Preliminary report on the outcome of tilted implants with longer lengths (20-25 mm) in low-density bone: one-year follow-up of a prospective cohort study

A Technical Note on a Modified Subcrestal Buccal Flap Approach to All-on-Four: A Case Report

This case report describes a dual full-arch rehabilitation focusing on a modified buccal incision for installation of four implants for full-arch rehabilitation of an edentulous maxilla. A modified buccal incision was performed in the subcrestal buccal region to promote direct access to the periosteum without incising the muscles in the region. For the installation of anterior implants, an 8.5 mm implant was locked in the cortical bone of the alveolar ridge and in the cortical bone of the floor of the pyriform cavity. The drilling point of the posterior implants was defined using the anterior implants as a visual reference, and the entry point could be visually estimated from the topography of the palatal surface of the maxilla. After bone leveling, the drilling enlargement sequence was carried out using drills that allowed the installation of long implants (18 mm). Straight mini-abutments were installed in the anterior implants and angled at 30º in the posterior implants. The flap was then perforated in the exact region where the mini-abutments were located. The buccal incision line was sutured with continuous 5-0 nylon suture. On the following day, aesthetic tests were carried out with teeth mounting. The patient presented minimal edema, and the lip motricity and smile width were completely preserved. The prosthesis was delivered five days after surgery. The suture was removed, and the prosthesis was installed while maintaining compression on the gingival tissue. The patient reported no pain during the prosthesis installation. The modified buccal flap enables implant placement for full-arch rehabilitation of an edentulous maxilla.

Influence of abutment angulation on implant failure in immediately placed and restored implants in the esthetic zone

Background: Tooth extraction socket in the aesthetic area is a major indication for immediate implant placement greatly improving patient satisfaction and preserving the alveolar ridge. However, the effect of non-axial force on the peri-implant bone with subsequent early implant failure remains unclear. Objective: Evaluate the prognosis of tilted implants immediately placed and restored with angled abutments in comparison to straight implants restored with straight abutments in the esthetic area (anterior or premolars) using computer-aided surgical guides. Material and methods: Badly decayed non-restorable teeth in the aesthetic zone (anterior or premolars) were extracted atraumatically. Immediately after guided implant insertion, the abutments were adjusted and placed according to the allocation group (0, 15, or 25-degree angle) then a temporary crown was performed out of occlusion in centric and eccentric relation. Early implant failure was assessed at three and six months. Results: There was no statistically significant difference between the two groups (P=0.305). Straight and angled abutment groups showed 6 (14.3%) and 8 (20%) failed cases, respectively. The post-hoc subgroup analysis showed no statistically significant difference between angle 15 and angle 25 degree groups where (P=0.686) or between Anterior and Premolar groups (P=0.853). Conclusion: There was no statistically significant difference in the failure rate when comparing angled to straight immediately placed & restored implants. This applies to both anterior and premolar implants.

Ten-year follow-up of full-arch rehabilitations supported by implants in immediate function with nasal and full-length palatine bicortical anchorage on the anterior maxilla

PURPOSE

To evaluate the immediate function of anterior maxillary implants.

METHODS

One hundred nine patients (42 males and 67 females; average age 55.2 years; range 38-81 years) were followed for 10 years. One hundred eighty-eight implants using nasal and full-length palatine cortical anchorage were inserted in the anterior section of the maxilla together with 188 tilted implants placed posteriorly. Outcome measures were implant success and survival, prosthesis survival, bone loss, and the incidence of biological and mechanical complications. Cumulative success and survival were computed through Kaplan-Meyer product limit estimator (at patient level) and life tables (implant level).

RESULTS

Four patients lost one implant each, giving a 10-year cumulative survival rate of 95.8% and 97.7% using the patient and the implant as the unit of analysis, respectively. The prosthesis survival rate was 98.2%, and the average marginal bone loss was 1.79 mm (1.06 mm). The cumulative success rate was 89.1% and 92.5% using the patient and the implant as the unit of analysis, respectively.

CONCLUSION

Full-arch fixed prosthetic rehabilitations supported by immediately functional implants inserted in the anterior maxilla with bicortical anchorage together with posterior-tilted implants are viable in the long term.

Biomechanical behavior of atrophic maxillary restorations using the all-on-four concept and long trans-sinus implants: A finite element analysis

Background. Maxillary bone atrophy with a considerable amount of pneumatization and anterior expansion of the maxillary sinus might be a situation limiting oral rehabilitation with osseointegrated implants. Therefore, the present study aimed to biomechanically evaluate two rehabilitation techniques for maxillary bone atrophy: all-on-four and long trans-sinus implants.

Methods. Two three-dimensional models consisting of atrophic maxilla with four implants were simulated. In the M1 model, two axially inserted anterior implants and two tilted implants, 15 mm in length, placed tangential to the maxillary sinus’s anterior wall were used. In the M2 model, two axially inserted anterior implants and two trans-sinus tilted implants, 24 mm in length, were used. For the finite element analysis (FEA), an axial load of 100 N was applied on the entire extension of the prosthesis, simulating a rehabilitation with immediate loading. The peri-implant bone and the infrastructure were analyzed according to the Mohr-Coulomb and Rankine criteria, respectively.

Results. The results were similar when the stresses on peri-implant bone were compared: 0.139 and 0.149 for models 1 and 2, respectively. The tension values were lower in the model with trans-sinus implants (27.99 MPa).

Conclusion. It was concluded that the two techniques exhibited similar biomechanical behavior, suggesting that the use of long trans-sinus implants could be a new option for atrophic maxilla rehabilitation.

Implant and prosthesis survival rates of full-arch immediate prostheses supported by implants with and without bicortical anchorage: Up to 2 years of follow-up retrospective study

OBJECTIVES

To compare implant and prosthesis survival rates between full-arch immediate prostheses supported by 4 hydrophilic implants with bicortical anchorage and by 5 or 6 hydrophilic implants placed without bicortical anchorage.

MATERIAL AND METHODS

The sample was retrospectively selected and comprised completely edentulous patients treated with full-arch immediate prostheses supported by Morse Taper hydrophilic implants. The selected patients were divided into four groups, according to the region of implant placement and type of anchorage. Differences in implant and prosthesis survival rates between groups, as well as the influence of bicortical anchorage on implant primary stability, were verified using Fisher's exact tests (significant at p < .05).

RESULTS

The sample comprised 392 implants, 72 were placed in the maxilla with bicortical anchorage, and 85 were placed without. In the mandible, 140 implants were placed with and 95 were placed without bicortical anchorage. The follow-up period was up to 24 months. A 98.8% implant survival rate was observed for the group of implants placed without bicortical anchorage in the maxilla, and of 100% for the other groups. The overall implant survival rate was 99.7% (391 of 392 implants). Prosthesis survival rate was 100% for all groups. No differences were observed between groups with respect to implant and prosthesis survival rates. Significantly higher primary stability was observed for implants placed with bicortical anchorage in both jaws.

CONCLUSION

Predictable results and high survival rates were achieved within the period evaluated by the present retrospective study, with immediate full-arch prostheses when only four hydrophilic implants are placed bicortically.

Extraction of Maxillary Impacted Teeth with Simultaneous Immediate Full Mouth Loading Using Long Implant: A Case Report

Here, we describe the provision of an implant-supported prosthesis in a patient with impacted teeth in the maxilla, which complicated implant placement and necessitated utilization of the extraction sockets of previously impacted teeth and residual submerged roots. The patient was a 63-year-old man who visited our clinic with the chief complaint of difficulty in mastication. Numerous residual roots were observed in the maxilla, and radiographic imaging revealed that the residual roots of teeth #13 and #16 were fully impacted. The patient complained of a strong sensation of a foreign body in the area of a denture support overlying these residual roots. Therefore, the impacted teeth were extracted, 5 implants placed, and a temporary prosthesis provided. Given the necessity of placing the implant through the extraction socket of the impacted canine (#13), favorable initial stability was achieved using a long (>20 mm) implant. Moreover, autogenous bone obtained by osteotomy was grafted onto the extracted impacted tooth socket. The clinical condition was stable at approximately 1 year after implant placement and so the final prosthesis was delivered, with periodic check-ups being performed every 3 months thereafter. After 4 years, the patient has reported no symptoms. Clinically, there are no signs of inflammation, and the postoperative condition is deemed to be very favorable.

Evaluation of Crestal Bone Loss Around Straight and Tilted Implants in Patients Rehabilitated by Immediate-Loaded Full-Arch All-on-4 or All-on-6: A Prospective Study

The aim of this prospective study was to compare implant success rate and crestal bone loss around tilted and straight implants supporting immediate-loading full-arch rehabilitations. Twenty consecutive patients with edentulous jaws treated between June 2013 and July 2015 who satisfied all inclusion and exclusion criteria were included in the study. All patients were rehabilitated through a full-arch restoration supported by 4 or 6 immediately loaded implants. Clinical and radiographic examinations were scheduled every 12 months to evaluate implant success rates and crestal bone levels. Significant differences in crestal bone levels and success rates between straight and tilted implants were investigated by means of independent statistical analysis; differences were regarded as significant if P < .05. Seventy straight and 50 tilted implants were placed to rehabilitate 14 mandibles and 12 maxillae in 20 patients. After a follow-up of 12 to 36 months, survival rate was 97.1% for straight implants and 96.0% for tilted implants; while success rates were 94.3% and 94.0%, respectively. Success and survival rates were not significantly different (P > .05). Change in crestal bone level was 0.5 ± 0.4 mm for straight implants and 0.6 ± 0.4 mm for tilted implants (P > .05). Straight and tilted implants seemed to have similar behavior after immediate loading rehabilitations. After functional loading, straight and tilted implants did not differ significantly in clinical outcome.

Implant-Supported Immediately Loaded Fixed Full-Arch Dentures: Evaluation of Implant Survival Rates in a Case Cohort of up to 7 Years

BACKGROUND

The treatment of severely atrophied and edentulous jaws by means of fixed implant supported solutions is a challenging procedure.

PURPOSE

The immediate loading of four to six axial and tilted implants offers the possibility to overcome elaborate hard tissue augmentation procedures but lacks implant and patient related data on implant survival rates.

MATERIALS AND METHODS

This retrospective 7-years clinical trial investigated the implant survival rates of 2,081 implants (380 patients, 482 jaws) using an immediate loading protocol with either 4, 5, or 6 implants per restoration. Survival rates were calculated concerning implantation related factors (jaws/number of supporting implants/angulations/diameters/lengths) and patient related factors (medical status/smoking).

RESULTS

Overall survival of 2,081 implants was 97.0% on implant level. Survival rates of implantation related factors did not yield significant differences. Significant differences were yield between healthy patients and patients with osteoporosis (p = .002) and the medical status group "other" (p = .032), respectively. Smokers yielded a significantly higher survival than nonsmokers (p = .002).

CONCLUSIONS

It is assumed that four implants per jaw serve as a sufficient implant number for full arch restorations in both, the mandible and the maxilla. Osteoporosis under the medication with bisphosphonates seems to be a risk factor for implant survival. The authors suggest that the effect of smoking on ISRs remains controversial within this treatment concept.

Double Full-Arch Versus Single Full-Arch, Four Implant-Supported Rehabilitations: A Retrospective, 5-Year Cohort Study

PURPOSE

To report the 5-year outcome of the All-on-4 treatment concept comparing double full-arch (G1) and single-arch (G2) groups.

MATERIALS AND METHODS

This retrospective cohort study included 110 patients (68 women and 42 men, average age of 55.5 years) with 440 NobelSpeedy groovy implants. One hundred sixty-five full-arch, fixed, immediately loaded prostheses in both jaws were followed for 5 years. G1 consisted of 55 patients with double-arch rehabilitations occluded with implant-supported fixed prostheses, and G2 consisted of 55 patients with maxillary single-arch rehabilitations or mandibular single-arch rehabilitations occluded with natural teeth or removable prostheses. The groups were matched for age (±6 years) and gender. Primary outcome measures were cumulative prosthetic (both interim and definitive) and implant survival (Kaplan-Meier product limit estimator). Secondary outcome measures were marginal bone levels at 5 years (through periapical radiographs and using the patient as unit of analysis) and the incidence of mechanical and biological complications. Differences in survival curves (log-rank test), marginal bone level (Mann-Whitney U test), and complications (chi-square test) were compared inferentially between the two groups using the patient as unit of analysis with significance level set at p ≤ 0.05.

RESULTS

No dropouts occurred. Prosthetic survival was 100%. Five patients lost 5 implants (G1: n = 3; G2: n = 2) before 1 year, rendering an estimated cumulative survival rate of 95.5% (G1: 94.5%; G2: 96.4%; Kaplan-Meier, p = 0.645, nonsignificant). The average (SD) marginal bone level was 1.56 mm (0.89) at 5 years [G1: 1.45 mm (0.77); G2: 1.67 mm (0.99); p = 0.414]. The incidence rate of mechanical complications (in both interim and definitive prostheses) was 0.16 and 0.13 for G1 and G2, respectively (p = 0.032). The incidence rate of biological complications was 0.06 and 0.05 for G1 and G2, respectively (p = 0.669).

CONCLUSIONS

Based on the results, rehabilitating double- or single-arch edentulous patients did not yield significant differences on survival curves. The incidence of mechanical complications was significantly higher for double-arch rehabilitated patients but nevertheless, these mechanical complications did not affect the long-term survival of either the prostheses or the implants.