Journal of Dental Implant Research 2024; 43(1): 1-8
Assessment of stability of early loaded nano-coated hydroxyapatite implants in posterior maxilla
Ola Abdelsamad Amin1 , Ingy Mohamed Shehata2 , Heba Mohamed Kamel3 , Nader Nabil Elbokle4
1Oral and Maxillofacial Surgery Department-Faculty of Dentistry, MSA University, 2Oral and Maxillofacial Surgery, Faculty of Dentistry, Modern Science and Arts University, 3Oral and Maxillofacial Surgery, Faculty of Dentistry, Cairo University, 4Oral and Maxillofacial Surgery, Faculty of Dentistry, Cairo University-Dean of Faculty of Dentistry, MSA University, Giza, Egypt
Correspondence to: Ola Abdelsamad Amin,
Oral and Maxillofacial Surgery Department-Faculty of Dentistry, MSA University, Giza 00202, Egypt. Tel: +01118102019, Fax: +(202)3837-1543, E-mail:
Received: February 8, 2024; Revised: March 4, 2024; Accepted: March 6, 2024; Published online: March 30, 2024.
© The Korean Academy of Implant Dentistry. All rights reserved.

This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Purpose: This study assessed the stability of nano-coated hydroxyapatite implants in the posterior maxilla after early loading.
Materials and Methods: This study was conducted on nine patients missing at least one maxillary posterior tooth. Ten nano-coated hydroxyapatite implants were inserted in nine patients and subjected to early loading according to the secondary stability readings taken by Osstell®. The implant stability was measured at the time of implant insertion (T0), 4 (T1), 6 (T1 modified), weeks, and four months (T2) after surgery. Cone-beam computed tomography (CBCT) was performed in all patients before treatment started. Nine implants healed well, but one implant failed due to infection.
Results: The secondary stability results six weeks after implant insertion were sufficient for implant loading. Significant differences were observed between T0, T1, T1 modified, and T2.
Conclusions: Nano-coated hydroxyapatite implants are a good choice in the posterior maxilla because they allow early loading.
Keywords: Dental implants, Implant stability, Implants surface treatment, Implants surface coating

Implant stability is a measurement of the clinical immobility of implants also an indicator of osseointegration. An implant's stability in the surrounding bone is essential to allow for continued healing and bone formation after insertion and to allow for the best possible stress distribution from masticatory and occlusal functional stresses through the implant tissue interface. While secondary stability is needed following osseointegration, which occurs throughout function, primary stability is needed at the time of implant placement. These prerequisites for healing, function, and stability differ slightly from one another1).

A popular biomedical tool for assessing implant stability is Resonance Frequency Analysis. It is a non-invasive analytical technique that evaluates the stability of the implant and the density of the bone at different stages using vibration and the structural analysis principle. Implant Stability Quotient, or ISQ, is a unit used to measure implant stability. Its value reflects the implant stability in the bone regarding primary and secondary stability2).

Numerous studies have been conducted on coatings made of Calcium Phosphates, such as Hydroxyapatite. Nanoscale alteration of implant surfaces was proven by studies to enhance the biomimicry of dental implants due to the interaction of extracellular matrix proteins, growth factors, and many osteogenic potential cells at this scale. It's interesting to note that the possibility of improving osseointegration has been studied by applying nanostructured CaP to implant surfaces. It has been noted that electro-polished surfaces with nanometer-sized HAP coatings can increase bone-to-implant contact by about 300% compared to surfaces without coatings3).

To date only few clinical studies have attempted to test the early loading of Nano-coated Hydroxyapatite implants in posterior maxilla and their effect on marginal bone loss. Therefore, the objective of this study is to demonstrate the ability of nano-coated hydroxyapatite implants to achieve rapid osteointegration in posterior maxilla and qualify for early loading and achieve minimal marginal bone loss.


This study was conducted on a total of nine patients who had at least one missing maxillary posterior tooth seeking restoration. A total of ten implants were inserted.

1. Inclusion criteria

•Patients with missing upper posterior teeth and seeking implant placement.

•Patients who have adequate bone height and width that allows implant placement.

•Patients free from any condition that may compromise the final outcome of the dental implantation procedure (ex: bruxism, previous radiation).

2. Exclusion criteria

•Patients with systemic diseases that may hinder the normal healing process, for example Diabetes mellitus, Peripheral vascular disease and peripheral vascular disease.

•Patients with intra-bony lesions or infections that may retard the healing.

3. Surgical approach

Cone beam CT scans were carried out preoperatively for all patients to measure the available bone length and width (Fig. 1), and exclude the presence of any pathologic condition that might affect implant placement.

Figure 1. Photograph showing bone height and width using CBCT.

•Infiltration local anesthesia (Articaine HCL 4% with epinephrine 1/100000) was injected intraorally on the site of implant placement and a paracrestal incision was made at the edentulous area extending one tooth mesial and distal to the edentulous area to create a full thickness mucoperiosteal flap.

•Sequential drilling under copious irrigation was done till the desired implant size.

•All implants used for this study were bone level ETIII NH implant with open thread and tapered body implant by Hiossen (Fig. 2).

Figure 2. Clinical photograph showing ETIII NH implant.

•Implant was placed with 35 newton-meter according to the manufacturer’s instructions.

•Primary implant stability was measured immediately post-operatively (T0) using the Osstell ISQ system, one reading was taken for each of the four aspects of the implant.

•Implant Stability Measurement:The implant stability was measured at the time of insertion using the Resonance Frequency Analysis via the Osstell ISQ system.The system includes the use of a SmartPegTM attached to the dental implant or abutment by means of an integrated screw.The SmartPeg is excited by a magnetic pulse from the measurement probe on the handheld instrument. The resonance frequency, which is the measure of implant stability, is calculated from the response signal and Results are displayed on the device as the Implant Stability Quotient (ISQ). The SmartPeg probe was held close to the SmartPeg to measure the ISQ value from the buccal, palatal, mesial and distal aspects, 4 readings were taken from each aspect then the mean value for each aspect was calculated. The final readings for the buccal, palatal, mesial and distal aspects then were added to each other, then the mean value for the whole implant was calculated.

•Closure of the mucoperiosteal flap with absorbable suture.

4. Post-operative care

•Post-operative medications:

Patients were prescribed:

1.Antibiotics: Amoxicillin 875 mg and Clavulonic acid 125 mg tablets every 12 hours for 5 days post-sur-gically.

2.Analgesic: Diclofenac Potassium 50 mg analgesic tablets three times daily for 3∼5 days post-sur-gically.

•Mouth rinsing with Chlorhexidine 3 times daily starting one day postoperatively.

5. Follow up & Evaluation

First visit after 1week for suture removal and healing assessment.

Implant exposure was done after 4 weeks through a paracrestal incision at the implant site, then a healing abutment was put after stability measurements were taken until the delivery of the final restoration.

Implant exposure was done after 4 weeks through a paracrestal incision at the implant site, then a healing abutment was put after stability measurements were taken until the delivery of the final restoration.

•Assessment of implant stability:

-Secondary stability was measured 4 weeks (T1) which was the proposed time for loading according to Alabed Mela et al., 6 weeks (T1 modified) and 4 month (T2) post-operatively.

-Final restoration was constructed after 6 weeks post-operatively.

-Final restoration was done after confirmation of adequate secondary stability for implant loading according to the evidence-based Osstell ISQ scale.

-Patients’ satisfaction survey was done throughout the treatment phases to assess the overall satisfaction from the procedure (Fig. 3).

Figure 3. Patients’ Satisfaction Sur-vey.

•Statistical analysis:

-Data was analyzed using IBM SPSS advanced statistics (Statistical Package for Social Sciences), version 21 (SPSS Inc., Chicago, IL). Numerical data was described as mean and standard deviation or median and range, as appropriate. In the primary outcome the distribution of data was normal and the data were paired and more than 2 groups, so repeated measure ANOVA test was done. A p-value ≤ 0.05 will be considered statistically significant. Regarding the secondary outcome there were only 2 variables in the same subject so Paired T-test was used.

•Assessment of the marginal bone height:

-Marginal bone loss was measured at 4 weeks (M0), and 3 months after loading (M1) post-operatively by CBCT (Fig. 4).

Figure 4. Photograph showing marginal bone height measurement using CBCT, A: Sagittal cut, B: Coronal cut.

In this study a total of 10 implants were inserted in 9 patients that had at least a missing one maxillary posterior tooth and were selected from the Out Patient Clinic of Oral and Maxillofacial Surgery Department, Faculty of Oral and Dental Medicine, Cairo University.

The selected patients were 7 females and 3 males. Their age ranged from 22∼57 years with mean of 38.3 years (7±5). The total implants placed were 10 implants.

1. Assessment of implant stability

Implant stability was measured at time of insertion (T0), 4 (T1), 6 (T1 modified), weeks, and 4 months (T2) post-operative as shown in (Table 1, 2), between 4 and 6 weeks a healing abutment was put.

Table 1 . Table showing paired t-test

MeanStd. deviationP value
Pair 1T0 (at insertion) - T1 (4 weeks)24.94412.411<0.001
Pair 2T0 (at insertion) - T1 (modified - at 6 weeks)3.77811.054.335
Pair 3T0 (at insertion) - T2 (4 month after insertion)−1.88910.706.611
Pair 4T1 (4 weeks) - T1 (modified - at 6 weeks)−21.16721.665.019
Pair 5T1 (4 weeks) - T2 (4 month after insertion)−26.83320.955.005
Pair 6T1 (modified - at 6 weeks) - T2 (4 month after insertion)−5.6673.279.001

Table 2 . Table showing descriptive statistics of implant stability

Descriptive statistics

NMinimumMaximumMeanStd. deviation
T0 (at insertion)9517766.408.31
T1 (4 weeks)9246141.7218.95
T1 (modified - at 6 weeks)9507262.896.35
T2 (4 month after insertion)9558168.567.69

The decision to measure again after 6 weeks was made as the implant secondary stability results on 4 weeks did not qualify it for early loading, so the decision to wait for 2 more weeks was made measurements were taken again after 6 weeks post-operatively.

One implant failed after 4 weeks due to infection and was excluded from the statistical analysis.

Shapiro-Wilk test was done to detect data normality, and because the distribution of data turned out to be normal and the data were paired and more than 2 groups Repeated Measures ANOVA test was used to test the differences in implant stability score means among T0, T1, T1 modified, and T2. There was significant difference (F= 12.642, DF 3, P value <0.001), then Paired T-test was applied among the 6 pairs to assign difference among pairs at significance 0.008, there was significant difference among Pair 1 which was between T0 (at insertion) - T1 (4 weeks), Pair 4 which was between T1 (4 weeks) - T1 (modified - at 6 weeks), Pair 5 which was between T1 (4 weeks) - T2 (4 month after insertion), and Pair 6 which was between T1 (modified - at 6 weeks) - T2 (4 month after insertion), and the P value was <0.001, 0.019, 0.005, and 0.001 respectively (Table 1, 3).

Table 3 . Table showing repeated measures ANOVA

SourceMean squaremSig.
Implant stabilitySphericity assumed1380.174<0.001

2. Assessment of marginal bone loss

Marginal bone height was measured 4 weeks (H0), and 4 month (H1) post-operatively by CBCT.

Because the readings were two variables for the same subject Paired T-test was used to compare the mean baseline marginal bone level (H0) to the mean marginal bone level after 4 months (H1). There was non-significant difference, P value 0.45, the mean of the baseline marginal bone level was 7.07 (SD=0.77), and the mean marginal bone level after 4 month was 8.02 (SD=1.18), the difference was 15.53 (SD=4.72) (CI −1.25 to 1.98) (Table 4).

Table 4 . Table showing inferential statistic for marginal bone loss

M0 mean (SD)M1 mean (SD)95% CI of differenceP value

Lower limitUpper limit
7.07 (0.77)8.02 (1.18)−1.251.980.45

3. Patient satisfaction

Patients’ satisfaction survey was done for the process, the results of overall patient’s satisfaction showed that 91% of patients were very satisfied and 63% of patients were satisfied. (Fig. 5) shows the statistical data regarding patients’ satisfaction rate.

Figure 5. Bar chart showing patients’ satisfaction rates.

Early loading was done after 6 weeks after measurement of secondary stability and finding that the ISQ value is suitable for implant loading according to the evidence-based Osstell ISQ scale. Implant loading at six weeks was formerly regarded as an early loading according to Krawiec et al. The third and fourth weeks appear to be crucial for the process of secondary stability and osteointegration, though. The primary osseous tissue begins to mineralize during that time, and as a result, the bone tissue that surrounds an implant develops the mechanical properties that permit loading4).

Hiossen ET III implants with HAP Nano-coating and hydrophilic surface was used in this study, the advantages of HAP Nano-coating and surface hydrophilicity was discussed by Tallarico et al. In their study which concluded that implants with the new hydrophilic Nano-Hy-d-ro-yapatite (NH) surface of the Hiossen ET III implants appear to avoid the ISQ drop during the remodeling phase, allowing for benefits in immediate loading, poor bone quality, post extractive, smoking, and immuno-suppression disease5).

The hydrophilic surface of Hiossen ET III implant have greater surface energies, which accelerates the transition from the mechanical primary bone stability to the structural/biological secondary bone stability. This was supported by Velloso et al. which in their study reported increasing ISQ values during the follow-up period of hydrophilic SAE implant surface for 12 months after implant installation, and suggested that hydrophilicity of the implant surface optimized the healing process and bone repair. It also stimulates cellular responses, enhances gene expression, osteoblastic stimulation, helps in early osseointegration, and bone mineralization6).

The results of our study in the measurement of implant stability were similar to the results of a clinical trial by Körmöczi et al. who compared the primary stability and secondary stability of NH (bioabsorbable apatite nanocoating) and SLA (large-grit sandblasted and acid-etched) surface implants, SA (alumina sandblasted and acid-etched), and SA (alumina sandblasted and acid-etched) surface implants after 6 weeks. The results showed that all three groups could be used safely in case of early loading protocol after 6 weeks In the SLA group, the increase in implant stability over the course of six weeks was the lowest, while in the NH group, it was the highest7).

The results of Alabed Mela et al. clinical study also coincided with the results of our study, they evaluated the outcomes of 12 early-loaded implants in the posterior maxilla after 1 month of loading and found that the nanohydroxyapatite coating had a positive impact. They also found that the success rate achieved was 100% after 1 year post-loading and that the results had been encouraging in terms of stronger and more favorable bone regeneration, better Osseointegration, higher/better quality bone production, and improved secondary implant stability of implants, which coincides with our results8).

Tallarico et al. revealed similar results to our study from their Split-Mouth, Randomized Controlled Trial on 29 patients (mean age 59.9±11.3 years) who were treated and followed up to 1 year after loading. Fifty-eight implants were placed, 29 of which were Hiossen ET III implants with the sandblasted and acid-etched (SA) surface and 29 of which were Hiossen ET III implants with the new hydrophilic (NH) surface. The researchers concluded that NH implants are a viable alternative to SA surfaces because they appear to avoid the ISQ drop during the implant remodeling phase. This allows it to be used in immediate loading and early loading protocols, individuals with poor bone quality, smokers, and cases of immunosuppression9).

The results of a prospective case series study on early loading of titanium dental implants with a hydrophilic implant surface by Hicklin et al. confirmed that early functional loading of such implants is applicable, as the hydrophilic implant surfaces had increased wettability which enhanced the process of osseointegration, which goes in line with our results, however the loading in that study was done after 21 days in the posterior mandible of partially edentulous patients10).

Lang et al. also studied the early healing and osseointegration of the hydrophilic SLActive implants and found that when compared to the hydrophobic SLA surface, the degree of osseointegration for the hydrophilic SLActive was greater after 4 weeks, which proves that surface hydrophilicity of the implant can positively affect the process of osseointegration, which agrees with the results of our study11).

Our study's findings regarding the marginal bone loss surrounding the implants were comparable to those of a prospective randomised clinical trial conducted by Kim et al. on hydrophilic tapered implant surface at maxillary posterior area between two groups, one loaded after 6 weeks and the other after 12 weeks. The trial assessed marginal bone loss surrounding the implants and determined that, for all implants in the study, it was within a normal rate (less than 1 mm after 1 year postoperatively), with the exception of one implant. The study also found that in cases of hydrophilic tapered implants, a healing period of 6 weeks can produce clinical outcomes comparable to a healing period of 12 weeks, provided that bone quality is carefully considered in the event of early loading. This finding supports early loading at 6 weeks for such implants12).


Within the context of this study, the following conclusions can be listed:

1.Nano-coated hydroxyapatite implants are of good choice in posterior maxilla, and our preliminary results supports success of early loading at 6 weeks.

2.Nano-coated hydroxyapatite implants maintained marginal bone height at 4 months (No bone loss).


① Art Pharma® Iodine and Potassium Iodide quality products.


③ Osstell®, integration Diagnostic AB, Goteborg, Sweden.

④ Isuture Isorb: AlDawlia ICO, Asyut, Egypt.

⑤ Augmentin 1 gm. tablets, Smithkline Beecham Pharmaceuticals Co., Brentford, England.

⑥ Cataflam 50 mg. tablets, Novartis Pharma AG, Basle, Switzerland.

⑦ Oraldene; Chlorhexidine hydrochloride 125 mg in each 100 ml solution. EDCO, Egypt.

  1. Atsumi M, Park SH, Wang HL. Methods used to assess implant stability: current status. Int J Oral Maxillofac Implants 2007;22:743-54.
  2. Kittur N, Oak R, Dekate D, Jadhav S, Dhatrak P. Dental implant stability and its measurements to improve osseointegration at the bone-implant interface: A review. Mater Today Proc 2021;43:1064-70.
  3. Bryington MS, Hayashi M, Kozai Y, et al. The influence of nano hydroxyapatite coating on osseointegration after extended healing periods. Dental Materials 2013;29:514-20.
    Pubmed CrossRef
  4. Krawiec M, Hadzik J, Dominiak M, Grzebieluch W, Błaszczyszyn A, Kubasiewicz-Ross P. Early loading of titanium dental implants with hydroxyl ion modified surface: a 12-month prospective clinical trial. Applied Sciences (Switzerland) 2021;11.
  5. Tallarico M, Baldini N, Martinolli M, et al. Do the new hydrophilic surface have any influence on early success rate and implant stability during osseointegration period? four-month preliminary results from a split-mouth, randomized controlled trial. Eur J Dent 2019;13:95-101.
    Pubmed KoreaMed CrossRef
  6. Velloso G, Moraschini V, dos Santos Porto Barboza E. Hydrophilic modification of sandblasted and acid-etched implants improves stability during early healing: a human double-blind randomized controlled trial. Int J Oral Maxillofac Surg 2019;48:684-90.
    Pubmed CrossRef
  7. Körmöczi K, Komlós G, Papócsi P, Horváth F, Joób-Fancsaly Á. The early loading of different surface-modified implants: a randomized clinical trial. BMC Oral Health 2021;21.
  8. Alabed Mela O, Abdel- Monem Tawfik M, Mohamed Ahmed Said Ahmed W, El Din Hassan Abdel-Rahman F. Efficacy of nano-hydroxyapatite coating on osseointegration of early loaded dental implants. Int J Adv Res (Indore) 2022;10:564-75.
  9. Tallarico M, Baldini N, Gatti F, et al. Role of new hydrophilic surfaces on early success rate and implant stability: 1-year post-loading results of a multicenter, split-mouth, randomized controlled trial. Eur J Dent 2021;15:1-7.
    Pubmed KoreaMed CrossRef
  10. Hicklin S, Janner S, Schnider N, Chappuis V, Buser D, Brägger U. Early loading of titanium dental implants with an intraoperatively conditioned hydrophilic implant surface: 3-year results of a prospective case series study. Int J Oral Maxillofac Implants 2020;35:1013-20.
    Pubmed CrossRef
  11. Lang NP, Salvi GE, Huynh-Ba G, Ivanovski S, Donos N, Bosshardt DD. Early osseointegration to hydrophilic and hydrophobic implant surfaces in humans. Clin Oral Implants Res 2011;22:349-56.
    Pubmed CrossRef
  12. Kim SB, Yun PY, Kim SY, Yi YJ, Kim JY, Kim YK. Prospective randomized clinical trial of hydrophilic tapered implant placement at maxillary posterior area: 6 weeks and 12 weeks loading. The Journal of Advanced Prosthodontics 2016;8:396.
    Pubmed KoreaMed CrossRef

This Article

Author ORCID Information

Social Network Service



Indexed/Covered by

  • renew
  • banner_koreatoothbank