Private Practice New York, New York, USAUnited States
Columbia University College of Dental Medicine, New York, USAUnited States
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Placing an implant to replace missing teeth can be challenging because of lack of vertical and/or horizontal bone ridge, maxillary sinus pneumatization and inferior alveolar nerve position. Additional surgical procedures may be necessary, with varying predictability, where vertical augmentation being the least predictable. An alternative option is to place short implants and exclude the additional surgical grafting procedures. By reviewing studies, this paper explores the predictability of the short implants for use in the methods. Bicon SHORT® implants are available in 5 and 6 mm lengths and seem to be able to overcome such limits but more long-term studies are still needed to determine long-term prognosis and success of short implants in terms of them being comparable or equal to longer or standard length implants.
Keywords: Short implants; Bone augmentation; Ridge height; Implant length; Implant width
Placing an implant to replace missing teeth can be challenging because of lack of vertical and/or horizontal bone ridge, maxillary sinus pneumatization and inferior alveolar nerve position. Additional surgical procedures may be necessary, with varying predict- ability, where vertical augmentation being the least predictable. An alternative option is to place short implants and exclude the additional surgical grafting procedures. By reviewing studies, this paper explores the predictability of the short implants for use ® in the methods. Bicon SHORT® implants are available in 5 and 6 mm lengths and seem to be able to overcome such limits but more long-term studies are still needed to determine long-term prognosis and success of short implants in terms of them being comparable or equal to longer or standard length implants.
Keywords Short implants; Bone augmentation; Ridge height; Implant length; Implant width.
INTRODUCTION aforementioned surgical procedures. One such study by Scarano et atients lose their teeth for various reasons such as caries, peri- odontal disease or trauma. When patients are missing a tooth/ this paper is to explore the predictability of the placement of short P teeth, they have several options for replacement, such as remov- implants to replace missing teeth. able dentures, fixed prostheses and endosteal implants. Which op- tion is best for the patient depends on several factors such as oral MATERIALS AND METHODS anatomy, esthetics and finances. Implants are often appealing to patients because of their ability to closely mimic a natural tooth in Papers were chosen from those published between 2012 through terms of appearance and function. However, placing an implant 2021. Studies needed to include placement of short implants. Ad- can be challenging because of bone ridge height and/or width, ditional maxillary sinus pneumatization and position of the inferior alve- plants, a olar nerve, and these may require additional surgical procedures such as maxillary sinus membrane elevation, and bone graft, dis- traction osteogenesis, guided bone regeneration, onlay bone graft and displacement of the inferior alveolar nerve. With these pro- cedures, there can be additional complications such as infection, sinus membrane perforation, flap dehiscence and post-operative 1 literature. In an attempt to propose a classification scheme, they pain. The predictability of success of these procedures is also variable. Vertical bone grafting is the most unpredictable since the patient after the procedure still may not have gained enough bone height to position a standard-size implant. An alternative option is to place a short implant, which may exclude the need for the cc Copyright 2021 by Fine JB. This is an open-access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0), which al4 showed no complications and predictable rehabilitation of the atrophic posterior mandible with short implants. The purpose of criteria could include comparison to standard length im- range of prosthesis and placement in grafted bone sites.
Studies Al-Johanny et al tried to propose an implant design based clas- sification system classifying for implant design, length and diam- eter of implants to try to standardize terminology in the scientific 2 looked at 1) clinical studies, 2) intervention studies based on im- plant length and/or diameter, 3) studies that clearly stated the mea- 3 surements and names of their implants and 4) studies based on the implant systems of some manufacturers which are listed in Table 1. Based on the terms used most frequently, they made a classifica- ure from the end (base) to the neck of the implant regardless of tion with Extra-narrow, Narrow, Standard and Wide in regards to the length of the platform. The main advantage to this classifica- implant diameters and Extra-short, Short, Standard and Long in tion is to allow for standardization in communication and research regards to the implant length as listed in Table 2. The diameter was and allows comparisons of study results and methodologies. Limi- defined as the width of the implant at the neck area regardless of tation of this study is that it was difficult to create a systematic ap- the diameter of the platform. The length was defined as the meas- proach to answer the question (replacement of missing teeth) and
Table 1. Table 1. Implant Systems 5 ones, so it’s better not to include in vitro studies) studies were not • Straumann (Andover, MA, USA) included and therefore other implants may also have been over- • Astra Tech (Mölndal, Sweden) looked. The authors advice this classification for future studies.
• Nobel Biocare (Kloten, Switzerland) • XiVE (Mannheim, Germany) • OsteoCare (Berkshire, UK) • Camlog (Basel, Switzerland) • Zimmer (Carlsbad, CA, USA) • 3MESPE (3M,St.Paul,MN, USA) with high failures rates because of a smaller bone to implant con- • ANKYLOS (Mölndal,Sweden) tact and • Bicon (Boston, MA, USA) been conducted comparing the in vivo placement of short implants • BioHorizon (Birmingham, AL, USA) to the placement of standard length implants with additional surgi- • IntraLock (Boca Raton, FL,USA) cal grafting procedures.
• MIS (Vienna, Austria) • BIOMET3i (Carlsbad,CA,USA)
Table 2. Table 2. Implant Classification Measurements • Diameter bone quality and risk factors, such as smoking, age and periodon- o Extra-narrow: <3 mm tal disease. A resorbed mandible of any bone quality with a ridge o Narrow: ≥3 mm-<3.75 mm height <8 mm will need advanced surgical procedures, while a re- o Standard: ≥3.75 mm–<5 mm
o Wide: ≥5 mm • Length o Extrashort: ≤6 mm mend a sinus lift procedure where the ridge height is <5 mm and in o Short: >6 mm-<10 mm type IV o Standard: ≥10 mm-<13 mm short implants where the ridge height is ≥6 mm in any bone quali- o Long: ≥13 mm
Table 3. Table 3. Biomechanical Considerations 1. Diagnostic a. Implant diameter–wider implant will increase the primary stability and functional surface area at the crest bone level.
b. Crown/implant ratio–improvements of surfaces and implant systems allow high crown/implant ratio. c. Bone quality–primary factor for short implant success.
d. Lack of cantilevers–eliminating cantilevers favors biomechanics.
e. Number of implants–multiple implants will increase functional surface area.
f. Implant design–surface area can be increase by: i.Thread number–more ii.Thread depth–deeper iii.Thread shape–square has higher bone implant contact iv. Implant surface–rough microtopography 2. Surgical a.Two step–advocated for short implants because it provides good stability during healing phase. b. Adapted surgical protocol–possibly eliminated steps in standard surgical protocol such as countersink or final drill. 3. Prosthetic a. Implant to abutment connection–morse taper connection induces less marginal bone loss, internal hex implant abutment connection shows wider force distribution and platform switching maintains crest bone.
b. Occlusal table–small table reduces offset loads on implant.
c. Incisal guidance–should be similar to natural teeth.
d. Splinting–increase functional surface area or support and transmits less force to prosthesis. that animal (in vitro studies are far from the aim to set a predictable success rate of short implants compared with the standard length While there are multiple definitions for which length an implant is qualified as a short implant, for this paper it has been defined as less than 8 mm. Benefits of a short implant are a less invasiveness/more simplicity, shorter surgical time and lower mor- bidity rates and cost. However, short implants are often associated disadvantage in the crown to implant ratio. Studies have Jain et al7 summarized biomechanical considerations bro- ken into 3 categories: 1) diagnostic, 2) surgical and 3) prosthetic.
These three categories are further broken down (Table 3). They 5 also included Nisand et al8 guidelines for placement of short im- plants and additional surgical procedures based on bone height, sorbed mandible of any bone qualities with a ridge height ≥8 mm, can receive short implants. For the resorbed maxilla, they recom- bone where the ridge height is 5-6 mm. They recommend ties and where the ridge is 5-6 mm in bone type I, II, III bone. The above mentioned guidelines are applicable in ridges which are wide enough to place an implant of at least 5 mm in diameter. Their for treatment in the posterior maxilla and mandible based on sev- indications for short implants supported prostheses whether fixed eral parameters such as scientific evidence, operator surgical skill or removable were as follows: and experience and patient’s preference. For the posterior max- 1. Single and multiple fixed prosthesis in posterior jaw (mandible). vertical bone height: 1) ) in case of 6-8 mm of bone, short den- 2. Four short implants for an overdenture or 6 short implants for tal implant and 2) ) in case of >8 mm of bone , standard length a fixed prosthesis in the severely resorbed edentulous mandible. implant with transcrestal sinus floor membrane elevation. For the 3. Two short distal to longer implants placed in the premaxilla for posterior mandible based on vertical bone height: 1) in case of 10 a maxillary overdenture or fixed prosthesis. mm, standard-length implant. They feel that short dental implants Their conclusions were: short implants can be successful when the biomechanical factors and clinical protocols are taken A Short into account in the pre-operative planning of intervention and prosthesis. A number of studies summarized in Table 5 find that short im- Goncalves et al9 developed a standard evaluation protocol surgery may be needed to augment the bone prior to placing a based on their systematic review of essential parameters required standard length implant. However, they also agree that more stud- to access the long-term clinical performance of short and extra ies need short implants. Their proposed protocol includes both surgical and prosthetic parameters of the patient and implant, both surgical and prosthetic (Table 4). It is advocated that it will help regiment fur- short implants are reserved for situations when there is a lim- ther investigations and help in the decision making process. ited amount of available bone height. Bicon SHORT® implants Thoma et al10 in a narrative review created a decision tree a bacterially-sealed, 1.5 degree locking taper abutment to implant
Table 4. Table 4. Patient and Implant Parameters 1. Biological parameters c.Type a. Plaque index d.Type of abutments b. Bleeding index e. Splinted c. Probing depth f. Prosthesis material d. Pain g. Cemented or screwed
2. Observation a. Parafunction b. Smoking habits c. Diabetes d. Alcoholism e. Osteoporosis f. Radiotherapy in head/neck 3. Implant parameters a. Brand b. Length c. Diameter d. Surface treatment e. Shape f. Abutment connection 4. Surgical parameters a. Bone level b. Location c. Bone density d. Insertion torque e. Loading protocol f. Primary stability g. Healing cap (submerged or transmucosal) h. Special surgical technique (mini sinus lift, split crest) i. Biomaterial illa they recommend the following choice as based on the residual have a number of advantages for the patient and clinician.
Implant System plants are a favorable option, especially in sites where an additional to be conducted and more long-term results are needed.
Bicon implant system32 has challenged the concept that ® are short dental implants in 5 mm and 6 mm height. They have 5. Prosthetic protocols a. Location b. Distance between implants of prosthesis h. Platform switching i. Cantilever length j. Occlusion 6. Radiographic parameters a. Anatomical crown length b. Implant length c. Crown height space d. Resorption e. Bone gain 7.Additional parameters (integrity of prosthesis) a. Major failures: i. Fracture of bridge ii. Fracture of implant iii. Infection iv. Implant mobility or removal v. Before loading vi. After loading b. Minor failures i. Fracture of retention screw ii. Fracture of esthetic veneering iii. Decementation
Table 5. Table 5. Summary of Studies
Reference No. of patients Grouping 11 60 edentulous patients total, Stellingsma et al Group 2-4 IMZ apical screws (lengths 13,15 each group 20 patients 12 60 partially edentulous patients, Long–1 to 3 submerged 9.6 mm or longer Felice et al each group 30 patients implants in vertically augmented bone Rossi et al 45 patients test Fan et al 60 patients group Total of 1269 patients who 15 1650 standard implants Lemos et al received a total of 2631 dental implants 33 patients-short implant (6 mm) group 16 20 patients-sinus floor elevation 45 implants inserted in each group Bechara et al (lateral technique)/standard length implant (≥10 mm) group 101 patients with partial Group short–6 mm length implants, 50 17 edentulism in the posterior patients, 67 implants Pohl et al maxilla and remaining bone Group long-11-15 mm length implants and height of 5-7 mm simultaneous sinus grafting, 51 patients, 70 18 Review–24 papers out of 253 Esfahrood et al papers selected Survival Rates and p value Cumulative 10 year implant survival rate: Group 1-transmandibular implant (base Group 1=76.3%; Group 2=88%; Group 3=98.8% plate,4 implant posts (8, 10 or 12 mm Between Groups 1 and 2- logrank test,p=0.068, not sig length) and 5 cortical screws) Groups 2 and 3–logrank test,p=0.009, sig; Groups 1 and 3–logrank test,p=0.0001, sig or 18 mm) implants in augmented bone Ten year retreatment rate: Group 3-4 short (length 8 or 11 mm) Twin Group 1=30%; Group 2=5%; Group 3=0% Plus IMZ implants Between Groups 1 and 2 and Groups 1 and 3–logrank test,p=0.007, sig Groups 2 and 3–logrank test,p=0.317, not sig Up to 5-years after loading: Long (n=25): prosthesis failures (patients)=5(5); Short–1 to 3 submerged 6.6 mm long Implant failures (patients)=5(4); Augmentation procedures=2 implants Complications (patients)=25(21); Short (n=27): prosthesis failures (patients)=5(5); Implant failures (patients)=5(3) Complications (patients)=6(6) 61 total inserted implants (long) and 60 total p value: inserted implants (short) prosthesis failures=1.00; Implant failures=1.00; Complications <0.0001 Both groups had statistically significant marginal peri-implant bone loss at loading, 1,3 and 5-years after loading (p<0.001) Survival rates after 5-years: 86.7% test; 96.7% control 60 moderately rough surface implants Radiographic bone levels around implants 30 implants (6 mm long, 4.1 mm diameter)– Median value: At time of surgery 30 implants (10 mm long, 4.1 mm diameter)– 1.8 mm test; 2.08 mm control;p<0.05 control At 5 year follow-up 2.23 mm test; 2.70 mm control;p<0.05 554 implants: Survival rate p=0.96, not significant 265 implants, 24 patients in short implant Complication rate p=0.02, significant, short group had lower complications compared to long group 289 implants, 36 patients in long implant Surgical time p<0.05, significant, shorter time for short group group Implant survival p=0.24, not sig Marginal bone loss p=0.06 not sig 981 short implants Complications p=0.08, not sig Prosthesis failures p=0.92, not sig IImplant survival rate at 3 years=100% short, 95% standard p=0.38, not sig Mean ISQ (implant stability quotient) Values: At placement=68.2 short, 67.8 standard,p=0.1 At delivery of final restoration=69.5 short, 69.4 standard,p=0.9 After 1-year=71.0 short, 71.5 standard,p=0.1 At 3-years=71.6 short, 72.4 standard,p=0.004, sig Mean MBL (marginal bone loss): At 1-year=0.14 mm short, 0.21 standard,p=0.006, sig At 3-years=0.20 mm short, 0.27 standard,p=0.01, sig Surgical time and cost significantly higher in standard group,p<0.0001 33 year follow-up – 94 patients with 129 implants Group short–45 patients, 61 implants Group long–49 patients, 68 implants Implant survival rate 100% in both groups Marginal bone level (MBL) changes -0.44 mm short, 0.45 long,p>0.05 MBL implant placement to 3 year follow-up 137 implants placed p= 0.974: Group short=-0.44+/-0.56 mm,p=0.000 Group long=-0.43+/-0.58 mm,p=0.000 MBL implants loaded to 3 year follow-up, p=0.110: Group short=-0.1+/-0.54 mm,p=0.636 Group long=-0.25+/-0.58 mm,p=0.004 implants Probing pocket depth at 3 year follow-up–significantly less short group, p=0.035 Plaque accumulation: At 1 year follow-up,p=0.098; At 3 year follow-up,p=0.262 Bleeding on probing: At 1 year follow-up, higher number of sites short group,p=0.034 At 3 year follow-up,p=0.380 Survival rate of short implants in the posterior edentulous maxilla is high and applying short implants under strict clinical protocols seems to be a safe and predictable technique 19 88 implants in 53 patients (33 sinus grafting-control group Bechara et al women, 20 men) 45 implants placed without grafting–test 20 45 partially edentulous patients 22 patients, 51 implants–augmentation group Pieri et al evaluated after 5-years 23 patients, 46 implants–short group Case report 21 1 patient with 2 failing 4.1x4 mm (2) Benatto et al zygomatic fixtures removed 4.8x6 mm (1) and replaced with 4 short 3.3x8 mm (1) implants 110 patients and 110 implants 3 of 6 or 10 mm length placed Svezia et al 105 implants: Internal hex=60 Conical connection=50 6 11 trials, 420 patients 911 dental implants Cruz et al Palacios et al 458 short implants, 488 regular implants 22 acid-etched (mod-SLA), soft tissue level Rossi et al 35 consecutive patients 637 short implants placed in Papaspyridakos 392 patients 23 Standard implants >6 mm et al 653 standard implants were inserted in 383 patients ISQ (implant stability quotient): Initial Sample=68; Control=66.8;Test=69.1;p=0.003 sig Notable increase over time 45 implants inserted simultaneously with Sample=1.8,p=0.001; Control=4.6,p=0.000 Test=3.2,p=0.000 Marginal bone level (MBL) changes group In sample during first year of loading=0.18,p=0.017 Later changes=0.06,p=0.5 Significant difference between first year of loading and later,p=0.000 Significant strong negative correlation between MBL changes during 3-year loading period and implant’s diameter, rho=-0.432,p=0.000 8 surgical complication in augmentation group vs none in short group, p=0.003 1 short implant failed before loading and 1 standard length implant failed 4-years after,p=1 8 biological and 2 prosthetic complications in augmentation group vs 3 biological and 3 prosthetic complications in short group,p=0.09 and p=1.0, respectively Mean marginal bone loss: 1.61+/-1.12 mm augmentation group; 0.68 +/- 0.68 mm short group p=0.0002 Straumann SLAactive: Patient had remission of sinusitis episodes and no other signs or symptoms. The extra short implants had excellent stability Success rate after 24-months similar between groups=98.3% (6 mm) vs 100% (10 mm),p=0.361 Final group: Success rate after 2-years similar between internal hex vs conical 105 patients connection=100% vs 97.7%,p=0.233 Statistically significant loss marginal peri-implant bone in both groups=0.38 6 mm=58 mm (6 mm) vs 0.43 mm (10 mm),p=465 10 mm=47 At 24-months, loss marginal peri-implant bone internal hex vs conical connection,p=428; Operator,p=0.875 Survival rate,p=0.86 Amount of marginal bone loss,p=0.08 Higher rates of bio complications for long implants associated with maxillary sinus aug,p<0.00001 Higher prosthetic complication rate for short implants,p=0.010 Implant failure rate,p>0.05 Mean differences of marginal bone loss, at loading p=0.18 Mean differences of marginal bone loss at 1-year follow-up, significant in short group,p=0.002 The marginal bone level variation from prosthesis delivering and 10-year follow-up ranged from -2.2 to 0.8 mm.
The mean bone loss for implants between the prosthesis delivery and the 2-, 5-, and 10-year follow-up period were -0.4 mm, -0.7 mm, and -0.8 mm, respectively.
Statistically significant differences were found between prosthesis Forty 6 mm modified sandblasted large-grit delivering and all periods (p<0.001) evaluated as well as between 2 and 5-years (p=0.013) and 5-10-years (p<0.001) implants were installed in the distal segments Bone level changes in mm (yearly visits) of 35 consecutive patients Prosthesis delivery—2 years=-0.4 (0.5) Prosthesis delivery—5 years=-0.7 (0.6) Prosthesis delivery—5 years=-0.6 (0.6) Prosthesis delivery—10 years=-0.8 (0.7) 5 years—10 years=-0.2 (0.4) p<0.05 between prosthesis delivery and the yearly visits.
Implant survival rate with a follow-up from 1 to 5-years Short implant survival rate ranged from 86.7% to 100%, Standard implant survival rate ranged from 95% to 100% Short implants ≤6 mm The risk ratio (RR) for short implant failure compared to standard implants was 1.29 (95% CI: 0.67, 2.50,p=0.45) The heterogeneity test did not reach statistical significance (p=0.67) The prosthesis survival rates short implant groups ranged from 90% to 100% longer implant groups ranged from 95% to 100% 24 50 patients 75 implants=30 in maxilla, 45 in mandible Anitua et al Two groups were identified: Short-short splinted group (SS), when both implants had 6.5 mm A total of 48 dental implants were placed in Anitua et al lengths 16 patients to support 24 two-implant fixed Short-long splinted group (SL), prostheses when one implant was longer than 6.5 mm.
26 225 patients Shi et al Group 2-8 mm implants+osteotome sinus 225 implants 27 62 extra short implants (5 and 6 mm) Amato et al 55 patients 28 50 ultra short sintered porous surface (5×5 Malchiodi et al 41 patients 29 One 4 mm implant failed to integrate Gašperšič et al 11 patients 30 Group 2-8 mm implants+osteotome sinus Shi et al 225 patients Five dental implants failed giving a survival rate of 93.3%.
All failures occurred in the mandible giving it a survival rate of 88.9%.
All failed implants showed an excessive marginal bone loss (>2 mm).The difference in the survival rate between the mandible and maxilla was not statistically significant (p=0.063) There was a statistically significant difference in the number of implants to which the short implant was splinted to.
The implants in the mandible were mostly splinted to one implant whereas in the maxilla they were splinted to 2 implants. p=0.000 Follow-up (months) 14±5 6.5-mm-long implant: Mesial bone loss (mm) 0.21±0.42 (SS); 0.51±0.88 (SL);p=0.949 Distal bone loss (mm) 0.37±0.55 (SS); 0.62±0.74 (SL);p=0.417 Splinting implant: Mesial bone loss (mm) 0.47±0.58 (SS); 0.36±0.67 (SL);p=0.688 Distal bone loss (mm) 0.37±0.55 (SS); 0.94±0.66 (SL);p=0.049 There were no statistically significant differences between the two groups regarding implant diameters of the extra-short (6.5 mm long) implants, p=0.255.
The diameter of the splinted implant was not statistically significant between the two groups,p=0.365 Significant differences regarding the lengths of the splinted implants, p<0.0001 Implant survival rates 3 groups with 75 implants each Group 1=96%; Groups 2 and 3=100% Group 1-6 mm implants alone No significant differences in implant stability quotient (ISQ) values, bleeding on probing (BOP), pocket probing depth (PPD), modified plaque floor elevation (OSFE) index (mPI) and marginal bone loss (MBL) were found among three groups. Group 3-10 mm implants+OSFE Significant higher value of intra-operative discomfort was found in group 6 mm (p=0.02).
Cumulative survival rates=99.3%; Standard=100% Extra short=98.4%; Short=100% Marginal bone loss (MBL) Implants immediately placed and loaded Extra short=0.35 +/- 0.24 mm, short=0.25+/-0.17 mm vs standard=0.92+/- 0.26mm,p<0.05 15 short implants (6.5 mm) Since extra short and short were platform switched, difference resulted 69 standard implants (≥10 mm) in absence (1.36 mm+/-0.19 mm) and in presence (0.48+/-0.32 mm) of platform switching in standard length,p<0.05 No difference between implants inserted in healed bone, fresh extraction sockets or with crestal approach sinus floor elevation Overall success rate=94%; Upper=94.4%; Lower=92.9%;p>0.05 No significant correlations between peri-implant bone loss and qualitative and quantitative variables. p-values all>0.05 Qualitative variables-sex, diabetes, smoking habit, antagonist dentition, type mm) of prosthesis (splint/no splint), site (upper/lower), site (upper premolar, upper molar, lower premolar, lower molar) Quantitative variables–age, follow-up, anatomical C/I ratio (crown/implant), clinical C/I ratio BL (bone level) Median (range) implant stability quotient At time of insertion In each patient, one 10 mm (n=11) and one 4 mm-61(14-72); 10 mm-66 (52-78) or two ultra short 4 mm (n=17) implants After 6-months 4 mm-68 (51-79); 10 mm-78 (60-83); p<0.05 All patients were restored with splinted Median (range) clinical crown/implant ratio metal-ceramic crowns connecting the 4 mm 4 mm-2.79 (1-3.66); 10 mm-1.06 (0.85-1.46);p<0.05 implant to the 10 mm implant Six-months after prosthesis rehabilitation, median (range) crestal bone loss 4 mm-0.3 mm (-0.7-1.7 mm); 10 mm-9.5 mm (-0.8-3.5 mm);p>0.05 225 implants with diameters of 4.1 and 4.8 Implant survival rates: mm and posterior maxillary residual bone 91.80% Group 1; 97.08% Group 2; 100.00% Group 3 height (RBH) 6-8 mm Implant survival rate in Group 1 was significantly lower than that in Group 1-6 mm implants alone Group 3 (p=0.029) A multivariate Cox model showed that the short-6-mm implants with wide floor elevation (OSFE) diameter had a protective effect on implant survival (hazard ratio: 0.59, Group 3-10 mm implants+OSFE) p=0.001) At the 3-year follow-up, 199 patients (Group No significant differences in bleeding on probing (BOP%), probing pocket 1: 67; Group 2: 62; Group 3: 70) were depth (PPD), modified plaque index(mPI), marginal bone loss (MBL) and re-examined complication-free survival rate were found among the three groups.
Pardo-Zamora 31 74 patients 19 were placed in the mandible et al connection and a sub-crestal positioning, sloping shouldered im- practitioners and patients for less invasive procedures and a rea- plant with a flattened tapered root form body. They claim that their sonable predictability which seems to have a promising trend. The plateau or fin design offers at least 30% more surface area that increased use of short implants in clinical practice will lead to im- other implants of similar size. The 5 or 6 mm implant provides proved surgical techniques and implant designs. The restoration five threads in the bone that is adequate to retain the implant and using short implants will increase in number with the awareness handle the occlusal forces despite a crown to implant ratio greater that the than 1:1. The use of short implants allows for a less invasive sur- term success. Short implants can be used instead of 10 mm im- gical procedure and less post-operative complications. The place- plants in areas of adequate bone height with the aim to avoid ma- ment can be also performed flapless. The osteotomy required for jor bone the 5 mm is about 6.5 mm in depth to allow for 1.5 mm sub-crestal placement this can be done with very slow drilling at 40 rpms and no irrigation. This also minimizes the surgical trauma to the site. parison between Straumann 6 mm tissue level implants to same Although the Bicon implant has threads, it is press fit into the site. brand 10 mm tissue level implants in non-grafted bone areas over It does not require a high-level of primary stability as is needed a 5 year period resulted that the 6 mm ones had a 91% survival rate with screw fit implants. The platform switch design allows for the compared to 100% of the 10 mm implants. The authors concluded implant allows for the crestal stability needed with short implants. that the The short implant can become the implant of choice re- survival rate. To complement, Scarano et al4 analysed 63 short im- gardless of the bone volume and restorative plan.33 This concept plants placed inpremolar and molar region of the posterior man- of a shorter implant length will allow for less surgically invasive dible. All short implants were splinted to at least one other implant. implant placement in all situations including those requiring verti- The short implants were machine collared and characterized by 2 cal sinus augmentation. portions Urdaneta et al34 performed a retrospective cohort study short implants had a survival rate of 98.5% as compared to 97.4% to evaluate 5 mm length implants where the same patients received for standard implants. There was no statistical difference of bone at least one 5 mm wide hydroxyapatite coated Bicon implant. They loss between the short and standard implants (p=0.1). They con- found that the survival of ultrashort (5 or 6 mm length) implants cluded that short implants can be used to predictably restore the were comparable to short (8 mm length) implants over an average posterior mandible and avoid the additional surgical procedures in of 20-months. These short implants can also be used in guided resorbed sites when splinted to a standard implant or another short implant surgery.35 implant.
DISCUSSION CONCLUSION Many implant companies are now incorporating short implants Clinicians should have short implants as an option for patients. (8 mm or less) into their product line. Four mm length implants Patients are actually available only from few brands. There is a demand by candidate for a short implant. Short implants may allow patients 12 month survival rate is 100% ISQ measurements made: on the implant placement (ISQ1); the prosthetic loading (ISQ2) at 12 months follow-up (ISQ3) Mean±SD ∆ ISQ2-ISQ1 -0.745±2.192 (short); -0.057±2.796 (standard);p=0.316 99 implants: ∆ ISQ3-ISQ2 short (7 or 8.5 mm); 0.298±1.876 (short); 0.654±1.781(standard);p=0.336 standard (10, 11.5, 13 or 15 mm) p-value=0.014 (short),p=0.043 (standard) 47 short implants in 33 patients Marginal Bone Level (MBL) at mesial and distal in both implant groups on 52 standard implants in 41 patients the day of surgery (MBL1); implant loading (MBL2) Short 12-months after loading (MBL3) 28 implants were placed in the maxilla Mean ±SD ∆ MBL2-MBL1 44 (93.61%) of these were in the molar and -0.263±0.244 (short); -0.305±0.272 (standard);p=0.324 premolar regions ∆ MBL3-MBL2 Standard implants -0.184±0.191 (short); -0.412±0.588 (standard);p=0.004 33 were placed in the maxilla p-value=0.009 (short),p=0.889 (standard) 19 were placed in the mandible There was no correlation between the increase in ISQ and bone loss/gain 24 in the anterior region (46.16%) in relation to the implants, regardless of their length.
28 in the posterior region (53.84%) A slightly positive correlation was found between the ∆ MBL2-MBL1 and ∆ MBL2-MBL3 values in the short implants (0.664,p=0.00000037).
No correlation was found between the increase in ISQ and bone loss/gain in relation to the implants, regardless of their diameter.
A weak correlation in wide diameter implants between ∆ ISQ1-ISQ2 and ∆ ISQ2-ISQ3 values (cc: 0.539,p=0.000194) and ∆ MBL1-MBL2 and ∆ MBL2- MBL3 values (cc: 0.467;p=0.0016) crown-to-implant ratio does not need to be 1:1 for long grafting procedures.
In the randomized clinical trial of Naenni et al36 a com- use of 6 mm single implants are a reasonable alternative to implants of standard length because of a minor difference in implant screw and transmucosal collar tissue level, con- nected to a titanium abutment by a chemical cement seal. The who cannot receive a standard sized implant may be a with unfavorable sites to receive a functional implant without ad- systematic review and meta-analysis of the essential assessment ditional surgeries that can lead to complications. However, while parameters. Braz Dent J. 2015; 26(4): 325-336. doi: 10.1590/0103- this may be a viable option, clinicians should be aware that more 6440201300265 studies are needed to determine long-term prognosis and pre- dictability of success of short implants and how they compare 10. Thoma DS, Cha J-K, Jung U-W. Treatment concepts for the to standard sized implants. Additional studies should compare posterior maxilla and mandible: Short implants versus long im- short implants to zygomatic implants, should compare different plants in augmented bone. J Periodontal Implant Sci. 2017; 47(1): jaw sites (mandible vs. maxilla, anterior vs posterior) and compare 2-12. doi: 10.5051/jpis.2017.47.1.2 single unit vs. multi-unit prosthesis with short implants. But as more short implants are being placed, there will be more long- 11. Stellingsma K, Raghoebar GM, Visser A, Vissink R, Meijer term (more than 5-years) data to evaluate short implants and their HJA. The extremely resorbed mandible 10-year results of a ran- function. domized controlled trial on 3 treatment strategies. Clin Oral Impl CONFLICTS OF INTEREST The authors declare that they have no conflicts of interest. Short implants versus longer implants in vertically augmented REFERENCES after loading follow-up. Eur J Oral Implantol. 2014; 7(4): 359-369.
1. Palacios JAV, Garcia JJ, Caramês JMM, Quirynen M, da Sil- 13. Rossi F, Botticelli D, Cesaretti G, De Santis E, Storelli S, Lang va Marques DN. Short implants versus bone grafting and stand- NP. Use ard-length implants placement: A systematic review. Clin Oral In- a 5-year follow-up prospective randomized controlled multicenter vest. 2018; 22: 69-80. doi: 10.1007/s00784-017-2205-0 clinic study. Clin Oral Impl Res. 2016; 27: 458-464. doi: 10.1111/ 2. Hameed MH, Gul M, Ghafoor R, Khan FR. Vertical ridge gain with various bone augmentation techniques: A systematic 14. Fan review and meta-analysis. J Prosthodont. 2019; 28(4): 421-427. doi: to 8 mm) versus longer implants (>8 mm) with sinus lifting in 10.1111/jopr.13028 atrophic posterior maxilla: A meta-analysis of RCTs. Clin Implant 3. Svezia L and Casotto F. Short dental implants (6 mm) versus standard dental implants (10 mm) supporting single crowns in the 15. Lemos CAA, Ferro-Alves ML, Okamoto R, Mendonca MR, posterior maxilla and/or mandible: 2-year results from a prospec- Pellizzer EP. Short dental implants versus standard dental implants tive cohort comparative trial. J Oral Maxillofac Res. 2018; 9(3): e4. placed in the posterior jaws: A systematic review and meta-analy- doi: 10.5037/jomr.2018.9304 sis. J Dent. 2016; 46: 8-17. doi: 10.1016/j.jdent.2016.01.005 4. Scarano A, Mortellaro C, Brucoli M, Lucchina AG, Assenza 16. Bechara S, Kubilius R, Veronesi G, Pires JT, Shibli JA, Man- B, Lorusso F. Short implants: analysis of 69 implants loaded in gano FG. Short (6 mm) dental implants versus sinus floor ele- mandible compared with longer implants. J Craniofac Surg. 2018; vation and placement of longer (≥10 mm) dental implants: A 29: 2272-2276. doi: 10.1097/SCS.0000000000004518 randomized controlled trial with a 3-year follow-up. Clin Oral Impl 5. Al-Johany SS, Al Amri MD, Alsaeed S, Alalola B. Dental im- plant length and diameter: A proposed classification scheme. J 17. Pohl Prosthodont. 2017; 26: 252-260. doi: 10.1111/jopr.12517 lor TD, 6. Cruz RS, Lemos CAdA, Batista VEdS, Gomes JMdL, Pellizzer vation procedures; 3-year results from a multicenter, randomized, EP, Verri FR. Short implants versus longer implants with maxil- controlled clinical trial. J Clin Periodontol. 2017; 44: 438-445. doi: lary sinus lift. A systematic review and meta-analysis. Braz Oral 10.1111/jcpe.12694 Res. 2018; 32: e86. doi: 10.1590/1807-3107bor-2018.vol32.0086 7. Jain N, Gulati M, Garg M, Pathak C. Short implants: new ho- implants in the posterior maxilla: A review of the literature. J rizon in implant dentistry. J Clin Diagn Res. 2016; 10(9): ZE14- Korean Assoc Oral Maxillofac Surg. 2017; 43: 70-76. doi: 10.5125/ ZE17. doi: 10.7860/JCDR/2016/21838.8550 jkaoms.2017.43.2.70 8. Nisand D, Renourd F. Short implant in limited bone volume. 19. Bechara S, Nimčenko T, Kubilius R. The efficacy of short Periodontol 2000. 2014; 66: 72-96. doi: 10.1111/prd.12053 (6 mm) 9. Goncalves TMSV, Bortolini S, Martinolli M, Alfenas BFM, Pe- ruzzo DC, Natali A, et al. Long-term short implants performance: Res. 2014; 25: 926-932. doi: 10.1111/clr.12184 12. Felice P, Cannizzaro G, Barausse C, Pistilli R, Esposito M.
posterior mandibles: A randomized controlled trial with 5-year of short implants (6 mm) in a single-tooth replacement: clr.12564 T, Li Y, Deng W-W, Wu T, Zhang W. Short implants (5 Dent Relat Res. 2017; 19: 207-215. doi: 10.1111/cid.12432 Res. 2017; 28: 1097-1107. doi: 10.1111/clr.12923 V, Thoma DS, Sporniak-Tutak K, Garcia-Garcia A, Tay- Haas R, et al. Short dental implants (6 mm) versus long dental implants (11-15 mm) in combination with sinus floor ele- 18. Esfahrood ZR, Ahmadi L, Karami E, Asghari S. Short dental dental implants with a novel thread design. Stomatologija.
20. Pieri F, Forlievesi C, Caselli E, Corinaldesi G. Short implants rate of ultra-short dental implants: Results of a 8- to 10-year ret- (6 mm) vs. vertical bone augmentation and standard-length im- rospective study. Clin Oral Investig. 2020; 24(9): 3213-3222. doi: plants (≥9 mm) in atrophic posterior mandibles: A 5-year retro- 10.1007/s00784-020-03195-7 spective study. Int J Oral Maxillofac Surg. 2017; 46: 1607-1614. doi: 10.1016/j.ijom.2017.07.005 29. Gašperšič R, Dard M, Linder S, Oblak Č. The use of 4-mm 21. Benatto GB, de Souza Bueno CR, Curvêllo VP, Filho HN. ple missing teeth in the posterior maxilla region with expanded Management of zygomatic fixture complication case using ex- maxillary sinus. An observational cases series: patient characteris- tra-short implants. J Craniofac Surg. 2017; 28(8): e797-e799. doi: tics and 10.1097/SCS.0000000000004171 41(2): 261-268. doi: 10.11607/prd.4389 22. Rossi F, Lang NP, Ricci E, Ferraioli L, Baldi N, Botticelli D. 30. Shi Long-term follow-up of single crowns supported by short, mod- Clinical, radiographic and economic evaluation of short-6-mm erately rough implants – a prospective 10-year cohort study. Clin implants and longer implants combined with osteotome sinus Oral Impl Res. 2018; 29: 1212-1219. doi: 10.1111/clr.13386 floor elevation in moderately atrophic maxillae: A 3-year rand- 23. Papaspyridakos P, De Souza A, Vazouras K, Gholami H, 10.1111/jcpe.13444 Pagni S, Weber HP. Survival rates of short dental implants (≤6 mm) compared with implants longer than 6 mm in posterior jaw 31. Pardo-Zamora G, Ortiz-Ruíz AJ, Camacho-Alonso F, Martín- areas: A meta-analysis. Clin Oral Implants Res. 2018; 29 Suppl 16: ez-Marco JF, Molina-González JM, Piqué-Clusella N, et al. Short 8-20. doi: 10.1111/clr.13289 dental implants (≤8.5 mm) versus standard dental implants (≥10 24. Anitua E, Alkhraisat MH. 15-year follow-up of short den- Int J Environ Res Public Health. 2021; 18(11): 5683. doi: 10.3390/ tal implants placed in the partially edentulous patient: Man- ijerph18115683 dible vs maxilla. Ann Anat. 2019; 222: 88-93. doi: 10.1016/j.
aanat.2018.11.003 32. Bicon Dental Implants. Since 1985 » Simple. Predictable.
25. Anitua E, Flores C, Flores J, Alkhraisat MH. Clinical effec- tiveness of 6.5-mm-long implants to support two-implant fixed 33. Vetromilla BM, Mazzetti T, Pereira-Cenci T. Short ver- prostheses in premolar-molar region: the influence of immediate sus standard implants associated with sinus floor elevation: An loading and the length of splinting implant. J Prosthodont. 2019; umbrella review of meta-analyses of multiple outcomes. J Pros- 28: e688-e693. doi: 10.1111/jopr.12761 thet Dent. 2020; S0022-3913(20)30429-7. doi: 10.1016/j.pros- 26. Shi J-Y, Li Y, Qiao S-C, Gu Y-X, Xiong Y-Y, Lai H-C. Short versus longer implants with osteotome sinus floor elevation for 34. Urdaneta RA, Daher S, Leary J, Emanuel KM, Chaung S-K. moderately atrophic posterior maxillae: A 1-year randomized The survival of ultrashort locking-taper implants. Int J Oral Max- clinical trial. J Clin Periodontol. 2019; 46(8): 855-862. doi: 10.1111/ illofac Implants. 2012; 27(3): 644-654. jcpe.13147 27. Amato F, Polara G, Spedicato GA. Immediate loading of A. Current state of the art of computer-guided implant surgery. fixed partial dental prostheses on extra-short and short implants Periodontol 2000. 2017; 73(1): 121-133. doi: 10.1111/prd.12175 in patients with severe atrophy of the posterior maxilla and man- dible: A up-to-4-year clinical study. Int J Oral Maxillofac Implants. 36. Naenni N, Sahrmann P, Schmidlin PR, Attin T, Wiedemeier 2020; 35: 607-615. doi: 10.11607/jomi.7943 DB, Sapata V, et al. Five-year survival of short single-tooth im- 28. Malchiodi L, Ricciardi G, Salandini A, Caricasulo R, Cucchi A, 2018; 97(8): 887-892. doi: 10.1177/0022034518758036 Ghensi P. Influence of crown-implant ratio on implant success implants splinted to 10-mm implants for replacement of multi- preliminary results. Int J Periodontics Restorative Dent. 2021; J-Y, Lai Y-R, Qian S-J, Qiao S-C, Tonetti MS, Lai H-C.
omized clinical trial. J Clin Periodontol. 2021; 48(5): 695-704. doi: mm): A one-year post-loading prospective observational study.
Profitable. Web site. www.Bicon.com. Accesses April 14, 2021.
dent.2020.08.002 35. D'haese J, Ackhurst J, Wismeijer D, De Bruyn H, Tahmaseb plants (6 mm): Arandomized controlled clinical trial. J Dent Res.