Screw-Type Collar vs. Non-Screw-Type Collar Implants-Comparison of Initial Stability, Soft Tissue Adaptation, and Early Marginal Bone Loss-A Preclinical Study in the Dog.

BACKGROUND: Implant neck characteristics may affect initial implant stability, soft tissue healing, and early marginal bone loss (EMBL) at second-stage surgery. The null hypothesis was that, following two-stage implant insertion, rough surface, non-screw-type collar implants will present lower EMBL at 2nd-stage surgery than rough-surface, screw-type collar implants. METHODS: The study comprised seven male beagle dogs (mean weight 10.57 ± 2.8 kg; range 9-17 kg). A novel implant design was developed, composed of 2 parts: an apical part resembling a regular threaded implant, and a coronal non-screw-type collar, 4.2 mm long, served as the study group, whereas standard threaded implants served as control. Twenty-eight implants were placed: two on each side of the mandible. All implants were sand-blasted/acid-etched and of similar dimensions. Each dog received four implants. To assess location (anterior vs. posterior) impact on the outcomes, implants were placed as follows: group I-posterior mandible right-non-screw-type collar implants; group II-anterior mandible right-similar non-screw-type collar implants. To assess the collar-design effect on the outcomes, implants were placed as follows-Group III-anterior mandible left-control group, screw-type collar implants; Group IV-study group, posterior mandible left-non-screw-type collar implants. The following parameters were measured and recorded: insertion torque, soft tissue healing, early implant failure, and EMBL at 2nd-stage surgery. RESULTS: No statistically significant differences were noted between groups I and II regarding all outcome parameters. At the same time, although insertion torque (55 N/cm) and early implant failure (0) were similar between groups III and IV, group III presented significantly poorer soft tissue healing (1.43 vs. 0.14) and increased marginal bone loss (0.86 vs. 0 mm). CONCLUSIONS: When a two-stage implant protocol was used, rough-surface non-screw-type collar implants led to superior outcomes at 2nd-stage surgery. Implant location did not affect the results. The significance of this result in preventing EMBL awaits further research.

Positive relationship between the dimensions of clinical gingival recessions and associated alveolar bone dehiscences: a biometric study.

OBJECTIVES: To analyze the relationships between the dimension of clinical gingival recession and of the actual bone dehiscence. METHOD AND MATERIALS: Data included measurements taken before and during root coverage surgical procedures. General health, smoking status, previous orthodontic treatment, probing depth, clinical measurements taken on gingival recessions, and the exposed alveolar bone dehiscences were recorded. Data were analyzed using descriptive statistics and linear regression model. RESULTS: Twenty-three patient files were available. The mean age was 31.3 ± 12.1 years (range 13 to 51 years). Eight patients had previous orthodontic treatment. Incisor, canine, and premolar recessions amounted to 9, 8, and 6 teeth, respectively. The deepest recession per patient was recorded. The mean alveolar bone dehiscence depth was 6.78 ± 1.2 mm (range 5 to 9 mm). Patient-related or systemic findings, preceding orthodontic treatment, and tooth type were not correlated with alveolar bone dehiscence dimensions. A significant association was found between clinical recession and the alveolar bone dehiscence depths (P < .001, Fisher exact test). On average, each 1 mm increase in clinical recession depth involved an increase of 1.45 mm in alveolar bone dehiscence depth (P < .001, linear regression). The ratio between the clinical recession depth and width was significantly associated with the depth of the bone dehiscence (P = .007, Fisher exact test). CONCLUSION: Within the limitations of the size of this study, clinical recession depth and width dimensions may help to predict the underling bone dehiscence magnitude. Gingival recession is associated with deformities of the underlying alveolar bone; this may be revealed during mucogingival procedures associated with full-thickness flaps. The association between the two may be of particular value to the operator as it may significantly affect the outcome of treatment. Furthermore, this relationship is of utmost importance in minimally invasive procedures that avoid flap elevation. A significant association was found between the depth of the clinical gingival recession and that of alveolar bone dehiscence. In addition, the ratio between the clinical recession depth and width was significantly associated with the depth of the bone dehiscence. Clinical recession depth and width dimensions may serve as an assessment predictor for the underling bone dehiscence magnitude.

Peri-implant disease affects systemic complete blood count values-an experimental in vivo study.

OBJECTIVES: To assess complete blood count (CBC) dynamics following ligature removal and open flap debridement in experimental peri-implantitis in dogs. MATERIALS AND METHODS: Seven male beagle dogs were included in the study. Four rough-surface implants were placed pair-wise in both sides of the mandible 14 weeks after tooth extraction. Second stage surgery was performed after 14 weeks. Experimental peri-implantitis was initiated 3 weeks later by ligature placement around the healing caps thus facilitating plaque accumulation and inducing inflammation and destruction of peri-implant tissues. Ligature removal and open flap debridement were performed 11 weeks later. The CBC values were compared with baseline after each procedure. Wilcoxon paired tests were conducted in order to identify statistically significant differences between baseline data and values obtained after each procedure. RESULTS: Following experimental peri-implantitis, statistically significant (p < 0.05) increases were noted for white blood cells-WBC (9.62 ± 4.34 vs. 6.48 ± 1.34 cells per microliter of blood × 1000), hemoglobin-Hb (15.25 ± 0.94 vs. 13.52 ± 1.46, grams per deciliter), red blood cells-RBC (7.26 ± 0.79 vs. 5.9 ± 0.61 cells per microliter of blood × 1000), mean corpuscular hemoglobin-MCH (23.64 ± 0.96 vs. 23.16 ± 0.83 picograms/cell), platelets-PLT (349.86 ± 51.05 vs. 277.57 ± 66 cells per microliter of blood × 1000), and mean corpuscular hemoglobin concentration-MCHC (35.83 ± 0.27 vs. 31.04 ± 0.48 grams per deciliter). A statistically significant (p < 0.05) decrease in values was noted only for after ligature removal and open flap debridement. Mean corpuscular volume-MCV values were significantly lower (65.99 ± 2.31 vs. 74.65 ± 2.85 femtoliter) following 1st ligature. Values returned to baseline after open flap debridement. CONCLUSIONS: Within its limits, the present data suggest that experimentally induced peri-implantitis affects CBC values. Following surgical treatment, CBC values returned to normal. Clinical relevance This is the first study suggesting possible relationships between peri-implantitis and CBC values. Future studies, confirming such correlation, may provide an insight into the importance of peri-implant maintenance and treatment to minimize supporting tissues disease and reduce systemic effects.

Allograft and Collagen Membrane Augmentation Procedures Preserve the Bone Level around Implants after Immediate Placement and Restoration.

Background: Immediate implant placement and restoration (IPR), is a reliable treatment modality. Purpose: This historical prospective study evaluated the medium-term outcomes of hard tissue after IPR in the anterior maxilla with simultaneous hard tissue augmentation. Methods: Seventy-three patients treated with single-implant IPR in the anterior maxilla were followed for 1-8 years. Treatment involved, atraumatic extraction, immediate implant placement and abutment adaptation, followed by simultaneous augmentation with mineralized freeze-dried bone allograft (FDBA) particles to fill the gaps and restore the ridge. The surgical site was stabilized with a resorbable collagen membrane, followed by the connection of an acrylic provisional restoration. Results: All implants osseointegrated during the follow-up period (mean, 34 ± 22 months). Radiographic evaluation of the distance between the implant shoulder (IS) and crestal bone level (CBL) was of 0.86 ± 0.86 mm and 0.8 ± 0.84 mm mesially and distally, respectively. Splitting the results into up to 3 years and 3-8 years of follow-up data, the corresponding values were 0.90 ± 0.83 and 0.68 ± 0.88 for the mesial aspect and 0.99 ± 0.87and 0.74 ± 0.83 for the distal aspect, respectively. Mean peri-implant probing depth was 3.63 mm (SD ± 1.06) and 16 implants (22%) presented at least one bleeding pocket of ≥5 mm (peri implant mucositis). Conclusions: The immediate replacement of a single maxillary tooth by implants combined with guided bone regeneration is a predictable treatment modality with favorable peri-implant bony response.

Clinicopathologic evaluation of malignancy adjacent to dental implants.

OBJECTIVE: The aim of this study was to describe a new case series of peri-implant malignancy, review the literature, and discuss the implications of malignancies resembling peri-implantitis. STUDY DESIGN: This study was a retrospective analysis of cases from 2000 to 2016. RESULTS: Seven patients (two males and five females), aged 44 to 89 years, were included, representing 1.5% of oral malignancy cases. Five cases were squamous carcinoma, one of basal cell carcinoma, and one of carcinoma of metastatic origin. Six cases presented with nonulcerated overgrowth, with bone loss in three and massive osteolysis in one. Misinterpretation as peri-implantitis delayed diagnosis in six cases. Risk factors included previous oral malignancy (2), potentially malignant conditions (2), and smoking (1). Of the 47 cases in the English language literature, 85% were squamous cell carcinoma and 8.5% had distant metastasis. Most cases had one or more risk factors. CONCLUSIONS: Peri-implant malignancy may represent up to 1.5% of oral malignancy cases. Clinical features imitating peri-implantitis may delay diagnosis. Lesions failing to respond to treatment, especially in patients with pre-existing risk factors, should significantly increase suspicion. Histopathology is crucial for diagnosis.

Esthetic Assessment of Implants Placed into Fresh Extraction Sockets for Single-Tooth Replacements Using a Flapless Approach.

BACKGROUND: To validate the concept of immediate implant placement and nonfunctional loading for use in the esthetically sensitive anterior maxilla, clinical trials should ideally include objective esthetic criteria. PURPOSE: This study analyzed procedural results as graded by the pink esthetic score and white esthetic score (PES/WES). METHODS: Thirty-nine suitable patients (mean follow-up 44.82 ± 28 months) were evaluated. RESULTS: Thirty-eight implants fulfilled stringent criteria for successful osseointegration: absence of peri-implant radiolucency, implant mobility, suppuration, and pain. The mean total PES/WES was 15.50 ± 2.67 (range: 10-20). The mean total PES of 7.92 ± 1.60 (range: 5-10) indicated favorable overall peri-implant soft-tissue conditions. Root convexity and texture (1.63 ± 0.54) and curvature of the facial mucosa (1.68 ± 0.47) and distal papilla (1.66 ± 0.48) had the highest mean values, whereas acceptable levels of facial tissue (1.53 ± 0.73) and mesial papilla (1.42 ± 0.64) were the most difficult to fully achieve. The mean mesial and distal bone loss at data collection was, was 1.19 ± 0.54 and 1.15 ± 0.51, respectively. Periodontal disease severity (advanced chronic and aggressive periodontitis) was significantly associated with a low total PES (p = .048). CONCLUSIONS: Objective PES/WES assessment validated immediate anterior maxillary single-tooth replacement and restoration as being a successful and esthetically predictable treatment modality in sites where the buccal bone had been preserved during the extraction at 1 year of follow-up.

Differences in crestal bone-to-implant contact following an under-drilling compared to an over-drilling protocol. A study in the rabbit tibia.

OBJECTIVES: The objective of this study is to compare bone-to-implant contact (BIC) between implants inserted at high torque due to under-drilling of the crestal bone to those inserted at low torque due to over-drilling of the crestal bone. MATERIALS AND METHODS: Forty implants with diameters of 3.75 mm (group A) or 3.55 mm (group B) were inserted in the proximal tibiae of NZW rabbits in two separate surgeries on day 0 or 21. Osteotomy of the crestal bone was finalized with a 3.65-mm drill. In group A, implants were inserted at torque ≥35 Ncm (under-drilling) and in group B with torque <10 Ncm (over-drilling). Implants and their surrounding bone were retrieved on day 42, thus creating 3- and 6-week observation periods, processed for non-decalcified histology and stained with toluidine blue. Crestal BIC (c-BIC) and total BIC (t-BIC) were measured. Wilcoxon test was used to evaluate differences between groups. RESULTS: Three weeks post-surgery, the mean c-BIC in group A was 16.3 ± 3.3 vs 31.5 ± 3.4 % in group B (P < 0.05). At 6 weeks, a similar trend was observed (group A: 28.7 ± 3.6 %; group B: 38.4 ± 4.9 %) (P > 0.05). No differences in t-BIC were noted at 3 weeks and at 6 weeks between the groups. CONCLUSIONS: Insertion of implants with an over-drilling protocol of the crestal aspect of the osteotomy resulted in increased short-term crestal bone-to-implant contact. CLINICAL RELEVANCE: Insertion of implants with a high torque following an under-drilling protocol, commonly used for immediate loading, may reduce crestal bone-to-implant contact at early healing stages.

Accelerated degradation of collagen membranes in diabetic rats is associated with increased infiltration of macrophages and blood vessels.

OBJECTIVES: Increased collagenolytic activity in diabetes may compromise collagen membrane (CM) survival. Tetracycline (TTC) possesses anti-collagenolytic properties and delays CM degradation. This study evaluated macrophage and capillary infiltration within CMs in diabetic rats. MATERIALS AND METHODS: Diabetes was induced in 20 Wistar rats by streptozotocin and 20 served as controls. Biotin-labeled CM discs were immersed in either TTC (50 mg/ml) or PBS. In each animal, 2 discs (TTC and control) were implanted under the parietal periosteum and rats were sacrificed at 2 or 4 weeks post-implantation. The area and thickness of the residual disc collagen were measured following staining with streptavidin, and the number of macrophages and blood vessels within the membranes was determined using specific antibodies (to CD68 and transglutaminase II, respectively). RESULTS: Diabetes significantly reduced the area and thickness of the CMs, while TTC increased CM thickness significantly in both groups of rats at 2 and 4 weeks. Diabetes increased the number of macrophages (∼eightfold at 2 weeks and ∼fourfold at 4 weeks), but TTC had no significant effect. Finally, diabetes increased the number of blood vessels within the discs (∼threefold at 2 weeks and ∼twofold at 4 weeks), while TTC had no effect. CONCLUSIONS: Diabetes increases degradation of native CMs and the number of blood vessels and macrophages within them. TTC immersion delays CM degradation without an apparent effect on macrophage and blood vessel penetration. CLINICAL RELEVANCE: Enhanced CM degradation in diabetic conditions which impair guided regenerative procedure outcome is apparently related to increased blood vessel formation and macrophage infiltration.

Histomorphometric analysis of maxillary sinus augmentation using an alloplast bone substitute.

PURPOSE: To evaluate the regenerative potential of a fully synthesized homogenous hydroxyapatite:ß-tricalcium phosphate 60:40 alloplast material in sinus lift procedures. MATERIALS AND METHODS: Hydroxyapatite:ß-tricalcium phosphate was used for sinus floor augmentation. After 9 months, 12 biopsies were taken from 12 patients. Routine histologic processing was performed and specimens were analyzed using a light microscope and a digital camera. RESULTS: Histologic evaluation showed 26.4% newly formed bone, 27.3% residual graft material, and 46.3% bone marrow. The osteoconductive index was 33.5%. CONCLUSIONS: Hydroxyapatite:ß-tricalcium phosphate 60:40 alloplast material was found to be biocompatible and osteoconductive in maxillary sinus augmentation procedures.

Histomorphometric analysis of newly formed bone after bilateral maxillary sinus augmentation using two different osteoconductive materials and internal collagen membrane.

Deproteinized bovine bone mineral (DBBM) and human freeze-dried bone allograft (FDBA) were compared in five patients undergoing bilateral maxillary sinus floor augmentation using DBBM on one side and FDBA on the contralateral side. After 9 months, core biopsy specimens were harvested. Mean newly formed bone values were 31.8% and 27.2% at FDBA and DBBM sites, respectively (P = .451); mean residual graft particle values were 21.5% and 24.2%, respectively (P = .619); and mean connective tissue values were 46.7% and 48.6%, respectively (P = .566). Within the limits of the present study, it is suggested that both graft materials are equally suitable for sinus augmentation.

Maxillary sinus augmentation by the crestal core elevation technique.

BACKGROUND: The crestal core elevation (CCE) technique is reportedly a less invasive procedure than the lateral window elevation technique. We retrospectively evaluated long-term outcomes of CCE procedures over an 11-year time period. METHODS: Core preparations were made after extractions of 57 upper molars in 45 patients. Extraction sites were drilled with a calibrated trephine bur to an estimated distance of 1 mm from the sinus membrane. The trephined interradicular bone and underlying sinus membrane were imploded into the sinus. The surgical crater and residual extraction socket were filled with deproteinized bovine bone mineral or freeze-dried bone allograft, stabilized, and protected with an absorbable collagen membrane and fully covered with coronally positioned flaps. Implants were placed 4 months later. Success was defined if ≥9 mm available bone height was available. Where the available bone height varied between 7 and 9 mm, implant placement was complemented using the bone-added osteotome sinus floor elevation technique; those sites were defined as a "partial success." RESULTS: The CCE technique was successful in 31 (68.9%) out of 45 sites, and partially successful in six (13.3%) out of 45 sites. Eight sites failed (17.8%). Surgical failures were caused by core detachment resulting in large tears of the sinus membrane. Implants placed in successful sites presented a 100% survival rate during the study duration. CONCLUSIONS: CCE implemented simultaneously with molar extractions provided therapeutic benefits and clinical limitations. The subsequent implant placement using CCE revealed an excellent survival rate in the study population evaluated.

Esthetic treatment of peripheral giant cell granuloma using a subepithelial connective tissue graft and a split-thickness pouch technique.

BACKGROUND: Peripheral giant cell granuloma (PGCG) is a reactive hyperplastic lesion involving the gingiva or alveolar mucosa consisting of proliferating endothelial cells, a rich capillary bed, chronic inflammatory cells, fibroblasts, and giant cells. After complete clinical removal of PGCG recurrence occurs in about 10% of cases, and may result in an esthetic and functional soft tissue defect. This report describes a surgical procedure involving complete removal of a gingival PGCG in the maxillary esthetic zone and immediate tissue restoration achieving complete gingival augmentation. METHODS: A 15-year-old female presented with a red, nodular, asymptomatic lesion, approximately 3.5 mm in diameter, located above the maxillary left lateral incisor. The lesion was excised down to the underlying root resulting in a 6 x 5-mm mucogingival dehiscence defect. Corrective surgery included a subepithelial connective tissue graft peripherally covered by the surrounding gingiva and stabilized by 5/0 resorbable sutures. RESULTS: Healing was uneventful, resulting in healthy and esthetic gingiva. Microscopic examination of the biopsy specimen was consistent with the diagnosis of PGCG. CONCLUSIONS: PGCG may follow an aggressive course, sometimes requiring preemptive surgical intervention. Grafting a subepithelial connective tissue graft peripherally covered by the surrounding gingiva, without raising a gingival flap, successfully eliminated the gingival defect. The free gingival margin of the neighboring teeth and the mucogingival junction remained unchanged.

Spontaneous pigmentation of non-pigmented palatal tissue after periodontal surgery.

BACKGROUND: A 22-year-old African American female was referred for augmentation of keratinized gingiva around implants at the right and left maxillary second premolar sites. Presurgical evaluation revealed generalized melanosis of the buccal gingiva and a lack of keratinized tissue around implants at sites #4 and #13. No pigmentation was noted on the palatal tissues. METHODS: Thick free gingival grafts were harvested bilaterally from the non-pigmented palate and secured to the recipient sites with bioabsorbable sutures. Hemostasis was achieved at the palatal donor sites with moistened gauze, and an acrylic stent was delivered for patient comfort. RESULTS: Both palatal donor sites healed with spontaneous pigmentation. The pigmentation intensified with time but resulted in no adverse outcome. CONCLUSIONS: Post-surgical healing in patients with gingival pigmentation is not entirely predictable, as multiple studies have demonstrated widely inconsistent results in regards to gingival pigmentation upon healing. When performing periodontal plastic surgery in patients with pigmented oral tissues, it is important to discuss all possible outcomes, including spontaneous pigmentation.

Evaluation of bone surface registration applying a micro-needle array.

AIM: In this study we present and evaluated a new registration technology for the jaw-bone surface. It is based on a micromechatronic device for the generation of a "mechanical image" of the bone surface by means of an array of micro-needles that are penetrating the soft tissue until they touch the surface of the bone. This "mechanical impression image" is aligned with the CT data set. MATERIAL AND METHODS: Based on laboratory measurements on 10 specially prepared jawbone models we evaluate the accuracy of this new registration method. RESULTS: Our measurements of the 10 specimens revealed a maximum overall location error of 0.97 mm (range: 0.35-0.97 mm). CONCLUSIONS: From the technical point of view the presented registration technology has the potential to improve the performance (i.e. accuracy and avoidance of errors) of the registration process for bony structures in selected applications of image-guided surgery.

Implant locating and placement based on a novel tactile imaging and registration concept: a technical note.

Computed-assisted surgery (CAS) has been designed to improve oral implant planning and positioning and to increase safety and operator comfort. This is especially important in the esthetic zone, at sites with bone deficiency, and when minimally invasive implant placement is the therapy of choice. Current available CAS systems are relatively large and expensive and require a lengthy learning period. This report presents a novel tactile imaging and registration concept that enables the operation of a newly developed computerized implant locating system. An intraoral bone-sounding device maps the surface of the jaw through the soft tissue. Bone contour data are registered over the computerized tomographic image. Guided by treatment preplanning software, a chairside robotic manipulator fabricates guiding sleeves that direct the drill and implant during the osteotomy and implant placement, respectively. The authors' clinical experience shows that tactile registration based the Implant Locating System is simple to use and provides accurate implant design and placement that requires only basic computer experience, minimal operational space, and low infrastructure investment. The system allows final adjustments at the time of operation, transforming each implant surgery into a fully monitored procedure.

Gingival depigmentation by erbium:YAG laser: clinical observations and patient responses.

BACKGROUND: Melanin, carotene and hemoglobin are the most common natural pigments contributing to the normal color of the gums. Although physiologic and ethnic melanin pigmentation is not a medical problem, complaints about "black gums" are common. Gingival depigmentation has been carried out using non-surgical and surgical procedures. Recently, laser ablation has been recognized as a most effective, pleasant and reliable technique. METHODS: The study included 10 patients who requested cosmetic therapy for melanin pigmented gums. Treatment was carried out using an erbium:YAG laser. The laser beam was set at 500 mJ/10 pulses/second. The beam was defocused to produce a 3 mm diameter circle, thus reducing the beam penetration to 2 to 4 microm/pulse while increasing the treated surface. The "brush" technique was applied until the gingival surface appeared clinically free of pigmentation. Patients were observed for 6 months. Each patient filled out a personal evaluation questionnaire for clinical analysis. RESULTS: Between 500 to 1,100 pulses/cm2 were recorded and a total of 800 to 2,200 pulses were required per patient, depending on the epithelium thickness and pigmentation. Treatment required only topical anesthesia. Healing was uneventful and required no supportive therapy. None of the patients experienced severe pain during or post-operatively. Mild pain or itching was common during the first week. Treatment was reported as generally pleasant. Follow-up during the 6 months showed no recurrences. CONCLUSIONS: Depigmentation of gingival melanin pigmentation by erbium:YAG laser radiation in a defocused mode was a safe and effective procedure. The esthetic results were pleasing and healing was uneventful. Since the erbium:YAG laser is available in the dental office, it seems to be the laser of choice for this procedure.