Posterior Edentulous Ridge Research Articles

Clinical Performance of Narrow-diameter Implants (NDIs) Supporting Fixed Prostheses in Stress-bearing Posterior Jaws: A Systematic Review

<p>Abstract: Objectives: Narrow-diameter implants (NDIs) may serve as a feasible treatment alternative for the rehabilitation of specific cases. The aim of this review article was to assess the clinical outcomes of restoring stress-bearing posterior edentulous ridges with NDIs. Materials and Methods: An electronic search was conducted in MEDLINE/PubMed and Cochrane Library databases and enriched by hand search. Prospective and retrospective clinical studies, from January 2000 to November 2021, with at least 10 patients and a follow-up period of at least 1-year after functional loading, were included. Marginal bone level (MBL) and implant survival/success rate were set as primary outcome variables. Results: From the initially identified 2,401 articles, 17 clinical studies fulfilled the inclusion criteria and were included. Of the selected studies, mean MBL after loading was within 2 mm at different time intervals up to 10 years. Recorded implant survival rate was 92.6-100%, 95.3-100%, 95.3-100%, and 95.1-97.9% after 1-, 3-, 5-, and 10-year, respectively, while success rate was 92.6-100%, 95-100%, and 95% at 1, 3, and 10 years. Biological and prosthetic complications were observed. Conclusions: Within the limitation of the present study, it could be concluded that the use of NDIs for rehabilitation of posterior jaws is a viable treatment alternative, with comparable MBL and implant survival/success rate to standard-diameter implants (SDIs).</p> <p> </p>

Survival Rates of Short Dental Implants (≤ 6.5 mm) Placed in Posterior Edentulous Ridges and Factors Affecting their Survival after a 12-Month Follow-up Period: A Systematic Review.

Dental implant placement in atrophic ridges is challenged by availability of bone and proximity to vital structures. Although short dental implants have been considered favorable, there is no consensus regarding their long-term survival and factors affecting it. This systematic review addressed the focused question, "What is the survival rate of short dental implants (SDI; length ≤ 6.5 mm) placed in posterior edentulous ridges without any ridge augmentation procedures and followed up for 12 months post-prosthetic loading, and what are the factors affecting their survival?" Based on a search of the indexed literature, 51 studies fulfilling the inclusion criteria were quantitatively reviewed. Overall SDI survival and factors influencing survival, such as anatomic location, surgical protocol, time of loading, type of prosthesis retention, nature of prosthesis, implant stability, crown-to-implant ratio (C/I ratio), and marginal bone loss at follow-up were evaluated. SDI survival based on clinical factors was compared to overall survival using odds ratio (OR), and continuously distributed data were evaluated using Pearson's correlation (P < .05). Based on this review, SDI placed in edentulous posterior regions of the maxilla and mandible have survival rates (96.45%) similar to those of conventional-length implants after a follow-up period of 12 months post-prosthetic loading. Except for smaller implant diameter (OR = 1.59, 95% confidence interval [CI] = 1.03-2.43, P < .05), screw-retained restorations (OR = 2.11, 95% CI = 1.25-3.57, P < .01), and C/I ratio ≥ 2 (Pearson's R = -0.694, P < .01), other variables relating to implant surgery, prosthetic loading, nature and type of prosthesis, and follow-up did not significantly affect SDI survival.

Maxillary removable partial denture combined with O’ring attachment implant: a case report

Oral rehabilitation with free-end removable partial denture (RPD) is one of the major challenges in prosthodontic dentistry. The absence of a distal abutment produces undesirable RPD movement during masticatory function due to the high resilience of the residual ridge, which limits the denture efficiency and may damage the abutment teeth and bone over time. The advent of dental implants made possible to substitute the missing teeth with fixed implant-supported dentures as the first choice treatment to overcome such inconveniences. However, this indication may not be suitable for all patients due to financial, anatomical or systemic health conditions. Nevertheless it is possible to improve free extension RPD by using implants in the posterior edentulous ridge to achieve biological, biomechanical, physiological and social benefits. This article aims to present a case report on oral rehabilitation in which a RPD was made combined with an implant for posterior support in a sizeable edentulous ridge. The patient appreciated the retention improvement and the aesthetic result. The combination of a RPD with a posterior implant is an alternative treatment for cases in which implant-supported fixed prosthesis is not indicated, reducing the displacement and minimizing the limitations of the free-end devices.

Subperiosteal Minimally Invasive Aesthetic Ridge Augmentation Technique (SMART): A New Standard for Bone Reconstruction of the Jaws.

Traditional guided bone regeneration techniques include flap mobilization and placement of a bone graft, often with the use of space-maintaining devices and cell-occlusive membranes. This approach is associated with frequent complications that negatively affect the outcome of the augmentation and the peri-implant soft tissue esthetics. Although current tunneling techniques have focused on periodontal soft tissue applications, earlier publications described their use for horizontal augmentation of mandibular posterior edentulous ridges in full-denture patients. More recently, the use of recombinant human platelet-derived growth factor (rhPDGF-BB) was tested with different bone matrices to treat maxillary anterior edentulous spans. The present case series reports the use of a subperiosteal minimally invasive aesthetic ridge augmentation technique (SMART) to treat 60 single and multiple edentulous, dentate, and implant sites on 21 patients and five treatment categories with a follow-up period ranging from 4 to 30 months. The technique includes the use of a laparoscopic approach to deliver a growth factor/xenograft combination into a subperiosteal pouch. No flap elevation, cell-occlusive membranes, space-maintaining devices, or decortication procedures were used. The results from this case series demonstrated predictable and consistent bone regeneration. The average gain in ridge width for all treatment categories was 5.11 mm (SD 0.76 mm), which compares favorably with previously published reports. Morbidity and complication rates were consistently reduced as well. Human histology results show xenograft particles surrounded by newly formed bone. The role of the periosteum as a source of pluripotent cells in growth factor–mediated bone regeneration is discussed.

Developing Stability of Posterior Mandibular Implants Placed With Osteotome Expansion Technique Compared With Conventional Drilling Techniques.

Clinical decisions regarding the stability and osseointegration of mandibular implants positioned using the bone expansion techniques are conflicting and limited. The objective was to evaluate the stability of implants placed using 2 surgical techniques, selected according to the initial width of the mandibular posterior edentulous ridge, with D3 bone density, during a 12-week period. Fifty-eight implants in 33 patients were evaluated. Thirty-two implants in 24 patients were positioned using the osteotome expansion technique, and 26 fixtures in 17 patients were installed using the conventional drilling technique. The implant stability quotient values were recorded at weeks 0, 1, 2, 3, 4, 6, 8, 10, and 12 postsurgery and evaluated using analysis of variance, independent, and paired t tests. Calibrated according to the stability reading of a 3.3-mm diameter implant, the osteotome expansion group was associated with a lower bone density than the conventional group (64.96 ± 6.25 vs 68.98 ± 5.06, P = .011). The osteotome expansion group achieved a comparable primary stability (ISQb-0, P = .124) and greater increases in secondary stability (ISQb-12, P = .07) than did the conventional technique. A D3 quality ridge with mild horizontal deficiency is expandable by using the osteotome expansion technique. Although the 2 groups presented similar implant stability quotient readings during the study period, the osteotome expansion technique showed significant improvement in secondary stability. The healing patterns for these techniques are therefore inconsistent.

Crestal bone resorption in augmented bone using mineralized freeze-dried bone allograft or pristine bone during submerged implant healing: a prospective study in humans.

There is limited evidence on the crestal bone level changes around implants placed in bone augmented by guided bone regeneration (GBR) during submerged healing. The purpose of this study was to prospectively compare radiographic crestal bone changes around implants placed in augmented bone with changes around implants placed in pristine bone. Patients receiving dental implants in the augmented or pristine mandibular posterior edentulous ridge were included in the study. The digital standardized radiographs from the implant placement procedure were compared to the radiographs from the second-stage procedure to evaluate the peri-implant marginal bone level changes. The soft tissue thickness (ST), width of keratinized mucosa (wKM), and early cover screw exposure (eIE) were measured at the time of the second-stage procedure. A total of 29 implants in 26 patients, 11 in augmented bone (test group) and 18 in pristine bone (control group), were analyzed. The mean peri-implant bone loss (ΔBL) was 0.74±0.74mm (mean±SD) in the test group and 0.25±0.55mm (mean±SD) in the control group. The differences between the test and control groups in the mesial, distal, and mean peri-implant crestal bone level changes were statistically significant (P=0.009, P=0.004, and P=0.001, respectively). The confounding factors (ST, wKM, and eIE) were adjusted. More peri-implant crestal bone loss during the submerged healing period was observed in augmented bone than in pristine bone. Augmented bone may not exhibit the same characteristics as pristine bone during the implant submerged healing period.

Strain characteristics of Marburg double crown-retained implant overdentures compared with bar and ball-retained implant overdentures, with and without a rigid major connector

It is hard to identify the most favorable retainer type and the denture design when considering strain levels around implants and in edentulous ridges for implant overdentures (IOVD). The purpose of this study was to evaluate the strain transmitted to the implants and edentulous ridges by Marburg double crown (MDC)-retained IOVD as opposed to bar and ball-retained IOVD and the efficiency of a rigid major connector in the maxilla. An in vitro maxillary model was prepared with 4 implants, with strain gauges placed distally to each implant and also in the anterior and posterior edentulous ridges. Five overdentures were fabricated for each MDC and each ball and bar attachment retainers. Vertical loads of 280 N were applied bilaterally on the first molar region. Then the palatal bars of each IOVD were disconnected, and loading procedures were repeated for the prostheses. No significant difference was observed among the MDC and the bar and ball-retained IOVD, with and without a rigid bar according to the data taken from both the implants and edentulous ridges. However, when the strain values attained from each strain gauge separately were considered, a slight difference was observed around the implants of ball-retained overdentures and in the edentulous ridges of MDC-retained overdentures. Within the limitations of this in vitro study, MDC-retained maxillary overdentures with 4 parallel and symmetrically placed implants can be used safely without a rigid major connector as with bar and ball-retained IOVD with regard to the strains generated in the edentulous ridge and around implants.

Retrospective clinical study on sinus bone graft and tapered-body implant placement

ObjectivesThis study evaluated implant success rate, survival rate, marginal bone resorption of implants, and material resorption of sinus bone graft in cases wherein tapered body implants were installed.Materials and MethodsFrom September 2003 to January 2006, 20 patients from Seoul National University Bundong Hospital, with a mean age of 54.7 years, were considered. The mean follow-up period was 19 months. This study covered 50 implants; 14 implants were placed in the maxillary premolar area, and 36 in the maxillary molar area; 24 sinuses were included.ResultsThe success rate was 92%, and the survival rate was 96.0%. The mean amount of sinus augmentation was 12.35±3.27 mm. The bone graft resorption rate one year after surgery was 0.97±0.84 mm; that for the immediate implantation group was 0.91±0.86 mm, and that for the delayed implantation group was 1.16±0.77 mm. However, the difference was not statistically significant. The mean marginal bone resorption one year after restoration was 0.17±0.27 mm (immediate group: 0.12±0.23 mm; delayed group 0.40±0.33 mm); statistically significant difference was observed between the two groups.ConclusionTapered body implant can be available in the maxillary posterior edentulous ridge which sinus bone graft is necessary.

Effects of the type and rigidity of the retainer and the number of abutting teeth on stress distribution of telescopic-retained removable partial dentures

Background/purposeLittle is known about the force-transmission characteristics and patterns of telescopic-retained removable partial dentures (RPDs) as related to their type and rigidity (rigid and/or resilient) and the number of abutting teeth supporting the telescopic dentures. In this study, we compared the strain around the abutting teeth and edentulous ridges supporting telescopic-retained RPDs with different designs using a strain gauge technique. Materials and methodsA maxillary model including four abutting teeth (# 14, 13, 23, and 24) was constructed and is referred to as Case 1. In total, four RPD frameworks (two resilient and two rigid) were fabricated for Case 1 with a conventional telescope retainer and attachment-retained telescopic retainer (ARTR) groups. A vertical static load of 280 N was applied, and strain values obtained from the strain gauges were recorded. RPDs were modified according to the following cases—Case 2 included teeth 14, 13, and 23; Case 3 included teeth 14 and 13; and Case 4 included teeth 13 and 23—and measurements were repeated. A randomized block analysis of the variance test was conducted using a general linear model procedure with statistical software. Multiple comparisons between groups were performed using Tukey’s honest significant difference test (α=0.05). ResultsRPDs with an ARTR produced more strain distal to the abutting teeth than RPDs with a conventional telescope retainer. Both retainer types with a rigid design produced more strain distal to the abutting teeth than did retainers with a resilient design. RPDs supported by four, three, and two unilateral abutting teeth produced similar strain patterns. RPDs supported by two bilateral abutting teeth produced the highest strain distal to the abutting teeth, but there was no significant difference between the strains produced by RPDs supported by either two unilateral or bilateral abutting teeth. The highest strain values were obtained from strain gauges distal to the “terminal” abutting teeth. Directions of the principal strain were in a vertical direction for gauges located distal to the terminal abutting teeth. More strain was produced on the posterior edentulous ridges. ConclusionRPDs with an ARTR and both retainer types with a rigid design produced more strain distal to the abutting teeth. Using more than two abutting teeth did not improve the strain patterns of the tested RPDs. More strain was produced on the posterior edentulous ridges.

Evaluation of Stress Patterns Produced by Implant-Retained Overdentures and Implant-Retained Fixed Partial Denture

The purposes of this study were to photoelastically measure the biomechanical behavior of 4 implants retaining different cantilevered bar mandibular overdenture designs and to compare a fixed partial denture (FPD). A photoelastic model of a human edentulous mandible was fabricated, which contained 4 screw-type implants (3.75 × 10 mm) embedded in the parasymphyseal area. An FPD and 3 overdenture designs with the following attachments were evaluated: 3 plastic Hader clips, 1 Hader clip with 2 posterior resilient cap attachments, and 3 ball/O-ring attachments. Vertical occlusal forces of 100 N were applied between the central incisor and unilaterally to the right and left second premolars and second molars. Stresses that developed in the supporting structure were monitored photoelastically and recorded photographically. The results showed that the anterior loading, the overdenture with 3 plastic Hader clips, displayed the largest stress concentration at the medium implant. With premolar loading, the FPD and overdenture with 3 plastic Hader clips displayed the highest stresses to the ipsilateral terminal implant. With molar loading, the overdenture with 3 ball/O-ring attachments displayed the most uniform stress distribution in the posterior edentulous ridge, with less overloading in the terminal implant. It was concluded that vertical forces applied to the bar-clip overdenture and FPD created immediate stress patterns of greater magnitude and concentration on the ipsilateral implants, whereas the ball/O-ring attachments transferred minimal stress to the implants. The increased cantilever in the FPD caused the highest stresses to the terminal implant.

903 高度な顎堤吸収を持つ下顎両側性遊離端義歯・支台歯とその周辺組織のインプラント支持による荷重伝達特性(J04-1 臨床医歯学における非・低侵襲計測技術の展開(1) 歯科・整形外科における計測および生体シミュレーション,ジョイントセッション,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

The purpose of this study was to photoelastically compare the load transfer characteristics of a distal extension RPD with implant assisted support in the posterior of a mandible with an atrophic edentulous ridge. The model included the anterior teeth and the first premolars bilaterally. Threaded implants, 3.75mm diameter 7mm length, were embedded 20mm distal to the first premolars on the posterior edentulous ridges. I-bar partial dentures with mesial rests were fabricated and physiologically adjusted to the models. The implant support conditions tested were healing abutments and 3mm ball attachments. Simulated vertical and lateral occlusal loads were applied at the first molar position and the stress developed in the abutment teeth were monitored photoelastically. Posterior implants with both healing abutment and ball attachments in the posterior of a mandible tended to assist support of a distal extension RPD and produce only low level stresses in the supporting atrophic edentulous ridge.

Effect of anchorage systems and extension base contact on load transfer with mandibular implant-retained overdentures

Statement of Problem. Controversy exists regarding the effect of anchorage systems and extension base contact on stress transfer to multiple implants by mandibular overdentures. Purpose. This simulation study measured photoelastically the biologic behavior of 4 implants retaining a mandibular overdenture. The purpose of the investigation was to compare the load transfer characteristics of different mandibular-retained overdenture designs, with and without edentulous ridge contact. Material and Methods. A photoelastic model of a human edentulous mandible was fabricated having 4 screw-type implants (3.75 × 10 mm) embedded in the parasymphyseal area. Substructure designs utilizing a cantilevered bar, spark erosion framework, noncantilevered bar, and solitary anchors were fabricated. A vertical load of 30 lb was applied to the first molar unilaterally on each of the 4 standardized overdenture prostheses, with and without a silicone tissue spacer, for a total of 8 tested conditions. Stresses that developed in the supporting structure were monitored photoelastically and recorded photographically. Results. Without the simulated tissue contact on the posterior edentulous ridge, the cantilevered bar framework caused the highest stresses to the terminal implant, followed by spark erosion framework, non-cantilevered bar, and solitary anchor design. With simulated tissue contact under the extension base, stress transfer to the distal implant was uniformly reduced to a low level. Conclusion. Without intimate extension base contact with the posterior edentulous ridge, the cantilevered anchorage systems generated the highest stresses, under load, to the ipsilateral terminal implant and the solitary anchor design transferred the least. With simulated intimate extension base contact, all anchorage systems transferred low stress to the distal implant region. For all conditions and designs, low stress was transferred to the contralateral side of the arch. (J Prosthet Dent 2000;84:327-34.)