|Year : 2017 | Volume
| Issue : 3 | Page : 74-79
Increased bone quantity around an ailing implant in esthetic zone using progressive bone loading: A case report
Safoura Ghodsi1, Amirreza Hendi2
1 Dental Research Center, Dentistry Research Institute, Department of Prosthodontics, Tehran, Iran
2 Department of Prosthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran
|Date of Web Publication||8-Aug-2017|
Department of Prosthodontics, Tehran University of Medical Sciences, School of Dentistry, Kargar Shomali, Hakim HWY, 14399591, Tehran
Source of Support: None, Conflict of Interest: None
Introduction: Progressive loading protocol is a high-demanding procedure suggested to increase the quality of bone when the implant is inserted in D3 or D4-typed bone. The purpose of this study was to present a case report regarding simultaneously progressive and immediately loading implants in the anterior position of the maxilla. Case report: One patient whose implants in the anterior maxilla (in site of teeth #7, #9, #11) had questionable to poor prognosis who was treated immediate and delayed progressive loading protocol and was followed up for 2 years. Discussion: Although the number of studies in this field is limited, it can be concluded that the progressive loading protocol can predictably enhance the treatment success in immediate-loaded implants with poor prognosis and when inserted in low quality bone such as the present case.
Keywords: Dental implant, immediate loading, implant-supported, progressive loading
|How to cite this article:|
Ghodsi S, Hendi A. Increased bone quantity around an ailing implant in esthetic zone using progressive bone loading: A case report. Dent Hypotheses 2017;8:74-9
| Introduction|| |
The success of dental implants depends on integration between the implant and the surrounding hard and soft tissues. Mechanical stresses that have both positive and negative consequences for bony tissue predominantly concentrate at the crestal region of an osseointegrated implant. The bone at the alveolar crest is a high stress-bearing area, and when overloaded, subjected to cervical cratering or “saucerization.” Initial breakdown of the implant–tissue interface generally begins at this area (early bone loss), and this phenomenon is a common prologue for the failure of an implant. Delayed implant loading (after 3 months in the mandible and 6 months in the maxilla) was mainly based on the belief that transfer of any micromotion to the implant surface during the healing period would result in fibrous encapsulation rather than osseointegration. However, the growing concern on patient esthetic demands questioned the acceptability of delayed loading protocol for all patients and attracted attention to immediate and early loading protocol, especially in the esthetic zone., Immediate loading is defined as placing the implant in functional occlusion at the time of the surgery or within 48 hours after placement.
To increase the primary stability of the implant, which has greater importance in the immediate loading protocol, various clinical techniques have been suggested such as the under-preparation of the implant site, use of a nonoccluding temporary prosthesis during the first 2 months of healing, or progressive loading of the implant.
In 1980 Carl E. Misch introduced the concept of progressive or gradual bone loading to use the advantages of controlled loading to increase bone density and stability. He declared that load control plays a critical role in the success of progressive loading protocol. This load-control concept was based on the absence of cantilevers and controlling the size of the occlusal table, direction and location of the occlusal contacts, and diet to help the bone to adapt to the increasing amounts of biomechanical stresses. This technique allows the bone to mature during the loading period without overloading the implant, which may lead to bone loss and implant failure. The bone adapts to a certain strain in the steady state. When the strain is gradually increased, the bone becomes mildly overloaded and compensates by increasing bone formation and density.
[Table 1] summarizes the available articles. The number of articles on progressive loading protocol is limited, mainly case reports, using this procedure in the posterior maxilla (especially in premolar area), within dependent restorations.,, The limitation in the application of the process goes back to the high-demanding nature of the progressive loading protocol. However, literature suggests that progressive bone loading could be a predictable procedure for immediately-loaded implants in high-risk situations such as augmented bone or softer bone types. Furthermore, clinical studies have reported a reduction in crestal bone loss, and an increase in bone density, around progressively-loaded implants compared with implants loaded in the conventional delayed manner. In routine clinical practice, a clinician may encounter questionable or high-risk situations where the safe margin of treatment is seriously limited. In such a situation in implant dentistry, if a pretreatment protocol could maintain or even enhance the peri-implant bone (that is the main determinant of treatment success), an unpredictable result could change to success. Progressive loading protocol is reported to have such a potential. This procedure concentrates the stress on crestal portion of the surrounding bone, however, in contrast to conventional loading, the amount of this stress is precisely controlled; and the gradually increasing load could be the success key even in the esthetic zone.
This case report aims at demonstrating the bone quantity increase using progressive bone loading around an ailing implant in the anterior sextant of the maxilla.
A 25-year-old woman was referred to the Department of Prosthodontics of the Faculty of Dentistry, Tehran University of medical science, Tehran, Iran. The patient was a nonsmoker, nonbruxer, and had no history of systemic diseases. Three implants (Implantium, Dentium, Seoul, South Korea) had been inserted 4 months ago in the anterior maxilla (one implant with 3.8 × 12 mm dimension for tooth #7 and two implants with 3.4 × 12 mm dimension for tooth #9 and #11), but one implant (in the #11 position) failed in osseointegration and was explanted in the second surgical session. Applying a single-stage approach and immediate implantation, a nonsubmerged implant (3.8 × 12 mm) had been reinserted at the same position [Figure 1]. The insertion torque of the latter implant was 35 N-cm.
|Figure 1: (a) Intraoral view after second surgical phase. Note the immediate implantation in tooth #11 position. (b) Radiographic view demonstrated bone loss around all 3 implants. Note the level of bone indicated by a red line|
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The surgeon in the referral form had clearly mentioned the questionable prognosis of the implants due to bone resorption around the inserted implants and the bone density, which was claimed to be D4, according to clinical and radiographic examinations. The patient had high esthetic demands, and while discussing the treatment options, she strongly refused delayed loading protocol and even temporary removable prosthesis option. Therefore, due to the importance of bone preservation in the esthetic zone, it was decided to progressively increase the load on ailing implants to improve the response of the bone. Consequently, the immediately placed implant (#11) was exposed to immediate progressive bone loading and the other implants sustained delayed progressive bone loading.
An open-tray impression of implants was taken on the same day of the surgery using a vinyl-polysiloxane materia (A-silicones, Kettenbach, Eschenburg, Germany). The final models were mounted on a nonarcon semiadjustable articulator (Hanau 96H2, Whip Mix Corp, USA), and anterior wax-up was performed to determine the prosthesis contour. The wax-up was indexed in silicone to use for abutment preparation and provisional restoration fabrication in the subsequent steps. The final abutments (Combi abutment, Dentium, Seoul, South Korea) were selected, secured on implant analogues in the cast, and prepared for height, parallelism, and position within the prosthesis wax-upped contours. A transitional acrylic prosthesis was fabricated using temporary heat-cured acrylic resin (Meliodent, Bayer Dental Co, Wasserburg, Germany) on cast. The occlusion was adjusted following Misch protocol in a manner that the restoration was infraocclusion in the centric and all eccentric positions. Within 24 hours, the abutments were transferred to the patient’s mouth and torqued to 20 N-cm.Temporary crowns were cemented with zinc oxide eugenol cement (Temp-Bond, Kerr, West Collins, USA). During the first month, the acrylic provisional crowns were completely out of occlusion [Figure 2]. The free passing of 40-μm articulating paper (Arti-Fol, Bousch, Köln, Germany) through the occlusal contact in the maximum biting force was confirmed in all mandibular positions. The patient was asked to use a soft diet such as pasta, soup, and fish during this period. The occlusion and soft diet consumption were reevaluated and reemphasized during follow-up visits every 10 days. After 4 weeks, the occlusion of the restoration was adjusted and brought into light centric contacts by adding acrylic resin on the occlusal centric contact areas [Figure 3]. This was confirmed using a 40-μm articulating paper. The occlusal contacts of the restorations were eliminated during excursive movements and the diet remained soft. Two sessions with 4 weeks’ interval were arranged for the patient in which occlusal contacts, home care, and diet were reevaluated, and fiber containing foods were added to the diet. After 2 months, mutually protected occlusion was considered for excursive movements by adding acrylic resin to the restoration [Figure 4], and patient’s diet was returned to normal and raw vegetables and hard foods were added. One month later, the radiographic examination showed increasing bone height around implants, and the situation was ready for fabrication of final restoration. The transitional prosthesis was removed, abutments were torqued to 35 N-cm, and final impression of the abutments was taken applying vinyl siloxane impression material in the conventional impression technique. Metal ceramic restoration was fabricated in full centric occlusal contact, and mutually protected occlusion was considered for excursive movements. The occlusion was adjusted using 12-μm articulating paper (Arti-Fol, Bousch Co, Köln, Germany). The restoration was evaluated clinically and radiographically, and cemented with temporary cement (Temp-Bond, Kerr, West Collins, USA). The prosthetic restoration provided good aesthetic results and the patient’s smile esthetics was highly improved [Figure 5]. The first follow-up visit was scheduled for 4 weeks later. The patient was followed up every 3 to 4 months for 2 years. She was satisfied by the esthetic and functional results and the radiograph showed good bone-implant integration and increased bone height around all 3 implants [Figure 6].
|Figure 2: Temporary restoration placed completely out of centric or eccentric occlusal contact.|
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|Figure 3: Temporary restoration placed in 40 μ occlusal contacts in centric relation, eccentric contacts were eliminated|
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|Figure 4: Temporary crowns placed in full occlusal contacts in centric and eccentric relations|
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|Figure 6: (a) Radiographic view after 2 years. The level of bone is indicated by a blue line. (b) Superimposition of baseline and follow-up radiographic views. Compare the level of crestal bone in the primary (red) radiograph with the last (blue) radiograph after 2 years|
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| Discussion|| |
Immediate and early loading procedures provide benefits including reduced surgical steps by eliminating the second procedure, shortened treatment time, and providing a functional and psychological advantage of early prosthetic rehabilitation. However, the stability of the implant during accelerated loading procedures is not as predictable as delayed loading after implant osseointegration. Progressive loading protocol was introduced to increase the predictability of immediately-loaded implant treatment.
Progressive loading controls the level of stress transmitted to the susceptible crestal bone. The applied load matches and progresses more closely with the load-bearing capacity of the maturing bone. A study by Appleton compared two groups of patients with different loading protocols. The peri-implant bone around progressively-loaded implants demonstrated less crestal bone loss compared to delayed-loaded implants. Progressive loading procedure has been recommended for implants placed in softer bone types. A study by Misch revealed that the poorer the bone density (D3 and D4), the more dramatic is the decrease in Periotest values using progressive loading protocol. Periotest values relate to mobility and density of bone around the implant.
This case report presented a unique situation. One immediately progressively-loaded implant and two ailing implants with questionable prognosis and crestal bone loss up to their 5th thread that underwent delayed progressive-loading presented a high-risk situation in the anterior esthetic zone of the maxillary arch. A distinction has been made between irreversible failing implants and ailing implants. Ailing implant has been described in the literature as an implant that has not failed but needs some form of treatment modality to prevent failure and explantation. On the other hand, anterior maxilla has compromised bone density and sustained an increased angulation of occlusal loads., These situations put the implants at a high risk of failure. In the presented case, the surgeon reported D4 density in the peri-implant bone, and the patient demanded immediate restorative rehabilitation. However, the risk of failure with immediate loading is extremely high in the anterior maxillary area; progressive bone loading could enhance the prognosis of ailing implants and provide a more predictable option for high-risk situations.,, Splinting the progressively-loaded implants could increase the success rate and improve the results when other situations compromised the treatment results.,
The 2-year follow-up of the presented case confirmed that immediate progressive loading could immediately fulfill the esthetic and phonetic requirement, as well as increase the success potential in ailing implants. According to the primary compromised condition of the present case and considering the limited cases in available literature, it seems rational to consider the progressive loading protocol as a potentially rescue treatment modality. However, further clinical studies are recommended for documentation of the results obtained in case-based reports.
| Conclusion|| |
Considering the limitation in the present article, following conclusions could be obtained:
- The number of available articles in the field of progressive bone loading is limited, which could be because of the time-consuming procedure and the necessity of patient cooperation.
- The available articles clearly report that progressive bone loading protocol could increase the success rate in compromised situations, increasing surrounding bone density and volume.
- This case report showed that progressive bone loading with gradual increase in occlusal contact intensity could improve bone-implant contact in compromised situations.
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Conflicts of Interest
There are no conflicts of interest.
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