Replacement of a Molar With 2 Narrow Diameter Dental Implants

Single missing molar with wide mesiodistal length restored using a single or double implant-supported crown: A self-controlled case report and 3D finite element analysis

PURPOSE

Based on a self-controlled case, this study evaluated the finite element analysis (FEA) results of a single missing molar with wide mesiodistal length (MDL) restored by a single or double implant-supported crown.

METHODS

A case of a missing bilateral mandibular first molar with wide MDL was restored using a single or double implant-supported crown. The implant survival and peri-implant bone were compared. FEA was conducted in coordination with the case using eight models with different MDLs (12, 13, 14, and 15 mm). Von Mises stress was calculated in the FEA to evaluate the biomechanical responses of the implants under increasing vertical and lateral loading, including the stress values of the implant, abutment, screw, crown, and cortical bone.

RESULTS

The restorations on the left and right sides supported by double implants have been used for 6 and 12 years, respectively, and so far have shown excellent osseointegration radiographically.The von Mises stress calculated in the FEA showed that when the MDL was >14 mm, both the bone and prosthetic components bore more stress in the single implant-supported strategy. The strength was 188.62-201.37 MPa and 201.85-215.9 MPa when the MDL was 14 mm and 15 mm, respectively, which significantly exceeded the allowable yield stress (180 MPa).

CONCLUSIONS

Compared with the single implant-supported crown, the double implant-supported crown reduced peri-implant bone stress and produced a more appropriate stress transfer model at the implant-bone interface when the MDL of the single missing molar was ≥14 mm.

Finite Element Analysis and Fatigue Test of INTEGRA Dental Implant System

The study involved numerical FEA (finite element analysis) of dental implants. Based on this, fatigue tests were conducted according to the PN-EN 14801 standard required for the certification of dental products. Thanks to the research methodology developed by the authors, it was possible to conduct a thorough analysis of the impact of external and internal factors such as material, geometry, loading, and assembly of the dental system on the achieved value of fatigue strength limit in the examined object. For this purpose, FEM studies were based on identifying potential sites of fatigue crack initiation in reference to the results of the test conducted on a real model. The actions described in the study helped in the final evaluation of the dental system design process named by the manufacturer as INTEGRA OPTIMA 3.35. The objective of the research was to identify potential sites for fatigue crack initiation in a selected dental system built on the INTEGRA OPTIMA 3.35 set. The material used in the research was titanium grade 4. A map of reduced von Mises stresses was used to search for potential fatigue crack areas. The research [loading] was conducted on two mutually perpendicular planes positioned in such a way that the edge intersecting the planes coincided with the axis of the system. The research indicated that the connecting screw showed the least sensitivity (stress change) to the change in the loading plane, while the value of preload has a significant impact on the achieved fatigue strength of the system. In contrast, the endosteal implant (root) and the prosthetic connector showed the greatest sensitivity to the change in the loading plane. The method of mounting [securing] the endosteal implant using a holder, despite meeting the standards, may contribute to generating excessive stress concentration in the threaded part. Observation of the prosthetic connector in the Optima 3.35 system, cyclically loaded with a force of F ≈ 300 N in the area of the upper hexagonal peg, revealed a fatigue fracture. The observed change in stress peak in the dental connector for two different force application surfaces shows that the positioning of the dental system (setting of the socket in relation to the force action plane) is significantly decisive in estimating the limited fatigue strength.

Graftless Immediate Dual Implant Anatomic Placement With Immediate Provisional Passive Loading and Definitive Hybrid Crown for the Restoration of Mandibular Molar: A Clinical Report

Immediate implant placement is well-known science and treatment in implant dentistry. It is a multitasking treatment consisting of surgical, prosthodontic, and periodontal aspects, implemented to obtain long-term clinically esthetic and functioning prosthesis. Immediate placement enables clinicians to reduce the number of surgical steps and shorter treatment duration. It has become a standard surgical protocol in modern implant practice. According to existing literature, dual implant placement can be done to avoid any cantilever effect in a single implant and to distribute masticatory forces. This clinical report describes the extraction of an infected mandibular right first molar, (46, Federation Dentaire Internationale) followed by immediate dual placement of dental implants in the rinsed and cleansed sockets. The tooth was atraumatically extracted from the socket, and the latter was prepared to the required depth, and endosseous implants were placed in both the mesial and distal sockets. This atraumatic graft-free operating technique and immediate placement resulted in the preservation of hard and soft tissues. It also increased the patient's comfort, acceptance, and satisfaction due to immediate loading with a provisional removable prosthesis. This was later replaced with a dual screw-retained hybrid implant crown.

Influence of implant location on titanium-zirconium alloy narrow-diameter implants: A 1-year prospective study in smoking and nonsmoking populations

STATEMENT OF PROBLEM

Titanium-zirconium (Ti-Zr) alloy (Roxolid) narrow-diameter implants (NDIs) have been widely used for implant-supported prostheses in anterior and posterior regions in the jaws. However, the relationship between implant location and clinical outcome remains unclear.

PURPOSE

The purpose of this clinical study was to evaluate and compare the clinical and radiographic outcomes of NDIs placed in different regions of the jaws in both smokers and nonsmokers.

MATERIAL AND METHODS

Eighty-four participants scheduled to receive NDIs for tooth rehabilitation were included, and the inserted NDIs were divided into 3 groups depending on their locations: implants used to restore anterior teeth, implants used to restore premolars, and implants used to restore molars. Crestal bone loss (CBL), implant survival and success rates, bleeding on probing (BOP), and pocket probing depth (PPD) were evaluated 6 and 12 months after implant loading (α=.017 for implant survival and success rates after Bonferroni correction, α=.05 for other parameters).

RESULTS

Statistical analysis of 6- and 12-month CBL of all participants presented no statistically significant difference among the 3 groups. For smokers, the molar group presented significantly more CBL than the premolar group (0.90 ±0.94 versus 0.16 ±0.27 mm, P=.027) at the 6-month examination. The implant survival rates were 95.65%, 100%, and 100% for anterior, premolar, and molar regions, respectively (P=.283). No statistically significant difference was observed regarding periodontal parameters (P>.05).

CONCLUSIONS

Implant location has no influence on the clinical and radiographic parameters of Ti-Zr NDIs placed in a nonsmoking population. However, the combination of posterior location and smoking may induce higher risk of crestal bone loss. Caution should be taken when restoring molars for smokers with NDIs.

Prevalence and morphological variations of maxillary sinus septa in different age groups: a CBCT analysis

BACKGROUND

There are limited data from Saudi Arabia on the prevalence and characteristics of maxillary sinus septa.

OBJECTIVE

Determine the prevalence and morphological characteristics of septa in the maxillary sinus and their relationship to gender and age using cone beam computed tomography (CBCT).

DESIGN

Cross-sectional SETTING: CBCT images acquired from the maxillofacial radiology department in a dental school.

PATIENT AND METHODS

CBCT scans of 1010 maxillary sinuses from 505 patients were analyzed to determine the prevalence, location, type, and orientation of maxillary sinus septa. Descriptive statistics, chi-square tests and t tests were used to analyze the data.

MAIN OUTCOME MEASURES

The prevalence, location, type, and orientation of maxillary sinus septa.

SAMPLE SIZE

1010 sinuses from 505 patients.

RESULT

Approximately 46% of the studied patients had maxillary septa, which were present in 370 (37%) sinuses. About 64% of the septa were present on the right side and 85.7% of all septa were mediolater-ally oriented. The mean height of the septa was 6.06 mm (0.84) in the right sinuses and 5.70 mm (0.93) in the left sinuses. Multiple septa were found in 101 patients (20%). Among males, 58.5% had septa compared to 34% of females (P<.001.) A significant positive association was found between age and the presence and number of septa, P<.001.

CONCLUSIONS

Maxillary sinus septa were highly prevalent with various heights and directions among the studied sample. Careful assessment of different anatomic variation must be conducted prior to any maxillary sinus augmentation, particularly in older patients.

LIMITATIONS

Cross-sectional evaluation of CBCT images from one dental school patient population; thus, the findings cannot be generalized to other populations.

CONFLICT OF INTEREST

None.

In Vitro Effect of Drilling Speed on the Primary Stability of Narrow Diameter Implants with Varying Thread Designs Placed in Different Qualities of Simulated Bone

It is hypothesized that there is no statistically significant impact of drilling speed (DS) on the primary stability (PS) of narrow-diameter implants (NDIs) with varying thread designs placed in dense and soft simulated bone. The aim of this in vitro study was to evaluate the impact of DS on the PS of NDIs with varying thread designs placed in dense and soft simulated bone. Two hundred and forty osteotomies for placement of various implant macro-designs were divided into three groups (80 implants per group): Group A (NobelActive, 3.0/11.5 mm); Group B (Astra OsseoSpeed-EV, 3.0/11 mm); and Group C (Eztetic-Zimmer, 3.1/11.5 mm) implants. These implants were placed in artificial dense and soft simulated bone using DSs of 800 and 2000 revolutions per minute (RPM). Resonance frequency analysis (RFA) and implant stability quotient (ISQ) were assessed. Group comparisons were performed using the one-way analysis of variance with Tukey’s post hoc tests. Level of significance was set at P < 0.05. In groups A and B, there was no difference in the ISQ for NDIs inserted in dense bone at 800 and 2000 RPM. In Group C, ISQ was significantly higher for NDIs placed in dense bone at 800 PRM compared to 2000 RPM (P < 0.05). In Group A, ISQ values were significantly higher for NDIs inserted in soft bone at 2000 RPM as compared to those inserted at 800 RPM (P < 0.05). For NDIs, a lower drilling speed in dense artificial simulated bone and a higher drilling speed in soft artificial simulated bone is associated with high primary stability.

Replacement of a molar with two narrow-diameter dental implants

Dental implants have demonstrated a high degree of success in the restorations of teeth in partially or completely edentulous patients. However, when the buccolingual width of the edentulous crest is insufficient for the placement of standard sized implants, the use of two or more smaller diameter implants should be considered to avoid the need for invasive reconstruction techniques such as grafting procedures. The present case report describes the replacement of a single mandibular first molar with two narrow-diameter implants, in a 41-year- old male patient. No postoperative complications were reported in the 3-year follow-up period. The placement of two narrow-diameter implants replacing a missing mandibular molar could eliminate the mesiodistal bending, double the support capacity in the buccolingual direction, and minimize stress on the implants.

Peri-implant biomechanical responses to standard, short-wide, and double mini implants replacing missing molar supporting hybrid ceramic or full-metal crowns under axial and off-axial loading: an in vitro study

Background

The aim of this study was to evaluate the biomechanical response of the peri-implant bone to standard, short-wide, and double mini implants replacing missing molar supporting either hybrid ceramic crowns (Lava Ultimate restorative) or full-metal crowns under two different loading conditions (axial and off-axial loading) using strain gauge analysis.

Methods

Three single-molar implant designs, (1) single, 3.8-mm (regular) diameter implant, (2) single, 5.8-mm (wide) diameter implant, and (3) two 2.5-mm diameter (double) implants connected through a single-molar crown, were embedded in epoxy resin by the aid of a surveyor to ensure their parallelism. Each implant supported full-metal crowns made of Ni-Cr alloy and hybrid ceramic with standardized dimensions. Epoxy resin casts were prepared to receive 4 strain gauges around each implant design, on the buccal, lingual, mesial, and distal surfaces. Results were analyzed statistically.

Results

Results showed that implant design has statistically significant effect on peri-implant microstrains, where the standard implant showed the highest mean microstrain values followed by double mini implants, while the short-wide implant showed the lowest mean microstrain values. Concerning the superstructure material, implants supporting Lava Ultimate crowns had statistically significant higher mean microstrain values than those supporting full-metal crowns. Concerning the load direction, off-axial loading caused uneven distribution of load with statistically significant higher microstrain values on the site of off-axial loading (distal surface) than the axial loading.

Conclusions

Implant design, superstructure material, and load direction significantly affect peri-implant microstrains.

Case presentation of two patients using diagonal platform-switched double implants for maxillary single-first-molar replacement as the alternative of a single-tooth implant

A single-tooth implant restoration is generally performed for maxillary single-first-molar replacement. If the interdental space between the second premolar and the second molar is large enough, a double-implant placement can be performed to avoid creating mesiodistal cantilever and to distribute occlusal loading forces.

If there is not adequate space for a double-implant placement to be performed mesiodistally along the crest of the alveolar ridge line, they should be placed along a diagonal line offset lingually to increase the space. This procedure has two primary advantages. First, greater stability is provided by a double-implant placement. Resistance to lateral forces (palatal-buccal) is much stronger than two implants placed along the alveolar crest ridge line. Residual palatal and buccal bone can provide support against occlusal forces, provided that there is adequate residual bone in these regions.

If anatomical conditions are favorable, the placement of two diagonal implants in the palatal and buccal residual bones can be a rational procedure.

We report on two typical patients. The progress of these patients was followed using computed tomography for 7 and 6 years, respectively.

Selective laser melting of titanium alloy enables osseointegration of porous multi-rooted implants in a rabbit model

Background

Osseointegration refers to the direct connection between living bone and the surface of a load-bearing artificial implant. Porous implants with well-controlled porosity and pore size can enhance osseointegration. However, until recently implants were produced by machining solid core titanium rods. The aim of this study was to develop a multi-rooted dental implant (MRI) with a connected porous surface structure to facilitate osseointegration.

Methods

MRIs manufactured by selective laser melting (SLM) and commercial implants with resorbable blasting media (RBM)-treated surfaces were inserted into the hind limbs of New Zealand white rabbits. Osseointegration was evaluated periodically over 12 weeks by micro-computerized tomography (CT) scanning, histological analysis, mechanical push-out tests, and torque tests.

Results

Bone volume densities were consistently higher in the MRI group than in the RBM group throughout the study period, ultimately resulting in a peak value of 48.41 % for the MRI group. Histological analysis revealed denser surrounding bone growth in the MRIs; after 4 and 8 weeks, bone tissue had grown into the pore structures and root bifurcation areas, respectively. Biomechanics tests indicated binding of the porous MRIs to the neobone tissues, as push-out forces strengthened from 294.7 to 446.5 N and maximum mean torque forces improved from 81.15 to 289.57 N (MRI), versus 34.79 to 87.8 N in the RBM group.

Conclusions

MRIs manufactured by SLM possess a connected porous surface structure that improves the osteogenic characteristics of the implant surface.

Dental Implant Length and Diameter: A Proposed Classification Scheme

PURPOSE

To propose a length-and-diameter-based classification scheme for dental implants to standardize terminology in the dental literature and communication between interested parties.

MATERIALS AND METHODS

This study was mainly based on searching two major resources: published scientific research papers and 14 of the most popular dental implant manufacturers. Indexed databases were searched from January 2004 up to and including February 2016 using the keywords "dental implant length" and "dental implant diameter." Retrieved titles and abstracts were screened, and related full-text articles were reviewed. Full-text articles that clearly stated the terms and measurements of implants used were included and considered for proposing this classification scheme.

RESULTS

The initial search for implant diameter and length yielded 1007 and 936 articles, respectively. A total of 85 studies (41 about diameter, 44 about length) were selected and reviewed. The remaining studies (966 about diameter, 892 about length) that did not abide by the eligibility criteria were excluded. The terms "long," "short," "standard," "wide," and "narrow" were the most commonly used terms in the literature. A classification scheme for implants by diameter and length was proposed.

CONCLUSIONS

Indexed publications contain a variety of terms used by authors to describe diameter and length of dental implants without conformity and standardization. The classification scheme proposed in this article could serve as a reference for interested parties.

Consecutive Case Series of Healed Single-Molar Sites Immediately Restored with Wide-Diameter Implants: A 1-Year Evaluation

Introduction. To evaluate outcomes of wide-diameter (6 mm) implants immediately provisionalized with cement-retained single crowns in posterior molar sites. Materials and Methods. Forty-eight consecutive patients received a total of 53 moderately rough-surface, 6 mm diameter implants in healed sites. All implants were immediately provisionalized with a cement-retained provisional crown. Final prosthesis with cement-retained porcelain fused to metal crowns was delivered 3–6 months later. Patients were followed up for 1 year. Outcome measures were implant failures and success rate, complications, marginal bone levels, bone level changes, papilla index, bleeding on probing, and inflammation. Results. One patient was lost to follow-up. At one year, the implant survival and success rate were 98.1%. The mean marginal bone loss after 1 year was −0.17 ± 1.84 mm. Ideal papilla score was recorded at 83.8% of the sites. More than 95.6% of the sites showed no bleeding or inflammation. No procedure-related or device-related adverse events were reported. Conclusion. Wide-diameter (6 mm) implants can safely and successfully replace single posterior molars. Longer follow-up studies are necessary to evaluate the long-term success of these implants.

Immediate restoration of fixed partial prostheses supported by one-piece narrow-diameter selective laser sintering implants: a 2-year prospective study in the posterior jaws of 16 patients

PURPOSE

Selective laser sintering (SLS) is a new technique that allows implants to be produced by annealing titanium powder microparticles in a focused laser beam, according to a computer-generated model. The aim of this study was to evaluate the survival and success rate of immediately restored 1-piece narrow-diameter SLS implants, placed in the posterior jaws, after 2 years of functional loading.

MATERIALS AND METHODS

At the 2-year follow-up examination, several parameters were assessed. Success criteria included absence of pain, suppuration, exudation, implant mobility; distance between the implant shoulder and the first visible bone-to-implant contact <2.0 mm; and absence of prosthetic complications.

RESULTS

Thirty-seven implants were placed in the posterior jaws (14 maxilla, 23 mandible) of 16 patients (9 males, 7 females). The prosthetic restorations comprised 16 immediately restored fixed partial prostheses. No implant failure occurred, resulting in a 100% survival rate. The implant success was 94.6%, and the mean distance between the implant shoulder and the first visible bone-to-implant contact (DIB) was 0.4 ± 0.3 mm.

CONCLUSIONS

This study supports the hypothesis that 1-piece narrow-diameter SLS implants can be used in fixed prosthetic rehabilitations in the posterior regions of both jaws with a predictable positive outcome.

One-piece implants: placement timing, surgical technique, loading protocol, and marginal bone loss

PURPOSE

Osseointegration being an accepted and well-documented concept, attention is now directed towards simplification of the mechanical design of implants and towards achieving biomechanical success. The aim of this literature review is to provide an overview of the one-piece implant, with its advantages and disadvantages over a conventional two-piece implant.

METHODS

The PubMed database was searched in the English language using the keywords one-piece implant, single-piece implant, single-stage implant surgery, and two-piece implant. Articles were selected on the basis of whether they had sufficient information related to placement timing, surgical procedure used, loading protocol, follow-up periods, marginal bone loss, and implant success rates of one-piece implants. For inclusion, a study group must have had a minimum of 30 one-piece implants followed for at least 1 year.

DISCUSSION

Nineteen articles were subjected to the selection criteria. Out of 19 clinical trials only 11 met the selection criteria. Five parameters were taken into consideration for studying one-piece implants: placement timing, surgical technique, loading protocol, marginal bone loss, and implant survival rate. The data from the identified studies were tabulated according to these parameters and discussed.

CONCLUSION

Delayed placement of one-piece implants is more commonly practiced than extraction and immediate placement. Most surgeons prefer surgeries using flaps as compared to flapless surgeries, and in most cases, one-piece implants were loaded immediately. Limited literature reveals both positive and negative results regarding the effect of a one-piece implant system on surrounding hard and soft tissues.

Novel implant design for initial stability of dental implants inserted in fresh extraction sockets: a preliminary study

OBJECTIVES

To evaluate a novel implant design for immediate implantation. This implant presents a specially designed expanded diameter midcrestal "wing" thread, which is aimed to provide added bone contact for greater insertion torque and primary stability.

METHODS

Mandibular premolars were extracted in 2 mongrel dogs, and immediate dental implants were inserted into the fresh extraction sockets. Implants were evaluated for stability using a resonance frequency analysis device immediately after insertion and after 4 and 8 weeks. Removal torque of 1 randomly selected implant in each hemimandible was measured as well. At 8 weeks, the remaining 6 implants were processed histologically.

RESULTS

Mean implant stability quotient at implant placement was 64.38 (5.03) and 74.5 (3.08) at 8 weeks. Average removal torque immediately after implant placement was 49.65 (20.3) N.cm and 98.33 (12.34) N.cm at 8 weeks. The mean bone-to-implant contact value at 8 weeks was 38.89% (7.65%).

CONCLUSIONS

The examined implant with the expanded diameter midcrestal "wing" thread showed good results of resonance frequency analysis and removal torque during the initial healing phase, and as such, it might be used for immediate implantation and loading.