Prospective randomized clinical trial evaluating the effects of two different implant collar designs on peri-implant healing and functional osseointegration after 25 years.

OBJECTIVES: Evaluate the effects of two different machined-collar lengths and designs on peri-implant healing. MATERIAL AND METHODS: An implant with a microtextured surface and 3.6mm-long internal-connection machined collar was compared to two implants that had an identical 1.2mm-long external-connection machined collar, but one had the microtextured surface while the other's was machined. Participants received the three implants, with microgap at the crest, alternately at five sites between mental foramen, and a full-arch prosthesis. Peri-implant bone levels were measured after 23 to 26 years of function. Keratinized tissue height, plaque, probing depth, bleeding, and purulence were also evaluated. Descriptive and mixed models for repeated\measures analyses were used, with Bonferroni correction for pairwise comparisons. RESULTS: Twenty-two participants (110 implants) were evaluated at the 25-year examination. Microtextured implants with the longer machined collar had significantly greater mean marginal bone loss (-1.77mm ± 0.18, mean ± SE) than machined (-0.85mm ± 0.18, p < .001) and microtextured (-1.00 ± 0.18mm, p < .001) implants with the shorter machined collar. Keratinized tissue height was greater for internal-connection (0.74mm ± 0.10) versus external-connection (0.51 ± 0.08, p =  0.01) microtextured implants. No differences were observed for plaque (p = 0.78), probing depth (p = 0.42), bleeding (p  = 0.07), and purulence (p = 1.00). Implant survival rate was 99%. CONCLUSIONS: Implants with the 1.2mm machined collar limited bone loss to 1mm, while those with the longer machined collar showed > 1.5mm loss after 25 years of function with microgap at the crest. Internal-connection design and fixture surface microtexturing did not result in greater bone preservation. ClinicalTrials.gov Identifier: NCT03862482.

Long-term randomized clinical trial evaluating the effects of fixture surface acid-etching and machined collar design on bone healing.

OBJECTIVES: An implant with an acid-etched fixture surface and internal-hex collar may achieve greater osseointegration. The goal of this research was to study the effects on long-term bone healing of fixture surface acid-etching and machined collar design. METHOD AND MATERIALS: Three two-part implant types were compared: standard Brånemark (with an external-hex 1.2 mm long machined flat collar), Swede-Vent (a copy of the Brånemark design, with an identical collar but a fixture surface acid-etched to 1 to 3 µm), and Screw-Vent (with a fixture surface acid-etched identically to that of Swede-Vent, but a longer internal-hex machined flat collar that did not require countersinking). Fifty-eight subjects each received the three types in alternate fashion at five sites between mental foramen, and a fixed full-arch prosthesis. Abutment-implant interface/microgap (MG) was placed at the crest, and first bone-to-implant contact point-to microgap (fBIC-MG) was measured at mesial and distal sides of each implant. Mean fBIC-MG values were compared after 15 to 20 years of function. Statistical analysis was based on the mixed linear model with the level of significance set at P < .05 and Bonferroni correction for pairwise comparisons. RESULTS: Brånemark had less mean marginal bone loss (-1.08 mm, standard error [SE] 0.20) compared with Swede-Vent (-1.28 mm, SE 0.20), but pairwise comparisons showed that the difference was not statistically significant (mean difference of 0.20 mm, P = .662). Screw-Vent had the greatest loss (-1.92 mm, SE 0.20), and pairwise comparisons showed that the difference was statistically significant compared with Brånemark and Swede-Vent (difference ≥ 0.64 mm, P < .001). CONCLUSION: According to accepted standards for osseointegration, all three implant types achieved very acceptable long-term results. However, while Brånemark had the least bone loss, the implant with the acid-etched fixture surface and longer internal-hex collar design had the greatest loss. Within the confines of this study, shorter collar length of 1.2 mm may be more important to limit long-term bone loss with microgap placed at the crest.

Preservation of posterior mandibular extraction site with allogeneic demineralized, freeze-dried bone matrix and calcium sulphate graft binder before eventual implant placement: a case series.

OBJECTIVE: This case series reports short- and long-term healing, before and after placement of an implant, in posterior mandibular extraction sites grafted with demineralized, freeze-dried bone matrix (DFDBM) allograft mixed with calcium sulphate graft binder. METHODS: Three patients who underwent surgical extraction of a posterior mandibular molar experienced partial loss of the buccal bone plate at the extraction site. Alveolar bone reconstruction with a DFDBM allograft mixed with calcium sulphate graft binder was performed immediately. The graft was covered with a biodegradable regenerative membrane. For each of the 3 patients, the implant and healing abutment were placed after 6, 9 and 12 months, respectively, followed by crown placement 3, 5 and 5 months later, respectively. The implants were periodically re-evaluated, both clinically and radiographically, between 10 and 39 months after final insertion of the crown. An implant stability device was used to evaluate the long-term biological and functional stability of the implants. RESULTS: Upon exposure and implant placement, the grafted alveolar ridge in all patients presented appropriately sized, dense and well-vascularized bone, wide enough to receive the planned wide-platform implant. The long-term interface stability quotient ranged from 87 to 90. CONCLUSIONS: Posterior mandibular extraction sites with compromised buccal alveolar bone may be effectively managed by immediate alveolar augmentation using a mixture of DFDBM allograft and calcium sulphate graft binder. This approach provides ideal alveolar form and consistency for eventual placement of the implant.

Outcomes in the management of sternal dehiscence by plastic surgery: a ten-year review in one university center.

PURPOSE: Infection rates following median sternotomy vary between 0.2% and 10%. These cases are associated with morbidity and mortality rates between 10% and 25% and 5% and 20%, respectively. The purpose of this study was to evaluate patient outcomes following plastic surgery correction of sternotomy dehiscence (SD). METHODS: All patients operated on for an SD following coronary artery bypass graft surgery (CABG), between 1995 and 2005, with 1 or more flaps, were included. RESULTS: Eighty cases were identified over a 10-year period. The mean age was 64 (+/-9.1) years. Two or more procedures were required in 17.5% of patients, and the mortality rate within 30 days was 12.5%. Significant variability was revealed between the cumulative mortality rates of plastic surgeons, from 0.0% to 50.0%. Multiple associations were identified for poor outcome, including chronic renal insufficiency and early mortality, and obesity with risk of reintervention. CONCLUSION: Although patients who undergo surgical correction of a deep sternal infection usually tolerate their intervention well, the mortality within 30 days remains high. This study has identified several factors explaining morbidity and mortality in this patient population.

Paraspinous muscle flaps for the treatment and prevention of cerebrospinal fluid fistulas in neurosurgery.

STUDY DESIGN: A prospective clinical study was conducted to evaluate the efficacy of paraspinous muscle flaps in preventing and managing cerebrospinal fluid fistulas in high-risk neurosurgery patients. OBJECTIVES: To evaluate the efficacy of paraspinous muscle flap coverage using a "vest-over-pants" closure in the prevention and treatment of cerebrospinal fluid fistulas. SUMMARY OF BACKGROUND DATA: Previous studies have described paraspinous muscle flaps for the closure of complex spinal wounds, but none has addressed their use for the prevention and treatment of cerebrospinal fluid fistulas. METHODS: This prospective clinical study evaluated nine consecutive patients with either refractory cerebrospinal fluid fistulas or high risk for cerebrospinal fluid leaks after spinal surgery. Bilateral paraspinous muscle flaps were used as primary flaps and closed using an overlapping vest-over-pants technique in eight of nine cases. The latissimus dorsi and trapezius muscles were recruited as additional muscle flaps for closure of thoracolumbar and high thoracic deficits, respectively. RESULTS: Paraspinous muscle flaps provided immediate wound coverage in seven high-risk patients undergoing spinal surgery and two patients with recurrent cerebrospinal fluid fistulas. Postoperative hospitalization averaged 14.4 days. There was no evidence of a cerebrospinal fluid fistula after an average follow-up of 176.7 days. No wound infections occurred. The only complications were a superficial hematoma, which was drained percutaneously on postoperative day 6, and a seroma, which was drained during the follow-up period and eventually resolved. CONCLUSIONS: Paraspinous muscle flaps allow effective treatment and prevention of cerebrospinal fluid fistulas in selected high-risk patients and provide simple durable coverage of complex spinal wounds with minimal morbidity.