Leadership in an academic discipline.

Leading an academic discipline poses moral and ethical challenges, requiring a special set of capabilities. Leadership in a clinical academic discipline involves leading the transformation of education, research, leadership and patient care. Daily struggles within strategic, political and cultural milieu are the norm and effective leaders are able to navigate through these struggles and see opportunities for growth.

Gingival fibromatosis: a case report.

AIM: Gingival Fibromatosis is characterised by a large increase in the gingival dimension which extends above the dental crowns, covering them partially or completely. The causes of the disease may have a genetic origin, in which case gingival hyperplasia may occur in isolation or be part of a syndrome, or acquired origin, which comes from specific drugs administered systemically. A form of gingival fibromatosis of idiopathic origin has been described. The therapy involves mainly the surgical removal of the hyperplastic gingival tissue, although in these cases recurrences are frequent. CASE REPORT: A 9 years old male patient came to observation at the Clinic of Pediatric Dentistry of the Tor Vergata Polyclinic of Rome. After Primary Gingival Fibromatosis was diagnosed, the therapeutic choice was to wait and postpone gingivectomy at the end of the development phase.

Effect of soldering on metal-porcelain bond strength in repaired porcelain-fused-to-metal castings.

STATEMENT OF PROBLEM: Chemical bonding plays a major role in the adherence between metal and porcelain. The formation of an oxide layer on solder material has not been described in the literature. It is unknown whether the application of solder negatively affects the bond strength between porcelain and metal. PURPOSE: This in vitro study assessed the effect of solder on the bond strength between metal and porcelain. MATERIAL AND METHODS: Forty 20 x 6 x 0.5 mm patterns were divided into test (20) and control (20) groups. Test samples were perforated and repaired with solder, and 2 layers of opaque and dentin porcelain subsequently were applied on all samples. The samples were subjected to a 3-point flexural test on a screw-driven mechanical testing machine at a crosshead speed of 0.5 mm/min. Failure type (adhesive vs cohesive) was quantified by digitizing photographs of test and control samples. Three samples in each group also were examined with an SEM coupled with an x-ray energy-dispersive spectroscopy apparatus (SEM/EDS). Means and standard deviations of loads at failure, sample thickness, and surface area covered with porcelain were calculated, and data were analyzed with Student t test (P < or = 0.05). RESULTS: The mean fracture load for test samples was significantly greater than for control samples (P = 0.0038). Test samples also were significantly thicker (mean thickness difference 0.14 mm) (P = 0.0001). When the data were controlled for thickness by using a multiple linear regression analysis, no significant difference was found (P = 0.68). Test samples had a greater surface area covered with opaque porcelain (P = 0.0006) as determined by visual inspection. CONCLUSION: In this study, soldered and nonsoldered samples did not show any significant difference in porcelain-to-metal bond strength. Visual analysis revealed a significant difference in the amount of porcelain remaining on the fracture surface of the test and control samples; a complete quantitative elemental analysis with SEM/EDS is in progress.

Influence of metal surface finishing on porcelain porosity and beam failure loads at the metal-ceramic interface.

STATEMENT OF THE PROBLEM: Investigators suggest that metals should be finished in 1 direction before porcelain application to minimize metal irregularities and trapped contaminants. These irregularities are thought to be focal points for porosity and crack propagation. PURPOSE: This study investigated the influence of metal finishing and sandblasting on (1) porosity production at the porcelain-metal interface, and (2) porcelain-metal beam failure load. MATERIAL AND METHODS: Eighty cast metal samples were divided into 4 test groups: (A) bidirectional finish/sandblasting; (B) unidirectional finish/sandblasting (C) bidirectional finish only; and (D) unidirectional finish only. The porcelain applied was 1.5 mm thick. Samples were sectioned longitudinally. Half of the samples were subjected to a 3-point flexural test. The remaining samples were sectioned into 4 slices and were examined with a light microscope (x500). Number and diameter of porosities at the metal-porcelain interface were recorded. RESULTS: Mean loads at failure (lbs) were as follows: A, 11.1 +/- 1.3 (5.03 +/- 0.58 Kg); B, 11.2 +/- 1.7 (5. 08 +/- 0.77 Kg); C, 4.0 +/- 1.8 (1.81 +/- 0.81 Kg); and D, 5.0 +/- 2. 1 (2.26 +/- 0.95 Kg). Groups A and B were significantly different from groups C and D (P<.0001). Nonsandblasted samples (C and D) exhibited a separation at the ceramometal interface, which prevented quantification of porosity size and number. Average interface porosity sizes (microm) (A, 8.99 +/- 1.92; B, 10.03 +/- 1.86) showed no significant difference. The mean interface porosity number (A, 62. 3 +/- 16.02; B, 67.4 +/- 10.01) showed no significant difference. CONCLUSION: Direction of metal finishing did not affect the porosity number and size at the ceramometal interface or the beam failure loads. Sandblasting increased the beam failure loads. Nonsandblasted samples showed detachment of the porcelain from the metal.

Effect of ring liner and casting ring temperature on the dimension of cast posts.

STATEMENT OF PROBLEM: If a post does not fit passively, binding with the radicular tooth structure occurs, possibly increasing the risk for root fracture. Therefore, it is necessary to fabricate slightly undersized cast posts to allow for passive fit and cement placement. Shrinkage of the mold cavity may be a desired effect during the casting of posts. PURPOSE: This study evaluated the influence of: (1) a cellulose ring liner, and (2) a lower casting temperature of the metal ring, on the dimensions of a cast post. MATERIAL AND METHODS: Eighty plastic posts were divided in 4 equal groups (group 1, 815 degrees C, liner; group 2, 815 degrees C, no liner; group 3, 600 degrees C, liner; and group 4, 600 degrees C, no liner), invested in phosphate-bonded investment and cast with a noble alloy. Posts were measured at 2 locations, the tip and base, before and after casting. RESULTS: Investing in a lined metal ring and using a casting ring temperature of 815 degrees C (group 1) resulted in markedly oversized posts (tip: +25.8 microm; base: +20.3 microm). The absence of the cellulose liner in the casting ring (group 2) decreased the expansion of the investment producing slightly oversized castings (tip: +9.75 microm; base: +4.52 microm). Lined rings that were heated to a final temperature of 600 degrees C (group 3) produced posts that were oversized (tip: +16.65 microm; base: +11.05 microm). Final casting ring temperature of 600 degrees C and the absence of a cellulose liner (group 4) resulted in posts slightly undersized (tip: -4.1 microm; base: -2.2 microm). CONCLUSION: The use of 2 casting ring temperatures (815 degrees C or 600 degrees C) and the influence of a ring liner were investigated. Decreasing the casting ring temperature from 815 degrees C to 600 degrees C and the absence of a ring liner significantly decreased the dimensions of a cast post.

Face-bow record without a third point of reference: theoretical considerations and an alternative technique.

Accurate mounting of dental casts is achieved by transferring the tridimensional spatial relationship of the maxillary arch to an articulator. A face-bow is used to transfer this relationship to the articulator, usually by relating the face-bow to a plane of reference. The most common reference plane is the Frankfort plane, which has been assumed to be horizontal when the patient is in the natural head position. The axis-orbitale plane has also been considered horizontal and used as reference. However, it has been shown that both planes are not horizontal, and mounting a maxillary cast according to these planes can result in an inaccurate mounting. This article describes an alternative procedure for face-bow transfer without a plane of reference, and uses the angular relationship between the occlusal plane and the condylar path to mount the maxillary cast on the articulator. The elimination of a reference plane, to which relate the functional determinants of occlusion, avoids an additional source of error during the mounting procedure.

Alternative complete-arch cement-retained implant-supported fixed partial denture.

Early implant prostheses designs, which used screw-retained metal and acrylic resin structures, frequently left a space between the prosthesis and the soft tissue. Common deficiencies of this design included phonetic and esthetic problems and screw loosening. Cement-retained implant prostheses are also used in partially and completely edentulous patients, and are thought to have optimal occlusion and esthetics. Moreover, cement-retained prostheses may induce less stress on the implant, thereby maximizing the possibility of a passive fit. Porcelain fused to metal prostheses have been used mostly in partially edentulous situations. Recently, complete-arch porcelain fused to metal prostheses that replace hard and soft tissue have been used and, although this restoration can have excellent esthetics, there are disadvantages such as high cost, potential framework distortion during fabrication, and difficulty in repairing fractures of in-service porcelain. This article describes an alternative technique for the fabrication of a complete-arch, cement-retained, metal-acrylic resin implant-supported fixed partial denture. When compared with porcelain fused to metal complete-arch restorations, this prostheses is esthetic, has excellent retention and stability, yet is relatively inexpensive to fabricate, and requires less laboratory skill.

Alternative procedure for making a metal suprastructure in a milled bar implant-supported overdenture.

The predictability of implant-supported prostheses has been established. Although the original Brånemark design has been successfully used in the mandible, esthetic, speech, and hygiene-related problems have been reported in maxillary fixed prostheses. Implant-overdentures can overcome some of the problems encountered in maxillary fixed prostheses. Milled-bar implant-supported overdentures fabricated by electric discharge machining are characterized by stability similar to a fixed prostheses and are removable for hygiene procedures. However, the procedure is costly and requires highly trained technicians. An alternative procedure to produce an accurately fitting metal suprastructure is presented. This procedure does not require additional technical skills and uses instruments and materials that are readily available and relatively inexpensive. The use of simple and easy to replace attachments allows repairs to be performed in the dental office, thus reducing maintenance cost. The overall result is a prosthesis that incorporates the features of a spark erosion overdenture at a fraction of the cost and that is available to a broader patient population.

Loose joint bodies of the temporomandibular joint: a case report.

Osteochondral loose bodies are an uncommon finding in the temporomandibular joint (TMJ), but occur relatively frequently in large joints such as the knee, elbow, hip, wrist, and ankle. Loose joint bodies can be divided in three groups: 1) synovial chondromatosis; 2) osteochondral fracture fragments and; 3) cases of degenerative arthritis or avascular necrosis. The most common clinical features of loose joint bodies are pain, swelling, joint noise and impaired joint movements. A case of loose joint bodies of the temporomandibular joint is presented. The pantomograph and lateral cephalograph revealed several irregularly shaped, variably sized radiopaque structures in the region of the right temporomandibular joint. CT and MR scans confirmed the initial diagnosis. The dimensions of the loose joint bodies varied from 1-2 to 5-6 mm. In this patient, the loose joint bodies may have been secondary to osteoarthritis, may have preceded and caused the degenerative changes, or may be only a coincidental finding.

Tissue management with a new gingival retraction material: a preliminary clinical report.

A new retraction material (Merocel) was evaluated in a clinical trial with 10 selected abutments. Each selected abutment required an anterior single unit. A comparison of probing attachment level, bleeding on probing, and plaque index demonstrated highly successful periodontal maintenance. The main advantage of Merocel retraction material is that it is capable of innocuously expanding the gingival sulcus. This preliminary study suggested that a Merocel strip was a predictable retraction material in conjunction with impression procedures. The material was also evaluated by scanning electron microscopy and demonstrated promise in this investigation. The Merocel strip shows potential for other applications, but limitations of this material indicated that evolution of atraumatic gingival retraction should continue.

Ultrastructural aspects of duodenal mucosa repair during treatment of peptic disease.

We applied scanning electron microscopy (SEM) to the study of duodenal ulcer healing during treatment with an H2-receptor antagonist (ranitidine). We also evaluated the changes in the duodenal mucosa close to the lesion, which appeared endoscopically and histologically normal. Endoscopic biopsies were taken from 8 patients both on the edge of the ulcer and in the upper duodenum, before and after 1, 2, 3, 4 and 8 weeks of treatment. Endoscopy revealed a decrease of the ulcer crater after the first week and a complete healing after three weeks of therapy. The ulcer edge presented a subtotal mucosal atrophy, cellular exfoliation (dome-shaped cells) and changes in microvilli (bridging, branching, blebs). In the first week of treatment, reepithelization was observed: however, cellular exfoliation and changes in microvilli persisted at least up to the end of the first month of treatment. Short and stumped villi began to reappear after one month. The mucosa farthest from the lesion showed the same alterations but to a lesser extent. The changes tended to decrease after treatment. Two months after the end of treatment the duodenal mucosa was endoscopically and histologically normal, while SEM showed altered microvilli. SEM allowed us to investigate the morphogenesis of mucosal repair and to identify minimal cellular alterations which could represent the morphological basis of the disease and its possible recurrence.