Early Crestal Bone Loss Research Articles

High insertion torque versus regular insertion torque: early crestal bone changes on dental implants in relation to primary stability—a retrospective clinical study

The aim of the presented retrospective study was to evaluate the early crestal bone changes around an implant type designed for high primary stability. A total number of 111 implants placed clinically were evaluated regarding insertion torque, bone density, implant stability quotient (ISQ) and early crestal bone loss from standardized digital radiographs. The implants were allocated in two groups: the „regular torque “ group contained all implants that achieved less than 50 Ncm as final insertion torque (n = 63) and the „high torque“ group contained the implants that achieved 50–80 Ncm (n = 48). To avoid possible damage either to the implant´s inner connection or to the bone by application of excessive force, a limit of 80 Ncm was set for all surgeries. All implants underwent submerged healing for three months. ISQ measurements and standardized digital radiographs were taken at day of insertion and at day of second stage surgery. The bone loss was measured on the mesial and distal aspect of the implant. The data evaluation showed the following results: Mean bone loss was 0.27 ± 0.30 mm for the high torque group and 0.24 ± 0.27 mm for the regular torque group. The difference was not statistically significant (p = 0.552). In the two groups, no complications nor implant loss occurred. For the evaluated implant type, there was no significant difference in crestal bone changes and complication rate between high and regular insertion torque in the early healing period.Graphical

Evaluating Factors that Contribute to the Early Loss of Bone Around Submerged Implants Before they are Restored.

The aim of the present study was to examine various factors that may contribute to early crestal bone loss around submerged implants, prior to restoration. The research included a collective of 100 implants, procured from 60 participants. We allocated a total of 60 patients into two distinct groups: 20 individuals in the healthy group and 40 individuals in the ECBL group. Out of the complete population, 56 people were unaffected by diabetes, while six persons were smokers. Systemic antibiotics were administered to almost all patients (98%) throughout the implantation procedure. The implant implantation consisted of 69% nonmolar implants and 31% molar implants. Engaging in a guided bone regeneration (GBR) operation before implant implantation has been shown to be a statistically significant factor in preventing early crestal bone loss (ECBL).

Analysis of risk factors for early crestal bone loss in osseointegrated, submerged implants prior to restoration.

Evidence on the etiology behind bone loss around submerged, prosthetically nonloaded implants is still limited. The long-term stability and success of implants with early crestal bone loss (ECBL), especially when placed as two-stage implants, is uncertain. Hence, the aim of this retrospective study is to analyze the potential patient-level, tooth- and implant-related factors for ECBL around osseointegrated, submerged implants, before restoration as compared with healthy implants with no bone loss. Retrospective data were collected from patient electronic health records between 2015 and 2022. Control sites included healthy implants with no bone loss and test sites included implants with ECBL, both of which were submerged. Patient, tooth and implant level data were collected. ECBL was assessed using periapical radiographs obtained during implant placement and second-stage surgeries. Generalized estimating equation logistic regression models were used to account for multiple implants within patients. The total number of implants included in the study was 200 from 120 patients. Lack of supportive periodontal therapy (SPT) was shown to have nearly five-times higher risk of developing ECBL and was statistically significant (p<0.05). Guided bone regeneration (GBR) procedures before implant placement had a protective effect with an odds ratio of 0.29 (p<0.05). Lack of SPT was significantly associated with ECBL, while sites that received GBR procedures prior to implant placement were less likely to exhibit ECBL. Our results underscore the importance of periodontal treatment and SPT for peri-implant health, even when the implants are submerged and unrestored.

Evaluation of Peri-Implant Crestal Bone Loss with Different Implant Systems, Primary Stability, Bone Density and Soft Tissue Thickness: A Retrospective Study.

The purpose of this retrospective study was to compare, among various implant systems, the influence of primary stability and the bone density and soft tissue biotype of the patient on the amount of peri-implant crestal bone loss after 1 year using radiography. Included in this retrospective study were patient records of 3583 implant placements utilized from an online dental information archiving software (DIAS). Clinical and radiographic assessments were conducted concurrently with implant placement (baseline) and 1 year post surgery. Statistical analysis was done to examine the mean marginal bone loss significance in the three different implant systems groups (group I: Straumann Roxolid SLAc-tive, group II: Nobel Biocare CC, group III: Straumann SLA), different primary stability values, different bone density. and soft tissue biotype at the time of implant placement. A significant difference was observed in the crestal bone loss with different implant systems used. Group I showed significantly lesser amounts of crestal bone loss when compared to groups II and III. However, the differences in the bone density, ISQ values, and the soft tissue biotype did not exhibit a statistically significant difference in the amount of crestal bone loss. Significant MBL preservation for implants with Straumann SLActive when compared to Nobel Biocare CC and Straumann SLA implants. No significant changes were observed with respect to primary stability, bone density, and soft tissue thickness and no correlation among early crestal bone loss and IT, ISQ at surgery, and ISQ at reopening was observed. Straumann Roxolid SLActive implants showed less crestal bone loss probably owing to its hydrophilic surface modification. However, more studies need to be done to evaluate the same.

Early crestal bone loss around implants placed at previously failed sites compared with initially integrated implants: A retrospective cohort study.

There is minimal information on early crestal bone loss (CBL) associated with implants placed at failed sites. This retrospective cohort study aimed to evaluate CBL of surviving and restored implants placed at previously failed sites (replaced implants [RIs]) compared to that of implants initially integrated and restored (pristine implants [PIs]), within the same subjects from implant placement to 17 months post-delivery of restoration. Subjects who had both PI(s) and RI(s) were recruited. The following data were retrieved: patient demographics, implant locations, types of implant failure, use of bone graft procedure(s), and intraoral radiographs at implant placement (T0), restoration delivery (T1), and the post-restoration follow-up (T2). A blinded evaluator measured crestal bone levels at T0, T1, and T2. Forty-four implants (22 in the RI and 22 in the PI group) from the 22 subjects were reviewed. The 22 implants in the RI group were placed either at early failure (17) or late failure (5) sites. There was a 4.6 times higher likelihood of bone graft procedures performed in association with RIs compared to PIs when using a generalized linear mixed model. Differences in crestal bone levels were compared between the two groups at each time point. There were no significant differences in the mesial and mean crestal bone levels between the PI and RI groups. The RI group exhibited lower crestal bone levels on the distal side compared to the PI group at all time points. However, this difference was due to crestal bone level at T0 (p=0.039) not due to implant replacement (p=0.413) or bone graft procedure (p=0.302) when using mixed regression modeling. The effect of replacements of implants at failed sites on CBL was not significant. RIs, once integrated, exhibited the same pattern of CBL as pristine implants.

Association of interleukin-1, interleukin-6, collagen type I alpha 1, and osteocalcin gene polymorphisms with early crestal bone loss around submerged dental implants: A nested case control study

Statement of problemThe reason for variations in peri-implant early crestal bone loss is unclear but may be due to genetic differences among individuals. PurposeThe purpose of this nested case control study was to investigate the association of single-nucleotide polymorphisms of interleukin-1, interleukin-6, collagen type I alpha1, and osteocalcin genes to early crestal bone loss around submerged dental implants. Material and methodsDental implants were placed in the mandibular posterior region (single edentulous space) of 135 participants selected according to predetermined selection criteria. Bone mineral density measurement by using dual energy X-ray absorptiometry, cone beam computed tomography scans at the baseline and after 6 months, and interleukin-1A-889 A/G (rs1800587), interleukin-1B-511 G/A (rs16944), interleukin-1B+3954 (rs1143634), interleukin-6-572 C/G (rs1800796), collagen type I alpha1 A/C (rs1800012), and osteocalcin C/T (rs1800247) genotyping were performed in all participants. Early crestal bone loss measured around dental implants was used to group participants into clinically significant bone loss (BL)>0.5 mm and clinically nonsignificant bone loss (NBL)≤0.5 mm. Early crestal bone loss was calculated as the mean of the difference of bone levels at the baseline and bone levels after 6 months as measured with cone beam computed tomography scans. The obtained data for basic characteristics, early crestal bone loss, and genotyping were tabulated and compared by using a statistical software program (α=.05). ResultsAA genotype and the A allele frequency of interleukin-1B-511 and GG genotype and the G allele frequency of interleukin-6-572 were significantly higher in BL than in NBL (P<.05). Multiple logistic analysis suggested that interleukin-1B-511 AA/GG+AG and interleukin-6-572 GG/CC+CG genotype expression were significantly associated with early crestal bone loss (AA/GG+AG; P=.014, GG/CC+CG; P=.047) around dental implants. Other risk factors were not significantly different (P>.05). ConclusionsOf the genes studied, individuals with interleukin-1B-511 AA (rs16944) or interleukin-6-572 GG (rs1800796) genotype had higher susceptibility to early crestal bone loss around dental implants.

Association of interleukin-1 gene polymorphism and early crestal bone loss around submerged dental implants: A systematic review and meta-analysis.

Aim:Early crestal bone loss (ECBL) has been observed regardless of the absence of possible etiologic factors for bone loss during the healing phase and before the second-stage implant surgery. The purpose of this systematic review and meta-analysis was to correlate the possible association of interleukin-1 (IL-1) gene polymorphisms and ECBL (bone loss before the second-stage surgery) around dental implants.Settings and Design:Systematic review and meta-analysis following PRISMA guidelines.Materials and Methods:Considering the inclusion criteria, an electronic search by using specific keywords of three databases PubMed [(“Dental” OR “oral”) AND (“Implants*”) AND (“gene polymorphism” OR “genotype” AND (“IL-1” OR “interleukins”)], Cochrane library [implant AND (biomarker or cytokine), interleukin-1 or IL-1 AND implants], and EMBASE [(“gene polymorphisms”/de OR “interleukins”/cytokine exp OR “biomarker”:ti,ab,kw) AND (“dental implantation”/de OR “oral implant”)] and manual search from 1995 till March 2020 was made by 2 independently calibrated reviewers. ACROBAT-NRSI, Version 1.0.0 and Review Manager, Version 5.3, computer software were used for the risk of bias assessment and to conduct the meta-analysis respectively.Statistical Analysis Used:Cochran's Q test and I2 statistics.Results:Of 38 articles which were found eligible for full-text screening, two articles fulfilled the inclusion criteria and hence were included in the meta-analysis. The I2 statistic and Q-test values of the included studies revealed acceptable homogeneity for studied three IL-1 gene polymorphisms (IL-1A−889: I2 =0%, IL-1B − 511: I2 = 0%, IL-1B+3954: I2 = 24%). Forest plot of association between IL-1B−511 gene and ECBL revealed a significant association between 2/2 genotype of IL-1B−511 gene and an increased risk of ECBL (OR = 0.23, 95% CI = 0.09–0.58, Pheterogeneity= 0.68, I2 = 0%, and P = 0.002). Results of the IL-1A−889 and IL-1B+3954 gene revealed no significant associations between any genotype of these genes with risk of ECBL.Conclusions:There is an evidence of the association of IL-1B−511 (2/2) genetic polymorphisms and increased ECBL in the individuals of Asian ethnicity (OR = 0.23, P = 0.002).

Crestal Bone Stability around Implants with Horizontally Matching Connection after Soft Tissue Thickening: A Prospective Clinical Trial

It has been shown that thin mucosal tissues may be an important factor in crestal bone loss etiology. Thus, it is possible that mucosal tissue thickening with allogenic membrane might reduce crestal bone loss. The purpose of this study was to evaluate how implants with traditional connection maintain crestal bone level after soft tissue thickening with allogenic membrane. One hundred three patients received 103 internal hex implants of 4.6 mm diameter with regular connection. According to gingiva thickness, patients were assigned into A (thin tissues, n = 34), B (thin, thickened with allogenic membrane, n = 35), and C group (thick tissues, n = 34). Groups A and C had one-stage approach, and in group B, implants were placed in two stages. Radiographic examination was performed after implant placement, 2 months after healing, after restoration, and after 1-year follow-up. Crestal bone loss was calculated medially and distally. Significance was set to 0.05. After 1-year follow-up, implants in group A had 1.65 ± 0.08-mm bone loss mesially and 1.81 ± 0.06 mm distally. Group B had 0.31 ± 0.05 mm mesially and 0.34 ± 0.05 mm distally. C group implants experienced bone loss of 0.44 ± 0.06 mm mesially and 0.47 ± 0.07 mm distally. Differences between A and B, and A and C were significant (p = .000) both mesially and distally, whereas differences between B and C were not significant mesially (p = .166) and distally (p = .255). It can be concluded that thin mucosal tissues may cause early crestal bone loss, but their thickening with allogenic membrane may significantly reduce bone resorption. Implants in naturally thick soft tissues experienced minor bone remodeling.

Implant crest module: A review of biomechanical considerations

The success of dental implants has long been established through various studies with a particular emphasis laid on an implant design. Crest module is that portion of a two-piece metal dental implant, designed to hold the prosthetic components in place and to create a transition zone to the load bearing implant body. Its design, position in relation to the alveolar crest, and an abutment implant interface makes us believe that, it has a major role in integration to both hard and soft tissues. Unfortunately, in most clinical conditions, early tissue breakdown leading to soft tissue and hard tissue loss begins at this region. Early crestal bone loss is usually highest during the first year after placement ranging from 0.9 to 1.6mm and averaged 0.05-0.13 mm in the subsequent years . Various hypotheses have been stated to reason it however, none has been proved convincingly. In light of this, various attempts have been made to overcome this undesirable bone loss, by varying an implant design, the position, surgical protocol, and the prosthetic options. Irrespective of an implant system and designs that are used, crestal bone loss of up to the first thread is often observed. The purpose of this review is to look into the various designs and treatment modalities, which have been introduced into the crest module of an implant body to achieve the best biomechanical and esthetic result.

Spontaneous early exposure and marginal bone loss around conventionally and early‐placed submerged implants: a double‐blind study

The aim of this retrospective study was to compare the frequency of spontaneous early exposure of cover screws and marginal bone resorption in conventionally and early-placed submerged implants before second-stage surgery. A total of 103 Nobel Biocare Branemark implants were conventionally (Group 1), or early-placed (Group 2) in 46 consecutive patients following the two-stage surgical protocol. Patients in both groups received oral hygiene training in self-performed plaque control measures, including exposure of cover screws during healing. Spontaneous cover screw exposure (CSE) of each implant was recorded for both groups and scored from Class 0 (no perforation) to Class 4 (complete exposure). Plaque index scores were recorded and marginal bone-level (MBL) changes were measured in radiographs before second-stage surgery in a blind manner. MBL in Group 2 was higher than Group 1 in patients with or without interim prosthesis (P<0.05). The use of interim prosthesis did not increase MBL in Group 1, but led to higher MBL in Group 2. The percentage of non-exposed implants in Group 1 was higher than Group 2 (P=0.007, odds ratio=7). Group 1 implants had 11.5 times greater plaque index score 0 than those in Group 2 (P=0.031, odds ratio=11.5). The differences between MBL with regard to CSE scores 0 and 1-4 was significant for both sides in Group 2 and the mesial side in Group 1 (P<0.05). The difference between MBL with regard to plaque index scores 1-3 was similar in both groups (P>0.05). There is a direct relation between spontaneous early cover screw perforations with early crestal bone loss. Early-placed implants experienced more spontaneous perforations and associated bone loss in comparison with conventionally placed submerged implants. The use of interim dentures may lead to more CSE and consequent MBL in the early-placement protocol.

Effect of Dehiscences to the Bone Response of Implants With an Acid-Etched Surface: An Experimental Study in Miniature Pigs

Spontaneous early exposure of submerged implants during the healing phase as a factor for early crestal bone loss around the implants is still being controversially discussed. The aim of this study was to examine the potential impact of dehiscences on the osseointegration process of acid-etched dental implants with a shortened healing period in the maxilla. Five animals received a total of 15 titanium implants 8 weeks postextraction. Eight of these implants were placed in the maxilla to osseointegrate within a shortened healing period of 3 months, whereas the remaining implants were inserted in the lower jaw and served as controls with a regular healing time. Polyfluorochrome sequential labeling with xylenol orange, calcein green, and alizarin complexone was performed 2, 5, and 8 weeks after implant placement. After 12 weeks of unloaded and submerged healing, the animals were killed and the implants removed en bloc. After the processing of the undecalcified PMMA-embedded samples, thin ground sections (40-60 µm) were made. The histomorphometric determination of the bone-to-implant contact (BIC) was calculated using light microscopy. The peri-implant bone apposition rate and the direction of bone growth were determined with the fluorescence microscope. For statistical evaluation, the Mann-Whitney U test, Wilcoxon signed ranks test, and Friedman test were chosen. During the healing period, nonartificial dehiscences were observed at 9 implants. The average BIC was 54.19% (14.51%-68.97%). There were significantly lower BIC rates detected for the cervical part of the implants compared with the middle part. An influence of dehiscences on the osseointegration could not be proven. There were no significant differences between the BIC values of the upper and lower jaw. During the observation period from the third to the eighth week after implantation, the average new bone formation rate was 2.32 µm/d (1.76-2.82 µm/d). During this period, the amount of new bone growth decreased insignificantly. Based on the sequence of the polyfluorochrome labeling, an implantopetal (53.03%) as well as an implantofugal bone growth (46.97%) have been observed. It could be assumed that the acid-etched implants offered a prerequisite to osseointegrate under a shortened healing period. The observed dehiscences seemed not to have compromised the rate of osseointegration.

Influence of Abutment Connections and Plaque Control on the Initial Healing of Prematurely Exposed Implants: An Experimental Study in Dogs

Spontaneous early implant exposure is believed to be harmful, resulting in early crestal bone loss around submerged implants. The purpose of this study was to examine the influence of abutment connections and plaque control on the initial healing of prematurely exposed implants in the canine mandible. Bilateral, edentulated, flat alveolar ridges were created in the mandible of 10 mongrel dogs. After 3 months of healing, two implants were placed on each side of the mandible following a commonly used two-stage surgical protocol. Implants on each side were randomly assigned to one of two procedures: 1) connection of a cover screw to the implant and removal of the gingiva to expose the cover screw; and 2) connection of a healing abutment to the implant so that the coronal portion of the abutment remained exposed to the oral cavity. In five dogs (plaque control group), meticulous plaque control was performed. In the other five dogs (no plaque control group), plaque was allowed to accumulate. At 8 weeks post-implantation, microcomputed tomography was performed at the implantation site to measure bone height in the peri-implant bone. The plaque control group had greater vertical alveolar ridge height (9.7 +/- 0.5 mm) than the group without plaque control (7.4 +/- 0.7 mm; P <0.05). In the plaque control group, the average bone height was greater with the abutment-connected implant (10.1 +/- 0.5 mm) than with the partially exposed implant (9.3 +/- 0.5 mm; P <0.05). In the group without plaque control, the average bone height was greater with the partially exposed implant (8.2 +/- 0.6 mm) than with the abutment-connected implant (6.5 +/- 0.7 mm; P <0.05). These results suggest that the placement of healing abutments and meticulous plaque control may limit bone loss around submerged implants when implants are partially exposed.

Influence of premature exposure of implants on early crestal bone loss: an experimental study in dogs

Several studies have reported on spontaneous early exposure of submerged implants, suggesting that exposed implants have greater bone loss than nonexposed implants. The purpose of this study was to compare the effects of implant-abutment connections and partial implant exposure on crestal bone loss around submerged implants. Bilateral, edentulated, flat alveolar ridges were created in the mandible of 6 mongrel dogs. After 3 months of healing, 2 fixtures were placed on each side of the mandible following a commonly accepted 2-stage surgical protocol. The fixtures on each side were randomly assigned to 1 of 2 procedures. In the first, a cover screw was connected to the fixture, and the incised gingiva was partially removed to expose the cover screw (partially exposed group). In the second, a healing abutment was connected to the fixture so that the coronal portion of the abutment remained exposed to the oral cavity (abutment-connected group). After 8 weeks, micro-computed tomography (micro-CT) at the implantation site was performed to measure the bone height in the peri-implant bone. Data were analyzed by Wilcoxon's signed rank test. The average bone height was greater for the abutment-connected fixture (9.8 +/- 0.5 mm) than for the partially exposed fixture (9.3 +/- 0.5 mm; P < .05). These results suggest that when implant exposure is detected, the placement of healing abutments may help limit bone loss around the submerged implants.

The causes of early implant bone loss: myth or science?

The success of dental implants is highly dependent on integration between the implant and intraoral hard/soft tissue. Initial breakdown of the implant-tissue interface generally begins at the crestal region in successfully osseointegrated endosteal implants, regardless of surgical approaches (submerged or nonsubmerged). Early crestal bone loss is often observed after the first year of function, followed by minimal bone loss (< or =0.2 mm) annually thereafter. Six plausible etiologic factors are hypothesized, including surgical trauma, occlusal overload, peri-implantitis, microgap, biologic width, and implant crest module. It is the purpose of this article to review and discuss each factor Based upon currently available literature, the reformation of biologic width around dental implants, microgap if placed at or below the bone crest, occlusal overload, and implant crest module may be the most likely causes of early implant bone loss. Furthermore, it is important to note that other contributing factors, such as surgical trauma and penimplantitis, may also play a role in the process of early implant bone loss. Future randomized, well-controlled clinical trials comparing the effect of each plausible factor are needed to clarify the causes of early implant bone loss.

Reverse torque testing and early loading failures: help or hindrance?

Reverse torque testing has been suggested to reduce the incidence of early loading failures during the first year of loading. However, the variables of bone density at stage II uncovery, the assessment of a small degree of implant rotation, and the effect of implant size and design have not been adequately evaluated. In addition, bone is weakest to shear forces, yet this is the primary force applied with reverse torque testing. This article reviews the benefits and disadvantages of reverse torque testing and suggests early crestal bone loss and failure of implants may be the result of this test, especially in less dense bone types. In addition, a nomenclature of implant failures is introduced to improve the correlation of information in the literature to the failure of implants in clinical practice.