Vertical ridge augmentation using xenogenous bone blocks: a comparison between the flap and tunneling procedures.

PURPOSE: Previous studies have shown that the subperiosteal tunneling procedure in vertical ridge augmentation accelerates healing after grafting and prevents graft exposure, with minor postoperative complications. It is conceivable that new bone formation would be greater with the tunneling procedure than with the flap procedure, because the former is minimally invasive. This hypothesis was tested in this study by comparing new bone formation between the flap and tunneling procedures after vertical ridge augmentation using xenogenous bone blocks in a canine mandible model. MATERIALS AND METHODS: Two Bio-Oss blocks were placed on the edentulous ridge in each side of the mandibles of 6 mongrel dogs. The blocks in each side were randomly assigned to grafting with a flap procedure (flap group) or grafting with a tunneling procedure (tunneling group). RESULTS: The mean percentage of newly formed bone within the block was 15.3 ± 6.6% in the flap group and 46.6 ± 23.4% in the tunneling group. CONCLUSION: Based on data presented in this study, when a tunneling procedure is used to place xenogenous bone blocks for vertical ridge augmentation, bone formation in the graft sites is significantly greater than when a flap procedure is used.

Minimally invasive ridge augmentation using xenogenous bone blocks in an atrophied posterior mandible: a clinical and histological study.

PURPOSE: Although various techniques for the treatment of an atrophic alveolar ridge have been described in the literature, these procedures have increased the morbidity and discomfort for the patient. The purpose of this study was to evaluate histological and clinical results in 9 patients who underwent a subperiosteal tunneling procedure with a Bio-Oss block onlay graft in an atrophic area of the mandible. PATIENTS AND METHODS: Nine months after grafting, at the time of dental implantation, biopsy samples were taken from the grafted areas of 9 patients and were analyzed histologically. RESULTS: New bone formation through the bovine bone block was observed consistently in the 9 cases. There was direct deposition of bone on the surface of the graft material. CONCLUSION: The results of this study indicated that ridge augmentation using a subperiosteal tunneling procedure with Bio-Oss bone blocks might be useful for implant placement in the atrophic alveolar ridges.

A comparative study on the extractions of partially impacted mandibular third molars with or without a buccal flap: a prospective study.

PURPOSE: The present report describes a flapless extraction method for partially impacted mandibular third molars and compares the effects of flap and flapless extractions of the teeth in terms of postoperative pain, swelling, and pocket depth of the second molar. PATIENTS AND METHODS: A prospective study was performed of 27 patients who underwent bilateral extraction of partially impacted mandibular third molars. Two molars in the same patient were extracted on each side, either with or without a buccal flap. RESULTS: The postoperative pain, swelling, and pocket depth of the second molar were all significantly greater on the side that underwent flap extraction than on the side that underwent flapless extraction (P < .05). CONCLUSIONS: Our results support the clinical use of flapless extractions when the distal surface of the crown is completely anterior to the anterior border of the mandibular ramus and the occlusal surface of the impacted tooth is level or nearly level with the occlusal plane of the second molar.

The use of autologous venous blood for maxillary sinus floor augmentation in conjunction with sinus membrane elevation: an experimental study.

BACKGROUND: There have been reports of successful bone formation with sinus floor elevation induced by simply elevating the maxillary sinus membrane and filling the sinus cavity with a blood clot. PURPOSE: We investigated the feasibility of maxillary sinus floor augmentation using the patient's own venous blood in conjunction with a sinus membrane elevation procedure. MATERIALS AND METHODS: An implant that protruded 8 mm into the maxillary sinus after sinus membrane elevation was placed in the maxillary sinus of six adult female mongrel dogs. The resulting space between the membrane and the sinus floor was filled with autologous venous blood retrieved from each dog. The implants were left in place for 6 months. RESULTS: During the experimental period, the created space collapsed and the sinus membrane fell down onto the implant. A small amount of new bone formation occurred in the space created by the collapsed membrane. The average height of newly formed bone around the implants in the sinus was 2.7+/-0.7 mm on the buccal side and 0.6+/-0.3 mm on the palatal side. CONCLUSION: The results of this pilot study indicate that blood clots do not have sufficient integrity to enable the sinus membrane to remain in an elevated position for therapeutically effective periods of time. Accordingly, it is recommended that this method be used only when a small amount of new bone formation is necessary around implants in the maxillary sinus cavity.

Simultaneous flapless implant placement and peri-implant defect correction: an experimental pilot study in dogs.

BACKGROUND: Minimally invasive implant surgery allows clinicians to place implants in less time, without extensive flaps, and with less bleeding and postoperative discomfort. The purpose of this study was to evaluate a new surgical technique by which implants are inserted in a deficient alveolar ridge using a flapless technique simultaneously with a peri-implant defect correction that is performed using a subperiosteal tunneling procedure. METHODS: Bilateral, horizontal defects of the alveolar ridge were created in the mandibles of five mongrel dogs. After 3 months of healing, one implant was placed on each side of the mandible by a flapless procedure. The exposed threads of the implant on one side of the mandible were covered with a 1:1 autogenous bone/xenograft mixture using a subperiosteal tunneling technique. Four months later, biopsies of the implant sites were taken and prepared for ground sectioning and analysis. RESULTS: All implants were well osseointegrated with the host bone. All of the peri-implant defects at the test sites were covered with tissue that resembled bone. In all specimens, a mixture of bone, connective tissue, and residual bone particles was observed in the graft area. In the control sites, where no graft was used, none of the exposed threads on any implants were covered with new bone. CONCLUSION: This preliminary report indicates the potential use of a minimally invasive flapless technique as a substitute for a more invasive implant placement and ridge augmentation procedure.

The effect of thick mucosa on peri-implant tissues: an experimental study in dogs.

BACKGROUND: Findings from animal studies have indicated that the implant-mucosal barrier consists of a junctional epithelium approximately 2 mm long and a connective tissue compartment about 1 to 1.5 mm high. It may be argued that different features develop in the implant-mucosal barrier when it is placed within the alveolar bone with thick mucosa. The aim of this study was to examine the influence of a thick mucosa on peri-implant tissue healing around dental implants. METHODS: The bilateral fourth mandibular premolars and all maxillary premolars were removed in six mongrel dogs. On one side (test side) of the mandible, a standardized bone defect (8.0 mm in height) was created in the premolar region, whereas no defect was created on the other side (control side). After 3 months of healing, one implant was placed on each side of the mandible; a long abutment (12 mm in height) was connected to the fixture on the bone defect side, whereas a normal abutment was connected to the fixture on the control side. After a healing period of 6 months, all dogs were sacrificed to evaluate peri-implant tissues. RESULTS: The height of the mucosa, the length of the junctional epithelium, and the height of the zone of connective tissue integration were significantly greater in the thick mucosa than in the normal mucosa (P <0.05). No significant difference was found between the control and test sides in the marginal level of bone-to-implant contact. CONCLUSIONS: The junctional epithelium extended more apically in the thick mucosa than in the normal mucosa. However, additional marginal bone resorption was not observed at the thick mucosa sites.

Ingestion of orthodontic anchorage screws: an experimental study in dogs.

INTRODUCTION: Sharp-edged foreign bodies that are accidentally swallowed can become lodged in the stomach. This animal study was undertaken to determine the outcome of orthodontic anchorage screw ingestion. METHODS: We evaluated radiographs of 10 mixed-breed dogs that ingested 10 orthodontic anchorage screws and 10 reamers (1 screw and 1 reamer per dog). RESULTS: All orthodontic anchorage screws and all but 2 reamers were spontaneously passed within 7 days. CONCLUSIONS: Further investigation is needed to determine whether the results of our animal study agree with clinical findings.

Alginate-calcium microsphere loaded with thrombin: a new composite biomaterial for hemostatic embolization.

To date, transcatheter arterial embolization (TAE) has become a standard treatment to control intracavitary bleeding as an alternative to surgery. Due to excellent biocompatibility and no residual in vivo, biodegradable materials are preferred in TAE. However, gelfoam is the only commercially available biodegradable embolic material used to treat blunt trauma of solid abdominal viscera until now, and controversial on its stability and reliability never stopped in the past five decades. In this study, a new biodegradable macromolecule material (thrombin-loaded alginate-calcium microspheres, TACMs) was prepared using electrostatic droplet techniques and a special method was developed for hemostatic embolization. Thrombin was successfully loaded into microspheres with high encapsulation efficiency and drug loading capacity. A burst release of TACMs was observed at early stage and sustained release later on, with the activity of thrombin preserved well. The strength of TACMs mixed thrombus, which was used as embolic agent, increased in a dose-dependent manner after TACMs were added. In addition, the TACMs were verified to be of no cytotoxicity and systemic toxicity, and biodegradable in vivo. Finally, the results of preliminary applications revealed that the TACMs could serve as an effective and promising embolic material for blunt trauma and hemorrhage of solid abdominal viscera.

A comparative study of the regenerative effect of sinus bone grafting with platelet-rich fibrin-mixed Bio-Oss® and commercial fibrin-mixed Bio-Oss®: an experimental study.

Anorganic bovine bone (Bio-Oss®) particles are one of the most popular grafting materials. The particles are often mixed with platelet-rich fibrin (PRF) or a commercial fibrin (Tisseel®) to form a mouldable graft material. The objective of this study was to compare the potentials of PRF-mixed Bio-Oss® and Tisseel®-mixed Bio-Oss® to enhance bone regeneration in a canine sinus model. Six mongrel dogs were used in this study. After elevating the sinus membrane in both maxillary sinus cavities, an implant was placed into the sinus cavity. In one of the sinus cavities, the PRF/Bio-Oss® composite was grafted, and the Tisseel®/Bio-Oss® composite was grafted in the other sinus cavity. After a 6 month healing period, bone formation in the graft sites and bone-implant contact were evaluated. The mean osseointegration rate was 43.5 ± 12.4% and new bone formation rate 41.8 ± 5.9% in the PRF/Bio-Oss® composite sites. In the Tisseel®/Bio-Oss® composite sites they were 30.7 ± 7.9% and 31.3 ± 6.4%. There were statistically significant differences between the groups. The findings from this study suggest that when platelet-rich fibrin is used as an adjunct to Bio-Oss® particles for bone augmentation in the maxillary sinus, bone formation in the graft sites is significantly greater than when Tisseel® is used.

Study on the adsorption property of lysozyme on weak cation exchanger based on monodisperse poly(glycidymethacrylate-co-ethylenedimethacrylate) beads.

A type of weak cation exchanger was prepared based on poly(glycidylmethacrylate-co-ethylenedimethacrylate). The effects of pH and ionic strength on the adsorption behavior were studied, and the results suggested that the adsorption of lysozyme onto a weak cation exchanger is electrostatic interaction, and that the adsorption behavior is in accordance with the Langmuir adsorption model with a correlation coefficient greater than 0.99. It was also found that increasing ionic strength led to a decrease of the adsorption of lysozyme from 49.50 to 28.09 mg/g. Preliminary chromatographic experiments were conducted to test the separation properties of the weak cation exchanger, and the results demonstrated that the retention time of different proteins could be predicted in order of their isoelectric point.

Flapless implant surgery using a mini-incision.

BACKGROUND: Traditional flapless implant surgery using a soft tissue punch device requires a circumferential excision of keratinized tissue at the implant site. A new flapless implant technique that can submerge implant fixtures is needed. PURPOSE: This article describes a flapless implant surgery method using a mini-incision and compares the effects of soft tissue punch and mini-incision surgery on both the amount of osseointegration and the bone height around the implants using a canine mandible model. MATERIALS AND METHODS: Bilateral, edentulated, flat alveolar ridges were created in the mandibles of six mongrel dogs. After a 3-month healing period, two implants were placed on each side of the mandible using either soft tissue punch or mini-incision procedures. After an additional 3-month healing period, a second stage surgery and transmucosal abutment attachment was performed for mini-incision implant cases. Following a 2-month healing period, the dogs were sacrificed to evaluate the osseointegration and bone height around the implants. RESULTS: Average bone height was 9.6 ± 0.4 mm in the soft tissue punch group and 9.8 ± 0.3 mm in the mini-incision group (p > .05). Average osseointegration was 70.4 ± 6.3% in the soft tissue punch group and 71.2 ± 7.1% in the mini-incision group (p > .05). No significant differences were noted between the two groups in vertical alveolar ridge height or bone/implant contact. CONCLUSIONS: Our findings support the clinical use of mini-incision implant surgery at sites where implants need to be protected below the soft tissue during the early phase of healing, particularly for patients with poor bone quality and/or low primary implant stability.

Ridge alterations following immediate implant placement and the treatment of bone defects with Bio-Oss in an animal model.

BACKGROUND: Conflicting data exist on the outcome of placing Bio-Oss® (Geitslich Pharm AG, Wolhausen, Switzerland) into extraction sockets. It is therefore relevant to study whether the incorporation of Bio-Oss into extraction sockets would influence bone healing outcome at the extraction sites. PURPOSE: The aim of this study was to assess peri-implant bone changes when implants were placed in fresh extraction sockets and the remaining defects were filled with Bio-Oss particles in a canine mandible model. MATERIALS AND METHODS: Six mongrel dogs were used in the study. In one jaw quadrant of each animal, the fourth mandibular premolars were extracted with an elevation of the mucoperiosteal flap; implants were then placed in the fresh extraction sockets and the remaining defects were filled with Bio-Oss particles. After 4 months of healing, micro-computed tomography at the implant sites was performed. Osseointegration was calculated as the percent of implant surface in contact with bone. Additionally, bone height was measured in the peri-implant bone. RESULTS: Average osseointegration was 28.5% (ranged between 14.8 and 34.2%). The mean crestal bone loss was 4.7 ± 2.1 mm on the buccal aspect, 0.4 ± 0.5 mm on the mesial aspect, 0.4 ± 0.3 mm on the distal aspect, and 0.3 ± 0.4 mm on the lingual aspect. CONCLUSION: The findings from this study demonstrated that the placement of implants and Bio-Oss® particles into fresh extraction sockets resulted in significant buccal bone loss with low osseointegration.

Comparison of flap and flapless procedures for the stability of chemically modified SLA titanium implants: an experimental study in a canine model.

BACKGROUND: Flapless implant surgery has been shown to accelerate recovery and increase the vascularity of the peri-implant mucosa after implant placement. OBJECTIVE: The aim of this study was to compare dental implant stabilization patterns between flap and flapless implant surgeries over the first 8 weeks after implant placement. STUDY DESIGN: In 6 mongrel dogs, bilateral, edentulated, and flat alveolar ridges were created in the mandible. After 3 months of healing, 2 implants (Straumann SLA-active) were placed in each side of the mandible using either a flap or flapless procedure. The implant stability quotient (ISQ) that was obtained from Osstell Mentor was measured at the time of implantation and weekly over the first 8 weeks after implant placement. RESULTS: Implants stabilized more quickly without flap elevation than with flap elevation. For flapless implants, an increase in stability occurred after 2 weeks without a period of decreasing stability. However, for flap implants, a shift in implant stability from decreasing stability to increasing stability occurred after 2 weeks. CONCLUSION: In the canine model, flapless surgical placement of implants may increase the initial stability of implants compared with implants placed after the reflection of the mucoperiosteal flap.

A 1-year prospective clinical study of soft tissue conditions and marginal bone changes around dental implants after flapless implant surgery.

BACKGROUND: Despite several reports on the clinical outcomes of flapless implant surgery, limited information exists regarding the clinical conditions after flapless implant surgery. OBJECTIVE: The objective of this study was to evaluate the soft tissue conditions and marginal bone changes around dental implants 1 year after flapless implant surgery. STUDY DESIGN: For the study, 432 implants were placed in 241 patients by using a flapless 1-stage procedure. In these patients, peri-implant soft tissue conditions and radiographic marginal bone changes were evaluated 1 year after surgery. RESULTS: None of the implants were lost during follow-up, giving a success rate of 100%. The mean probing depth was 2.1 mm (SD 0.7), and the average bleeding on probing index was 0.1 (SD 0.3). The average gingival index score was 0.1 (SD 0.3), and the mean marginal bone loss was 0.3 mm (SD 0.4 mm; range 0.0-1.1 mm). Ten implants exhibited bone loss of >1.0 mm, whereas 125 implants experienced no bone loss at all. CONCLUSION: The results of this study demonstrate that flapless implant surgery is a predictable procedure. In addition, it is advantageous for preserving crestal bone and mucosal health surrounding dental implants.

Effects of flapless implant surgery on soft tissue profiles: a prospective clinical study.

BACKGROUND: Flapless implant surgery has been suggested as a suitable treatment modality for the preservation of soft tissue after implant placement. PURPOSE: The purpose of this study was to determine the extent of soft tissue profile changes around implants after flapless implant surgery. MATERIALS AND METHODS: A total of 44 patients received 76 implants using a flapless implant procedure. The marginal level of the peri-implant soft tissue was evaluated using dental casts 1 week, 1 month, and 4 months after implant placement. RESULTS: The mean soft tissue levels around implants showed 0.7 ± 0.3 mm of coronal growth 1 week after surgery. At 1 month, the levels were 0.2 ± 0.2 mm coronal growth and at 4 months, the values were 0.0 ± 0.3 mm. Soft tissue profiles assessed 4 months after flapless implant placement were similar to profiles assessed immediately before implant placement. CONCLUSION: Flapless implant surgery is advantageous for preserving mucosal form surrounding dental implants.

Effects of soft tissue punch size on the healing of peri-implant tissue in flapless implant surgery.

OBJECTIVE: In an attempt to help produce guidelines for the use of soft tissue punches, this animal study was undertaken to examine the effects of soft tissue punch size on the healing of peri-implant tissue in a canine mandible model. STUDY DESIGN: Bilateral, edentulous, flat alveolar ridges were created in the mandibles of 6 mongrel dogs. After a 3-month healing period, 3 fixtures (diameter 4.0 mm) were placed on each side of the mandible using 3-mm, 4-mm, or 5-mm soft tissue punches. After subsequent healing periods of 3 weeks and 3 months, the peri-implant mucosa was evaluated using clinical, radiologic, and histometric parameters, which included gingival index, bleeding on probing, probing pocket depth, marginal bone loss, and vertical dimension measurements of the peri-implant tissues. RESULTS: The results obtained showed significant differences (P < .05) between the 3-mm, 4-mm, and 5-mm tissue punch groups for the length of the junctional epithelium, probing depth, and marginal bone loss at both 3 weeks and 3 months after implant placement. When the mucosa was punched with a 3-mm tissue punch, the length of the junctional epithelium was shorter, the probing depth was shallower, and less crestal bone loss occurred than when using a tissue punch with a diameter >or=4 mm. CONCLUSIONS: The results show that the size of the soft tissue punch plays an important role in achieving optimal healing. The findings support the use of a tissue punch slightly narrower than the implant itself to obtain better peri-implant tissue healing around flapless implants.

A retrospective study of the effects of sinus membrane elevation on bone formation around implants placed in the maxillary sinus cavity.

OBJECTIVE: The aim of this study was to investigate the height of new bone formation in the maxillary sinus after implants were inserted into the maxillary sinus without any additional grafting material after sinus membrane elevation. STUDY DESIGN: Nine patients with a combined total of 10 implants that were inserted into the maxillary sinus more than 4 mm (range, 4-6 mm) after sinus membrane elevation were evaluated for endosinus bone gain and crestal peri-implant bone loss 4 months after implantation using computerized tomography and dental radiographs. RESULTS: The mean endosinus bone gain was 3.5 +/- 0.6 mm. The mean crestal peri-implant bone loss was 0.1 +/- 0.1 mm. CONCLUSION: The results indicated that elevation of the sinus membrane without the addition of a bone-grafting material led to bone formation in the sinus.

Morphogenesis of the peri-implant mucosa: a comparison between flap and flapless procedures in the canine mandible.

OBJECTIVE: Although it has been shown that the exclusion of the mucoperiosteal flap can prevent postoperative bone resorption associated with flap elevation, there have been only a few studies on the peri-implant mucosa following flapless implant surgery. The purpose of this study was to compare the morphogenesis of the peri-implant mucosa between flap and flapless implant surgeries by using a canine mandible model. STUDY DESIGN: In six mongrel dogs, bilateral edentulated flat alveolar ridges were created in the mandible. After 3 months of healing, 2 implants were placed in each side by either the flap or the flapless procedure. Three months after implant insertion, the peri-implant mucosa was evaluated by using clinical, radiologic, and histometric parameters, which included the gingival index, bleeding on probing, probing pocket depth, marginal bone loss, and the vertical dimension of the peri-implant tissues. RESULTS: The height of the mucosa, length of the junctional epithelium, gingival index, bleeding on probing, probing depth, and marginal bone loss were all significantly greater in the dogs that had the flap procedure than in those that had the flapless procedure (P < .05). CONCLUSION: These results indicate that gingival inflammation, the height of junctional epithelium, and bone loss around nonsubmerged implants can be reduced when implants are placed without flap elevation.

Blood vessels of the peri-implant mucosa: a comparison between flap and flapless procedures.

OBJECTIVE: The vascularity of a peri-implant tissue is a very important parameter in the establishment and maintenance of healthy tissue after dental implant insertion. The purpose of this study was to compare the vascularity of the peri-implant mucosa between flap and flapless implant surgeries by using a canine mandible model. STUDY DESIGN: In six mongrel dogs, bilateral, edentulated, and flat alveolar ridges were created in the mandible. After 3 months of healing, 2 implants were placed in each side by either flap or flapless procedure. After another healing period of 3 months, biopsies were obtained, prepared for light microscopy, and exposed to morphometric measurements. RESULTS: The supracrestal connective tissue lateral to the implant was found to be more richly vascularized in the flapless group than in the flap group. CONCLUSION: These results suggest that the flapless procedure may increase the vascularity of the peri-implant mucosa.

Effects of sinus membrane elevation on bone formation around implants placed in the maxillary sinus cavity: an experimental study.

OBJECTIVE: The aim of this study was to investigate the amount of augmented bone tissue formed in the maxillary sinus after sinus membrane elevation and the simultaneous insertion of titanium implants without additional grafting material. STUDY DESIGN: An implant was placed bilaterally in the maxillary sinus of 6 adult female mongrel dogs in such a way that it protruded 4 mm or 8 mm into the maxillary sinus after sinus membrane elevation. The implants were left in place for 6 months. RESULTS: The mean height of newly formed bone in the sinus was 3.3 mm on the side with the 4 mm protruding implant and 3.2 mm on the side with the 8 mm protruding implant. There was no difference between the 2 sides regarding new bone height in the sinus (P > .05). CONCLUSIONS: The results indicate that the length of implant protrusion into the sinus cavity after sinus membrane elevation is not related to the height of new bone in the sinus.