transverse deficiency are presented.

Multiple central giant cell lesions with a Noonan-like phenotype.

A small number of patients with the phenotypic features of Noonan syndrome have also developed giant cell lesions of the jaws similar to those seen in cherubism. This case report describes an individual with the features of the recently described Noonan-like/multiple giant cell lesion syndrome. Previously reported cases and issues relative to diagnosis and management are considered.

Changes in the nasal and labial soft tissues after surgical repositioning of the maxilla.

Accurate prediction of postsurgical function and esthetics of the nose and upper lip requires an understanding of the relationship between maxillary surgical movement and soft tissue change. Thirty-two patients underwent Le Fort I osteotomies, some with concomitant mandibular procedures. Preoperative, postoperative, and 1-year postsurgical data derived from cephalometric and nasolabial cast analysis were compared to assess skeletodental changes, soft tissue changes, and stability. A multiple stepwise regression (including age, gender, alar cinch suture, V-Y closure, and contouring of the anterior nasal spine as variables) indicated that accurate prediction equations could be formulated, particularly if the patients were grouped by vector-specific maxillary movements. In general, the base of the nose widened in all patients regardless of the vector of surgical maxillary movement. An associated shortening of the nose was found. The nasolabial angle decreased or remained constant in most patients. The upper lip widened and lengthened at the philtral columns. Narrow noses widened more than did broad noses and alar cinch suturing widened the alar base even more. Results indicated that soft tissue changes associated with maxillary surgery may be more affected by the position of the soft tissue incision and methods used in closure than by the surgically induced hard tissue change.

Osseous changes following placement of the transmandibular implant system in edentulous mandibles.

The transmandibular implant system is designed for the reconstruction and rehabilitation of the endentulous mandible utilizing an extraoral approach. Transmandibular implants were placed in 19 patients and mandibular bony changes were followed using standardized panoramic radiography. Eleven sites were identified on each postoperative radiograph and the percentage of radiographic enlargement was calculated for each site. The true bony changes were then computed for both short-term (9.4 months) and long-term (53.4 months) follow-up. Patients with an average mandibular height in the saddle areas of 3.5 to 8.9 mm showed bilateral bony regeneration in the saddle areas and over the most distal cortical screws of the implants. Most of these bony changes were seen in the first year, but continued beyond that time. Patients with residual bone height of 9.0 to 12.9 mm had little bone change, while patients with bone height of 13.0 to 20.5 mm demonstrated slight resorption. Theories for the observed changes are presented. The transmandibular implant is especially indicated for the severely atrophic mandible because its position within the mandible and the rigid box frame design of the implant promote bilateral bone regeneration distal to the framework of the implant.

The Dentofacial Deformity Program of the University of Michigan: organization, analysis of data, and benefits of program.

The Dentofacial Deformity Program of the University of Michigan was established in 1984 to provide a consulting service for the diagnosis, treatment recommendations, and management of patients with dentofacial deformities. This program was designed as a service commitment for the patient, referring doctors, and the medical and dental communities. Educational and research aspects of the program provide benefits for orthodontic and oral and maxillofacial surgery graduate students, and the dental school faculty. The organization, data analysis, and education, research, and service benefits of this program are discussed.

The transmandibular implant: implant reconstruction and rehabilitation for the atrophic mandible.

The transmandibular implant is specifically designed for the reconstruction and rehabilitation of the severely atrophic mandible utilizing an extraoral approach. The unique design and surgical protocol of the transmandibular system have proven to be predictable and successful. The indications, implant design and materials, surgical technique, advantages, and disadvantages of the transmandibular system are presented in this article.

The effects of maxillary surgery on nasal respiration.

Le Fort I osteotomies frequently involve impaction of the maxilla into the nasal cavity, potentially affecting nasal form. It has been speculated that a concomitant change in nasal function may occur. The purpose of this study was to determine if there is an association between maxillary position and nasal function and to evaluate the influence of Le Fort I surgery on nasal function. Presurgical and postsurgical nasal resistance and percent nasal respiration were compared in 36 patients. Results indicated a mean change in nasal resistance 1 year after surgery, but mean percent nasal respiration did not change significantly. No prediction could be made for any patient relative to the effect of maxillary surgery on the nasal function parameters. No consistent association could be found between the amount or direction of maxillary surgical movement or the position of the maxilla and nasal respiration.

Evaluation of anterior maxillary alveolar ridge resorption when opposed by the transmandibular implant.

Fifteen edentulous patients with complaints regarding denture comfort and/or function were treated with the transmandibular implant. All patients were restored with conventional maxillary dentures opposed by implant-supported removable prostheses. Two to 4 years after surgery, these patients were evaluated for vertical and horizontal maxillary bone loss with a radiographic analysis developed by the authors. With this technique, attention was focused on vertical alveolar ridge resorption in the anterior maxilla. Although the sample size was small, the findings from this study indicate that vertical bone loss in the anterior maxilla does occur when a maxillary denture is opposed by an implant-supported overdenture. Comparison of these results with a previous study that evaluated anterior maxillary resorption when a complete maxillary denture opposed natural mandibular anterior teeth and a distal extension removable partial denture demonstrated no statistically significant difference.

Allogeneic bone for secondary alveolar cleft osteoplasty.

The purpose of this retrospective clinical study was to determine the efficacy of allogeneic bone for secondary alveolar cleft osteoplasty. Twenty-four patients with unilateral cleft lip and palate treated with allogeneic bone grafts were examined by a surgeon, orthodontist, and prosthodontist 20 to 47 months after surgery. Radiographic and clinical examination of the periodontal status of the teeth adjacent to the cleft and their antimeres were compared for differences with Student's t test and the Wilcoxon test. Radiographs indicated complete bone bridging in 21 patients. Two of the remaining three patients had a 1-mm radiolucent gap in the cleft site. The third patient had a 6-mm-wide radiolucency and recurrence of an oronasal fistula which was regrafted with autogenous bone. No statistically significant differences between the cleft and noncleft tooth antimeres were found for plaque, gingivitis, bleeding, sulcus depth, or level of attachment. A statistically significant difference in the amount of attached gingiva was found between the cleft and noncleft tooth antimeres. Nine patients with missing lateral incisor teeth avoided prosthetic replacement by orthodontic movement of the canine tooth into the grafted edentulous space. In those cases where the maxillary canine was unerupted at the time of the surgery, eruption into the graft occurred. Stability of the maxillary segments was sufficient to allow prosthodontic restoration with a fixed partial denture in those cases where it was indicated.

Multicenter follow-up study of the transmandibular implant.

The purpose of this multicenter study was to review the results of treatment and identify complications in edentulous patients who were treated with the transmandibular implant. A total of 190 patients were treated in four university departments. These patients presented for treatment with mandibular bone heights that ranged from 4 to 18 mm (mean, 10 mm). After postoperative periods that ranged from 3 months to 5 years, 182 of the 190 implants (95.8%) were stable and functional. Three implants were removed due to perioperative fractures in mandibles with 4 to 6 mm of bone height. Five were removed due to infection which occurred within the first 3 months after surgery. Reversible complications that developed in 22.2% of the patients were treated successfully. The 182 implants in function demonstrated no mobility and no infrabony pockets around any of the transmucosal posts. The results of this study demonstrate that the transmandibular implant has acceptable predictability and reliability for reconstruction of patients with severe atrophy of the mandibular alveolar process.

The transmandibular implant: a 2-year prospective study.

Thirteen consecutive patients with complaints of dysfunction and pain associated with a mandibular denture were treated with the transmandibular implant. The implant was placed from a submental approach with an atraumatic surgical technique. No load was placed on the implant for 12 weeks. Patients were evaluated for pain, paresthesia, healing of the submental wound, soft tissue response, radiographic change, and mobility of the implant for a period of 2 years. Patient satisfaction was recorded at the 1- and 2-year examinations. The results demonstrate the reliability and reparability of the transmandibular implant system.