Case Report
Success is not about Height; Short Implants: A Case Report 
,
Ruparani Bodduru1 
,
Motilal Jangid1 ,
Abhishek Singh Nayyar2 2 Department of Oral Medicine and Radiology, Saraswati Dhanwantari Dental College and Hospital and Post-Graduate Research Institute, Maharashtra, India
Author Correspondence author
International Journal of Clinical Case Reports, 2016, Vol. 6, No. 20 doi: 10.5376/ijccr.2016.06.0020
Received: 14 May, 2016 Accepted: 23 Aug., 2016 Published: 25 Aug., 2016
Khushboo D., Ruparani B., Motilal J., and Abhishek S.N., 2016, Success is not about height; short implants: A Case Report, International Journal of Clinical Case Report, 6(20): 1-7 (doi: 10.5376/ijccr.2016.06.0020)
During the past decades, implant treatment has been a successful option for tooth replacement. After tooth loss, however, severely atrophic residual alveolar ridges are quite common, especially in patients who have been edentulous for a longer period of time. Posterior areas of the maxilla and mandible are areas of greater anatomical constraints. Lots of research and advances have occurred in field of Oral Implantology and short dental implants are one of them. But success rates for these short dental implants were also considered dubious. Most important factor that was to be considered was crown-implant ratio. Over the period of time and with improvisation of implant designs, even short dental implants have provided predictable results. The purpose of this case report is to reveal success journey of short dental implants.
Introduction
During the past decades, implant therapy has been a successful option for tooth replacement. After tooth loss, however, severely atrophic residual alveolar ridges are quite common, especially in patients who have been edentulous for a long period of time. Posterior areas of the maxilla and mandible have greater anatomical limitations. Reduced alveolar bone height is a definite constraint to implant therapy, unless a procedure such as ridge augmentation or sinus floor elevation is performed. These techniques imply greater morbidity, longer treatment times and higher costs. Sinus cavity in the maxilla and inferior alveolar nerve proximity in the mandible are the definite anatomical constraints where short dental implants may be considered as an alternative treatment option. Short dental implants reduce surgical risk of sinus perforation and mandibular paresthesia with an overall reduction in surgical complications. The use of short dental implants, in the posterior regions, reduces the need for bone augmentation procedures prior to or in conjunction with implant placement in maxilla and mandible. Due to the decreased length of the drills and implants, the osteotomy preparation implies lesser risk of overheating the bone. In case of apical root proximity, short dental implants can be the only possible choice. In short, short dental implants reduce treatment time, complications as well as the overall costs related to the graft procedures (Misch, 1999). All these factors make short dental implants a highly attractive restorative option. Most of the authors consider implants with length lesser than 10mm as short implants (Deporter et al., 2005; Misch et al., 2006; Tawil et al., 2006; Morand and Irinakis, 2007; Nisand and Renouard, 2014). Some researchers stated that short dental implants are those with length equal or smaller than 10mm (Gentile et al., 2005). Other researchers believed that short dental implants should have length smaller than 8mm and implants with implant length less than 5mm are to be considered as extra-short implants (Renouard and Nisand, 2006). Again, despite being advantageous in a plethora of clinical situations, there are several studies which state that reducing implant height is also associated with increased implant failures. The common reasons cited for failure of short dental implants, used commonly in maxillary and mandibular posterior areas because of severe anatomic constraints, include a higher bite force, bone density in the region and increased crown height (Misch, 1999). Herein, we are presenting one such case wherein short dental implants were placed in a situation with obvious anatomic constraints and they proved successful.
1 Case Report
A 39 year old female patient reported to the Department of Periodontics and Oral Implantology with missing upper right back teeth (Figure 1) since 3 years and wanted replacement of the same. All treatment options including fixed partial denture, removable denture and implants were explained to the patient wherein the patient opted for implant-supported rehabilitation of missing maxillary right posterior teeth. Cone Beam Computed Tomography (CBCT) scan of 14, 15, 16 region was advised (Figure 2). Dimensions of bone available included a mesio-distal length of edentulous segment to be of 23mm; crown height space of 5 mm in 14, 7 mm in 15 and 5 mm in 16 region; bucco-lingual width of 5.1 mm in 14, 4.6 mm in 15 and 4.7 mm in 16 region; and an alveolar bone height of 12.3 mm in 14, 10.1mm in 15 and 8.9mm in 16 region (Figure 3). So, it was decided to place implants of dimensions 3.75/ 11.5, 3.75/ 8, and 3.75/ 8 in the 14, 15 and 16 regions. A mid-crestal incision followed by a crevicular incision was given in edentulous ridge in 13 till 17 region. A muco-periosteal flap was reflected from 13 till 17 region using a periosteal elevator (Figure 4). Then, osteotomy sites were prepared using drills in sequential manner in 14, 15, 16 region and implants were placed in respective osteotomy sites followed by cover-screws placement (Figure 5a; Figure 5b; Figure 5c). Sutures were given to close the flap (Figure 6). Patient was advised to take antibiotic (amoxicillin with clavulanic acid, 625 mg, TDS) and anti-inflammatory (ketoprofen, 100 mg, TDS) for five days. Patient was also asked to rinse with chlorhexidine 012% twice daily. Patient was re-called after a week's time for suture removal. Three months after implant placement, patient was re-called again for second stage of the procedure and placement of healing abutments (Figure 7). The patient was then re-called after fifteen days of the second stage procedure and impression was taken (Figure 8) and sent to laboratory along with abutments and lab analogue. A trial was then taken after ten days and final prosthesis was given after that (Figure 9). Splinting of implants was done for dissipation of lateral forces and better biomechanical design. The patient was then re-called after one month of prosthetic loading to check occlusal discrepancies, if any, and overall status of the prosthesis. IOPARs were taken at 1 month, 6 months and 1 year follow-up visits after prosthesis delivery to check for the bony changes around implants although no bony changes including resorptive changes were noted and patient was satisfied with the prosthesis.
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Figure 1 Missing upper right back teeth |
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Figure 2 Cone Beam Computed Tomography (CBCT) scan of 14, 15, 16 region |
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Figure 3 Dimensions of bone available |
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Figure 4 Muco-periosteal flap reflected from 13 till 17 region |
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Figure 5a Osteotomy sites being prepared using drills in sequential manner in 14, 15, 16 region |
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Figure 5b Implants placed in respective osteotomy sites |
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Figure 5c Cover-screws placed over Implants |
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Figure 6 Sutures given to close the flap |
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Figure 7 Placement of healing abutments after three months of implant placement |
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Figure 8 Impression taken after fifteen days of placement of healing abutments |
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Figure 9 Final prosthesis given after a trial was taken after ten days |
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2 Discussion
It has always been considered that more the height of the implants selected, more is the success rate of the treatment. Advantages of increased implant length include increased initial stability, long-term resistance to bending moment forces and decreased risk of movement at the interface (Misch, 1999). In 2004, Feldman S et al compared the 5-year survival rate of short dental implants with acid-etched surfaces to short, machined-surfaced implants. Survival rates were 97.7% and 91.6%, respectively (Feldman et al., 2004). Bahat O placed 732 implants in the posterior maxillae of 213 partially edentulous patients and reported a failure rate of 9.5% for 7mm implants as compared to a mere 3.8% for all other lengths. Patients were evaluated after a 5-to 70-month follow-up period, with a mean of 30.3 months (Bahat, 1993). Van et al (1990) found that longer and/or wider implants failed to a lesser extent as compared to shorter, standard implants (7, 10 and 13 mm lengths) in a prospective study involving 558 implants placed in 159 partially edentulous patients, however, he also concluded that failures appeared more in patients with poor bone quality. In a retrospective study, Scurria et al. (1998) concluded that shorter implants and implants with diameters less than 4 mm have a decreased survival probability. A total of 384 implants were placed and subsequently supported 108 prostheses. Short dental implants experienced lower survival (higher failure rates) when compared with longer implants in another study conducted by Sheldon W et al. (Sheldon et al., 2000). A review of literature related to implant failures and length published by Goodacre et al. in 2003 stated that implant smaller than 10 mm have increased failure rates (Misch, 1999). There are only a few studies which state that even short dental implants have good success rates and that disadvantages of short dental implants could be compensated by increasing the diameter, splinting of the implants together, decreasing crown height, decreasing the cantilevers used, increasing the surface area and exerting minimum lateral forces (Misch, 1999). Over a 6-year period, ten Bruggenkate CM et al placed 253 short implants (6 mm in length) in 126 patients who were then followed-upto for 1-year to 7-years Survival of the short dental implants was comparable with the longer implants from the same implant system. Although the clinical results of the 6mm implants were favorable, the authors recommended that short dental implants be used in combination with longer implants, especially in less denser bone (ten Bruggenkate et al., 1998). According to Jensen O, osseo-integrated 7mm implants were supposed to have a better prognosis than longer implants without cortical continuity (Jensen, 1989). Friberg B et al found the 5-year survival rate to be 95.5% for a cohort of short Brånemark system implants (Friberg et al., 2000). Davarpanah M et al found a success rate of 98.4% at a 3-year follow-up of short Osseotite implants (Davarpanah et al., 2001). Fugazzotto PA et al in 2004 evaluated 7 to 9mm long implants placed in posterior regions of maxilla and showed a success rate of 95.1 % up to 84-months of function (Fugazzotto et al., 2004). Hagi D et al, in their study, concluded that dental implant surface geometry played a major role in implant success (Hagi et al., 2004). Sintered porous surfaced implants performed well compared to threaded implants in short lengths. Finite Elemental Analysis (FEA) has demonstrated that horizontal and vertical occlusal forces placed on implants were distributed primarily in the crestal bone rather than along the entire implant/bone interface. Lum LB concluded that short dental implants served as well, as longer ones, based on FEA (Lum, 1991). After osteo-integration, the crestal bone received the majority of the occlusal load (Lum, 1991; Matsushita et al., 1990; Holmes et al., 1997). Arlin ML evaluated 630 implants and found a success rate of 94.3% for 6mm length implants; for 8mm length implants, success rate was 99.3%; and for 10-16mm length implants, a success rate of 96.9% was found during a 2-year follow-up period. 11 losses occurred in implants placed into type II or IV bone. The two 6.0mm length implants lost during osseo-integration phase had been placed into type IV bone. By comparing bone augmentation and longer implants to shorter implants’ placements, the latter was found to be simpler, less time-consuming, cost-effective, and with low morbidity (Arlin, 2006). Romeo E et al assessed the clinical efficacy of different size implants (8-10mm length and with 3.75, 4.1, 4.8mm width). Success rates during 14-years follow-up period for all standard and short dental implants reached 97.9% and 97.1%, respectively. Thus, it could be concluded that placement of varied size implants did not compromise implant success in the population studied (Romeo et al., 2006). In the study conducted by Griffin TJ et al, 168 implants (6x8mm) with hydroxy-apatite treated surface, were placed in 167 patients. Success rate was found to be 100% in a following-up period of 68-months (Griffin et al., 2004). Gentile MA et al investigated the success rate of Bicon TM short implants (6x5.7 mm) compared to longer implants. After a 12-months' follow-up, success rate reached 95.2% for shorter implants and an equal success rate for long implants without statistically significant differences (p=0.78). The results showed short dental implants to be equally effective as standard implants (Gentile et al., 2005). Barboza E et al assessed the clinical performance of short dental implants (220, 9mm length; 128, 10mm length with diameter of 3.5, 4, or 5 mm), during a 6-year follow-up study. Success rate reached 96% (334 implants). The results obtained proved that short dental implants could be used safely for supporting prosthesis in the rehabilitation of lost teeth displaying success and longevity rates similar to longer implants (Barboza et al., 2007). Maló P et al found short dental implants placed into atrophic mandibles provided results similar to the longer implants placed into higher bone volumes (Maló et al., 2007). According to Misch, implant diameter is more important than height (Misch, 1999). An increase in surface area is more dependent upon implant diameter than length once maximum length has been determined as early bone loss and complications relate mainly to crestal bone regions since horizontal and vertical occlusal forces placed on implants are supposed to be distributed primarily in the crestal bone rather than along the entire implant/bone interface as demonstrated by Finite Elemental Analysis (FEA). Reduced alveolar bone height can limit the use of implants. More dense bone can accommodate a shorter implant while in less dense bone, a longer implant is more favorable. However, some risk factors, such as increased crown height and higher bite forces, might increase stress when using short dental implants. To improve the biomechanical situation in such cases, it is necessary to find methods that reduce forces on the implants. Eliminating or minimizing the lateral force on the prosthesis and force distribution from splinting multiple implants plays a significant role in reducing stress on implants (Misch et al., 2006). Anitua E et al conducted a study on 1287 implants less than 8.5mm in length placed in 661 patients in a 7-year follow-up study finding a 99.3% implant survival rate with a mean follow-up period of 47.9 months and concluding that short dental implants were safe and predictable (Anitua and Orive, 2010). Another study published by Koo KT et al in 2010 reported a cumulative one-to-five-year survival rate of 95.1% with no statistically significant difference between maxillary and mandibular placement for one or two-stage implants and short or longer implants (Koo et al., 2010). Telleman G et al evaluated the estimated implant survival rates of short (<10 mm) dental implants placed in partially edentulous patients through a systematic review of the literature and analyzed a total of 2611 short implants (5-9.5 mm in length). they concluded a fair evidence that short (less than10 mm) dental implants could be placed successfully in partially edentulous patients although with a tendency towards an increasing survival rate per unit of implant length (Telleman et al., 2011). Karthikeyan I et al systematically evaluated the publications published between 1991 and 2011 in relation to short dental implants (≤7 mm length) placed in the maxilla and mandible and included 28 studies representing one randomized controlled trial, 12 prospective and 10 retrospective studies and concluded that the survival rate of short dental implants increased gradually from 80% to 90% with recent studies showing upto 100% success rates (Karthikeyan et al., 2012).
3 Conclusion
Implant design and properties and the surface condition of implants might modify the percentage of bone-implant contact which in turn implies, greater the percentage of bone contact, lesser the stress, applied to the bone-implant interface. Over the period of time, implant designs has undergone lot of changes and implant surface texture has also changed from smooth machined surface to rough acid etched, sand blasted and plasma sprayed surface. These changes might be considered responsible for the increased success rates of short dental implants observed in the recent studies. The short dental implants used in this case report had rough, acid-etched surface that showed significantly greater bone-implant contact compared to machined or polished surfaces.
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