PubMed ID (PMID): 33491363Pages 311-312, Language: English
PubMed ID (PMID): 33491364Pages 318, Language: English
PubMed ID (PMID): 33491365Pages 321-342, Language: English
Purpose: The purpose of this systematic review was to assess the histological healing outcomes at the bone–titanium interface of loaded and unloaded dental implants placed in humans.
Materials and methods: An electronic search was conducted using the PubMed, Embase and Cochrane Central Register of Controlled Trials (Central) databases up to and including April 2020 to identify clinical trials reporting human histological data of bone healing around titanium dental implants placed in healed alveolar ridges. The search was conducted by two independent reviewers with no language restrictions. The risk of bias of each included study was assessed using the Cochrane Collaboration’s domain-based, two-part tool.
Results: Of the 4564 potentially eligible articles, only 25 were included in this systematic review (13 randomised and 12 controlled clinical trials), with a total of 548 micro/transitional implants evaluated. The marked heterogeneity between studies did not allow the data to be combined for meta-analyses. In general, based on mean values of bone-to-implant contact (range 9% to 73%), bone density outside the threaded area (range 14.9% to 31.6%), bone density in the threaded area (range 17.9% to 56.9%) and osteocyte index (range 19.79 to 37.88 cells/mm2), all implant surface modifications demonstrated osseointegration potential. Furthermore, immediate loading was related to higher bone-to-implant contact, bone density outside the threaded area and osteocyte index; longer healing periods to higher bone-to-implant contact; and smoking to lower bone-to-implant contact, bone density in the threaded area and bone density outside the threaded area.
Conclusions: Despite the fact that several modifications were made to the implant surface, when considering the values for bone-to-implant contact, bone density in the threaded area, bone density outside the threaded area and osteocyte index, machined surfaces showed the worst healing outcomes. Nevertheless, osseointegration was improved by both immediate loading and longer healing periods and worsened by smoking.
Keywords: dental implants, endosseous, osseointegration, wound healing
The authors report no conflict of interest related to this study.
PubMed ID (PMID): 33491366Pages 345-353, Language: English
Purpose: The purpose of this study was to examine the possible association between implant insertion torque and marginal bone resorption.
Materials and methods: Electronic and manual searches were conducted for articles published up to and including March 2020. The databases consulted were MEDLINE (PubMed), Embase, Scielo and Cochrane Library. Meta-analyses were performed to evaluate the marginal bone resorption around dental implants placed with high insertion torque values (≥ 50 Ncm) compared to marginal bone resorption around dental implants placed with low to moderate (< 50 Ncm) insertion torque values.
Results: A total of five prospective studies and two randomised clinical trials were included in the qualitative analysis. Three of them were analysed quantitatively. The meta-analyses did not show a statistically significant difference between the groups at 3, 6 or 12 to 15 months.
Conclusions: No association between insertion torque value and peri-implant marginal bone resorption was found. Further studies of higher methodological quality are necessary to evaluate the possible correlation.
Keywords: bone remodelling, bone resorption, dental implants, insertion torque
The authors declare no conflicts of interest. No funding was received for this review.
PubMed ID (PMID): 33491367Pages 355-368, Language: English
Background: Peri-implant marginal bone loss is influenced by the interaction between tissues and the implant–abutment complex. The implant–abutment connection geometry is considered to be one of the factors that most affects peri-implant bone remodelling.
Purpose: The primary purpose was to compare the clinical and radiographical differences between implants sharing the same macrogeometry but with two different connections. The secondary aims were to measure implant success and survival rate, primary and secondary stability, and the correlation between changes in marginal bone level and clinical variables. Additionally, a neural network was developed and tested to anticipate the impact of the insertion torque curve on marginal bone loss.
Materials and methods: Patients requiring at least two implants in the posterior region were randomly divided into two groups. The implants presented the same micro- and macrotopography with different internal connections, conical standard (CS) and internal hex (IH). Upon implant surgery (T0), insertion torque, implant stability (implant stability quotient values were recorded by resonance frequency analysis), soft tissue height and the amount of keratinised gingiva were assessed. Stability was remeasured at the time of prosthetic connection (stage-two surgery) using a one-abutment one-time protocol and a fully digital workflow. At 6 months and 1 year after implant loading, periodontal parameters were assessed and periapical radiographs were taken. To study the differences between the two groups and the different variables, paired t test and generalised estimating equations models were adopted. Cluster analysis was used to assess the correlation between torque insertion/clinical profiles and changes in marginal bone level.
Results: A total of 33 patients (17 men, 16 women, mean age 67.4 ± 14.5 years) were included in the study. No dropouts were reported. Fifty-three implants (26 CS and 27 IH) were inserted in the maxilla, and 15 (8 CS and 7 IH) in the mandible. No implants failed. Marginal bone loss at 6 months after prosthetic loading was 0.33 ± 0.34 mm for CS and 0.43 ± 0.37 mm for IH (P = 0.125), and after 1 year was 0.48 ± 0.18 mm for CS and 0.57 ± 0.24 mm for IH. A statistically significant difference between the implant stabilty quotient values for the test and control groups was demonstrated at T0 (P = 0.03) and at stage-two surgery (P = 0.000122). The generalised estimating equations model showed that soft tissue height (P = 0.012), keratinised gingiva (P = 0.05) and insertion torque (P = 0.042) had a significant effect on marginal bone loss, while the other variables did not play a statistically significant role. The neural network showed good sensitivity, accuracy, precision and specificity.
Conclusions: The present research showed that different implant–abutment connections with the same implant macrogeometry have a significant effect on marginal bone loss. Better outcomes were observed in the CS group compared to the IH group. Marginal bone loss was found to be influenced by different individual and clinical factors.
Keywords: implant connection, implant microgeometry, implant stability, implant stability quotient value, marginal bone levels, neural network, randomised controlled trial, shoulderless preparation, zirconia abutment
The authors declare no conflicts of interest related to this study.
PubMed ID (PMID): 33491368Pages 369-383, Language: English
Purpose: The purpose of this study was to evaluate the 2-year outcomes of the one-tooth onetime complete digital workflow, allowing the immediate loading of a single implant in the posterior region with a final CAD/CAM crown made of a polymer-infiltrated ceramic network.
Materials and methods: A series of 10 implants were placed, and an intraoral scan was taken after surgery. A final screw-retained polymer-infiltrated ceramic network crown was manufactured chairside and placed the same day in full occlusion. Marginal peri-implant bone changes and soft tissue health were evaluated, and restoration performance was assessed using FDI World Dental Federation criteria and pink and white aesthetic scores. Patient-reported outcome measures and data on the time required to perform the procedures were collected.
Results: After 2 years, the implant survival rate was 100%. The debonding of one crown from its titanium base led to prosthodontic survival rate of 90% and the remaining crowns were all considered successful. The mean marginal peri-implant bone changes yielded 0.87 mm (standard deviation 0.96 mm) and 0.55 mm (standard deviation 0.53 mm) after 1 and 2 years, respectively. Mild or no inflammation of peri-implant soft tissue was observed in most implants. The total treatment time was 175 minutes and patient-reported outcome measures displayed high patient satisfaction.
Conclusions: This study constitutes the first report examining immediate loading of a single implant in the posterior region with a final crown in occlusion. In this case series, the 2-year outcomes of the one-tooth one-time protocol seem rather promising and fulfilled patient expectations. However, these preliminary results need to be confirmed by randomised controlled trials, and patient selection is likely to be a key factor in the success of this procedure.
Keywords: CAD/CAM, dental implant, digital workflow, immediate loading, intraoral scan (IOS), polymerinfiltrated ceramic network (PICN)
Amélie Mainjot cohabits with the founder of the company MaJEB, which contributes to the development of polymer-infiltrated ceramic network materials. Prof Lambert has collaboration agreement
PubMed ID (PMID): 33491369Pages 387-399, Language: English
Aims: While numerous materials are available for sinus floor elevation, plant-based alternatives still hold promise of overcoming concerns about allogeneic or xenogeneic materials. Thus, the present authors designed a randomised clinical trial to histologically compare an almost pure hydroxyapatite (HA) to a biphasic calcium phosphate comprising 80% β-tricalcium phosphate (β-TCP) and 20% hydroxyapatite (β-TCP/HA), all of phycogenic origin.
Materials and methods: Twenty patients scheduled for lateral window sinus floor elevation were randomised to either an HA or a β-TCP/HA group. Biopsy specimens were taken 3 months after sinus floor elevation and during implant surgery after 6 months. One ground section per biopsy specimen (N = 40) was stained, scanned and histomorphometrically analysed for new bone, old bone, soft tissue, graft, bone infiltration of graft, bone-to-graft contact and penetration depth.
Results: At 6 months, more new bone was seen in the β-TCP/HA group (P = 0.011), whereas more residual graft was present and in more extensive contact with new bone in the HA group. More pronounced alterations, and smaller particle sizes, of graft surrounded and infiltrated by bone were seen in the β-TCP/HA group. The less extensive bone-to-graft contact in the β-TCP/ HA group reflected a more advanced state of resorption, while infiltration of residual graft material by bone was also increased in this group.
Conclusions: Proper healing was seen in both groups, with the graft materials guiding the formation of new bone, which grew especially well through the particles of the highly osteoconductive and resorptive β-TCP/HA material. HA was very stable, without significant resorption, but was extensively in contact with new bone after 6 months.
Keywords: biocompatible materials, bone substitutes, calcium phosphates, hydroxyapatites, sinus floor elevation
This study was partially supportedby Dentsply Sirona Implants(I-BI-14-077; Mannheim, Germany) and the materials investigated in the study were providedfree of charge for patients’ use;
PubMed ID (PMID): 33491370Pages 401-409, Language: English
Purpose: Few case reports have been published on creeping attachment around dental implants. This study aimed to assess changes in the level of the mucosal margin following placement of free gingival grafts around single implants exhibiting mucosal recession with < 2 mm keratinised mucosa compared to that of implants with ≥ 2 mm keratinised mucosa.
Materials and methods: A total of 12 subjects with one or more implants were included. Nineteen implants displaying implant thread and/or prosthetic abutment exposure with < 2 mm keratinised mucosa were treated using free gingival grafts (FGG group), and 11 implants exhibiting ≥ 2 mm keratinised mucosa did not receive free gingival grafts (control group). The width of keratinised mucosa and the amount of mucosal recession were measured by a blind evaluator (MC).
Results: A continual reduction in mucosal recession was observed at the 6- and 12-month followups in all except two of the FGG group implants, while no change in the level of the mucosal margin was observed in the control group. This postoperative coronal migration of the mucosal margin resulted in a 0.7-mm mean reduction in mucosal recession after 12 months in the FGG group.
Conclusion: The level of the mucosal margin around implants exhibiting mucosal recession along with a lack of keratinised mucosa migrated coronally following free gingival grafts, and creeping attachment was observed in a number of patients.
Keywords: case series, mucosal recession, single implant, soft tissue management
The authors declare that there are no conflicts of interest related to this study.
PubMed ID (PMID): 33491371Pages 410, Language: English