James C. Lemon

Guided tissue fabrication from periosteum using preformed biodegradable polymer scaffolds

A successful tissue engineering method for bone replacement would imitate natural bone graft by providing the essential elements for new bone formation using synthetic scaffolds, osteogenic cell populations, and bone induction factors. This is a study of the suitability of various formulations of poly(DL-lactic-co-glycolic acid) (PLGA) foams to provide a tissue conducting scaffold in an ovine model for bone flap fabrication. Three formulations were used of different copolymer ratio and molecular weight. Porous wafers of PLGA were stacked into rectangular chambers (volume 4 cm3) enclosed on five sides. Some chambers also contained autologous morcellized bone graft (MBG). The chambers were inserted with the open face adjacent to the cambium layer of the periosteum in rib beds of seven sheep and harvested after 8 weeks in vivo. Gross and histologic examination of the resulting tissue specimens demonstrated molded units of vascularized tissue generally conforming to the shape of the chambers and firmly attached to the periosteum. Polymer degradation appeared to occur by varying degrees based on polymer formulation. New bone formation was observed only in areas containing MBG. There was no evidence of significant inflammatory reaction or local tissue damage at 8 weeks. We conclude that a PLGA foam scaffold is (1) an efficient conductor of new tissue growth but not osteoinductive, (2) contributes to the shape of molded tissue, and (3) biocompatible when used in this model. Further studies are warranted to develop practical methods to deliver bone induction factors to the system to promote osseous tissue generation throughout the synthetic scaffold.

Color stability of facial prostheses

The limited service of facial prostheses is the result of degradation of the elastomer and color instability. Deterioration may be caused by many factors, which include environmental exposure and changes in humidity. This investigation assessed the efficacy of an additive, intrinsic, broad-spectrum ultraviolet light absorber on the color stability of a pigmented facial elastomer. Samples were weathered artificially and outdoors at exposure levels of radiant energy of 150 to 450 kJ/m2. The samples changed color slightly but perceptibly. Artificial aging caused a greater change than outdoor aging. The ultraviolet light absorber UV-5411 did not protect the samples from color changes.

Facial prosthetic rehabilitation: Preprosthetic surgical techniques and biomaterials

Purpose of reviewAttention to detail ensuring a successful facial prosthetic rehabilitation must be considered a priority at the time of presurgery, surgery, and at every stage in fabricating the prosthesis. Teamwork between the surgeon and maxillofacial prosthodontist will ensure an optimal surgical preparation and definitive prosthesis. Recent findingsEvidence of interaction between team members can most certainly be encouraging to the patient. During the prosthetic phase of treatment, focusing on tissue assessment, impression making, sculpting, mold fabrication, familiarity with materials, appreciation of color, delivery of instructions, and patient education will ensure a satisfactory outcome. With the desire, determination, and encouragement from the restorative team to make the most of this artificial replacement, a patient can have a higher quality of life and a more normalized lifestyle. SummaryThis review presents current concepts regarding facial prosthetic rehabilitation of patients with head and neck cancer and facial prosthetic biomaterials.

Oral and dental management of the cancer patient: prevention and treatment of complications

Aggressive cancer therapy places patients at greater risk for oral complications and treatment-related consequences. Unfortunately, prevention and/or treatment of such oral sequelae has become an often overlooked priority of the treatment team. We describe a philosophy of management of the cancer patient that specifically emphasizes the prevention and treatment of oral complications associated with cancer therapy. These concepts and principles are based on treatment protocols and ongoing clinical research at The University of Texas M. D. Anderson Cancer Center in Houston, Texas.

Technique for fabricating a mirror-image prosthetic ear

A simple technique for producing a mirror image of a cast for sculpting an auricular prosthesis is described. A transparency copy of the cast assist the operator in sculpting the contours of the facial prosthesis.

Experience with Barton button and peristomal breathing valve attachments for hands‐free tracheoesophageal speech

Tracheostoma breathing valves permit hands‐free tracheoesophageal (TE) speech production; however, few laryngectomees routinely use them because of problems with attachment.

Facial moulage: The effect of a retarder on compressive strength and working and setting times of irreversible hydrocolloid impression material

STATEMENT OF PROBLEM Irreversible hydrocolloid is widely used as an impression material for fabrication of extraoral maxillofacial impressions. A disadvantage of irreversible hydrocolloid, however, is its limited working time. PURPOSE This study tested the compression strength (elastic recovery) and working and setting times for an irreversible hydrocolloid impression material after a retarder was added. MATERIAL AND METHODS The irreversible hydrocolloid (Jeltrate) was mixed with water in a standard water/powder mixture of 18 mL (1 unit) of water and 7 g (1 unit) of the impression material. Test specimens (n = 3) were prepared by adding 2, 4, 6, and 8 drops of monobasic sodium phosphate (the retarder) to each. Three other specimens, to which no retarder was added, served as the control. Specimens were prepared according to the American National Standards Institute/American Dental Associations specification no.18 guidelines for irreversible hydrocolloid impression material. Immediately after the specimens were prepared, the flat end of a polished rod of poly(methyl methacrylate) was placed in contact with its exposed surface and quickly withdrawn. The working-time experiment was a pass/fail test conducted 30 seconds before the initial setting time. The initial setting time was established as extending from the start of the mix to the time when the impression material no longer adhered to the end of the rod. To determine how the compressive strength of the modified irreversible hydrocolloid (with retarder added) compared with that of the control, the mean stress at maximum load (Mpa) was analyzed. The compressive strength (MPa) was calculated. Statistical analysis consisted of descriptive statistics and regression analyses. RESULTS The results of this experiment demonstrated that the elastic recovery of the irreversible hydrocolloid did not change with the addition of sodium phosphate (2 to 8 drops). The percent recovery with was 95.95% +/-.42%, 96.33% +/-.82%, and 96.28% +/-.53% for 0 (control), 2 and 8 drops, respectively. Average setting times for control specimens were 2 minutes 20 seconds +/- 0 seconds for the control specimen (0 drops) to 11 minutes 20 seconds +/- 1 minute 50 seconds for the test specimen with 8 drops. There was a direct relationship (R(2) = 0.85) between the number of drops added and the setting time. All control specimens and test specimens containing 2, 4, 6, and 8 drops of monobasic sodium phosphate produced acceptable levels of elastic recovery (> or =95%). CONCLUSION Within the limitations of this study, predictable longer working and setting times were demonstrated for the irreversible hydrocolloid specimens with 1 to 8 drops of the sodium phosphate solution tested. The specimens with 8 drops of retarder solution exhibited variable setting times and would not be suitable for clinical use. The compressive strength of the modified irreversible hydrocolloid material tested was compromised because of the addition of sodium phosphate solution; however, recovery from deformation remained satisfactory as retarder solution was added.

The efficacy of antifungal agents incorporated into a facial prosthetic silicone elastomer

Microbiologic isolation techniques and scanning electron microscopy were used to determine whether a fungus is associated with the black discoloration of some silicone nasal prostheses. Colonies of fungal growth were seen on scanning electron micrographs of the affected areas of a nasal prosthesis, and a fungus belonging to the genus Penicillium was isolated from similar areas. Disk diffusion tests determined that the antifungal agent clotrimazole, when incorporated into silicone samples, was effective in inhibiting in vitro growth of the fungus.

A shade guide for acrylic resin facial prostheses

The value and success of a well-fitting and anatomically correct prosthesis are compromised if the color does not match the adjoining tissue. Color and color science are reviewed to help develop a simplified acrylic resin shade guide to aid in fabricating acrylic resin facial prostheses. This guide will help the clinician obtain a good intrinsic shade and minimize extrinsic coloration.

Total midface reconstruction after radical tumor resection: A case report and overview of the problem

We report an unusual repair of a massive midface defect resulting from resection of a recurrent squamous cell carcinoma of the nasal vestibule. The defect included both maxillas, the hard palate, the upper lip, and all nasal and perinasal tissues. After treatment, reconstruction was accomplished using prostheses and autologous tissue transferred from local and distant sites. The osseous component of the transferred tissue permitted placement of osseointegrated implants for fixation of maxillary and nasal prostheses. The rationale for this reconstruction and the problems associated with midface reconstruction after radical tumor resection are discussed.