Faculty Bibliography

OBJECTIVES: Bone formation and maintenance around implants placed immediately after tooth extraction may be affected by implant surface treatment and compromise long-term esthetic results. This study morphometrically evaluated buccal bone loss and bone-to-implant contact (BIC) of four implant systems placed immediately after tooth extraction in a dog model. MATERIAL AND METHODS: The premolars of eight beagle dogs were bilaterally extracted with a full-thickness flap, and root-form dental implants were placed on the root extraction socket. Implants (n = 16 each) with different surface treatments were placed from sites 1 to 4 and alternated between animals to allow evaluation of the same number of implants at sites and evaluation time points. Implant surface treatments were as follows: anodized, discrete crystalline deposition, SLActive, and microblasted. The left and right side provided implants that stayed for 2 and 4 weeks, respectively. Submerged healing was allowed and bone-to-implant contact (BIC) and buccal bone loss were morphometrically measured. Linear mixed models (P < 0.05) were used to assess differences between groups, across time, and their interaction. RESULTS: Buccal bone loss was observed to approximately double between 2 and 4 weeks (P = 0.01). BIC also increased between 2 and 4 weeks, by 20-25% (P = 0.01). These changes were statistically similar for each surface. CONCLUSION: When placed immediately after tooth extraction, the evaluated histomorphometric parameters vary only with time.

PURPOSE:: Slow-resorbing deproteinized bovine bone grafts have presented high success rates when used for sinus augmentation. However, histologic evaluation shows that this material is eventually excreted as a result of a foreign body reaction. The purpose of this study was to compare and to evaluate the performance of a recently introduced particulate porous graft material, consisting of pure titanium granule (PTG) to the deproteinized bovine bone grafts, when used as a sinus augmentation material. MATERIALS AND METHODS:: To understand the histological aspects of PTG, deproteinized bovine particulates (Bio-Oss) and PTG were placed contralaterally as sinus grafting materials in 2 patients. After 9 months, biopsies were performed for histologic and 3-dimensional analysis. RESULTS:: Both materials were in contact with newly formed bone. The Bio-Oss showed signs of foreign body reaction. In contrast, bone filled the space between the single PTG particulates, and no foreign body reaction was observed. CONCLUSIONS:: From a bone formation perspective, PTG grafts were comparable with the commonly used Bio-Oss grafts and may be regarded as a possible alternative for permanent grafting in sinus augmentation.

Although histology has proven to be a reliable method to evaluate the ossoeintegration of a dental implant, it is costly, time consuming, destructive, and limited to one or few sections. Microcomputed tomography (microCT) is fast and delivers three-dimensional information, but this technique has not been widely used and validated for histomorphometric parameters yet. This study compared microCT and histomorphometry by means of evaluating their accuracy in determining the bone response to two different implant materials. In total, 32 titanium (Ti) and 16 hydroxyapatite (HA) implants were installed in 16 lop-eared rabbits. After 2 and 4 weeks, the animals were scarified, and the samples retrieved. After embedding, the samples were scanned with microCT and analyzed three-dimensionally for bone area (BA) and bone-implant contact (BIC). Thereafter, all samples were sectioned and stained for histomorphometry. For the Ti implants, the mean BIC was 25.25 and 28.86% after 2 and 4 weeks, respectively, when measured by histomorphometry, while it was 24.11 and 24.53% when measured with microCT. BA was 35.4 and 31.97% after 2 and 4 weeks for histomorphometry and 29.06 and 27.65% for microCT. For the HA implants, the mean BIC was 28.49 and 42.51% after 2 and 4 weeks, respectively, when measured by histomorphometry, while it was 33.74 and 42.19% when measured with microCT. BA was 30.59 and 47.17% after 2 and 4 weeks for histomorphometry and 37.16 and 44.95% for microCT. Direct comparison showed that only the 2 weeks BA for the titanium implants was significantly different between microCT and histology (p = 0.008). Although the technique has its limitations, microCT corresponded well with histomorphometry and should be considered as a tool to evaluate bone structure around implants. (c) 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.

Few studies have evaluated the effects of titanium (Ti) surface modifications on polymorphonuclear neutrophils (PMNs). Human PMNs' viability and release of key mediators-such as IL1beta, IL6, TNFalpha, IL12, IL10, IL4, TGFbeta1, IL8, IP-10, and Mig-were evaluated on three different Ti surface treatments: (1) machined Ti; (2) alumina-blasted and acid-etched Ti (AB/AE); and (3) calcium phosphate coating of 300-500 nm by ion beam onto the AB/AE Ti surface (CaP). A polystyrene surface was used as a negative control. The PMNs were purified from whole human blood and cultured for 6 h. Cell viability was determined by flow cytometry, and the supernatant was evaluated to determine the levels of cytokines and chemokines. Results showed that the percentage of viable cells was significantly lower on the CaP surface compared to the control (p < 0.05) relative to the other groups. No differences in the levels of IL8, MIG, and IP10 were detected between groups. Significantly higher levels of IL1beta (p = 0.046) and TNFalpha (p = 0.016) were detected for the CaP surfaces compared to AB/AE surface only. The levels of IL4, IL10, and TGFbeta1 secreted from the PMNs in the CaP group were significantly lower than in the control and machined groups (p < 0.05) that were statistically comparable to AB/AE. Overall, the addition of a thin CaP coating to the AB/AE Ti surface influenced the secretion profile of pro-inflammatory cytokines due to the higher release of pro-inflammatory cytokines (IL1beta and TNFalpha) on these surfaces.

This study aimed to determine the effect of a bioactive ceramic coating on titanium in the nanothickness range on human osteogenic cells, peripheral blood mononuclear cells (PBMC) and on osteogenic cells co-cultured with PBMC without exogenous stimuli. Cell viability, proliferation, adhesion, cytokine release (IL1beta, TGFbeta1, IL10 and IL17) and intracellular stain for osteopontin and alkaline phosphatase were assessed. Morphologic evaluation showed smaller and less spread cell aspects in co-culture relative to osteogenic cell culture. Cell viability, proliferation and adhesion kinetics were differently influenced by surface texture/chemistry in culture versus co-culture. Cytokine release was also influenced by the interaction between mononuclear and osteogenic cells (mediators released by mononuclear cells acted on osteogenic cells and vice versa). In general, 'multi-cell type' interactions played a more remarkable role than the surface roughness or chemistry utilized on the in vitro cellular events related to initial stages of bone formation.

This study evaluated the histometric characteristics of the peri-implant mucosa of human subjects that received textured implant abutments with conventional (implant and abutment with same diameter) or platform-switched (implant diameter wider than that of the abutment) configurations. Wider and longer connective tissue around platform-switched implants was observed compared to that with conventional abutments. Despite the different dimensions between the two abutment types, the abutment-soft tissue interaction was similar for both groups at the histometric level.

BACKGROUND AND PURPOSE: Treacher Collins syndrome is an autosomal dominant craniofacial disorder affecting derivatives of the first and second branchial arches. Given the conflicting reports in the literature regarding the extent of anterior-posterior and vertical (superior-inferior) dysplasia of the cranial base, maxilla, and mandible, this study was designed to provide a comprehensive lateral cephalometric assessment of the craniofacial morphology of unoperated patients with Treacher Collins syndrome. METHODS: The records of 45 patients with Treacher Collins syndrome registered at the Institute of Reconstructive Plastic Surgery of the NYU Langone Medical Center from the period of 1975 to 2008 were reviewed. Inclusion criteria included (1) patients between with the ages of 5 and 17 years, (2) no history of prior surgical intervention to correct skeletal deformity, and (3) diagnostic quality lateral cephalograms. Twenty patients satisfied the inclusion criteria with 12 male and 8 female patients in the sample and a mean age at the time of the lateral cephalogram of 8.8 years (range 5.2 to 16.7 years). Thirty angular and linear variables were measured to assess anterior-posterior and vertical (superior-inferior) position of the cranial base, maxilla, and mandible. Each patient's measurements were compared to age-matched and sex-matched control samples derived from the Moyers growth studies. The mean and standard deviation for each variable was then determined. RESULTS: Lateral cephalometric analysis showed decreased anterior, posterior, and total cranial base lengths and a reduced cranial base angle. The anteroposterior dimension or length of the maxilla is deficient and the maxilla is positioned posteriorly with respect to the cranial base. Both anterior and posterior facial heights (superior-inferior dimension) are decreased. Lower face height is increased, whereas total face is decreased. The maxillary and functional occlusal planes are tipped upwards posteriorly. The mandibular morphology is characteristically small in both body length and total mandibular length, and the maximum ramus width is also deficient. The mandibular plane angle and gonial angle are increased. The mandible is retropositioned. CONCLUSIONS: A lateral cephalometric analysis is described that provides a skeletal basis for the hallmark clinical findings associated with Treacher Collins syndrome. This is of importance because an understanding of the underlying skeletal dysmorphology may shed light on the etiology and growth pattern, and impacts the overall treatment planning for skeletal correction.

BACKGROUND: Le Fort III distraction advances the Apert midface but leaves the central concavity and vertical compression untreated. The authors propose that Le Fort II distraction and simultaneous zygomatic repositioning as a combined procedure can move the central midface and lateral orbits in independent vectors in order to improve the facial deformity. The purpose of this study was to determine whether this segmental movement results in more normal facial proportions than Le Fort III distraction. METHODS: Computed tomographic scan analyses were performed before and after distraction in patients undergoing Le Fort III distraction (n = 5) and Le Fort II distraction with simultaneous zygomatic repositioning (n = 4). The calculated axial facial ratios and vertical facial ratios relative to the skull base were compared to those of unoperated Crouzon (n = 5) and normal (n = 6) controls. RESULTS: With Le Fort III distraction, facial ratios did not change with surgery and remained lower (p < 0.01; paired t test comparison) than normal and Crouzon controls. Although the face was advanced, its shape remained abnormal. With the Le Fort II segmental movement procedure, the central face advanced and lengthened more than the lateral orbit. This differential movement changed the abnormal facial ratios that were present before surgery into ratios that were not significantly different from normal controls (p > 0.05). CONCLUSION: Compared with Le Fort III distraction, Le Fort II distraction with simultaneous zygomatic repositioning normalizes the position and the shape of the Apert face. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

BACKGROUND: The present study demonstrates our experience with a novel use of the Platysma in facial reanimation, as a balancing procedure by counteracting an overactive free muscle transfer, and improving oral continence by re-establishing the oral sphincter mechanism. MATERIAL AND METHODS: Twelve patients, nine female (75%) and three male (25%), with a mean age of thirty-eight years (range: 2-66) are presented. Of these, in seven patients (58%) who had excessive excursion of the free muscle, the contralateral pedicled platysma was transferred to counteract the excessive pull. Four patients (33%) underwent bilateral platysma transfer for oral sphincter restoration, while one (8%) had ipsilateral platysma transfer. Evaluation of aesthetic and functional results was performed by a panel of three independent observers, and the long term efficacy of the procedure was assessed through a patient questionnaire. RESULTS: All patients demonstrated significant upgrading of their oral competence associated with eating, drinking and smiling, as it was confirmed by the behavioural analysis (p < 0.01). Six of the ten patients that were available, responded to the Quality of Life Questionnaire. Five out of six were satisfied with their mouth appearance when they smile and five patients have a regular diet and without drooling. CONCLUSION: A novel use of Platysma transposition is described that can substitute for a paralysed orbicularis oris muscle in restoring oral sphincter function or to counter balance an excessively active free muscle that was previously transferred for smile restoration. This novel Platysma transfer technique is intended to be used as an adjunct to other reanimation procedures.