Scalloped Dental Implants: A Retrospective Analysis of Radiographic and Clinical Outcomes of 17 NobelPerfectTM Implants in 6 Patients

BACKGROUND

The scalloped dental implant (NobelPerfect, Nobel Biocare, Yorba Linda, CA, USA) is designed to biologically guide and facilitate interproximal bone remodeling during healing and to maintain bone height and papillae during functional loading. The design features of the scalloped implant include hard and soft tissue apposition areas, which are parallel to each other and mirror the cementoenamel junction. The hard tissue surface area is intended for osseointegration. The soft tissue surface area is meant to support the connective tissue zone and to provide a space for the subgingival margin of the restoration. Current literature on the clinical performance of the scalloped dental implant is limited.

PURPOSE

The aim of this study was to evaluate whether the scalloped dental implant maintains interproximal bone and the overlying soft tissue.

MATERIALS AND METHODS

Radiographs for six patients (mean age 40.5 years) treated with 17 implants (NobelPerfect) were reviewed for an 18-month follow-up evaluation of bone response. Orthodontic movement and/or autogenous bone augmentation had been provided to obtain the best possible soft and hard tissue dimensions prior to implant placement. A surgical guide was used for an optimal implant placement. No surgical flap was reflected, and implants were placed a minimum of 2 mm and a maximum of 3 mm apical (midbuccally) to the most apical portion of the surgical guide. Final optimal rotational alignment was achieved in all cases by not exceeding 45 Ncm. Implants were immediately restored with provisional crowns. Photographic documentation provided the basis for analysis of papillary response. Radiographic change in the interproximal bone level was obtained by computer analysis (ImageJ for Windows, National Institutes of Health, Bethesda, MD) by measuring the distance from the interproximal shoulder of the scalloped implant to the crest of the bone.

RESULTS

When the scalloped implants were placed adjacent to existing natural dentition, the average bone level at placement and at 6, 12, and 18 months was -1.7, -3.5, -3.8, and -3.9 mm, respectively, compared with -1.0, -3.6, -4.3, and -4.4 mm respectively, when placed adjacent to other scalloped implants. Papillae formation exhibited no differences from the configuration that typically results after placement of conventional dental implants. Moreover, bone loss around the scalloped implants was notably greater than that expected after traditional implant placement.

CONCLUSION

This chart review of 17 scalloped implants, followed for 18 months, determined that the scalloped implant design resulted in bone loss that was more severe than that associated with properly placed conventional dental implants. Further, the design showed no evidence of exceptional capacity to increase or maintain soft tissue height.

Use of stereolithographic templates for surgical and prosthodontic implant planning and placement. Part I. The concept

Surgical and prosthodontic implant complications are often an inadvertent sequelae of improper diagnosis, planning, and placement. These complications pose a significant challenge in implant dentistry. Presented in this article is a technique using a highly advanced software program along with a rapid prototyping technology called stereolithography. It permits graphic and complex 3D implant simulation and the fabrication of computer-generated surgical templates. These templates seat directly on the bone and are preprogrammed with the individual depth, angulation, and mesio-distal and bucco-lingual positioning of individual implants as planned during the 3D computer simulation.

Bone height measurements around a dental implant after a 6-month space flight: a case report

PURPOSE

In space, astronauts are subject to microgravity, which reduces skeletal loading and osteoblast function and can cause bone resorption and a decrease in bone density. No known research to date has studied the effect of microgravity on dental implants. This study evaluated peri-implant bone changes around a dental implant placed in a French astronaut who spent 6 months in Russia's Mir Space Station.

MATERIALS AND METHODS

Measurements were performed by 2 examiners before the flight (baseline), after the flight (stage 1), and following a recovery period (stage 2). Standardized periapical radiographs were taken, and data were recorded using a photomicroscope and a measuring scale.

RESULTS

Cumulatively, the implant sustained 0.43 mm of mesial bone gain and 0.31 mm of distal bone loss.

DISCUSSION

The observed peri-implant bone height changes were within normal limits and the implant appeared very stable during the course of this study.

CONCLUSION

Peri-implant bone levels remained stable after 6 months in microgravity, and the implant continued to function without complications.

Three-dimensional accuracy of implant placement in a computer-assisted navigation system

PURPOSE

To evaluate the 3-dimensional accuracy of dental implant drilling in a computer-assisted navigation (CAN) system using simulated mandible models.

MATERIALS AND METHODS

Eight acrylic resin models were fabricated to simulate human mandibles containing mandibular canal (MC). Computerized tomography (CT) scans were obtained for each model, and the data were transferred to the system for dental implant planning. The models were mounted on a phantom head to simulate surgical situation. The assessment parameters included entry point localization, drill path angulation, and drilling depth, which were directly measured by sectioning of the models.

RESULTS

Eighty drill holes were made on the 8 models. The entry point localization showed a mean deviation of 0.43 mm (range, 0 to 2.23 mm; SD, 0.56 mm) from the plan. The angulation showed a mean deviation of 4.0 degrees (range, 0 to 13.6 degrees; SD, 3.5 degrees). The drill aimed at stopping as close to the upper border of the MC as possible without perforating it, and 65% (52) of the drill holes managed to come within 1 mm. Another 5% of the holes stopped 1 to 2 mm above the MC. None of the drill holes stopped more than 2 mm above the MC. However, 30% (24 of 80) of the drill holes perforated the upper border of MC, and the mean depth of perforation was 0.37 mm (range, 0.01 to 1.04 mm; SD, 0.28 mm).

DISCUSSION AND CONCLUSION

The CAN system identified the entry location and angulation with mean deviations of 0.43 mm and 4 degrees, respectively. About two thirds of the drillings achieved accuracy within 1 mm above the MC. Thirty percent perforated into the MC, and the maximal depth was 1.04 mm. In the planning stage, the maximal depth of the implant should be at least 1.1 mm above the superior border of MC as a safety margin.

Effect of Flapless Implant Surgery on Soft Tissue Profile: A Randomized Controlled Clinical Trial

BACKGROUND

Flapless implant surgery has been suggested as one possible treatment option for enhancement of implant esthetics.

METHODS

Twenty-four patients with a missing tooth in the premaxillary region were randomly assigned to one of two groups (12 each): immediate loading (IL) or delayed loading (DL) (loading after 4 months). An endosseous implant was placed in each patient via a flapless surgery. Clinical measurements including the papillary index (PPI) (0, no papilla; 1, less than half; 2, more than half but not complete fill; 3, complete fill; and 4, overfill), marginal levels of the soft tissue (ML), probing depths (PDs), modified bleeding index (mBI), modified plaque index (mPI), and the width of the keratinized mucosa (WKM) were performed at baseline (at the time of loading) and at 2, 4, and 6 months.

RESULTS

The soft tissue profile remained stable up to 6 months, without significant differences between the two groups (mean PPI and ML at 6 months, 2.16 and 0.30 mm, respectively). Mean PPI in the IL group significantly increased from 1.50 at baseline to 2.09 at 2 months, and the significance remained up to 6 months (2.30 at 6 months) (P <0.05), whereas in the DL group, no significant changes were found from baseline to 6 months in mean PPI (2.06 at both time points). Mean PPI increased over time when two treatment groups were combined; however, no statistical significance was found. In ML, the difference at baseline between the two groups (-0.28 mm for DL versus 0.17 mm for IL; P <0.05) was no longer significant at 2 months (0 versus 0.08 mm for DL and IL, respectively) and thereafter (P >0.05). No significant differences were detected between groups at each time and over time in the other clinical parameters, PD, mBI, mPI, and WKM (P >0.05).

CONCLUSIONS

The results of this study indicate that creeping attachment (i.e., soft tissue recovery) might occur within 2 months after IL. The study suggests that flapless implant surgery provides esthetic soft tissue results in single-tooth implants either immediately or delayed loaded. Other long-term randomized controlled clinical trials with a large sample size and comparison group (i.e., implant surgery with flap) are recommended to verify the conclusions drawn in this preliminary study.

Zygomatic Implants—Protocol for Immediate Occlusal Loading: A Preliminary Report

PURPOSE

To investigate the modified protocol for immediate occlusal loading of the zygomatic implants and to report the preliminary results of this modified protocol.

MATERIALS AND METHODS

Four male patients and 1 female patient with edentulous maxillae were consecutively treated with the zygomatic implants under general anesthesia. All 5 patients were examined by computed tomography and investigated by the SimPlant software (Materialise NV, Leuven, Belgium). Based on the virtual surgical plans, mucosa-supported surgical guides were manufactured by rapid prototyping technique before implant operation. Instead of making a Le Fort I Osteotomy incision or a crestal incision, buccal vestibular incision was used to expose the surgical site for the zygomatic implant osteotomy and placement. Three patients had their remaining upper teeth removed on the same day as implant placement. One patient had undergone simultaneous placement of upper and lower implants followed by immediate loading. The immediate loading protocol was a 2-stage method using a customized provisional fixed prosthesis.

RESULTS

Ten zygomatic implants and 20 normal implants were installed in these 5 patients. These 5 patients were reviewed regularly for 6 to 10 months after immediate loading. The zygomatic implants were considered to be successful when they were asymptomatic with no clinical mobility and no sign of infection. All the zygomatic implants and normal implants were investigated individually after removing the provisional prosthesis and were found to be clinically stable and asymptomatic.

CONCLUSION

According to our observation, immediate occlusal loading of the zygomatic implants has a very good potential for success, as much as immediate occlusal loading of normal dental implants. The surgical placement of the zygomatic implant is simplified and facilitated by making use of the computer-assisted planning and the rapid-prototyping surgical guides.

Tooth position in full-mouth implant restorations--a case report

Reconstructing the edentulous mouth with opposing, fixed, implant-supported metal-ceramic restorations demands great attention to detail. This article reviews the basic principles of tooth position in dentate patients and in complete denture prosthodontics and relates them to the edentulous patient undergoing implant restoration. Determining gnathologic points and recognizing anatomic landmarks found in the edentulous jaws aid in correct tooth positioning, resulting in proper comfort, function, speech, esthetics, and a prearranged occlusal scheme, all of which are critical factors behind restorative-driven implant dentistry.

Therapeutic management for immediate implant placement in sites with periapical deficiencies where coronal bone is present: technique and case report

A surgical approach is presented that enables the clinician to repair apical bony defects during immediate dental implant placement without compromising the integrity of the coronal bone and gingiva. This apical surgical technique retains the soft tissue form in the coronal aspect of the gingiva and allows the clinician to repair the apical bone loss or fenestration. A clinical case is presented to describe the technique. This technique is utilized in cases of immediate implant placement. After extraction of the tooth, the socket is evaluated. In cases where coronal bone is intact but apical bone is deficient, a flap technique is utilized to expose the defect. The implant osteotomy is prepared, and the implant is placed. A healing cap or gingival prosthetic component is connected. The bony defect is repaired with a bone graft and, where necessary, a membrane. The apicoectomy flap is sutured. The clinical results obtained using this technique will enable the clinician to accomplish the bone regenerative procedure without extending the flap to the coronal aspect of the socket during immediate implant placement. This technique assists in the maintenance and integrity of the soft tissue form, which is critical for optimal esthetic results.

A retrospective analysis of peri-implant tissue responses at immediate load/provisionalized microthreaded implants

PURPOSE

The aim of this retrospective study was to examine the peri-implant tissue status at immediately provisionalized anterior maxillary implants 12 to 30 months following tooth replacement.

MATERIALS AND METHODS

This is a retrospective study of 43 microthreaded, TiO2 grit-blasted implants placed in healed ridges and immediate extraction sockets to restore maxillary anterior and premolar teeth in 28 patients. The cortical bone position relative to the implant reference point was evaluated at implant placement and 6 to 30 months following restoration. Radiographs were assessed using 7x magnification. The distance from the reference point to the cortical bone was measured to +/- 0.1 mm. The relationship of the peri-implant mucosa to the incisal edge of the definitive prosthesis was recorded.

RESULTS

Four implants in 3 individuals failed during the first 6 weeks following placement and provisional loading. Cortical bone adaptation from the time of implant placement up to 30 months following restoration ranged from 0.0 mm to 1.5 mm (average, 0.33 +/- 0.40 mm mesially and 0.28 +/- 0.37 mm distally). The mean radiographic measurements from the interproximal crestal bone to the contact point were 4.53 +/- -0.91 mm (mesial) and 4.06 +/- 0.98. Maintenance and growth of papilla was observed in this group of immediate provisionalized single-tooth implants. Definitive abutment or abutment screw loosening was not observed.

DISCUSSION

The linear clinical and radiographic measures of peri-implant tissue responses suggest that proper implant placement is followed by supracrestal biological width formation along the abutment and preservation of toothlike tissue contours. This may influence buccal peri-implant tissue dimensions.

CONCLUSIONS

Generalized maintenance of crestal bone and the increased soft tissue dimension with maintenance of peri-implant papilla were identified as expected outcomes for immediate loading/provisionalization of microthreaded, TiO2 grit-blasted implants. Control of peri-implant tissues can be achieved to provide predictable and esthetic treatment for anterior tooth replacement using dental implants.

Immediate Occlusal Loading of OsseotiteR Implants in Mandibular Edentulous Patients: A Prospective Observational Report with 18-Month Data

PURPOSE

To evaluate the efficacy of treatment consisting of placement and immediate occlusal loading of implants in 27 patients with edentulous mandibles.

MATERIALS AND METHODS

Twenty-seven patients were treated in two private practice settings. One hundred fifty-one implants were placed and immediately occlusally loaded with fixed implant prostheses (15 cement-retained, 12 screw-retained) on the day of implant placement. The implant-retained prostheses were inserted within 5 hours of implant placement. Patients were followed for at least 18 months. The required criteria for immediate occlusal loading was primary implant stability of at least 30 Ncm of insertion torque. The implant prostheses were removed at least 12 months post-placement and the implants were evaluated for primary clinical stability and radiographic bone apposition to implants.

RESULTS

At the 12-month follow-up appointments, cumulative survival rates of 98.0% and 100% were recorded for implants and prostheses, respectively. Three implants failed within 3 months. All other implants were clinically successful.

CONCLUSIONS

Immediate occlusal loading of multiple, splinted mandibular implants is an effective treatment when implants are stable at insertion and are rigidly splinted with implant-retained prostheses.

Preliminary report on a staged ridge splitting technique for implant placement in the mandible: a technical note

PURPOSE

Narrow edentulous alveolar ridges less than 5 mm wide require horizontal augmentation for the placement of screw-type dental implants. A staged approach to ridge splitting in the mandible to decrease the risk of malfracture during osteotomy is presented.

MATERIALS AND METHODS

Five consecutive patients with 6 long-span edentulous areas of the mandibular ridge were included in this study. After corticotomy of a rectangular buccal segment and a 40-day healing period, the mandibular ridge was split, leaving the buccal periosteum attached to the lateralized segment. Seventeen dental implants were placed, and the gap between the implants and the bone filled with a mixture of venous blood and a porous algae-derived hydroxyapatite.

RESULTS

All buccal segments fractured as planned at the basal corticotomy during ridge splitting. After 6 months, all implants were stable and surrounded by bone; prosthetic loading with fixed partial dentures was successful in all cases.

DISCUSSION

In the mandible, greenstick fracture during widening with osteotomes has not been controllable to date because of cortical thickness of the bone; the risk of malfracture during single-stage ridge splitting was high. With this approach, the location of the greenstick fracture is predetermined, and the perfusion for the buccal segment remains intact, although vascularization shifts from internal perfusion from spongy bone after the first intervention to external perfusion from the periosteum after the second intervention. The buccal cortical segment remains a pedicled graft after ridge splitting.

CONCLUSION

The preliminary results of this report indicate that staged ridge splitting can be a safe technique which overcomes the problems associated with single-stage ridge expansion/ridge splitting procedures without causing significant delay in treatment.

Histomorphometric evaluation and clinical assessment of endosseous implants in iliac bone grafts with shortened healing periods

PURPOSE

In the present study solid monocortical hipbone onlay grafts of the maxilla were analyzed histologically after a healing period of 3 months. The clinical success of the implants placed in the grafted bone was evaluated.

MATERIALS AND METHODS

Nineteen patients underwent augmentation with avascular iliac bone. A 2-stage procedure was performed with a 3-month healing period between graft and implant placement. At implant placement bone biopsy samples were taken at the proposed implant sites.

RESULTS

Of the 117 implants placed, 1 was not osseointegrated at the time of abutment connection. No implants were lost after loading during an observation period of up to 3 years. Clinical appearance of the augmented bone after 3 months showed a dense cortical layer with good blood perfusion. Histologic specimens were analyzed quantitatively and showed an average of 43.2% newly formed bone.

DISCUSSION

Histomorphometry showed that the amount of newly formed bone after 3 months was comparable to that found after a healing period of 4.5 months. The clinical success of the implants placed after the shortened healing period was comparable to that found in nonaugmented bone.

CONCLUSION

This study showed that after avascular iliac bone grafting, 3 months of revascularization was sufficient to ensure the secure placement of dental implants in second-stage surgery for this patient population.

Surgical Technique for Achieving Implant Parallelism and Measurement of the Discrepancy in Panoramic Radiograph

PURPOSE

This article describes a surgical technique for achieving implant placement parallelism and presents an equation concept to predict the bone depth available for implant placement by measuring the discrepancy of the panoramic radiograph compared with a clinical situation in cases in which a wide edentulous area is present.

MATERIALS AND METHODS

A surgical template with tube technique in combination with measurement of the vertical dimension of the mandible bone available for implant placement was used to treat 2 patients in whom 7 and 3 implants, respectively, were inserted in the lower and upper jaws.

RESULTS

All implants were successfully implanted into their reliable positions. In regard to the position of an important area such as the inferior alveolar nerve and maxillary sinus, this predictive equation can provide an extra margin of security.

CONCLUSION

A partial denture surgical template technique with tube technique using a Coen's drill guide in combination with a mathematical equation to find the clinical-radiographic discrepancy can be used as an alternative method in placement guidance of dental implant insertions and its fixed prosthetic treatment planning in a wide edentulous area.

Minimally invasive antral membrane balloon elevation followed by maxillary bone augmentation and implant fixation

The posterior maxillary segment frequently suffers from insufficient bone mass to support dental implants. Current bone augmentation methods, including the lateral maxillary approach (ie, hinge osteotomy) and sinus elevation by osteotome, have many shortcomings. The objective of our study was to assess the safety and efficacy of minimally invasive antral membrane balloon elevation (MIAMBE) followed by bone augmentation and implant fixation (executed during the same procedure). Alveolar crest exposure and implant osteotomy were followed by sequential balloon inflations yielding > 10 mm MIAMBE. A mix of autologous fibrin and bone particles with bone speckles was injected beneath the antral membrane. Implants were fixated into the osteotomies, and primary closure was performed during the same sitting. A total of 24 patients were enrolled. Successful conclusion of this procedure was accomplished in 91.6% of the initial 12 patients and 100% in the second dozen cases without significant complications. Patient discomfort was minimal. Long-term follow up revealed satisfactory bone formation, resulting in adequate implant stability. We conclude that the protocol of MIAMBE results in an excellent success rate, low complication rate, minimal discomfort, and long-term safety and durability. Because it requires only basic equipment and a short learning curve, this clinical approach should be widely employed.

Fixed ceramometallic prostheses over anterior and transzygomatic implants by using the sinus slot technique--report of a case

Atrophy of the upper jaw poses problems for fixed rehabilitation of implants. Of the different management possibilities that have been developed, transzygomatic implant placement is a good option and affords a high success rate. These implants are positioned in zygomatic bone by using 2 possible techniques. We present a 48-year-old woman with severe posterior maxillary atrophy in which the canine and frontozygomatic prominence were used to place 6 anterior and 2 transzygomatic implants by using the sinus slot technique for fixed bridge rehabilitation. The advantages of the sinus slot technique over the sinus window technique are discussed.

Dental implants placement in conjunction with osteotome sinus floor elevation: a 12-year life-table analysis from a prospective study on 588 ITIRimplants

OBJECTIVES

The purpose of this prospective study was to evaluate the clinical success of placing ITI dental implants in the posterior maxilla using the osteotome technique.

MATERIAL AND METHODS

All implants were placed following a one-stage protocol (elevating the sinus floor and placing the implant at the same time). Five hundred and eighty-eight implants were placed in 323 consecutive patients with a residual vertical height of bone under the sinus ranging from 6 to 9 mm. The mean observation follow-up period was 59.7 months (with a range of 12-144 months). This prospective study not only calculated the 12-year cumulative survival and success rates for 588 implants by life-table analysis but also the cumulative success rates for implant subgroups divided per implant length and the percentage of sinus membrane perforation were evaluated.

RESULTS

The 12-year cumulative survival and success rates were 94.8% and 90.8%, respectively. The analysis of implant subgroups showed slightly more favourable cumulative success rates for 12 mm long implants (93.4%) compared with 10 and 8 mm long implants (90.5% and 88.9%, respectively). During the study period, only 13 perforations of the Schneiderian membrane were detected with a perforation rate of 2.2% (13 perforations/601 treated sites). Ten perforations out of 13 were caused during the first half of the study period and of these, seven were detected during the first 3 years of this prospective study.

CONCLUSION

Based on the results and within the limits of the present study, it can be concluded that ITI implant placement in conjunction with osteotome sinus floor elevation represents a safe modality of treating the posterior maxilla in areas with reduced bone height subjacent to the sinus as survival and success rates were maintained above 90% for a mean observation period of approximately 60 months. Shorter implants (8 mm implants) did not significantly fail more than longer ones (10 and 12 mm implants): the differences were small compared with the number of events; hence, no statistical conclusion could be drawn. But, from the clinical point of view, the predictable use of short implants in conjunction with osteotome sinus floor elevation may reduce the indication for complex invasive procedures like sinus lift and bone grafting procedures.

A simplified protocol for the immediate loading of the edentulous arch

Restoring dentitions with dental implants is an extremely gratifying procedure for the dental professional. However, the traditional approach of delayed loading requires surgical, prosthetic and patient management gymnastics, often necessitating extended treatment over one year, with multiple relines of fixed provisional restorations or even long periods with removable prostheses. The purpose of this article is to outline a simplified protocol for the immediate loading of the edentulous arch. By adhering to this protocol, the dental team can provide patients with an immediate functional, esthetic and fixed restoration, thereby avoiding the multitude of issues associated with delayed loading and enhancing patient satisfaction.

[Preliminary clinical study of microimplants in the restoration of edentulous jaws]

OBJECTIVE

To investigate if magnetic- attached overdenture supported by microimplants of 2.5 mm in diameter was able to function properly.

METHODS

Fourteen microimplants were placed in 4 patients. Implants were exposed 3 months later and magnetic abutments were connected directly. X-ray was taken during the 3 year follow-up to examine marginal bone level. Peri-implant soft tissue was also checked. Denture retention, chewing stability and overall satisfaction with the microimplants retained overdenture were evaluated.

RESULTS

All of the 14 microimplants achieved initial primary stability without infection or any other postoperative complications. No implant was lost during the follow-up period. Only one magnetic abutment fractured one year after restoration and was replaced. X-ray showed highly stable marginal bone level around the microimplants. The patients were satisfied with the restoration.

CONCLUSIONS

The microimplants retained overdenture leads to a significant improvement of function despite of the small dimensions of these implants. In particular for elder patients with severe residual ridge resorption, this treatment represents a less invasive alternative compared to conventional implant systems.

Transcrestal sinus floor elevation: report of a case series

The technique of the osteotome-mediated transcrestal sinus floor elevation is described in a series of case reports. Fifty-five patients received a total of 66 implants over a period of 6 years. Bio-Oss was added in more than 60% of cases to increase the stability of the lifted area. The surgical procedure appeared to be a safe method that was well supported by the patients. It was applied for different prosthetic indications in partially and completely edentulous situations. The survival rate of the implants during the healing phase was 98.5%, and it was 100% after loading. The patients' responses to the Summers technique were evaluated by means of short interviews and visual analog scales (VAS), and the answers were compared with those from a group of patients who had received implants in the same location during the same period but without the osteotome technique. The answers regarding pain were not different between the groups. However, significantly more patients who had received the implants by means of the osteotome technique judged the surgical procedure as highly uncomfortable. It is concluded that patients need to be well prepared for the procedure.

Effects of different inter-implant distances on the stress distribution around endosseous implants in posterior mandible: A 3D finite element analysis

PURPOSE

The aim of this study was to evaluate the effects of different inter-implant distances on stress distribution in the bone around the endosseous titanium implants under vertical, oblique and horizontal loads in the posterior mandibular edentulousim by finite element analysis (3D FEA).

MATERIALS AND METHODS

3D FEA models representing mandible and ITI implant (Straumann, Waldenburg, Switzerland) were simulated. The distances in-between the units were set at 0.5, 1.0 and 2.0 cm. Vertical (V) 70 degrees N, 60 degrees oblique (BL) 35 degrees N in buccolingual direction and horizontal (MD) 14 degrees N in mesiodistal direction loads were applied to each of these designs. The principal stresses (tensile and compressive stress) on each model were calculated using MSC MARC finite element analyze solver software.

RESULTS

The tensile stress (P(max)) values have been evaluated that they rose at the cervical region of buccal side when the inter-implant distances increased under V and BL loads and they diminished while the inter-implant distances decreased. In short inter-implant distances the compressive stress (P(min)) has been presented with increased values and found at the lingual surface of the cervical region.

DISCUSSION

The results of this study indicated that the magnitude of the stress was influenced by complex factors such as the direction of loads and the distance between adjacent fixtures. The stress occurring around fixtures differs significantly with various types of inter-implant distance.

CONCLUSION

The evaluation of tensile and compressive stresses for cortical and cancellous bone under V, MD and BL loading conditions in aspect of inter-implant distance shows; the 1.0 cm of inter-implant distance is the optimum distance for two fixture implantation.

Minimally invasive extraction and immediate implant placement: the preservation of esthetics

Extraction sites in the esthetic zone present an obvious restorative challenge. This case report describes a surgical technique for the preservation of anterior esthetics that combines minimally invasive extraction with immediate implant placement. This single-stage approach preserves site morphology by protecting and supporting existing hard and soft tissues. Clinical success appears to be attributable to several important features of the technique. The first step involves the elevation, luxation, and extraction of the tooth using either a flapless or minimally invasive approach that reduces trauma to the adjacent tissues. The second step involves appropriate orientation, placement, and stabilization of the implant to preserve facial bone and soft tissue contours. Implant placement is accomplished using particulate freeze-dried bone allograft and enamel matrix derivative to achieve ridge preservation and bone augmentation. The composite graft material is considered critical for predictably resolving osseous voids and promoting implant integration, and consideration is given to the concept of osteogenic "jumping distance" between the implant and the eccentric walls of the alveolus. Finally, preservation of the soft tissue architecture during wound healing is achieved by placement of either a fixed or removable restoration. Consistent implant integration and preservation of the hard and soft tissue complexes have been achieved using this approach.

Immediate transition to an implant-supported dentition

Immediate implant placement and loading is becoming increasingly acceptable. However, to be successful, very careful case selection is required, and even if this is achieved, the clinical situation that develops as soon as the natural teeth are removed may prove much less adequate for implant stability, positioning, and survival than anticipated. It makes sense to "over engineer" a case and to place more implants rather than fewer to ensure adequate support during the critical early phase of therapy, particularly when the implants are loaded at the time of placement. It also should be appreciated that immediate transition induces gross changes that can make it difficult to predict the final esthetic outcome.