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Comparing the effect of two different implant surface technologies on successful osseointegration in over-prepared osteotomy sites with reduced primary stability.

Institute of Dentistry

About the Project


Research leading to the development of newer dental implant materials as well as understanding the cellular and acellular healing mechanisms between implant surface and surrounding hard and soft tissues have been in progress for over six decades.

Commercially pure titanium is the material of choice in implant dentistry for biocompatibility and osseointegration, (Grandin et al., 2012). The physicochemical properties (chemical composition, surface roughness, micro/nanotopography, wettability, surface charges, etc.) of the titanium implant surface have the most important influence on cell adhesion, proliferation, differentiation and bone matrix deposition (Feng et al., 2004, MacDonald et al., 2004). Hence,
significant improvements and implant surface treatments as a result of continuing research and development have been made in order to enhance the treatment prognosis. Employing different techniques in preparation of implant surfaces (such as acid etching, anodization, plasma spraying, grit blasting or combinations) contributed to materials with improved biocompatibility and integration processes (Jemat et al., 2015, Bauer et al., 2013, Kim et al., 2013).

In the majority of the currently available rough surface titanium implants, critical period occurs 2 - 4 weeks after insertion when osteoclastic activity has reduced the initial mechanical primary stability, and insufficient new bone has produced to provide an equivalent or greater amount of compensatory biological stability (secondary stability). The sum of primary and secondary stability is referred to as total stability. A delay in the healing process leads to a marked decrease in the total stability of the implant between weeks 2 and 4, making this “stability dip” a critical time in the osseointegration process. Most implant failures occur in this critical early period (Buser et al., 2004) as the implant faces the greatest risk from micro-motion during this time (Raghavendra 2005). A tolerable range of micro-motion for a roughened implant surfaces has been reported within a range of 50 and 150μm (Szmukler-Moncler et al 2004).
Recent developments in implant surface technologies has been aimed at an attempt to speed up the process of early osseointegration.

Despite numerous preclinical and clinical investigations there is no evidence to show whether SLActive implants enhance performance in compromised osteotomy sites and if the increased hydrophilicity and surface free energy initiates immediate bone formation resulting in earlier secondary stability to compensate for the lack of primary stability to maintain enough total stability in the critical 2 to 4 week period as compared to the conventional SLA implants.


Hydrophillic implants (SLActive®) would successfully osseointegrate within the critical period of 2 to 4 weeks even when placed in over-prepared osteotomy sites as compared to the conventional hydrophobic (SLA®) implants.
Chemically modified hydrophillic implants (SLActive®) would successfully osseointegrate within a critical period of 2 to 4 weeks when compared to the conventional hydrophobic (SLA®) implants even when placed in over-prepared osteotomy sites with reduced primary stability.


To determine the influence of chemically modified hydrophilic (SLActive®) vs hydrophobic (SLA®) implant surfaces on osseointegration in over-prepared osteotomy sites.
To compare the speed and degree of osseointegration at SLActive® and SLA® implant surfaces during early phases of healing in over-prepared osteotomy sites.
To evaluate the influence of increasing osteotomy widths on osseointegration of the SLActive® vs SLA® implant surfaces.
To evaluate if the hydrophilic nature of the SLActive® implant surface would compensate for the lack of primary stability and lead to uneventful healing.

Lack of primary stability (PS) results in fibrous encapsulation rather than osseointegration leading to implant failure. Most failures occur between week 2 and 4 after placement, whilst it faces the greatest risk from micromotion. SLActive implants develop quicker secondary stability in terms of bone implant contact (BIC) when compared to SLA. As increasing number of implants are being placed in compromised sites, a clinician often faces situations where PS cannot be achieved where as if SLActive implants were to initiate immediate bone formation it may compensate for lack of PS, lead to successful osseointegration as compared to the SLA.

Research environment:

Queen Mary University of London is a highly-ranked research university and a member of the UK’s Russell Group of leading universities.

Funding Notes

We will consider applications from prospective students with a source of funding to cover tuition fees and bench fees for three years full-time or 6 years part-time. Both self-funded and sponsored students will be considered.

UK and EU nationality self-funded students might be eligible for both the cost of tuition fees and a yearly stipend over the course of the PhD programme from the Student Finance England: View Website


How to apply:
For more information regarding the project, please contact Dr S. Shahdad (

Applications should be submitted through the Queen Mary application system. Please indicate the project title and supervisor in the ‘Research Degree Programmes - Additional Questions’ section of the application.

Alongside the application form, please send the following supporting documents:
• Curriculum Vitae (CV)
• Copies of your degree certificates with transcripts
• Proof of English language ability for overseas applicants from non-English speaking countries
• A one-side A4 statement of purpose. This should set out your previous academic or other experience relevant to the proposed research; why you wish to undertake this research at QMUL; your previous research or professional training and what further training you think you will need to complete a PhD; and what ethical issues you will need to consider in undertaking this research.
• Two references. At least one reference must be from an academic referee who is in a position to comment on the standard of your academic work and suitability for postgraduate level study. Where appropriate, a second referee can provide comment on your professional experience.

Please contact Charlotte Royle ( with any queries about the application process.

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