Flexible (Polyactive®) versus rigid (hydroxyapatite) dental implants

In a beagle dog study, the peri-implant bone changes around flexible (Polyactive®) and rigid hydroxyapatite (HA) implants were investigated radiographically by quantitative digital subtraction analysis and by assessment of marginal bone height, with the aid of a computerized method. A loss of approximately 1 mm of marginal bone height was observed for both the dense Polyactive and the HA implants, after 6 months of loading. This value appeared to be stable from 12 weeks of loading onward. Along the total length of the implant during the first 6 weeks of loading, both the flexible (dense Polyactive) and the rigid (HA) implants showed a decrease in density. However, after this 6-week period, the bone density around the implants increased, and after 18 weeks the original bone density was reached. The flexible Polyactive implants provoked less decrease in density than the rigid HA implants, although not to a statistically significant level. This finding sustains the hypothesis that flexible implant materials may transfer stresses to the surrounding bone more favorably

Bone loss in implants placed at subcrestal and crestal level: A systematic review and meta-analysis

Background: To assess differences in marginal bone loss in implants placed at subcrestal versus crestal level. Methods: An electronic and a manual research of articles written in English from Jaunary 2010 to January 2018 was performed by two independent reviewers. Clinical trials comparing bone loss for implants placed at crestal and subcrestal level were included. Pooled estimates from comparable studies were analyzed using a continuous random-effects model meta-analysis with the objective of assessing differences in crestal bone loss between the two vertical positions. Results: 16 studies were included; 10 studies did not encounter statistically significant differences between the two groups with respect to bone loss. Three articles found greater bone loss in subcrestal implants; while 3 found more bone loss in crestal implants. A meta-analysis for randomized control trial (RCT) studies reported an average and non-statistically different crestal bone loss of 0.028 mm. Conclusions: A high survival rate and a comparable bone loss was obtained both for crestal and subcrestal implants’ placement. Quantitative analysis considering a homogenous sample confirms that both vertical positions are equally valid in terms of perimplant bone loss. However, with respect to soft tissue; in presence of a thin tissue; a subcrestal placement of the implant should be preferred as it may reduce the probability for the implant to become exposed in the future and thus avoid the risk of suffering from peri-implant pathologies

Comparison of digital protocols for the measurement of peri-implant marginal bone loss

The measurement of peri-implant marginal bone loss is currently carried out using digital methods of radiographic analysis assisted by various types of software. The purpose of this study was to compare the characteristics of three different softwares: specific radiology software for the development and visualization of radiological images in DICOM format (3Dicom Viewer®), advanced level software for professional editing of bitmap images (or raster graphics) (Adobe Photoshop®), and mid-level software for processing bitmap-type images, programmed in Java and in the public domain (ImageJ®). It was verified that the three softwares used are valid for the measurement of peri-implant marginal bone loss provided that the appropriate protocol is fulfilled. The results showed no significant differences between Adobe Photoshop® and ImageJ® with respect to 3Dicom Viewer® in the measurements of mesial and distal bone loss of the implants, without influence of the dental sector where they were located. The measurements made with ImageJ® looked more like those of the control software (3Dicom Viewer®) than those of Adobe Photoshop®, but with a greater degree of dispersion. Thus, Adobe Photoshop® is a slightly inaccurate method but with less dispersion

Early marginal bone loss around three different implant systems: prospective cohort study

AIM: To evaluate early bone loss around three different implant systems (Straumann Bone Level. Noble Biocare Replace, 3i Biomet Certain) and compare them to each other in a prospective clinical study using clinical and radiographic measurements. MATERIALS AND METHODS: Twenty-three patients were recruited for the study. Three implant systems were included in study design; one system was abandoned due to lack of subjects. Two implant systems (Nobel Biocare Replace n= 12, Straumann Bone Level n= 11) were evaluated. Periodontic residents placed the implants. Radiographic and clinical measurements were obtained at two different time points, at the time of implant placement and at the time of second stage surgery. RESULTS: Mean clinical bone loss was 0.14 ± 0.20 mm, and 0.72 ± 1.02 mm for Straumann and Nobel Biocare respectively. The mean change in the radiographic bone loss for Straumann and Nobel Biocare was 0.23 ± 0.26 mm and 0.53 ± 1.06 mm. There was no statistically significant difference between the two groups. CONCLUSION: Nobel Biocare Replace tapered implants showed a two and five times higher average bone loss in radiographic and clinical parameters respectively, compared to Straumann implants. However, this difference did not reach statistical significance in either the clinical or the radiographic measurement. It is suggested that study size should be increased

Radiological assessment of peri-implant bone loss: a 12-month retrospective study

Introduction: Following dental implant loading, marginal bone loss after one year must be evaluated to check correct maintenance of the bone levels. Objectives: To assess implant treatment success and quantify marginal bone loss 6 and 12 months after loading. Material and method: Sixty-one MIS® implants with a 1.8 mm machined neck were placed in 26 patients. Implant success was based on the criteria of Buser. Radiological controls were made 6 and 12 months after loading, measuring bone loss mesial and distal. Results: Twenty-two patients with 56 implants were included: 32 in the maxilla and 24 in the mandible. Two implants failed in two patients during the osseointegration phase (both in the maxilla), yielding an implant success rate of 96.4%. After 6 months, bone loss was 0.80±1.04 mm mesial and 0.73±1.08 mm distal, while after 12 months bone loss was 0.92±1.02 mesial and 0.87±1.01 distal. Conclusions: Bone loss 6 and 12 months after machined neck implant placement was within the normal ranges described in the literature

The Effect of Biologic Materials and Oral Steroids on Radiographic and Clinical Outcomes of Horizontal Alveolar Ridge Augmentation.

The purpose of this study was to investigate if the addition of biologic materials and/or oral steroids would affect horizontal bone gain, or the bone density of the grafted bone in horizontal alveolar ridge augmentations. A retrospective chart review was completed to assess the clinical and radiographic outcomes of 53 ridge augmentation patients. An average bone gain of 3.6mm of width was found in our study based on radiographic analysis. There were no statistically significant differences found in the linear bone gain with the addition of biologic materials and steroids. A marginally statistically significant difference was found in the bone density when biologics were added (p-value=0.0653). No statistically significant difference found in the bone density with the addition of oral steroids. The use of tenting screws and resorbable occlusive membranes and a combination of allograft and xenograft bone materials provides significant clinical and radiographic dimensional changes in alveolar ridge width

Factors Associated With Radiographic Vertical Bone Loss Around Implants Placed in a Clinical Study

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142291/1/aape0137.pd

Single implants in the anterior maxilla in young adults

Background: Single anterior implants are frequently used in the treatment of patients with single anterior tooth loss. Compared with other types of implant treatments, single implants are commonly performed in younger patients where the cause of tooth loss often is non-inflammatory. However, there is a scarcity of long-term follow-up studies, especially in the cohort representing the younger segment of the adult population. Lack of periodontal mechanoreceptors (PMRs) around implants and reduced function of PMRs around teeth connected in full-arch bridges have been shown to affect the oral fine motor control. However, there is no study on the comparison of oral fine motor control between single anterior implants and the alternative treatment, a 3-unit bridge. Aims: The objective of this thesis was to investigate the performance of single anterior maxillary single implants in young adults. The specific aims of Studies I and II was primarily to report long-term survival, success, complications, radiological findings and movement of adjacent teeth after 14–20 years follow-up. The secondary aims were to explore correlations between changes in marginal bone levels in relation to probing depth (PD), occlusal contact, and nicotine use, and to investigate the associations between the movement of adjacent teeth, patient and implant characteristics, and the aesthetic assessment of the implant crown. Study III aimed to compare oral fine motor control of patients with single anterior tooth loss treated with 3-unit resin-bonded bridges (RBBs) or single implants. Materials and methods: In Studies I and II, 40 out of 42 patients who received single anterior implants were re-examined after a period of 14–20 years. Data were collected to assess the long-term survival, success, biological findings and complications of the implants. After 14-20 years, radiological findings were compared with baseline data. A 3- D analysis and calculations were used to investigate the movements of teeth adjacent to the single implants and their associations with patient and implant characteristics. Additionally, an assessment of perceived aesthetics was performed. In Study III, a behavioral hold-and-split test was conducted on 16 patients with missing maxillary central incisors. The test was performed twice, once with a 3-unit resin-bonded bridge (RBB) and once with a single implant. The conditions connected tooth (CT), pontic (P), freestanding tooth (T) and single implant (SI) were tested for differences regarding the variables hold force, variability of hold force, split force and duration of split. Results: In Study I, the cumulative survival rate for implants (CSRi) was 96.1% whereas that for crowns was of 80.4% (CSRc). All the remaining implants were considered successful. The mean marginal bone loss was 0.1 ± 1.1 (range, -5.1–1.6) mm and the mean PD was 4.0 ± 1.8 (range, 0–9) mm after 14–20 years follow-up. There was no significant correlation found between marginal bone levels and PD, implant occlusion, or nicotine use (p >0.05). Technical and/or biological complications were found in 50% of the patients, but only 22% required substantial further treatment. In Study II, the 3-D movements of teeth adjacent to the single implant showed a mean movement of 1.0 ± 0.5 mm in the incisal direction (vertical; Y-axis), 0.5 ± 0.8 mm in the bucco-lingual direction (sagittal; Z-axis) and −0.0 ± 0.1 mm in the mesio-distal direction (horizontal; X-axis). No patient showed a completely stable vertical relationship (Y-axis). Lower anterior facial height (LAFH) ≥70 mm was significant correlated with more severe vertical tooth movement (>1 mm) (p <0.05). Furthermore, implants in occlusion, implants in central incisor position and in patients when trauma was the reason for tooth loss were significantly correlated with less movement of teeth adjacent the single implants (p <0.05). Despite the infraposition the patients rated the esthetic of the implant crown to a VAS score of 85% ± 19% (range, 20%– 100%). Significantly lower VAS scores (p <0.05) were correlated with increased tooth movement in patients with central incisor implants. The dentist ratings of 67% ± 23% (range, 10%–100%) were significantly lower that the patients (p <0.05). In Study III, significantly higher (p <0.05) hold force, variability of hold force and split force was found for the single implants compared to the adjacent teeth. Further, the pontic of the RBB showed higher hold forces (p <0.05) than the adjacent connected tooth in a similar manner as the implant. However, no significant differences (p >0.05) were found between the tooth connected in the RBB and the freestanding tooth. Conclusion: Within the limitations of the studies this thesis highlights that single anterior maxillary implants in young adults show good long-term performance with high success and survival rates and only small changes in marginal bone levels. Complications occur over time; however, they do not seem to be of great concern to the patients. Positional changes of adjacent teeth in relation to the single implants occur over time in all patients but to different degrees. However, the changes seem to be more extensive in patients with LAFH ≥70mm, patients without implant occlusion, patients with implants in the lateral and canine positions, and patients with tooth loss caused by reasons other than trauma. Only few patients (10%) found the differences in tooth position esthetically disturbing while the dentist was more critical. Furthermore, single implants show impaired oral fine motor control in relation to freestanding adjacent teeth which was also observed for pontics in relation to connected teeth. However, teeth connected in 3-unit anterior bridges appear to maintain sensitivity in oral fine motor control. Clinical implications: This thesis suggests that patients planned for single anterior maxillary implants should be provided with information that the implant is expected to perform well overtime. However, the implant crown will most likely end up in infraposition in relation to the adjacent tooth. In most patients this will not cause an esthetic problem but in young adults with a long remaining lifetime, the need to change or repair the implant crown may occur once or a few times. To minimize the risk of infraposition, it is advisable to delay anterior maxillary single implant treatment for as long as possible. Patients with a lower anterior facial height of more than 70 mm or implants in lateral or canine position might be in higher risk of more severe infrapositio

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

Research on oral/dental intra-osseous implantology focuses primarily on discovering techniques that promote mechanical and/or biological osseointegration over the short-term. The present clinical research documents the effects of implant collar length, external versus internal connection collar design, and fixture surface microtexturing on bone and soft-tissue peri-implant healing after 25 years of function with complete mandibular dental prostheses.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