Immediateearly function of neoss implants placed in maxillas and posterior mandibles: an 18month prospective case series study

Immediate/Early Function of Neoss Implants
Placed in Maxillas and Posterior Mandibles:
An 18-Month Prospective Case Series Study
Leonardo Vanden Bogaerde, MD, DDS;* Giorgio Pedretti, MD, DDS;† Lars Sennerby, DDS, PhD;‡
Neil Meredith, DDS, PhD§
Background: An increasing number of studies show that immediate/early function of dental implants can be as successfulas two-stage procedures. However, the results may not be universal for all implant types and it is important that newimplants are tested for this treatment modality.
Purpose: The aim was to evaluate an immediate/early function protocol in the maxilla and in the posterior mandible usingNeoss implants (Neoss Ltd., Harrogate, UK).
Materials and Methods: A total of 21 patients were provided with 69 Neoss implants (4 mm in diameter and 9–15 mm inlength) and a provisional bridge within 7 days (mean 4.6 days). Sixteen implants were placed in immediate extraction siteswhere seven were treated with autologous bone grafts (n = 6) or bone grafts + resorbable membrane (n = 1). A final fixedprosthesis was made 3 to 6 months later. The patients were followed-up with clinical examinations for 18 months. Inaddition, the implants were monitored with resonance frequency analysis (RFA) measurements at surgery and after 1, 2,and 6 months. Intraoral radiographs were taken after surgery and after 1, 6, and 18 months.
Results: One implant in an extraction site in the maxilla failed after 1 month, giving a survival rate of 98.5% after 18 months.
The mean marginal bone loss was 0.7 mm (SD 0.7) after 18 months. RFA showed a mean implant stability quotient (ISQ)value of 68.1 (SD 8.8) at surgery, which increased to 73.7 (SD 5.7) after 6 months. The primary stability for maxillary andmandibular implants was similar, although mandibular implants showed slightly higher values with time. Implants inextraction sockets showed a lower initial stability than in healed sites, ISQ 65.8 (SD 7.5), which increased to ISQ 67.5 (SD6.9) after 6 months. The failed implant showed an ISQ of 74 at placement, which decreased to 42 1 month after surgery.
Conclusion: Within the limitations of the present study, it is concluded that immediate/early function with Neoss implantsis a reliable method with an implant survival rate comparable to that of the traditional two-stage protocol.
KEY WORDS: clinical study, dental implants, immediate/early function, radiography, resonance frequency analysis traditional healing period of 3 to 6 months. However, Immediate loading is today a commonly used term in the applied load is often reduced or even absent; there- the dental field and indicates the possibility of applying fore, it is more correct to use the term "immediate/early an occlusal load to dental implants earlier than the function" rather than "immediate/early loading." More-over, the subdivision between "immediate function" – *Private practice, Concorezzo, Italy; †private practice, Lecco, Italy; when the prosthesis is applied within hours from the ‡Professor, Department of Biomaterials, Institute of Surgical Sciences, implant insertion – and "early function" – when the Sahlgrenska Academy, Gothenburg University, Sweden; §Professor, prosthesis is applied earlier than the traditional period Bristol Dental School and Hospital, Bristol University and Neoss Ltd.,Harrogate, UK of 3 to 6 months – has been accepted at a previousconsensus conference.1 Reprint requests: Dr. Leonardo Vanden Bogaerde, Via Dante 32, 20049Concorezzo, Italy; e-mail: [email protected] The possibility to rehabilitate the aesthetics of a 2008, Copyright the Authors patient in a very short period and avoiding a removable Journal Compilation 2010, Wiley Periodicals, Inc.
prosthesis are without any doubt the main reasons for which the immediate function therapy is performed.
Clinical Implant Dentistry and Related Research, Volume 12, Supplement 1, 2010 Moreover, occlusal loading of the implants can be 96.8% after 18 months. The result obtained in that study allowed to assure a certain degree of masticatory func- was significantly better than those obtained in previous tion in accurately evaluated and monitored patients. Not studies in which cylindrical implants were used.6,7A to be disregarded is the observation that early function perspective clinical study confirmed the possibility to may have a favorable effect on bone formation and use implants with favorable geometry in the posterior mineralization,2 determining a higher degree of bone– regions of the maxillas, obtaining a survival rate of 98%, implant contact.3 after 1 to 2 years.11 The first procedures of immediate function were The mechanical anchorage of the implant in the carried some 20 years ago and essentially considered the bone (primary stability) tends to decrease during the chin symphysis, an area of the mandible characterized first weeks following the positioning12 and is progres- by a high bone density. The results of many clinical sively replaced by an anchorage of biological type, tied to studies have confirmed the validity of the technique the implant surface (secondary stability). During the last applied to the anterior mandible.4–5 Afterward, the pos- years, a progressive abandon of the smooth surface sibility to intervene also in areas where the bone quality (machined) in favor of a rougher surfaces has been is less favorable, like the upper arch or, in some cases, the observed. While the surface does not seem to have any posterior mandible areas, was investigated. Glauser and particular influence on the primary stability,8,13 on the colleagues6 treated different areas of the arches with an secondary stability, it does influence it in a determining immediate loading procedure, obtaining a survival rate way, accelerating the osseointegration process. A con- of 66% in the posterior maxilla; while in the other areas trolled study was carried out in a dog mandible,14 com- the survival was up to 91%. Grunder and colleagues7 paring implants with machined surface (control side) inserted 48 implants in totally edentulous upper and with implants with oxidized rough surface (test side), lower arches. At the follow-up after 2 years, six implants with a resonance frequency (resonance frequency analy- failed in the posterior areas, resulting in a survival rate of sis [RFA]) monitoring. After 3 weeks, the test implants showed a value of implant stability quotient (ISQ) It was then understood that the primary stability of greater than that of the control implants. Another his- the implant is fundamental to obtain the successful tomorphometrical and biomechanical study performed outcome of immediate function in areas with poor bone on rabbits15 put in evidence that implants with a rough quality. Apart from the bone density, the primary stabil- (oxidized) surface showed after 6 weeks higher values of ity seems to be related to the surgical technique (under- bone–implant contact (BIC) and of "removal torque" preparation of the site) and particularly to the geometry than those of implants with machined surface. Such of the implant.
results have also been confirmed by Henry and col- In an experimental study, Glauser and colleagues8 leagues16 in a study on a dog in which implants with inserted implants with a different geometry and ana- rough surface showed, after 6 weeks, an extraction lyzed the initial stability by the insertion torque and the torque higher than that of implants with machined resonance frequency. The authors concluded that the positioning of slightly tapered implants in a cylindrical Vanden Bogaerde and colleagues17 carried out a site gives a greater stability in comparison with cylindri- multicenter study with a protocol similar to the one of cal implants. These data have been clinically confirmed the previous study of the same authors,10 except for the by a study in which the survival rate of implants in soft use of implants with rough (oxidized) surface. One bone has been higher than that obtained with cylindrical hundred eleven implants were positioned in edentulous implants.9 It seems that the implant tapered design areas of the maxillas and posterior mandibles and early creates bone compression at the moment of the implant loaded within 9 days from the insertion. The follow-up insertion and therefore a better stability.
after 18 months showed the failure of one implant only, In a multicenter perspective study, Vanden Bogaerde with a survival rate of 99.1%. The average marginal bone and colleagues10 installed 124 slightly tapered implants resorption has been 0.8 mm with a loss mainly concen- with a smooth surface in upper arches and posterior trated in the first 6 months. The effectiveness of the use mandibles and loaded them within 15 days from the of the rough, oxidized surface has been confirmed by a surgery. The total survival rate of the implants was 1 year perspective clinical research.18 The authors Immediate/Early Function of Neoss Implants positioned 102 implants with rough surface, mainly in the posterior areas of the maxillas and in the presence of (OPGs) and/or computed tomography scans.
soft bone, obtaining an implant survival rate of 97.1%.
Inclusion criteria were (1) need of implant- Once more, a comparative study19 using implants with supported crown or bridge in the partially edentulous smooth surface (machined) and implants with rough mandible or maxilla; (2) available bone for at least surface (oxidized), inserted in posterior mandibles and 9-mm long and 4-mm wide implants; (3) minimal peak early loaded, showed a greater success for the rough insertion torque of 30 Ncm; (4) minimal ISQ value of 50 implants (10% more) compared with the machined (Osstell™, Osstell AB, Gothenburg, Sweden); and (5) ones. The same authors histologically investigated the signed informed consent to participate and to follow a osseointegration process in implants subjected to early maintenance and observation program for 18 months.
loading, inserting nine supplementary implants in five The exclusion criteria were (1) noncompensated dis- voluntary patients.20 Such implants were extracted after eases; (2) poor oral hygiene; and (3) the presence of a 5 to 9 months of function and the histological analysis "deep bite" in the superior central incisors.
revealed a BIC rate of 84.5%.
Smoking, bruxism, and periodontal disease were The aim of the present work is to evaluate the considered only as risk factors. Patients with periodon- immediate/early loading in the maxilla and in the man- titis were treated before implant surgery. Immediate dible with a new type of implant (Neoss Implant placement of implants in extraction sockets was allowed.
System) with rough surface (bimodal) and a geometry All patients were carefully informed about the slightly tapered in its apical part.
procedure and gave their written consent to partici-pate. They could at any time point refuse further MATERIAL AND METHODS
Patient Selection A total of 21 patients (12 females and nine males; mean age 60 years, range 32–79) coming from two clinical Neoss™ implants (Neoss Ltd., Harrogate, UK) were used centers were consecutively included in the study.
in the study (Figure 1). This implant is characterized by Twenty-seven partially edentulous areas were treated; 16 a positive tolerance, signified by a slightly tapered geom- situated in the upper arch and 11 in the lower arch etry. The implant has a modified surface obtained by double particle blasting (Bimodal™ surface, Neoss Ltd.), The preoperative assessments included clinical first with larger ceramic particles to obtain a macror- oughness and then with smaller particles to obtain a TABLE 1 Position and Length of the Implants (4 mm in Diameter) Used in
the Study

Clinical Implant Dentistry and Related Research, Volume 12, Supplement 1, 2010 3.0 mm, and 3.4 mm). In the presence of very soft bone,an under-preparation technique was used with 3.0 or3.2 mm as final diameter.
To preserve the cortical bone as much as possible, the use of countersink was avoided. Thus, the implantswere generally placed with the implant collar above thebone crest.
In the immediate postextractive sites, careful curet- tage of the socket was performed just after the extractionof the tooth to remove any residual inflammatory tissueor periodontal ligament. The postextraction siteswere divided into groups according to the followingclassifications21: ESND (extraction socket, no defect) – When thediameter of the socket was smaller than that ofthe implant and no defect remained adjacent to theimplant.
ESCD (extraction socket, closed defect) – When thediameter of the socket was larger than that ofthe implant and one defect remained adjacent to theimplant but with bone walls preserved (closeddefect). This was treated with autologous bone Figure 1 Design of the Neoss™ implant used in the study. The
grafts taken from the neighboring areas with a bone implant has a 1.9-mm high collar and a threaded body with a scraper (Micross®, Meta, Reggio Emilia, Italy).
positive tolerance and vertical flutes. The Bimodal™ surface isachieved by blasting with two different sizes of ceramic ESOD (extraction socket, open defect) – When the diameter of the socket was larger than that ofthe implant and one defect remained adjacent to theimplant but without bone walls (open defect). This microroughness. According to the manufacturer, the was treated with autologous bone and a resorbable roughness is higher on the body and less at the neck of polyglycolid acid (PGA)-trimethylene carbonate the implant.
(TMC) membrane (WL Gore & Associates Inc., A total of 69 implants were inserted: 41 in the upper Flagstaff, AZ, USA) was used.
arch and 28 in the posterior area of the mandible(Table 2). Implants with lengths of 9 to 15 mm and a TABLE 2 Number of Patients, Prostheses, and
diameter of 4 mm were inserted (Tables 1 and 2).
Implants Used in the Study
Sixteen implants were positioned in immediate pos- textraction sites.
Surgical and Prosthetic Procedures The patients were given 2 g of amoxicillin (Zimox®, Pfizer, Italy Srl) before implant surgery. The implant sites were exposed via a midcrestal incision followed by a releasing distal incision. A full thickness flap was elevated and the positions of the implants were marked with a round bur. Then, the receiving sites were prepared with cylindrical burs of increasing diameter, accordingto the recommendations of the manufacturer (2.2 mm, GBR = guided bone regeneration.
Immediate/Early Function of Neoss Implants After the complete positioning of the implants, sterile impression transfers were connected and the flapswere sutured. Impressions were taken with an open trayusing Impregum NF® (ESPE, Seefeld, Germany).
Healing abutments were attached to the implants.
A bite registration was taken in centric relation with occlusion waxes. The impressions were sent to thelaboratory for the manufacturing of the temporaryprosthesis.
The patients were treated with a postsurgical anti- biotic therapy (amoxicillin, Zimox®, Pfizer, Italy Srl), 1 gtwice a day for 6 days, starting just before surgery, an Figure 2 Edentulous space in the lower posterior arch.
anti-inflammatory therapy, (nimesulide, Aulin®, Roche,Milan, Italy), twice a day for 4 days, and they wereinstructed to rinse with 2% solution of chlorexidine, implants two ISQ values, one low and one high. Of the twice a day for 10 days.
two values, only the greater one was registered as recom- A temporary prosthesis made of acrylic with a metal mended by the manufacturer.
reinforcement, without distal extensions, with a reduced As previously mentioned, a baseline threshold value platform, and flattened cusps was delivered within 7 of 50 ISQ was scheduled as a minimum stability quo- days (average 4, 6 days, range 0–7 days). In the wait- tient in order to perform the procedure of immediate ing period, the patients did not use any removable The occlusion was in centric, with light contacts, Implant Survival Criteria possibly avoiding lateral and protrusion contacts. The An implant was considered surviving if it is clinically occlusion marking paper had to leave less marked stable and if it complies with the function of supporting impressions on the prosthesis and on the implants com- the prosthesis and is causing no discomfort to the pared to those of the adjacent teeth. A fixed final pros- patient. Failure was defined as removal of an implant thesis made of porcelain casted on golden alloy was due to any reason.
made after 3 to 6 months.
Radiographic Examination Twenty of the patients were followed up for a period Intraoral radiographs were taken after insertion of the of 18 months and only one patient discontinued the implant (baseline), and then after 1, 6, and 18 months treatment. Figures 2 to 6 show a clinical case of partial from the installation of the implant using a parallelingtechnique (Dentsply RINN, Elgin, IL, USA).
The radiographs were examined by an independent radiologist. The upper corner of the coronal shoulder ofthe implant was used as reference point. Measurementsfrom the reference point to the first bone contact at themesial and distal aspects of the implant were performed.
A mean value was calculated for each implant and timepoint.
Implant stability measurements were performed at base-line and after 1, 2, and 6 months using RFA measure-ments (Osstell Mentor™, Osstell AB) expressed in ISQunits. This novel wireless RFA technique gives for many Figure 3 Two implants positioned with a full thickness flap.

Clinical Implant Dentistry and Related Research, Volume 12, Supplement 1, 2010 Figure 4 After connecting the transfers to the implants, the
flaps were sutured and an impression taken.
Figure 6 The follow-up after 18 months shows an optimal
maintenance of the bone marginal level.
edentulism in the posterior lower arch. Figures 7 to 11show a case of partial edentulism in the maxilla with the some particulate autologous bone. One case presented presence of a high bone deficiency.
an "open" defect with no walls (ESOD group) and wastreated with bone grafts and a resorbable membrane Clinical Examination One of the 69 implants was diagnosed as a failure, giving Radiographic Examination a survival rate of 98.5% after 18 months. The failureoccurred 4 weeks after placement in an immediate pos- The radiographic measurements showed that the base- textraction site in the anterior maxilla in a patient line bone level was situated 0.8 mm (SD 0.2) (n = 58) affected by serious periodontitis.
from the top of the collar and 1.7 mm (SD 0.3) (n = 47) Sixteen implants were inserted in immediate pos- and 1.4 mm (SD 0.6) (n = 57) after 6 and 18 months, textraction sites (Table 1). In nine cases, the implant respectively (Table 2). Thus, a marginal bone resorption diameter was equal or larger than that of the postextrac- of 0.9 mm (SD 0.3) (n = 47) after 6 months and 0.7 mm tion socket and filled the receiving site completely (SD 0.7) (n = 53) after 18 months were seen (Table 3).
(ESDN group). In seven cases, a "gap" remained between The proportion of implants showing more than 2-mm bone and implant and regenerative therapy was per- bone resorption was 13.2% and no implant showed formed. In six of these cases, the defects were of the more than 3-mm bone loss over 18 months (Table 4).
"closed" type (ESCD group) and they were filled with Figure 7 Two implants positioned in the superior maxilla, in
immediate postextraction sites. The distal implant shows a large
Figure 5 The final gold-ceramic prosthesis after 3 months.
surface and exposed implant threads.
Immediate/Early Function of Neoss Implants Figure 8 The bone defect has been filled with a mixture of
Figure 11 After 6 months, the surgical reentry shows complete
autologous bone/bovine bone deproteinized and then covered coverage with new bone of the previously exposed implant area.
with a reabsorbable membrane.
The resonance frequency reveals a significant increase (implantstability quotient [ISQ] 61), compared with the baseline (ISQ51).
A total of 59 implants were systematically analyzed with 8.8), 66.0 (SD 8.5), 69.1 (SD 6.9), and 73.6 (SD 5.7) at RFA measurements. The mean ISQ values were 68.1 (SD baseline and after 1, 2, and 6 months, respectively.
There was no major difference in stability between the maxilla, although mandibular implants showedslightly higher values with time (Figure 12).
The implants positioned in the postextraction sites with "closed" defects (n = 6) showed an average ISQ of65.8 (SD 7.5) at baseline, which increased to 67.5 (SD6.9) after 6 months (Figure 13).
The only implant associated with an "open" defect showed a rather low starting value, ISQ 51, which TABLE 3 Results from Radiographic Measurements
Based on Mean Values of Distal and Mesial Aspects
Figure 9 The flaps were sutured around the transfers and an
impression was taken.
0.8 (SD 0.2) (n = 58) 1.7 (SD 0.3) (n = 47) 0.9 (SD 0.3) (n = 47) 1.4 (SD 0.6) (n = 57) 0.7 (SD 0.7) (n = 53) TABLE 4 Distribution of Marginal Bone Loss after
18 months in Function
Figure 10 After 4 days, the temporary prosthesis was applied.
Clinical Implant Dentistry and Related Research, Volume 12, Supplement 1, 2010 Figure 12 Graph showing the stability of maxillary and
Figure 14 Graph showing the development of seven implants
mandibular implants with time. ISQ = implant stability showing falling stability from baseline to 1 month. Hatched line showing the mean stability of the seven implants. ISQ = implantstability quotient.
remained unchanged during 4 weeks (ISQ 52) and then significantly increased after 8 weeks to 56 and finally 64 The present study confirms the results from previous after 6 months (Figure 13).
clinical investigations that good outcomes can be The implant that failed (position 12) was installed obtained with early loading of implants positioned in in an immediate postextractive site and, at the moment the upper arch and in the posterior lower arch, regions of the insertion, it had an ISQ 74. After 4 weeks, the which often are characterized by poor quality patient reported pain in that area and the analysis with bone.9,10,11,17–19,21 There are many advantages with this the resonance frequency showed a value of ISQ 42 method such as (1) preservation of the aesthetics; (2) associated with an initial mobility of the implant and the early occlusion loading, even if often reduced; (3) very appearance of bone peri-implant rarefaction. With these rapid procedure and therefore less discomfort for the clinical conditions, it was impossible to save the implant, patient; (4) lower number of operating stages for the and a decision was reached to remove it.
dentist; (5) probable less bone marginal resorption;22 Some implants (n = 7) showed a significant and (6) possible advantages for the peri-implant bone decrease of their stability at 1 (n = 3) and after 2 months generation. Concerning the latter, it has been observed (n = 4), maintaining, however, the anchoring in the that cylindrical implants with machined surface sub- bone and showing even a significant recovering after 6 jected to immediate function have a positive effect on months (n = 5) (Figure 14). Only two implants showed a the osteogenesis.2 When implants are loaded for 12 continuous decrease of stability up to 6 months.
weeks, the presence of peri-implant osteoid tissue andthe BIC increase significantly. Another study on pri-mates confirmed that immediately loaded implantsshow a greater BIC (62.4%) compared with that of notloaded implants (56.3%).3 According to our protocol, immediate postextrac- tion sites (n = 16) were included with the purpose topreserve the bone ridge level as much as possible. It hasbeen observed that after the extraction of the tooth, abone ridge resorption of even 50% takes place after 1year, with 2/3 of this process occurring during the first3 months.23 Maintenance of the ridge is particularlyimportant in those situations where the height of theavailable bone is limited and the implant can help to Figure 13 Graph showing development of stability for implants
maintain the existing bone. Even more important is in healed sites, in closed extraction defects, and in one case withan open extraction defect. ISQ = implant stability quotient.
the need to maintain the marginal bone level and, Immediate/Early Function of Neoss Implants consequently, the soft tissue level too, in the front areas interesting to observe the progressive increase of the of the arches where the aesthetics play a fundamental implant stability (Figure 12), probably proportional to role. It has been demonstrated that the positioning of an the bone regeneration. The second surgical phase after 6 implant in a fresh extraction site can prevent the resorp- months (Figure 11) showed an almost total coverage of tion, especially on the buccal side where the bone is the implant surface, which was previously exposed, demonstrating that the guided bone regeneration can In a study using immediate function in the front take place also in case of implants subjected to immedi- areas of the maxilla, implants were positioned also in immediate postextractive sites.26 The authors observed A noninvasive method for the evaluation of the that all implant failures occurred in the postextractive implant stability has been proposed by Meredith and sites and concluded that such sites represented a risk colleagues28 Such device measures the resonance fre- factor for the immediate function protocol. On the con- quency of a transducer tied to the implant or to the trary, an 18-month perspective clinical study demon- abutment. The transducer transmits the vibrations of strated the possibility to carry out an immediate sinusoidal type which are received by a second frequency function protocol with success also in postextractive analysis element. The stability values are expressed in sites, provided the respect for a rigorous clinical proto- ISQ. According to the authors, the resonance frequency col.21 The authors positioned 50 implants in 22 edentu- is determined by the rigidity of the implant/tissues inter- lous areas in the maxilla or in the posterior mandible, face and by the distance between the transducer and classifying the defects according to the preservation or the first bone contact. In following studies, the same not of the surrounding bone walls. The peri-implant researchers have been able to confirm the correlation defects were treated with particulate autologous bone between the measurements with the resonance fre- grafts or grafts associated with resorbable membranes.
quency and the rigidity of the implant inside the bone All the implants had to have a sufficient primary stability tissue.29–30 Glauser and colleagues31 carried out a study as evaluated by the resonance frequency. At the end of on 23 patients subjected to the procedure of immediate the follow-up period, all the implants resulted to be function, monitoring for 1 year the stability of the stable, with a total survival rate of 100%.
implant by means of the resonance frequency. The The healing of peri-implant defects, following the authors observed that the implants subjected to a suc- implant insertion in postextractive sites, depends also on cessive failure showed a continuous drop of stability up the dimension of the residual "gap." Wilson and col- to the loss of the implant. Moreover, low stability values leagues27 evaluated the bone healing around implants after 1–2 months seemed to indicate an increased risk of inserted just after the tooth extraction and retrieved failure. In another experimental study, some implants after 6 months for histological analysis. The BIC was with machined and rough surface were positioned in 72% on the control side (not postextractive areas), 50% dog mandible.32 Around the implants, in subgingival for implants with an initial defect equal or less than position, some ligatures were applied for 3 months with 1.5 mm, and 17% for implants with an initial defect of the purpose to cause an experimental peri-implantitis.
4 mm. Therefore, the bigger the initial defect, the smaller Afterward, a regenerative therapy was started, including debridement and cleaning of the implant surface. For In the present study, 16 implants were inserted in the monitoring of the implant stability, the resonance fresh postextractive sites. Nine of these implants com- frequency was used. During the peri-implantitis phase, pletely filled the sockets (ESND group), and did not it has been possible to observe a loss of bone associated require a regenerative therapy. Near to six implants, to the drop of implant stability. Later, such stability there were defects with preserved walls (ESCD group), tended to increase during the healing phase and it was and a regenerative treatment was executed with particu- more pronounced in the case of implants with rough late autologous bone taken from the neighboring areas surface. The authors concluded that there is a direct with a "scraper." Only one implant presented a serious correlation between the marginal bone level and the defect with the lack of walls (ESOD group), and this resonance frequency values.
area was treated with autologous bone covered with a According to some authors, a significant drop of resorbable membrane (Figure 8). In this last case, it was stability occurs after some weeks from the implant Clinical Implant Dentistry and Related Research, Volume 12, Supplement 1, 2010 insertion. According to some authors, this period can be the implant from the occlusion. The successive control quantified in 2 to 4 weeks12–33 and according to others up after 6 months showed a recovery of stability with an ISQ to 2 months.31 The reason for such decrease could be value greater than the initial one. In the present study, the attributed to the bone relaxation after the compression implant that failed had an extremely rapid drop of stabil- due to the insertion and to the bone adaptation during ity and it has been impossible to intervene before losing the healing phase. Other authors30–34 have instead the integration. After 4 weeks, the patient reported pain, noticed a maintaining of the bone stability during the swelling, and a bone rarefaction in the interested area.
first weeks or even a small increase.34 In the present This was probably due to an infection that occurred study, the mean ISQ values at baseline remained because of bacteria trapped during the implant insertion; unchanged at 1 and 2 months. This behavior could indi- as a matter of fact, it concerned an immediate postextrac- cate that the initial stability of the Neoss implants tive site in a patient affected by a serious form of (Neoss Ltd.) is not tied to the excessive compression of periodontitis. However, as observed also in a precedent the bone tissue at the moment of the implant insertion.
study,21 a drop of stability during the first weeks does not The mean resonance frequency values, registered at necessarily signify an imminent risk of implant loss. In baseline (mean ISQ 68.1) indicate that the implants uti- the present study, on some implants (n = 7) a decrease of lized a sufficient level of primary stability also in the stability was observed after 4 weeks (n = 3) and 8 weeks maxillary regions where the bone quality is less favor- (n = 4), without any clinical signs from the implants able. No significant differences were observed between regarding a loss of anchorage. Some of them (n = 5), after the upper arch (mean ISQ 68.8) and the lower arch 6 months, showed a significant increase of the resonance (mean ISQ 67.3). These values are higher than those value (Figure 13).
reported for Straumann implants34 (mean ISQ 57.4) The marginal bone level measurements showed an and comparable with those reported for Branemark35 average bone loss of 0.7 mm over 18 months, which is implants (mean ISQ 67.4). In the present work, the similar to the value that have been reported from our analysis at 6 months evidenced a consistent increase of group for other implant designs10,17,21 The bone level stability (mean ISQ 73.6), indicating a successful process after 18 months was on average still situated on the of implant osseointegration. It has been noticed that the collar, ie, 1.4 mm below the reference point on the 1.9- lower the initial value of ISQ, the larger the growth mm-high collar. More than 20% of the implants showed registered at 6 months.
an increase of the bone level, which may be explained by In the immediate postextraction sites ESCD, even the fact that many implants were placed in extraction though there was a residual defect, stability at baseline of sockets. About 13% of the implants showed more than ISQ 65.8 was obtained, which is comparable to that of 2-mm bone loss, but no implants lost 3 mm or more implants positioned in healthy bone. Only, at the level over 18 months in function.
of the implant positioned in a site ESOD, the initialvalue was rather low (ISQ 51), probably because of the extensive lack of the surrounding bone. After 8 weeks, Within the limitations of the present study, it is the resonance frequency was already giving a signifi- concluded that immediate/early function with Neoss cantly increased value (ISQ 56), indicating that a regen- implants (Neoss Ltd.) is a reliable method, with an erative process was taking place. After 6 months, the implant survival rate comparable with that of the tradi- value was further increased (ISQ 64), and the second tional two-stage protocol.
surgical intervention confirmed that the bone regenera-tion had occurred (Figure 10).
CONFLICT OF INTEREST STATEMENT
Sometimes, the resonance frequency enables to dis- The authors have no conflicts of interest to declare.
cover a dangerous drop of stability before having an [Correction added after online publication 24 May implant failure. In a perspective clinical study, Vanden 2010: Conflict of Interest Statement added.] Bogaerde and colleagues,21 with the resonance frequency,evidenced a significant and progressive loss of stability of an implant. Such decrease of stability progressed up to 1. Aparicio C, Rangert B, Sennerby L. Immediate/early loading the sixth week, after which a decision was made to remove of dental implants: a report from the Sociedad Española de Immediate/Early Function of Neoss Implants Implantes World Congress consensus meeting in Barcelona, implant design with turned or oxidized surface. An experi- Spain, 2002. Clin Implant Dent Relat Res 2003; 5:57–60.
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