Faculty Bibliography

PURPOSE: The aim of this research was to evaluate the fatigue behavior and reliability of monolithic computer-aided design/computer-assisted manufacture (CAD/CAM) lithium disilicate and hand-layer-veneered zirconia all-ceramic crowns. MATERIALS AND METHODS: A CAD-based mandibular molar crown preparation, fabricated using rapid prototyping, served as the master die. Fully anatomically shaped monolithic lithium disilicate crowns (IPS e.max CAD, n = 19) and hand-layer-veneered zirconia-based crowns (IPS e.max ZirCAD/Ceram, n = 21) were designed and milled using a CAD/CAM system. Crowns were cemented on aged dentinlike composite dies with resin cement. Crowns were exposed to mouth-motion fatigue by sliding a WC-indenter (r = 3.18 mm) 0.7 mm lingually down the distobuccal cusp using three different step-stress profiles until failure occurred. Failure was designated as a large chip or fracture through the crown. If no failures occurred at high loads (> 900 N), the test method was changed to staircase r ratio fatigue. Stress level probability curves and reliability were calculated. RESULTS: Hand-layer-veneered zirconia crowns revealed veneer chipping and had a reliability of < 0.01 (0.03 to 0.00, two-sided 90% confidence bounds) for a mission of 100,000 cycles and a 200-N load. None of the fully anatomically shaped CAD/CAM-fabricated monolithic lithium disilicate crowns failed during step-stress mouth-motion fatigue (180,000 cycles, 900 N). CAD/CAM lithium disilicate crowns also survived r ratio fatigue (1,000,000 cycles, 100 to 1,000 N). There appears to be a threshold for damage/bulk fracture for the lithium disilicate ceramic in the range of 1,100 to 1,200 N. CONCLUSION: Based on present fatigue findings, the application of CAD/CAM lithium disilicate ceramic in a monolithic/fully anatomical configuration resulted in fatigue-resistant crowns, whereas hand-layer-veneered zirconia crowns revealed a high susceptibility to mouth-motion cyclic loading with early veneer failures

Reconstruction following oncologic resection in the head and neck is complex due to large surgical defects left after removal of skin, subcutaneous, and skeletal structures. It is essential to adequately fill the defect as well as provide an acceptable tissue match in terms of tone, texture, thickness and contour. A 55-year-old male presented with an advanced melanoma in the right pre-tragal area. Surgical resection was performed including a total auriculectomy. A tunnelled right supraclavicular artery island (SAI) flap was used to repair the surgical defect. A Doppler probe ensured adequate circulation within the flap, especially in the distal tip. Reconstruction using the SAI flap after oncologic ear resection reduced operating room time, required less technical expertise, and provided excellent tissue match compared to more traditional methods of surgical defect reconstruction including free flaps, local flaps, and pedicled myocutaneous flaps. Successful use of the SAI flap in this case further expands the flaps versatility. We recommend that the reconstructive surgeon consider the SAI flap when presented with challenging infratemporal fossa and lateral skull base cases.

OBJECTIVE: The aim of this study was to evaluate the effect of surface treatment at the cervical region of endosseous dental implants on the alveolar bone remodeling after implantation immediately after tooth extraction in a dog model. STUDY DESIGN: The third and fourth premolars of 6 dogs were bilaterally extracted with a full-thickness flap, and threaded implants presenting a textured or a polished surface at the cervical regions were placed on the distal root extraction sockets. Submerged healing was allowed for 4 weeks, and bone-to-implant contact (BIC) and buccal and lingual bone loss were morphometrically measured. RESULTS: The BIC and lingual bone loss were not significantly different between textured and polished groups. Significantly lower buccal bone loss (P < .01) was observed for the textured surface at 4 weeks in vivo. CONCLUSION: Textured surface implants placed immediately after tooth extraction resulted in less bone loss only at the buccal cervical region compared with smooth surface implants.

Exercise-induced acute compartment syndrome of the thigh is an uncommon entity. We present a rare case of bilateral exercise-induced three-compartment syndrome of the thighs that required fasciotomies. The objective of this study was to understand the history, physical examination, signs, symptoms, pathophysiology, diagnosis, and treatment of compartment syndrome and rhabdomyolysis. A 42-year-old man presented to the Emergency Department (ED) complaining of worsening pain and swelling in both thighs 45 h after performing a lower extremity exercise regimen. The patient's thighs were tender and swollen, but there was no ecchymosis or evidence of trauma. Admitting serum creatinine kinase (CK) was 106,289 U/L. Treatment for rhabdomyolysis was initiated. The next day, he complained of escalating bilateral thigh pain. Repeat serum CK was 346,580 U/L. The patient was diagnosed with bilateral thigh compartment syndrome and immediately taken to the operating room for fasciotomies. Postoperatively, the patient's symptoms improved rapidly and his serum CK quickly returned to normal. His incisions were closed and he returned to normal activities of daily living. Because exercise-induced compartment syndrome is an extremely rare diagnosis with a high risk of poor outcome, this article serves to emphasize the importance of considering this diagnosis during the work-up of patients presenting to the ED with rhabdomyolysis

OBJECTIVES: To evaluate the effect of framework design on the fatigue life and failure modes of metal ceramic (MC, Ni-Cr alloy core, VMK 95 porcelain veneer), glass-infiltrated alumina (ICA, In-Ceram Alumina/VM7), and veneered yttria-stabilized tetragonal zirconia polycrystals (Y-TZP, IPSe.max ZirCAD/IPS e.max,) crowns. METHODS: Sixty composite resin tooth replicas of a prepared maxillary first molar were produced to receive crowns systems of a standard (MCs, ICAs, and Y-TZPs, n=10 each) or a modified framework design (MCm, ICAm, and Y-TZPm, n=10 each). Fatigue loading was delivered with a spherical steel indenter (3.18mm radius) on the center of the occlusal surface using r-ratio fatigue (30-300N) until completion of 10(6) cycles or failure. Fatigue was interrupted every 125,000 cycles for damage evaluation. Weibull distribution fits and contour plots were used for examining differences between groups. Failure mode was evaluated by light polarized and SEM microscopy. RESULTS: Weibull analysis showed the highest fatigue life for MC crowns regardless of framework design. No significant difference (confidence bound overlaps) was observed between ICA and Y-TZP with or without framework design modification. Y-TZPm crowns presented fatigue life in the range of MC crowns. No porcelain veneer fracture was observed in the MC groups, whereas ICAs presented bulk fracture and ICAm failed mainly through the veneer. Y-TZP crowns failed through chipping within the veneer, without core fractures. CONCLUSIONS: Framework design modification did not improve the fatigue life of the crown systems investigated. Y-TZPm crowns showed comparable fatigue life to MC groups. Failure mode varied according to crown system

The review considers management strategies for malignant melanoma metastatic to the larynx. This rare clinical entity lacks clear treatment recommendations because extirpative surgery can often result in severe functional debilitation in patients with limited life expectancy. Here, we report a case of melanoma metastatic to the larynx in a patient with a prior history of Hodgkin lymphoma. The patient was treated with partial laryngectomy and local radiation therapy. The rationale for treatment decisions and for surgical and radiotherapeutic techniques and the associated literature are discussed

The gracilis myocutaneous flap has limited functional donor site morbidity and effectively contours genitoperineal reconstructions. When harvested using a traditional vertical skin paddle, distal-tip necrosis (secondary to inconsistent perforator anatomy) is a well-documented complication. Orienting the skin paddle transversely provides a reliable alternative with a shorter rotational arc but results in a more conspicuous deformity and smaller skin paddle when primary closure is desired. On the basis of recent anatomic studies, we designed a pedicled gracilis myocutaneous flap with a bilobed cutaneous paddle to maximally incorporate both the transverse and longitudinal dimensions of the flap's nearly circular angiosome. The bilobed design allows harvest of a larger transverse skin flap (with a shorter arc of rotation) while a shorter, more dependable vertical skin flap is inset into the transverse flap donor site (rather than inside the critical wound bed). Herein, we detail our surgical technique and provide 2 illustrative case examples.

PURPOSE: To test the strength to failure and fracture mode of three indirect composite materials directly applied onto Ti-6Al-4V implant abutments vs cemented standard porcelain-fused-to-metal (PFM) crowns. MATERIALS AND METHODS: Sixty-four locking taper abutments were randomly allocated to four groups and were cleaned in ethanol in an ultrasonic bath for 5 min. After drying under ambient conditions, the abutments were grit blasted and a custom 4-cusp molar crown mold was utilized to produce identical crowns (n = 16 per group) of Tescera (Bisco), Ceramage (Shofu), and Diamond Crown (DRM) according to the manufacturer's instructions. The porcelain-fused-to-metal crowns were fabricated by conventional means involving the construction and a wax pattern and casting of a metallic coping followed by sintering of increasing layers of porcelain. All crowns were loaded to failure by an indenter placed at one of the cusp tips at a 1 mm/min rate. Subsequently, fracture analysis was performed by means of stereomicroscopy and scanning electron microscopy. One-way ANOVA at 95% level of significance was utilized for statistical analysis. RESULTS: The single load to failure (+/- SD) results were: Tescera (1130 +/- 239 N), Ceramage (1099 +/- 257 N), Diamond Crown (1155 +/- 284 N), and PFM (1081 +/- 243 N). Stereomicroscopy analysis showed two distinct failure modes, where the loaded cusp failed either with or without abutment/metallic coping exposure. SEM analysis of the fractures showed multiple crack propagation towards the cervical region of the crown below a region of plastic deformation at the indenter contact region. CONCLUSION: The three indirect composites and PFM systems fractured at loads higher than those typically associated with normal occlusal function. Although each material had a different composition and handling technique, no significant differences were found concerning their single load to fracture resistance among composite systems and PFM.