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Introduction: During vocal fold vibration, the medial surface of both folds forms a convergent shape during opening and a divergent shape during closing. A greater maximum divergence angle is associated with greater closing forces which will increase the closing speed of the glottis. An increased closing speed results in a greater acoustic intensity and greater vocal efficiency. Indentation testing showed that as the strain increases, the inferior aspect of the folds becomes stiffer than the superior aspect, resulting in the vertical stiffness gradient (VSG). We hypothesize that a reduction of the vertical stiffness gradient will reduce the maximum divergence angle., Methods: Four excised canine larynges were tested. Stress-strain curves of the superior and inferior aspects of the fold in the mid membranous plane of the baseline larynges were taken using the indentation method. Calcium hydroxylapatite (CaHA) crystals were then injected into the superior aspect of the fold. The stress-strain tests were repeated. Particle imaging velocimetry (PIV) of the intraglottal velocity fields was performed in three larynges at different subglottal pressures in the mid coronal plane for the baseline and CaHA-injected larynges., Results: CaHA injection reduced the inferior-superior stiffness gradient in all larynges. The maximal divergence angle was markedly reduced. In some cases, there was not a divergent angle., Discussion: Marked reduction of the vertical stiffness gradient significantly reduces the maximum divergence angle. Clinical implications will be discussed., Level of Evidence: NA Laryngoscope, 131:E1934-E1940, 2021., (© 2020 The American Laryngological, Rhinological and Otological Society, Inc.)

Objective: To evaluate the safety of office-based calcium hydroxylapatite (CaHA) injection laryngoplasty via the cricothyroid approach through an analysis of all procedures performed over a period of 10 years at a single institution., Methods: In total, 962 office-based CaHA injection laryngoplasty via the cricothyroid approach procedures were performed by a single physician at our institution between 2007 and 2016. From these, 955 procedures performed in 617 patients were included in our analysis. The medical records of all 617 patients were retrospectively reviewed. We classified all procedure-related complications according to the time of onset. Complications that occurred during the procedure were considered intraprocedural complications, whereas complications that developed within 1 week after injection and those that developed after 1 week and were recorded more than twice in the medical records were considered acute and delayed complications, respectively. Failed cases were categorized separately as failure., Results: Five cases were failed (0.5%). Intraprocedural complications included superficial injection in eight cases (0.8%). Acute and delayed onset of dyspnea was observed in three (0.3%) and two (0.2%) cases, respectively. The incidence of failures and major complications requiring active intervention was 1.6%., Conclusion: Our findings suggest that office-based CaHA injection laryngoplasty via the cricothyroid approach is as safe as conventional transoral injection laryngoplasty., Level of Evidence: 4 Laryngoscope, 129:2361-2365, 2019., (© 2019 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives: Ideal long-term vocal fold augmentation materials should be biocompatible, easily administered, allow tissue integration for long-term effect, and remain at the site of injection. A novel silk protein particle suspended in hyaluronic acid (Silk-HA) has been developed specifically for vocal fold augmentation to address this unmet need. This article presents the 6-month, preclinical findings of a canine vocal fold injection trial for Silk-HA., Methods: Twelve beagle dogs were injected transorally in the lateral/deep aspect of their right thyroarytenoid muscles with 0.3 cc of Silk-HA or calcium hydroxylapatite in carboxymethyl cellulose (CaHA-CMC). The Silk-HA particle injectable was delivered via a custom catheter, whereas CaHA-CMC was delivered through a commercially available malleable needle. The six dogs from each material group were sacrificed 6 months from the injection date for the evaluation of implant longevity, immune response, and material migration., Results: Silk-HA provides immediate medialization of the right vocal fold, lasting for a minimum of 6 months in a canine model. Silk-HA and CaHA-CMC both demonstrate similar inflammatory responses. The Silk-HA was shown to remain without migration at the site of injection in all six canine subjects, whereas CaHA-CMC demonstrated migration in four of the six canines. In two canines implanted with CaHA-CMC, material was discovered to migrate to the retropharyngeal lymph nodes., Conclusion: In a canine subject model, the Silk-HA material compares favorably in terms of longevity and immune response to CaHA-CMC. The lack of migration of the Silk-HA material demonstrates a promising potential for vocal fold injection in the clinic., Level of Evidence: NA Laryngoscope, 129:1856-1862, 2019., (© 2018 The American Laryngological, Rhinological and Otological Society, Inc.)

Objective: Calcium hydroxyapatite (CaHA) is a common material for vocal fold injection augmentation. Durability is variable, and factors involved in implant longevity are not understood. Animal models of osteoporosis show decreased bone density and increased mineral liberation, suggesting CaHA retention may be altered in these conditions., Study Design: Prospective murine investigation., Methods: Fourteen skeletally mature, 10-month-old female Sprague-Dewley rats were treated by one of three interventions: oophorectomy, laparotomy without oophorectomy (sham), or monthly risedronate injection (90 μg/kg, subcutaneous). CaHA was implanted into the right lateral thigh muscle in all animals at the time of procedure or first risedronate injection. After 17 weeks, all rats were sacrificed, and the residual CaHA isolated from excised lateral thigh muscle through incubation in a 900 °C calcinator for 9 hours., Results: Mean CaHA mass remaining in the oophorectomy group was 65.9 (standard deviation ± 16.1) mg, compared to 44.4 ± 10.0 mg CaHA in the risedronate group and 48.6 ± 7.5 mg in the sham group. One-way analysis of variance found a statistically significant difference between the oophorectomy and risedronate groups but not between the sham and other groups, F(2,11) = 4.404, P = 0.039., Conclusion: Persistent estrogen deficiency in a murine model of osteoporosis demonstrated decreased rate of CaHA resorption. This suggests that hormone alterations associated with osteoporosis may alter the longevity of CaHA implant resorption through an uncertain mechanism., Level of Evidence: NA. Laryngoscope, 2576-2580, 2018., (© 2018 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives/hypothesis: In-office laryngology procedures are important in the treatment of voice and swallowing disorders. Patient tolerance determines which procedures can be performed without sedation or formal anesthesia. This study examines pain perception during and after in-office vocal fold injection augmentation., Study Design: Prospective cohort study., Methods: Patients scheduled for office-based vocal fold injection augmentation were prospectively enrolled at an academic voice center. The short-form McGill Pain Questionnaire was administered before, during, and after the procedure and on postprocedure days 1, 3, and 7. Pre- and postprocedure vital signs were recorded and heart rate was continuously monitored. Telephone questionnaires were completed on postprocedure days 1 and 3., Results: Forty-five patients consented to participate in our study (24 males, mean age 61 years). Most patients experienced mild to moderate pain with increasing heart rate during the procedure. Pain remained or increased 20 minutes after the procedure and improved but persisted for 1 day. Sensory and affective discomfort was endorsed by the majority. A minority of patients experienced bruising and changes in swallowing with diet modification for 3 days after the procedure. Sixteen percent had discomfort after 1 week., Conclusions: This is the first prospective study examining patient perception of pain during and after in-office injection augmentation using a validated scale and pain descriptors with extended follow-up. The results may offer guidance for patient counseling, consent, and treatment to improve tolerance and success., Level of Evidence: 4. Laryngoscope, 128:929-934, 2018., (© 2018 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives/hypothesis: To evaluate the short-term voice outcomes of vocal fold augmentation using fat compared to calcium hydroxylapatite product Radiesse Voice (Merz Aesthetics)., Study Design: Retrospective study design., Methods: Sixty-six consecutive patients with vocal fold insufficiency were recruited, including the final 33 patients treated with fat and all 33 patients treated with calcium hydroxylapatite product. Before April 2011, fat augmentation was the standard treatment; from April 2011, only calcium hydroxylapatite product was used. For all subjects, videolaryngostroboscopic evaluation, s/z ratios, and voice handicap index (VHI) were analyzed., Methods: Treatment outcomes were evaluated 3 months after the augmentation. Two patients augmented with fat (both after 6 months), versus four augmented with calcium hydroxylapatite product (mean after 7 months), needed reintervention. Mean VHI decreased from 18 points in the fat augmentation group compared to 17 points in the calcium hydroxylapatite group. Mean s/z ratio changed -0.33 in the fat augmentation group compared to -0.46 in the calcium hydroxylapatite group., Conclusion: This retrospective cohort demonstrates that there are no short-term differences in VHI outcome or number of reinterventions for augmentation with fat compared to calcium hydroxylapatite product Radiesse Voice (Merz Aesthetics)., Level of Evidence: Level 4., (© 2014 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives/hypothesis: To evaluate the effect of radiation therapy on voice outcome and duration of effect of calcium hydroxylapatite (CaHA) injection laryngoplasty in unilateral vocal fold paralysis (UVFP) patients., Study Design: Retrospective case series., Methods: UVFP patients treated with CaHA injection laryngoplasty at the University of California San Francisco Voice and Swallowing Center were identified. Demographic information, history of irradiation to the larynx, and time to additional medialization procedures were obtained. Examinations at presentation and follow-up were analyzed for laryngostroboscopic parameters and CAPE-V scores., Results: Four nonirradiated and five irradiated patients underwent a total of six and nine injection laryngoplasties, respectively. Time to additional procedures was longer in irradiated patients (P = 0.02). Prior to injection, nonirradiated patients had more severe glottic insufficiency (P = 0.007, 0.002) than did irradiated patients. Postinjection, irradiated patients demonstrated improvement in overall voice quality, breathiness, and loudness, while nonirradiated patients demonstrated improved overall quality, breathiness, pitch, and loudness. Voice quality was not statistically different between patient groups., Conclusion: CaHA injection laryngoplasty improved voice quality in both irradiated and nonirradiated patients. Nonirradiated patients experience greater vocal improvement compared to irradiated patients. Vocal cord stiffness due to radiation-induced changes may be responsible for the lack of improvement in pitch. Time to additional procedures was longer in irradiated patients and may be secondary to effects of prior radiation on graft resorption. Vocal fold medialization with CaHA injection remains a safe and efficacious treatment for UVFP in both irradiated and nonirradiated patients., (© 2014 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives/hypothesis: To evaluate the potential for injectable, permanent bone augmentation by assessing the biocompatability and bioactivity of subperiosteal hydroxylapatite (Radiesse) deposition in a rat model., Study Design: Randomized controlled animal model., Methods: Fourteen adult Sprague Dawley rats were injected in the parietal skull with 0.2 ml of hydroxylapatite (10 animals) or 0.2 ml of a carrier gel control (4 animals), using a subperiosteal injection technique on the right and a subcutaneous injection technique on the left. At 1, 3, and 6 months, three rats (1 negative control, 2 variables) were sacrificed and the calvaria were harvested. At 12 months, the remaining five rats were sacrificed. After each harvest, the specimens were processed and then examined under both light and polarized microscopy for new bone growth at the injection sites., Results: The inflammatory response was limited with both hydroxylapatite and carrier injections. Injectables were still present 12 months after the injection. New bone formation was only observed when the injection was located deep to a disrupted periosteum The odds of new bone formation was 48.949 times higher (95% confidence intervals CI [2.637, 3759.961]; P=0.002) with subperiosteal hydroxylapatite injections compared to all other combinations of injection plane and injectable., Conclusions: This preliminary report of subperiosteal hydroxylapatite (Radiesse) injection in a rat model has verified the biocompatibility of injectable hydroxylapatite at the bony interface and suggests the potential for new bone formation., Level of Evidence: N/A., (© 2013 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives/hypothesis: To evaluate the safety and efficacy of endoscopic calcium hydroxyapatite injection in patients with patulous Eustachian tube., Study Design: Retrospective case series., Methods: Fourteen patients diagnosed with patulous Eustachian tube (PET) underwent endoscopic hydroxyapatite injection under general anesthesia. All patients had at least two of three major PET symptoms including voice autophony, breathing autophony, or aural fullness/pressure. Patients were evaluated postoperatively with nasal endoscopy and a symptom questionnaire., Results: Endoscopic Eustachian tube injection was performed in a total of 23 sides in 14 patients with an average volume of 2.1 cc injected per side. Mean follow-up was 17.5 months. The most common symptoms reported preoperatively were voice autophony (96%), breathing autophony (91%), and ear fullness (83%). A complete or significant response to treatment was noted in 13/22 sides with voice autophony (59%), 12/21 sides with breathing autophony (57%), and 12/19 sides with ear fullness (63%). All complete or significant symptom improvements remained durable through the entirety of the follow-up period. Four sides that had temporary or no improvement with treatment underwent repeat injection but did not achieve additional improvement. No intraoperative or postoperative complications were observed., Conclusion: Endoscopic hydroxyapatite injection of the Eustachian tube is a minimally invasive procedure that provided significant or complete relief of autophony and ear fullness in 57% to 63% of sides treated. The procedure is well tolerated and can be performed safely under endoscopic visualization. Hydroxyapatite injection may be a satisfactory alternative to more invasive treatments for PET., (© 2013 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives/hypothesis: Dorsal nasal irregularities after trauma, and various procedures such as excessive nasal hump resection, are major problems for patients who have undergone rhinoplasty. Many grafts have been described for the correction of dorsal nasal irregularities. In this study, we used an injectable implant, in combination with diced or block cartilage grafts, to test the efficacy of injectable calcium hydroxylapatite on the survival of diced or block cartilage grafts., Study Design: Prospective, controlled, parallel group animal study., Methods: Fourteen New Zealand white rabbits were used. Block cartilage and diced cartilage grafts, alone and in combination with injectable calcium hydroxylapatite, were placed subcutaneously in the rabbits' dorsal thoracolumbar region. On the 90th day following surgery, the graft areas were extracted immediately after the rabbits were sacrificed. Pathological examination was conducted on all specimens., Results: The pathologic and histochemical findings were compared between groups. There was chronic inflammation observed in all of the groups. However, none of the groups had metaplastic bone formation or calcification. The group that received diced cartilage in combination with the injectable implant received the highest scores for peripheral chondrocyte proliferation, matrix collagen, elastic fiber, and proteoglycan content (P < 0.05). A comparison of the block and diced cartilage grafts revealed that peripheral chondrocyte proliferation was more pronounced in the diced cartilage grafts (P < 0.05)., Conclusion: The use of calcium hydroxylapatite in combination with diced cartilage grafts does not have any long-term negative effects on chondrocyte viability., (Copyright © 2013 The American Laryngological, Rhinological and Otological Society, Inc.)

This study aimed to create a thick hydroxyapatite (HA) film on the surface of a human tooth via a powder jet deposition (PJD) device for dental handpieces, and to examine the microstructural and mechanical properties of the HA film. In particular, the effects of thermal stress on this film were evaluated. The HA film was created by blasting 3.18-μm HA particles, calcinated at 1,200°C, onto the enamel substrate at room temperature and atmospheric pressure. An HA film with an area of 3 mm × 3 mm was prepared and polished. The following HA film parameters were evaluated from the three-dimensional surface profile: surface roughness, Vickers hardness, and bonding strength before and after artificial aging induced by 500 cycles of thermal cycling (5-55°C). The HA particles in the deposited film were densely packed, and the surface of the HA film was unchanged after thermal cycling. There were also no significant differences in the hardness and the bonding strength of the HA film before and after thermal cycling. The HA film created in this study demonstrated excellent microstructural and mechanical properties, even after the application of thermal stress., (© 2013 Eur J Oral Sci.)

Objectives/hypothesis: This study aimed to demonstrate the radiological properties of hyaluronic acid (HA) and calcium hydroxylapatite (CAHA) on serial computed tomography (CT) and positron emission tomography (PET) scan., Study Design: Retrospective Case Series., Method: Retrospective chart and imaging analysis of patients who underwent HA or CAHA injection laryngoplasty., Result: Total of 243 patients who underwent more than one CT of PET after last injection laryngoplasty were included. Sixty-eight patients received HA injection and 175 patients received CAHA injection. In all cases HA showed hypo-density in CT and no abnormal uptake on PET. CAHA showed bright calcific density on CT scan and high uptake on PET but had disappeared with time in 18 months if injected less than 0.85 mL in amount., Conclusion: These findings support previous clinical studies on CAHA longevity and provide proper radiological interpretation on injection materials in the vocal folds., Level of Evidence: IV (Case series)., (Copyright © 2013 The American Laryngological, Rhinological and Otological Society, Inc.)

Statement of the Problem: Bleaching-related tooth sensitivity has been shown to be facilitated by the presence of enamel defects. A nano-hydroxyapatite (n-HAP) paste has been shown to repair these defects., Purpose of the Study: Using a randomized clinical trial, an n-HAP paste was investigated to determine its efficacy in reducing bleaching-related tooth sensitivity., Methods and Materials: An n-HAP paste (Renamel AfterBleach, Sangi Co., Ltd., Tokyo, Japan) and a placebo (zero-HAP) were randomly assigned for use in 42 participants. A 7% hydrogen peroxide gel was used twice daily for 14 days, with use of assigned desensitizer for 5 minutes immediately following. A diary was completed daily for 4 weeks to note: use of the agents and sensitivity on a visual analog scale (VAS). Three aspects of tooth sensitivity were investigated: percentage of participants; number of days; and intensity level. Color change was assessed., Results: For Groups zero-HAP and n-HAP, respectively, 51 and 29% of participants reported tooth sensitivity (p = 0.06). Days of sensitivity were 76 and 36, respectively (p = 0.001). Change in VAS score from baseline trended higher for group zero-HAP (p = 0.16). Color change was equivalent., Discussion: The data trend indicated group n-HAP experienced less sensitivity over all three measures. Only the number of days of sensitivity was statistically significant., Conclusion: Within the limits of the study it can be concluded that the use of the n-HAP paste was associated with a statistically significant reduction in the number of days of tooth sensitivity experienced during active bleaching., Clinical Relevance: For those using a tooth whitener without a desensitizing agent, this study indicates that a paste containing nano-hydroxyapatite crystal can effectively reduce the duration of tooth sensitivity., (© 2011 Wiley Periodicals, Inc.)

Background/aims: Absence of curative treatment creates urgent need for new strategies for unresectable hepatoma. Based on former discoveries of good liver cell compatibility, safety and tumour-specific inhibition of hydroxyapatite nanoparticles (nHAP), this work tries to make nHAP serve as gene vector in the hepatoma-targeted trans-arterial embolization (TAE) gene therapy to elevate and synergize the therapeutic efficacy of TAE and target gene therapy., Method: Following dosage and ratio optimization, polypolex formed by surface modified nHAP and p53 expressing plasmid was applied in vitro for human hepatoma HePG2 cell, and then in vivo for rabbit hepatic VX2 tumour by injection of polypolex/lipodoil emulsion to the hepatic artery in a tumour-target manner., Results: In vitro, the polypolex transfected only about 5% HepG2 cells, but can elevate the inhibition of its growth and apoptosis in a much more degree while keeping safe to the normal hepatocyte line, L02. In vivo, the emulsion, with better dispersion than the polypolex and more specific tumour-target than lipiodol, mediated specific 4% p53 expression and antitumoural nanoparticle retention in the target tumour site, also significantly reduced tumour growth and prolonged the animal survival times more than the lipiodol (P < 0.05)., Conclusions: In all, this new treatment based on nHAP can enhance therapeutic effect of HCC safely both in vitro and in vivo., (© 2012 John Wiley & Sons A/S.)

Objectives/hypothesis: To determine whether temporary vocal fold injection affects the need for permanent medialization laryngoplasty in patients with unilateral vocal fold paralysis (UVFP)., Study Design: Retrospective chart review., Methods: A total of 175 patients with dysphonia resulting from UVFP were identified. Patients with documented recovery of vocal fold mobility, <9 months of follow-up after diagnosis of UVFP, previous treatment at other institutions, neoplastic disease involving the larynx, or history of radiation to the larynx were excluded. Fifty-four patients met all inclusion/exclusion criteria. Rates of permanent medialization laryngoplasty in patients undergoing vocal fold injection were compared with those of patients who chose observation or voice therapy., Results: A total of 35% of patients underwent temporary injection medialization, and the remaining 65% chose conservative management. Five of 19 of the temporary injection medialization patients subsequently underwent permanent intervention compared to 23 of 35 of the conservative management group (P = .0131)., Conclusions: UVFP patients who underwent vocal fold injection with an agent intended to provide temporary medialization were statistically significantly less likely to undergo permanent medialization laryngoplasty compared to those patients who were treated with conservative management only., (Copyright © 2011 The American Laryngological, Rhinological, and Otological Society, Inc.)

Objectives/hypothesis: Studies have shown excellent results for 12-month post-injection augmentation data for calcium hydroxylapatite (CaHA) for glottal incompetence; however, the longevity of the material past one year was unknown. Our objective was to report the long-term effectiveness of CaHA as a vocal fold injectable by assessing data from a cohort of patients who underwent injection for glottal insufficiency., Study Design: Retrospective chart review., Methods: Patients who underwent CaHA injection for glottal insufficiency of any etiology were considered for inclusion in the study. The change in Voice Handicap Index (VHI)-10 scores between preinjection scores and best postinjection scores as well as between the preinjection and the most recent VHI-10 scores were used as primary outcome measures to determine the persistence of benefit or the time to loss of benefit. Complications among the cohort were identified., Results: Ninety patients who underwent 108 vocal fold injections with CaHA were evaluated for inclusion. Twenty patients with 22 injections met the criteria for inclusion. Fourteen of 22 (64%) subjects showed loss of benefit of the CaHA material. The average length of benefit was 18.6 months, with a range of 8 to 36 months. Three complications were identified among the original cohort of 108 injections., Conclusions: CaHA remains a safe and effective long-term vocal fold injectable with an average length of benefit of 18.6 months. Three complications were seen among 108 CaHA injections. CaHA is a long-term injectable with an excellent track record that does not appear to warrant concern for permanent or late complications., (Copyright © 2011 The American Laryngological, Rhinological, and Otological Society, Inc.)

Soft-tissue augmentation with hyaluronic acid and calcium hydroxyl apatite are among the most widely used minimally invasive cosmetic treatments for the correction of contour deficiencies and wrinkles of the face without the risk, recovery time, and expense of a major surgery. Training and experience in the art and science of fillers is essential for the successful creation of a more youthful and natural appearance. An understanding of the different products, the injection techniques, the indications, and the potential complications of each filler are paramount to success., (© 2011 Wiley Periodicals, Inc.)

Objectives/hypothesis: To determine whether injection laryngoplasty or medialization laryngoplasty is more effective in the long-term treatment of unilateral vocal fold paralysis (UVFP)., Study Design: A retrospective study of patients with UFVP who underwent either injection or medialization laryngoplasty at the University of Arkansas for Medical Sciences between July 29, 2003 and November 18, 2005., Methods: The data analyzed included patient characteristics and type of intervention, along with the pretreatment and post-treatment parameters of videostrobolaryngoscopy, perceptual voice analysis, and patients' subjective assessment of voice handicap., Results: Thirty-four patients were evaluated, 15 new and 19 from a previous study. The average time from intervention to post-treatment evaluation in the new cohort was 4.8 months (range, 1.5-10.5 months). The average time from intervention to post-treatment in the combined cohort was 6.4 months (range, 1-24 months). Improvements were demonstrated in each of the measured voice parameters in both the injection and the medialization groups, and no significant differences were found in the degree of improvement between the two groups. Limited data on aerodynamic and acoustic voice measurements showed a trend toward improvement in each treatment group., Conclusions: Injection and medialization laryngoplasty were comparable in achieving voice improvement at the average long-term follow-up of 6 months.

Objectives/hypothesis: Presbylaryngis is a normal part of the aging process, but many people visit hospitals with communication difficulties. The authors evaluated the efficacy of calcium hydroxylapatite (CaHA) injection laryngoplasty in patients with presbylaryngis., Study Design: Retrospective review., Methods: Thirty-three patients with diagnosed presbylaryngis were administered a CaHA injection, and 17 of these patients without other vocal pathologies were included in the analysis. All 17 were male (mean age 65.9 years), mean follow-up duration was 335 days, and all injections were performed through the cricothyroid membrane under local anesthesia in a clinic., Results: Subjective ratings, perceptual ratings, maximum phonation time, and closed quotients significantly improved after injection, and these improvements persisted without significant change for over 12 months. No major complications were encountered except for transient hematoma, pain, and a foreign body sensation., Conclusions: The authors conclude that CaHA injection laryngoplasty offers an effective and safe means of treating presbylaryngis.

Eroded dentine has a complex histological structure, and its organic fraction becomes increasingly exposed as a result of the continual action of acids. The present study sought to investigate the effects of brushing forces up to 4 N on mineralized and organic dentine fractions. The study was a cyclic demineralization and remineralization experiment (carried out over 9 d). Erosion was performed with HCl (6 x 2 min d-1), pH 1.6. Samples exposed to erosion alone served as controls; test samples were eroded and brushed with a powered toothbrush (2 x 15 s d-1), applying forces of 2, 3, or 4 N. Samples were analysed (using profilometry and longitudinal microradiography) before and after the removal of superficial organic material with collagenase. Randomly selected samples were subjected to scanning electron microscopy. Demineralized organic material was present on all samples regardless of brushing force. Loss values (determined using profilometry) after erosion only, and after brushing with forces of 2, 3, and 4 N, were 11.7 +/- 5.1, 13.6 +/- 11.2, 30.7 +/- 19.0, and 25.5 +/- 20.3, respectively, before treatment with collagenase, and 111.7 +/- 11.6, 122.0 +/- 11.8, 121.9 +/- 15.7, and 123.0 +/- 12.0, respectively, after treatment with collagenase. Microradiography confirmed the results. Significant effects of brushing force were only found on the demineralized organic fraction, and mineral loss was unaffected. The notion that eroded dentine is particularly prone to abrasion should be reconsidered.

Objectives: To evaluate the long-term effectiveness of calcium hydroxylapatite (CaHA) vocal fold injection for patients with glottal insufficiency., Study Design: Multicenter, open-label, prospective clinical study of CaHA vocal fold injection., Methods: Each patient served as his/her own control. Voice-related outcome measures were collected for pre-injection, 1, 3, 6, and 12 months., Results: Sixty-three patients were available for evaluation. Fifty-three percent of the injection procedures were done in the office. Fifty-seven percent of patients were diagnosed with unilateral paralysis and 43% with glottal incompetence with mobile vocal folds. Patient satisfaction 12 months after injection showed 67% reporting a significant improvement in voice and 81% reporting at least a moderate improvement in voice. Utilizing the Voice Handicap Index-10, visual analog scale (vocal effort), Consensus Assessment Perceptual Evaluation V (judgments of voice severity), and objective voice measures of glottal closure (maximum phonation time and S:Z ratio), paired t tests showed significant improvements after treatment. A 22% further treatment rate was found at the 12-month time point., Conclusions: One-year results in this large cohort of patients with glottal incompetence treated with CaHA vocal fold injection demonstrate that excellent clinical results were achieved.

Objective: The objective of this study was to describe the management of suboptimal injection of calcium hydroxylapatite during augmentation laryngoplasty., Study Design: A retrospective review was conducted at four Voice and Swallowing centers to identify patients who had a suboptimal injection of calcium hydroxylapatite during augmentation laryngoplasty., Results: Five patients (ages 19-75) were identified with an impaired voice secondary to a superficial injection of calcium hydroxylapatite or over-medialization of the true vocal fold. All patients underwent revision surgery with all experiencing subjective and objective improvement., Conclusion: Microflap excision can lead to successful return of vibratory function after a suboptimal injection of calcium hydroxylapatite. Complete control of the initial injection is paramount to avoiding this complication.

Objective/hypothesis: To determine whether injection laryngoplasty or medialization laryngoplasty is more effective in the treatment of unilateral vocal fold paralysis., Study Design: A retrospective study of patients with unilateral vocal fold paralysis who underwent either injection or medialization laryngoplasty at the University of Arkansas for Medical Sciences between July 29, 2003 and March 8, 2005., Methods: The data analyzed included patient characteristics and type of intervention, along with the pretreatment and posttreatment voice parameters of videostrobolaryngoscopy, perceptual analysis, and patients' subjective voice assessment., Results: Nineteen patients were evaluated. The average time from intervention to posttreatment evaluation was 3 (range, 1-9) months. Improvements were demonstrated in all three voice parameters in both the injection and the medialization groups. No significant differences were found in the degree of improvement between the two groups. Videostrobolaryngoscopy and the perceptual analysis, both rated by the authors, correlated well with each other, but they both correlated poorly with the patients' subjective voice analysis., Conclusions: Injection and medialization laryngoplasty were comparable in their improvement of subjective and objective voice outcomes. Both treatment modalities should be included in the otolaryngologist's armamentarium for managing unilateral vocal fold paralysis.

Dental plaque fluid is normally supersaturated with respect to enamel mineral but this may change to a state of undersaturation when plaque pH falls following sugar exposure, placing the adjacent enamel at risk of caries. We have determined the saturation status of the fluid in both resting and fermenting plaque following mineral supplementation. Eleven subjects abstained from oral hygiene and rinsed their mouth 3 times/d for 3 d with a placebo solution or with test solutions designed to enrich plaque with hydroxyapatite or fluorhydroxyapatite. On the morning of day 4, plaque samples were collected before and after exposure to 10% sucrose. Compared to the placebo, use of the test rinses resulted in significantly higher concentrations of Ca, P and F in plaque residue. In plaque fluid, higher post-sucrose Ca2+ free concentrations and saturation levels with respect to enamel mineral and fluorapatite were found after use of the hydroxyapatite rinse compared to the placebo, effects that probably resulted from the release of cell-bound Ca2+ as well as from the dissolution of apatite. Thus, some evidence was obtained that the test mouthrinses can counteract the fall in saturation level found when plaque is exposed briefly to sucrose. Potential long-term benefits of the test mouthrinses deserve further study.