How the thread of a dental implant impacts stability and osseointegration

They say it’s the little things that mean the most and when it comes to dental implants it’s true too. While the length and diameter of an implant can play a key role in the success of treatment,[i] so can its thread.

The thread design is purposefully created to improve osseointegration. The primary function of threads is to provide mechanical anchorage and distribute forces evenly into the surrounding bone. A threaded implant offers greater functional area than a smooth-side cylindrical or tapering implant, as it can be rigidly fixated, thereby limiting the microenvironment during wound healing.[ii]

One major impact of thread design is the long-term stability it can provide to the implant.[iii] The threads increase the surface area of contact between the implant and bone, allowing for better load distribution. This stability is essential during the initial healing phase and when the implant is subjected to functional loads. A stable implant helps minimise micromotion, which is crucial to promote proper bone healing and prevent implant failure.[iv]

Deep dive

The thread design influences the bone-implant interface. The dimensions, shape, pitch, and depth of the threads can affect the type and amount of bone formed around the implant. Studies have shown that deep threads can enhance the contact area between the implant and bone, resulting in a higher bone-to-implant contact ratio.[v]

The relevant characteristics of the thread that determine its functional surface and distribute the biochemical load are: depth, thickness, pitch, and face and lead angles. Some implants have double or triple-threaded implants. Compared with single-threaded implants, multiple-threaded implants can be inserted faster. However, finite element analysis has revealed that a single-lead thread provides maximum primary stability, followed by the double-lead threaded implant. A triple-threaded implant is said to be the least stable.[vi]

Thread pitch, or the distance between consecutive threads, also plays a crucial role in dental implant design. A larger thread pitch allows for faster insertion while maintaining stability. However, a smaller thread pitch provides better primary stability and resistance to rotational forces. The choice of thread pitch depends on various factors, including bone quality and the need for immediate stability during immediate loading protocols.[vii]

Another factor in thread design is the thread depth. The depth of the threads can influence the stress distribution within the bone. Studies have shown that shallow threads result in higher stress concentration at the implant-bone interface, potentially leading to bone resorption. On the other hand, deeper threads distribute the stress more evenly, reducing the risk of localised bone resorption and enhancing long-term implant survival.^v

Shape up

The thread shape is another essential aspect of implant design. Traditionally, v-shaped threads have been used as they offer good initial stability. However, recent advancements have led to the development of trapezoidal threads. Trapezoidal threads provide higher resistance to rotational forces, leading to enhanced primary stability. Furthermore, they facilitate better stress distribution and allow for optimal bone response during the healing process.[viii]

Additionally, the implant’s surface roughness texture is closely related to thread design. A rough surface promotes osseointegration by stimulating enhanced bone cell attachment and bone formation. Therefore, thread design influences the surface roughness and, consequently, the osseointegration potential of the implant.[ix]

Also implant surface microporosity can favour the osseointegration process. Various methods have been used to create porosity on an implant surface. In recent years, researchers developed tantalum-based, highly porous-surfaced implants with a trabecular bone-like surface topography which is said to improve the bone in-growth and bone on-growth properties of dental implants by increasing the surface-interface with bone tissue.[x]

In cases where there are challenging indications such as reduced interdental spaces and reduced bone availability, the Ø 2.9mm Helix GM Narrow from Neodent^®, a Straumann Group brand, provides an immediate, small diameter solution. Available in the UK from spring 2024, it provides a simple treatment protocol – regardless of whether guided or non-guided techniques are used. Giving confidence without compromising on strength, this implant offers flexibility for immediate aesthetic outcomes in limited interdental spaces. Boasting a dynamic, progressive thread design with double start threads and a rounded root with a v-shaped apex for self-cutting, it helps deliver high primary stability.

Thread design significantly impacts the success of dental implant procedures. The thread design affects implant stability, bone integration, and long-term survival. The dimensions, shape, pitch, and depth of the threads play a crucial role in achieving optimal load distribution, promoting osseointegration, and preventing implant failure.

For more information on Neodent^® visit
https://www.neodent-uk.co/portal

[i] Bataineh AB, Al-Dakes AM. The influence of length of implant on primary stability: An in vitro study using resonance frequency analysis. J Clin Exp Dent. 2017 Jan 1;9(1):e1-e6. doi: 10.4317/jced.53302. PMID: 28149455; PMCID: PMC5268121.[Accessed October 2023]

[ii] Pandey C, Rokaya D, Bhattarai BP. Contemporary Concepts in Osseointegration of Dental Implants: A Review. Biomed Res Int. 2022 Jun 14;2022:6170452. doi: 10.1155/2022/6170452. PMID: 35747499; PMCID: PMC9213185. [Accessed October 2023]

[iii] Alghamdi HS, Jansen JA. The development and future of dental implants. Dent Mater J. 2020 Mar 31;39(2):167-172. doi: 10.4012/dmj.2019-140. Epub 2020 Jan 22. PMID: 31969548.

[iv] Yamaguchi Y, Shiota M, Fujii M, Shimogishi M, Munakata M. Effects of implant thread design on primary stability-a comparison between single- and double-threaded implants in an artificial bone model. Int J Implant Dent. 2020 Aug 20;6(1):42. doi: 10.1186/s40729-020-00239-1. PMID: 32815046; PMCID: PMC7438427. [Accessed October 2023]

[v] Lee SY, Kim SJ, An HW, Kim HS, Ha DG, Ryo KH, Park KB. The effect of the thread depth on the mechanical properties of the dental implant. J Adv Prosthodont. 2015 Apr;7(2):115-21. doi: 10.4047/jap.2015.7.2.115. Epub 2015 Apr 23. PMID: 25932309; PMCID: PMC4414941. [Accessed October 2023]

[vi] Yamaguchi Y, Shiota M, Fujii M, Shimogishi M, Munakata M. Effects of implant thread design on primary stability-a comparison between single- and double-threaded implants in an artificial bone model. Int J Implant Dent. 2020 Aug 20;6(1):42. doi: 10.1186/s40729-020-00239-1. PMID: 32815046; PMCID: PMC7438427. [Accessed October 2023]

[vii] Menini M, Bagnasco F, Calimodio I, Di Tullio N, Delucchi F, Baldi D, Pera F. Influence of Implant Thread Morphology on Primary Stability: A Prospective Clinical Study. Biomed Res Int. 2020 Aug 5;2020:6974050. doi: 10.1155/2020/6974050. PMID: 32802868; PMCID: PMC7426766. [Accessed October 2023]

[viii] Ryu HS, Namgung C, Lee JH, Lim YJ. The influence of thread geometry on implant osseointegration under immediate loading: a literature review. J Adv Prosthodont. 2014 Dec;6(6):547-54. doi: 10.4047/jap.2014.6.6.547. Epub 2014 Dec 17. PMID: 25551016; PMCID: PMC4279055. [Accessed October 2023]

[ix] Kligman S, Ren Z, Chung CH, Perillo MA, Chang YC, Koo H, Zheng Z, Li C. The Impact of Dental Implant Surface Modifications on Osseointegration and Biofilm Formation. J Clin Med. 2021 Apr 12;10(8):1641. doi: 10.3390/jcm10081641. PMID: 33921531; PMCID: PMC8070594.[Accessed October 2023]

[x] Hamdan S. Alghamdi, John A. Jansen, The development and future of dental implants, Dental Materials Journal, 2020, Volume 39, Issue 2, Pages 167-172, Released on J-STAGE March 31, 2020, Advance online publication January 22, 2020, Online ISSN 1881-1361, Print ISSN 0287-4547, https://doi.org/10.4012/dmj.2019-140, https://www.jstage.jst.go.jp/article/dmj/39/2/39_2019-140/_article/-char/en [Accessed October 2023]

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I often talk about the opportunities afforded by digital technology in dentistry and in the wider healthcare sector. In particular, the advent and development of artificial intelligence (AI) offers significant potential for dental professionals and patients alike. An area I have not discussed at length before is the impact that AI-supported workflows can have on the patient-practitioner relationship.

I was interested to read the results from a new survey[i] that suggested AI could have a significant impact on patient perceptions of their dental care.

The idea is that AI-assisted technology validates the dentist’s diagnosis and consequent recommendations in the eyes of the patient. When looking at why patients trusted AI, the poll found that 44% believed it to facilitate less invasive treatment and 37% thought it would save them money. There was also a feeling among 32% of people surveyed that AI would avoid overdiagnosis, while 31% thought it would help to prevent systemic disease.

Overall, the survey found that 53% of participants were open to the use of AI in dentistry, and this increased to 59% when they understood that AI helps to catch issues early or lowers the need for invasive dental treatment in the future. Interestingly, the results demonstrated differences in opinion between age groups. Approximately 65% of baby boomers were more likely to trust their dentist’s decision with AI support, compared to the average of 59% across all participants. As might be more expected, millennials were most likely to trust AI in all categories and for all reasons.

So, what does this mean for us dental teams on the ground? That AI could well provide an effective tool in enhancing the patient-practitioner relationship and encourage treatment acceptance. If our patients are more comfortable with their diagnoses and our professional advice because an AI-assisted programme – which they deem unbiased – agrees, then this could help them accept the treatment that they need for better oral health.

Many of us already use some form of AI in the practice, but how much do we really promote this to patients? Could we do more to show them that we have technologies in place to double check our findings and provide checklists that ensure the accuracy and completeness of our treatment plans? Maybe a simple conversation about the equipment that we use to take and interpret radiographs, or the software utilised for treatment simulations and planning could inspire their confidence in us.

Patient trust is essential for the delivery of high-quality dental care. Only if they feel comfortable with our advice will they follow instructions and accept treatment recommendations. If AI can help us put their minds at ease, it could be a very useful tool indeed.

Dr Michael Sultan Bio:

EndoCare, led by Dr Michael Sultan, is one of the UK’s most trusted Specialist Endodontist practices. Through the use of the latest technologies and techniques, the highly-trained team can offer exceptional standards of care – always putting the patient first. What’s more, EndoCare is a dependable referral centre, to which dentists from across the country send their patients for the best in specialist endodontic treatment.

[i] Videa health. Poll: More than 90% of Americans know dental disease can increase potential risk for disease, and yet nearly 1 out of 2 have declined or delayed treatment. Business wire. https://www.businesswire.com/news/home/20231211171536/en/Poll-More-than-90-of-Americans[%E2%80%A6]d-Yet-nearly-1-out-of-2-Have-Declined-or-Delayed-Treatment [Accessed December 2023]