Short Implants and their role in prosthetic replacement of missing tooth

This is an seminar on short implants related to implant dentistry .
This gives the insight on what has happened since the evolution of short implants and its role in implantology .Their role as replacement of missing tooth in the atrophied maxillary and mandibular posterior regions

1. Short Implants Presented by Dr S M Sivaraman PG IInd year

2. Contents

3. Introduction What are short implants?

4. Short implant In place! A) Preoperative cone beam computed tomography scan of a missing left first molar showing 9.5 mm of available bone above the inferior alveolar nerve. ( B) Soft tissue healing 2 months after the placement of a short-length implant (8 mm in length and 5 mm in diameter). ( C) Periapical radiograph 3 years after loading. ( D) Clinical view of the prosthetic restoration after 3 years of loading

5. History When?

6. Indications In areas of reduced height such as maxillary posterior and mandibular posterior region following tooth extraction. Severely resorbed edentulous mandible To support single and multiple fixed restoration in the posterior jaws What is the need for short implants?

7. Merits The main advantage of using short implants is that it simplifies the implant surgery by avoiding the more invasive procedures like bone grafting, sinus lifting, nerve repositioning , etc., and thus decreases morbidity and reduces the healing period It reduces the duration period of the treatment and the cost factor. The poor quality of bone in the posterior region especially in the maxilla where short implants are mostly used is another contributing factor. What are the advantages?

8. Risk Factors Existing periodontal disease Smoking habits Age factor Systemic diseases What are the risk factors?

9. Implant Length Selection Over years the longest implant possible is always placed to improve the stability and crown to root ratio and bone to implant contact Nowadays bone to implant contact may also be improved by the use of micro rough surfaces. Adequate implant primary stability can be achieved through adapted surgical preparation and new implant designs. There are clinical situations in which the entire available bone should not be used instead the surgeon should do three dimensional plan for implant placement with limited resources. What is the ideal length?

10. Implant diameter Increasing the diameter of the implant is an effective method to increase the implant surface area. Wider diameter short implants will have increased FSA and improved primary stability . It allows engagement of a maximal amount of bone and better distribution of stress in the surrounding bone. An increase in the diameter reduces stress at the implant neck and is associated with good distribution of force compared with increases in implant length. Implant strength and fracture resistance can be improved by increasing the diameter of the implant. Wider implants also facilitate the creation of a better emergence profile, especially in the posterior segment. An increase in diameter by 1 mm will increase the surface area by 30–200% depending on the implant design . What is the role of implant diameter?

11. Surface topography Most of the earlier studies using short implants showed less favorable results as compared to longer implants because of the use of machined surface implants. The fact that alteration of the implant surface can influence the success of Osseo integration has been proven in various studies. This can be achieved by either subtractive processes like blasting , etching and oxidation, or additive processes like titanium plasma spraying, hydroxyapatite and other calcium phosphate coating and ion deposition Rough implants offer extensive area for Osseo integration. It increases the BIC and FSA in addition to improve the wettability of the implant surface. What is the role of surface topography?

12. Photo functionalization of implants Treatment of implants with ultraviolet (UV) light has been found to increase the BIC from 55% to near maximum level of 98.2%. This resulted in 3-fold increase in the strength of Osseo integration. This increase is attributed to the generation of super hydrophilicity, a significant decrease in surface hydrocarbons, and improvement in the electrostatic status of titanium surfaces after UV treatment. The biological effects along with UV-enhanced surface properties are collectively defined as photofunctionalization of titanium implants . What is the effect of photo functionalization on implants?

13. Macro geometric desig n Modifications in the macro geometry of the implant are advantageous in providing more area for BIC and FSA. Various thread shapes such as square, v-shaped , and reverse buttress are available for implants of which square threads provide more surface area for a given length of the implant. Increasing the number of threads per unit area (decreased thread pitch) and increasing the thread depth also enhance the FSA of short implants. Role of macro geometric design

14. Continued Macro geometry

15. Bone density Bone density is directly proportional to its strength. Less dense bone may demonstrate a reduction of its strength by 50-80% compared to higher density bone. Poor bone quality is strongly linked to higher failure rates in implants. Increased failure rates of short implants in the early trials were attributed to the use of machined implants in poor quality bone, especially in the posterior maxilla . This negative effect is somewhat dampened by rough surfaced implants now. Use of self-tapped implants has also brought down the failure rates. Use of bone expanders/condensers during osteotomy procedure also improves the bone density and there by increases the success of a short implant. Role of bone density

16. Crown - Implant ratio Anatomical and Clinical Crown to Implant ratio Güngör H ( 2016) studied the effects of C/I ratio using a 3-D finite element analysis on stress distribution both in bone and implant under axial and oblique loads. They found that the high C/I ratio affected both cortical and cancellous bone along with the implant under oblique and axial load with more stress under oblique load when compared to axial load.

17. Continued It has been proposed by Misch , that the higher the crestal stress, the higher the risk of crestal bone loss, and the higher the stress factor throughout the implant, the greater the risk for implant failure. Increasing C/IR amplifies the moment arm for any offset occlusal loads T echnical complications resulting due to increased CIRs are loosening of the screw, decementation of the crown, food accumulation in the interdental spaces and occlusal strain. And the biological hitches include peri-implantitis, formation of deep pockets, poor oral hygiene, pain, swelling, bleeding gums and transient paresthesia. Crown implant ratio

18. Continued Increased crown implant ratio (CIR) is a major concern with short implants. A 1:1.5 crown root ratio is suggested as most favorable and 1:1 as a minimum for a tooth abutment. short implants and the ideal CIR has not been established. Various studies have demonstrated high success rates with a CIR of up to 2 and increased CIR did not result in additional peri-implant bone loss . This was possible by giving due considerations for various stress reduction methods like avoiding lateral loads, cantilevers, etc. Crown to implant ratio

19. Increased Crown to implant ratio

20. Stress repartition and crown to implant length ratio A dogma states that the prognosis of abutment teeth and prosthetic rehabilitation is related to the crown-to-root ratio. According to this statement, it is assumed that for successful prosthetic rehabilitation the crown-to-root ratio should always be ≤1 . These guidelines are emprically used for implants According to the definition provided by Blanes et al ., two types of crown-to-implant ratio can be established 1.The anatomical crown-to-implant ratio; and 2.The clinical crown-to-implant ratio What is stress repartition?

21. Survival rate of short implants Annibali et al. 2012 in their systemic analysis and meta-analysis of short implants (less than 10mm) concluded that t he provision of short implant-supported prostheses in patients with atrophic alveolar ridges appears to be a successful treatment option in the short term; however, more scientific evidence is needed for the long term ’. Jokstad . 2011 in his systematic review of short implants ( less than 10mm) concluded that t here is growing evidence that placement of short (< 10 mm) implants can be successful in the partially edentulous patient. Survival rate

22. Survival rate Survival of the fittest Neldam & Pinholt (2012) in their systematic review on short implants ( ≤8 mm) concluded that Short implant length was not related to observation time, installment region, failures, and dropouts were not specified ; subsequently, it was not possible to perform a meta-analysis Renouard & Nisand (2006) in their structured systematic review concluded that The use of a short implant may be considered in sites thought to be unfavourable for implant success, such as those associated with bone resorption or previous injury and trauma. Whilst in these situations implant-failure rates may be increased, outcomes should be compared with those associated with advanced surgical procedures such as bone grafting, sinus lifting and the transposition of the alveolar nerve’

23. Short vs Long Felice et al (2011) in their Randomised controlled trial using short implants, long implants, sinus lift procedure concluded that Significantly more complications occurred in augmented patients. Their pilot study suggests that short implants may be a suitable, cheaper and faster alternative to longer implants placed in augmented bone. Survival rate?

24. Short implants vs Long implants Uehara P N et al (2018) in their meta – analysis of Randomized controlled trials to compare the marginal bone loss and survival rate of short implants with long implants in augmented bone areas of posterior atrophied maxilla and concluded that short implants had a similar survival rate as that of the longer implants placed in the bone augmented areas. They also concluded that short implants is a predictable alternative for rehabilitation of atrophied posterior regions. Survival rate?

25. Biomechanical methods of stress reduction Biomechanical methods to decrease the stresses to short implants are a critical factor in deciding the success of the treatment. These include decreasing force to the implant prosthesis and increasing implant surface area of prosthesis support

26. Stress minimizing surgery In 2011, the European Association of Dental Implantologists concluded its consensus conference on short implants with the following recommendation to avoid complications : ‘the implant surgeon and restorative dentist should have adequate clinical experience ’ The factors in consideration are 1.Experience 2.Non technical human factors 3.Morbidity

27. Experience Studies of neurocognitive activity show that the part of the brain that manages both complex and novel procedures lies in the prefrontal cortex, the most anterior region of the brain. Tasks utilizing the prefrontal cortex require conscious effort and, importantly , consume vast cognitive resources. Complex tasks, such as surgical procedures, as well as tasks that are unfamiliar, require the prefrontal cortex to remain active and the brain’s full resources to remain accessible. However, under some conditions, specifically stress, fatigue and burnout, this access becomes impaired . How experience of the practitioner plays a crucial role?

28. Role of experience Increase in experience Errors are narrowed down and the procedure is made in to simple.

29. Non-technical human factors Many nontechnical parameters, such as stress, fatigue, overconfidence and the lack of preparation or organization, can influence the outcome of a procedure. Stress is probably one of the complicating factors shared most widely by dental and maxillofacial surgeons. It is difficult for most practitioners to manage both the technical and emotional aspects of a patient who is usually under local anaesthesia. Role of non-technical human factors

30. Stress stress as a conflict of resource mobilization and accessibility: when knowledge exists but it is not immediately available when needed, stress occurs.

31. Morbidity Morbidity as a factor

32. Morbidity Short implants

33. Conclusion Short-length implants can be successfully used to support single and multiple fixed reconstructions in posterior atrophied jaws, even with increased crown to implant ratios. The use of short-length implants allows treatment of patients who are unable to undergo complex surgical techniques for medical, anatomic or financial reasons. Moreover, the use of shortlength implants in clinical practice reduces the need for complex surgeries, thus reducing morbidity, cost and treatment time

34. References Nisand D, Renouard F. Short implants in limited bone volume. Periodontol 2000. 2014;66:72–96. Shah AK. Short implants - When, where and how?. J Int Clin Dent Res Organ 2015;7:132-7 . Shetty S, Puthukkat N, Bhat SV, Shenoy KK. Short implants : A new dimension in rehabilitation of atrophic maxilla and mandible. J Interdiscip Dentistry 2014;4:66-70 . Blanes RJ. To what extent does the crown-implant ratio affect the survival and complications of implant-supported reconstructions ? A systematic review Clin Oral Implants Res 2009: 20( Suppl 4): 67–72 . Felice P, Checchi V. Bone augmentation versus 5-mm dental implants in posterior atrophic jaws. Fourmonth post-loading results from a randomised controlled clinical trial. Eur J Oral Implantol. 2009;2:267– 81 .