Hydroxyapatite-coated Dental Implants Research Articles

Immediate and early loading of hydrothermally treated, hydroxyapatite-coated dental implants: a 7-year prospective randomized clinical study

BackgroundExisting research on marginal bone stability around hydroxyapatite (HA)-coated implants often lacks adequate long-term follow-up. The purpose of this randomized prospective study was to evaluate the 7-year outcome of patients with immediate and early loaded single-tooth restorations supported by implants with plasma-sprayed, partially HA-coated surfaces. Forty-two patients in need of 50 single implants were treated in in the Postgraduate Periodontics Clinic of Louisiana State University School of Dentistry. Implants were randomly divided into 2 groups: Group A was immediately loaded, and Group B was early loaded. Continuous follow-up with periodic maintenance care and radiographic evaluations was performed. The primary outcome of interest was implant survival, characterized using the Kaplan–Meier method. Secondary study outcome consisted of peri-implant crestal bone level changes. Data on age, sex, bone quality, implant location, length and diameter, and prior augmentation of the site were collected. Multiple regression analyses were conducted to determine whether the independent variables were associated with bone loss.ResultsOne implant failed to maintain stability and was removed at 3 weeks. Thirty-four patients (14 males, 20 females with a total of 42 implants) completed the 7-year follow-up visit. Average age of evaluable patients was 52 in Group A and 55 in Group B. No significant difference was observed regarding sex and age distribution between the 2 groups. No significant difference was detected in the distribution of implant locations, types of bone, implant length, implant diameter, and augmentation status of the bone between the 2 groups. After 7 years of functioning for the 42 implants examined, implant survival rate was 100% for Group A and 95.5% for Group B. The results from this study of 50 implants showed that HA-coated Zimmer Tapered Screw-Vent Implants were clinically effective, with an overall cumulative 7-year survival rate of 98.0%. When comparing radiographic bone levels between 2-year and 7-year follow-ups, no significant differences in bone loss were found between Group A and Group B.ConclusionsAfter 7 years in function, implants partially coated with plasma-sprayed and hydrothermally treated HA were clinically predictable when restored in occlusion immediately after or 3 weeks after implant placement.

Clinical Investigation of Hydroxyapatite-Coated Dental Implants（SUMICIKON®）

Clinical Investigation of Hydroxyapatite-Coated Dental Implants（SUMICIKON®）

Periimplant bone-level reduction in relation to hydroxyapatite-coated dental implants that act as mandibular overdenture retainers: Results at 6 to 10 years

Edentulism in combination with chronic alveolar ridge resorption can lead to a debilitating oral state which conventional complete dentures cannot alleviate. The provision of anterior mandibular implants positively contributes to both function and an improved quality of life for these patients. However, individuals who could most benefit from the treatment are usually older and more likely to have or develop serious health issues. The purpose of the study was to assess the long-term success of one of the simpler implant treatments available and to consider the impact of a number of factors, including sex, age, health issues, and tobacco habits. This study also assessed the specific implant used, the Calcitek hydroxyapatite coated cylinder. Forty-one patients who received 102 implants for mandibular overdenture retention from 1 operator between 1996 and 2002 were included in the study. Measurements were made from a series of radiographs to assess the effect of periimplant bone loss on surviving implants after a period of implant function of between 6 and 10 years. The loss of 1 implant lowered the survival rate to 99%. The overall annual bone loss observed was 0.16 mm/year. Individuals with a significant comorbidity exhibited a slight but significant increase in annual bone loss. The implant system in this study performed to an acceptable level in a mixed cohort of older individuals, including those with a serious comorbidity or tobacco habit.

A Feasibility of Useful Cell-Based Therapy by Bone Regeneration with Deciduous Tooth Stem Cells, Dental Pulp Stem Cells, or Bone-Marrow-Derived Mesenchymal Stem Cells for Clinical Study Using Tissue Engineering Technology

This study investigated the effect of bone regeneration with dental pulp stem cells (DPSCs), deciduous tooth stem cells (DTSCs), or bone-marrow-derived mesenchymal stem cells (BMMSCs) for clinical study on hydroxyapatite-coated osseointegrated dental implants, using tissue engineering technology. In vitro, human DPSCs and DTSCs expressed STRO-1, CD13, CD29, CD 44, CD73, and osteogenic marker genes such as alkaline phosphatase, Runx2, and osteocalcin. In vivo, prepared bone defect model was implanted using graft materials as follows: platelet-rich plasma (PRP), PRP and canine BMMSCs (cBMMSCs), PRP and canine DPSCs (cDPSCs), PRP and puppy DTSCs (pDTSCs), and control (defect only). After 8 weeks, the dental implants were installed, and 16 weeks later the sections were evaluated histologically and histometrically. The cBMMSCs/PRP, cDPSCs/PRP, and pDTSCs/PRP groups had well-formed mature bone and neovascularization. Histometrically, the bone-implant contact was significantly different between the cBMMSCs/PRP, cDPSCs/PRP, pDTSCs/PRP groups, and the control and PRP groups (p < 0.01). These results demonstrated that these stem cells with PRP have the ability to form bone, and this bone formation activity might be useful for osseointegrated hydroxyapatite-coated dental implants with good levels of bone-implant contact.

Sinus Grafting With a Natural Flourohydroxyapatite for Immediate Load: A Study With Histologic Analysis and Histomorphometry

The goal of this retrospective study was to evaluate the survival rates of dental implants placed in sinuses grafted with a 50:50 composite ratio of autogenous bone and a natural flourohydroxyapatite (FHA) combined with platelet-rich plasma (PRP) using an immediate-load protocol. The authors hypothesized that a 50:50 composite ratio of FHA and autogenous bone combined with PRP would permit immediate loading without compromising implant survival rates. Eleven patients with bilateral partial edentulism of the posterior maxilla were enrolled in this retrospective study. Autogenous bone used in the graft procedure was harvested from the tibia of the left lower extremity. Each patient was grafted with a 50:50 composite ratio of autogenous bone and FHA. Membranes were not used to cover the lateral wall osteotomy site. Platelet-rich plasma was added to the graft material to accelerate and enhance bone regeneration. Four to 6 months after the grafting procedure, 37 hydroxyapatite-coated dental implants were surgically placed and immediately loaded between 72 hours and 5 days later with custom titanium abutments and acrylic provisional restorations placed out of functional occlusion. Six months later, definitive ceramometal restorations were cemented on to the custom abutments. Patients were observed over a 52-week period. The overall implant survival rate was 97.3%. Histologic and histomorphometric analysis of core samples revealed formation of new vital bone in different graft specimens ranging from 23% to 34%. In each core bone sample, 100% of the bone sample was determined to be vital. In the grafted maxillary sinus, the natural FHA combined with autogenous bone in a 50:50 composite ratio with PRP is a suitable graft material permitting immediate load without compromising implant survival rates while decreasing the overall healing time.

Immediate Load and Esthetic Zone Considerations to Replace Maxillary Incisor Teeth Using a New Zirconia Implant Abutment in the Bone Grafted Anterior Maxilla

The goal of this prospective clinical study is to evaluate a new all-ceramic implant abutment made from zirconium oxide during the immediate load of dental implants placed in the block grafted anterior maxilla. This new zirconia abutment gives the clinician the opportunity to provide the patient with an all-ceramic restorative system (abutment and crown) for an optimum esthetic result and a high level of patient satisfaction. A total of 9 hydroxyapatite-coated dental implants were surgically placed in 9 patients and were immediately loaded 5 to 7 days later with a custom composite provisional restoration that was placed out of functional occlusion. Each prefabricated, natural colored zirconia abutment was shaped and connected to the implant with a titanium screw. Provisional restorations were cemented to the zirconia abutment with the use of temporary cement. Twelve weeks later, the provisional restoration was replaced with an all-ceramic restoration. Over a 52-week observation period, no abutment fractures occurred, and no abutment screw loosening was observed. No implants failed. All 9 patients reported total satisfaction regarding esthetic quality of the all-ceramic restorative system (abutment and implant). Preliminary results of this clinical study indicate that this new zirconia abutment offers the clinician and the patient exceptional strength, optimal esthetics, and simplicity. It is of important clinical significance that use of this all-ceramic abutment eliminates the well-known disadvantages of metal abutments.

Immediate Load Protocol for Anterior Maxilla With Cortical Bone From Mandibular Ramus

To evaluate the concept of a nonfunctional immediate load protocol with single implants placed in the anterior maxilla that has been bone grafted with autogenous, block cortical grafts harvested from the ramus of the mandible. There were 19 hydroxyapatite-coated dental implants surgically placed in 19 patients, and immediately loaded between 48 hours and 3 days later with a custom acrylic provisional restoration that was placed out of functional occlusion. After 12 weeks, the definitive ceramo metal restoration was cemented to the custom abutment. Over a 1-year observation period, all implants continue to function. The preliminary results of this clinical study indicate that immediate, nonfunctional load with single implants is a predictable protocol in the bone grafted anterior maxilla in select cases.

Long-term changes of hydroxyapatite-coated dental implants.

There are many controversies about the long-term prognosis of hydroxyapatite (HA)-coated implants. Failure may be related to compositional and structural changes of the coating occurring during implantation. Two retrieved and two unused HA-coated blade-type implants were examined by stereomicroscopy, secondary electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and electron probe microanalysis. The objective was to investigate the HA morphology, composition, and structure, and to characterize the changes that occurred in the retrieved implant coatings. Retrieved implants presented partial loss of the coating, especially at the apical and mesiodistal edges. Remaining HA was thick and flattened in the cervical and central areas and gradually thinner and rougher towards the apical and mesiodistal edges. Increase of Cl and Mg, decrease of OH, and X-ray diffraction peak broadening were found in the retrieved implant coatings, in comparison with the unused implants. Morphological changes of the retrieved implants seem to depend on stress values in the surrounding bone and on implant mobility. Compositional changes and increased amount of lattice imperfections appeared in the retrieved implant coatings, as a result of ion substitutions in the apatite lattice. However, the present study could not confirm the influence of these changes on implant failure.

Fatigue properties of hydroxyapatite-coated dental implants after exposure to a periodontal pathogen.

We studied the fatigue properties of rods (4 mm diameter) of hydroxyapatite-coated, titanium alloy implant material after it was exposed to a periodontal pathogen, Actinobacillus actinomycetemcomitans (Aa). We varied the crystallinity of the hydroxyapatite (HA) coating in these rods to the levels of, 60.5%, 52.8%, and 47.8%. Each rod was first inoculated with Aa in the log phase of its growth cycle. After 48 h, we counted the adhered cells. We measured the dissolution of HA coating due to bacterial exposure alone by determining the calcium and phosphate concentrations in the bacterial growth media. Once the adherent bacteria were removed from these rods, we subjected them to 5 million cycles of fatigue testing after immersion in Lactated Ringer's solution. We then determined the calcium and phosphate concentrations in the fatigue media. We found additional coating loss after fatiguing of the samples. This coating loss was a cumulative effect of bacterial exposure and fatigue loading of the hydroxyapatite-coated dental implant alloy. The lower crystallinity sample showed a higher loss of coating within the range of crystallinity studied here. The HA coating in implants during clinical use may undergo such changes, because they are exposed to the same bacteria.

Sinus floor augmentation with simultaneous implant placement in the severely atrophic maxilla.

Dental implant placement associated with augmentation of the sinus floor in the severely atrophic maxilla can be performed in 1- or 2-surgical stages, depending on the height of the residual alveolar bone. A minimum of 4 to 5 mm of residual alveolar bone height is recommended for a 1-stage surgical procedure. The present study describes a 1-stage procedure in cases where the residual alveolar bone height in the posterior maxilla was 1 to 2 mm. A total of 55 hydroxyapatite-coated dental implants were inserted in 20 grafted sinuses of 20 patients. No case presented any difficulty in achieving initial stabilization and parallelism. No perforation of the sinus membrane or clinical complications of the sinuses were evident. Prior to exposure, radiographic evaluation revealed bone consolidation and a close bone-implant relation. At second-stage surgery, there was no clinical evidence of crestal bone loss around the implants. All implants were clinically osseointegrated. All patients received fixed implant-supported prosthesis. The mean follow-up was 26.4 months (range 15 to 39 months). There was no implant loss after loading. The following surgical modifications are essential: a wide lateral window opening, the use of a bone mill to homogenize the bone graft, meticulous condensation, and clinical measurements to ensure implant parallelism.

Maxillary sinus augmentation using different grafting materials and dental implants in monkeys. Part IV. Evaluation of hydroxyapatite-coated implants.

The aim of this study was to evaluate clinically, histologically and histometrically the use of hydroxyapatite-coated dental implants in conjunction with maxillary sinus augmentation procedures. In 4 adult male Rhesus monkeys (Macaca mulatta) the 3 maxillary molars on 1 side of the jaws were extracted and the remaining bone between the alveolar crest and the floor of the sinus was reduced to 3-4 mm. After 3 months, maxillary sinus augmentation procedures were performed in each monkey and the sinuses were grafted with a porous hydroxyapatite bone graft (Interpore-200). At the same time, 2 hydroxyapatite-coated cylinder implants (IMZ) were immediately placed into the augmented sinuses (i.e. simultaneous-implants-loaded group). Four months later, 2 additional similar implants were placed into the previously augmented sinuses (i.e. delayed-implants-loaded group). After 4 months, the abutment connection was performed and all 4 implants were loaded with a gold-alloy bridge for 6 months (i.e. until sacrifice of the animals). The contralateral side of each monkey received the same treatment with the exception that removal of the maxillary molars was performed 7 months after those in the opposite side, and that the implants in this side were not loaded. Thus, 2 additional study groups (i.e. simultaneous-implants-unloaded group and delayed-implants-unloaded group) were obtained. Clinically, all loaded and unloaded implants were stable the day of sacrifice. Histologically, the grafted sinuses exhibited a significant amount of new bone formation with integration of the porous hydroxyapatite graft particles and hydroxyapatite-coat of the dental implants to the new bone. Histometric analysis indicated that on the loaded side the implants placed simultaneously with the sinus lift procedure exhibited greater direct mineralized bone-to-implant contact than the delayed placed implants. In addition, the percentage of direct mineralized bone-to-implant contact was significantly greater in the residual bone in comparison to the augmented area in all groups. Loading of the implants exhibited a positive effect on the percentage of direct mineralized bone-to-implant contact in the augmented area. It could be concluded that hydroxyapatite-coated implants may be of benefit when used in conjunction with sinus augmentation procedures.

Effects of guided bone regeneration around commercially pure titanium and hydroxyapatite-coated dental implants. II. Histologic analysis.

The purpose of this study was to determine which treatment of a large osseous defect adjacent to an endosseous dental implant would produce the greatest regeneration of bone and degree of osseointegration: barrier membrane therapy plus demineralized freeze-dried bone allograft (DFDBA), membrane therapy alone, or no treatment. The current study histologically assessed changes in bone within the healed peri-implant osseous defect. In a split-mouth design, 6 implants were placed in edentulous mandibular ridges of 10 mongrel dogs after preparation of 6 cylindrical mid-crestal defects, 5 mm in depth, and 9.525 mm in diameter. An implant site was then prepared in the center of each defect to a depth of 5 mm beyond the apical extent of the defect. One mandibular quadrant received three commercially pure titanium (Ti) screw implants (3.75 x 10 mm), while the contralateral side received three hydroxyapatite (HA) coated root-form implants (3.3 x 10 mm). Consequently, the coronal 5 mm of each implant was surrounded by a circumferential defect approximately 3 mm wide and 5 mm deep. The three dental implants in each quadrant received either DFDBA (canine source) and an expanded polytetrafluoroethylene membrane (ePTFE), ePTFE membrane alone, or no treatment which served as the control. Clinically, the greatest increase in ridge height and width was seen with DFDBA/ePTFE. Histologically, statistically significant differences in defect osseointegration were seen between treatment groups (P < 0.0001: DFDBA/ePTFE > ePTFE alone > control). HA-coated implants had significantly greater osseointegration within the defect than Ti implants (P < 0.0001). Average trabeculation of newly formed bone in the defect after healing was significantly greater for HA-coated implants than for titanium (P < 0.0001), while the effect on trabeculation between treatments was not significantly different (P = 0.14). Finally, there were significantly less residual allograft particles in defect areas adjacent to HA-coated implants than Ti implants (P = 0.0355). The use of HA-coated implants in large size defects with DFDBA and ePTFE membranes produced significantly more osseointegration histologically than other treatment options and more than Ti implants with the same treatment combinations. The results of this study indicate that, although the implants appeared osseointegrated clinically after 4 months of healing, histologic data suggest that selection of both the implant type and the treatment modality is important in obtaining optimum osseointegration in large size defects.

Raman microprobe investigation of the calcium phosphate phases of three commercially available plasma-flame-sprayed hydroxyapatite-coated dental implants

The purpose of the current study was to evaluate the crystallographic properties of three commercially plasma-flame-sprayed hydroxyapatite (HAp) coatings on dental implants. For this purpose a Raman microprobe (MOLE U1000) was used. No preparation of the surfaces was necessary to examine the thin ceramic surface layers. Microspectra (5 µm) and macrospectra (100 µm) have been measured and compared to the spectra of crystalline and amorphous HAp as well as to the spectra of tricalciumphosphate. All implants showed spectra that were more like that of the amorphous phase of HAp than any of the other examined reference materials. However, the implant spectra exhibited an extra band that as yet has not been identified. This band is probably indicative of some structure within the sprayed amorphous phase. Such structural effects would result either directly from quenching from the plasma state or by incorporation of titanium into the lattice during plasma treatment.

Clinical comparison of hydroxyapatite-coated titanium dental implants placed in fresh extraction sockets and healed sites

The placement of hydroxyapatite-coated dental implants in fresh extraction sockets was compared to placement in adjacent healed sites in 14 patients. Systematic sequential documentation was obtained regarding periodontal health, radiographic bone levels, and implant stability at the time of implant placement, at uncovering, and from 8 to 24 months (mean 16 months) after loading and restoration delivery. There were no significant differences in any clinical parameter between those implants placed in fresh extraction sockets and those placed in healed areas. Periodontal health, maintenance of crestal bone levels, and implant stability were excellent for implants placed in both types of recipient sites. The results of this study suggest that hydroxyapatite-coated dental implants can be successfully placed in fresh extraction sockets utilizing otherwise standard implant placement techniques, and that they appear to clinically perform equally well in fresh sockets and healed sites. J Periodontol 1991; 62:468–472.