Interproximal contact loss between implant restorations and adjacent natural teeth: A systematic review and meta-analysis

Role of interproximal contacts in implant-supported crown stability: A finite element analysis study

STATEMENT OF PROBLEM

Screw loosening remains a frequent complication with implant-supported prostheses. While clinical evidence suggests that posterior single implant crowns present a high rate of complications, whether the absence of interproximal contacts with adjacent natural teeth is a contributing factor to these complications remains unclear.

PURPOSE

The purpose of this finite element analysis study was to evaluate the biomechanical behavior of single implant-supported crowns placed in the posterior mandible. Two variables were investigated: the impact of implant position (first molar versus second molar) and the nature of the interproximal contact with the adjacent teeth (mesial versus mesial and distal interproximal contacts).

MATERIAL AND METHODS

Three mandibular models were constructed using microtomography: fully dentate (control), partially edentulous with a missing second molar replaced by a single implant-supported crown (mesial interproximal contact only), and partially edentulous with a missing first molar replaced by a single implant-supported crown (mesial and distal interproximal contacts). The finite element analysis simulated occlusal loading during masticatory function. Stress distribution was evaluated by using the von Mises stress criterion, with principal stress analysis for bone anisotropy. Model validation was performed against experimental tooth displacement data.

RESULTS

Implants with both interproximal contacts (first molar position) exhibited more evenly distributed stress and significantly lower stress concentrations on the implant neck compared with the implant with only a mesial interproximal contact (second molar position). The second molar position showed higher stress at the implant-abutment connection.

CONCLUSIONS

Implant positioning and the number of interproximal contacts significantly influenced stress distribution and prosthesis stability. Implants placed between natural teeth present a lower risk of screw loosening and enhanced long-term crown stability.

Common Failures in Implant Prosthodontics

Implant prosthodontics encompasses a unique blend of biomaterials, biomechanics, and biology, and some amount of failures are inevitable. Though there is a wide range of failures in implant prosthodontics, the most common ones are related to technical complications, most of which can be prevented through proper treatment planning and appropriate choices in material selection and treatment techniques. This article describes the etiology, management, and prevention of the most common complications and failures in contemporary implant fixed and removable prosthodontics.

Metal-Free Custom-Made Zirconia Implants-A Prospective 5-Year Follow-Up Single-Arm Clinical Trial

BACKGROUND

Dental implants made of zirconia (ZrO2) are a potential alternative for titanium implants in dentistry because of their good biocompatibility, mechanical properties and excellent aesthetic results. However, solid long-term scientific data to prove clinical success of ZrO2 implants are scarce.

AIM

The aim of this study was to describe and to examine the clinical performance of custom-made two-piece ZrO2 implants, to identify possible influencing factors: a) manipulation of the implant after placement and b) the occlusal scheme on the survival rate, and to evaluate the performance of the implant-supported crown. This follow-up study collected and examined the 5-year data to answer the main question: What are the survival and the success rates of custom-made ZrO2 implants in the maxillary premolar region after 5 years?

MATERIAL AND METHODS

Of the 31 included patients in this prospective 5-year follow-up single-arm clinical trial, 30 received a custom-made ZrO2 implant to replace a missing single maxillary premolar, which was subsequently restored with a lithium disilicate crown. Parameters regarding clinical performance, marginal bone-level (MBL) changes, and patient-related outcome measures (PROMs) were assessed preoperatively, at the baseline, as well as 1 and 5 years after crown placement. Chances of survival and success of the implant were calculated and displayed using Kaplan-Meier statistics. Kaplan-Meier survival analysis was also performed with stratification based on the variables "manipulation of the implant prior to impression taking" and "occlusal scheme" and compared using log-rank tests. Bone-level moderation in time was compared using a paired samples t-test. Patient's expectations and satisfaction after 5 years were compared as a measure of fulfilled expectations, using a Wilcoxon signed-rank test. Performance of the implant-supported crowns was evaluated using validated criteria.

RESULTS

Survival and success probabilities after 5 years were, respectively, 75.8% (95% CI [60.0%; 91.0%]) and 71.0% (95% CI [54.0%; 88.0%]) for the custom-made ZV3 implants. No significant differences in survival rate were found after stratification on "manipulation of the implant" and on "occlusal scheme." Mean bone-level alteration between baseline and the first follow-up was +0.06 mm (95% CI [-0.23 mm; 0.12 mm]; SD = 0.42 mm) and between baseline and the second follow-up was +0.04 mm (95% CI [-0.35 mm; 0.26 mm]; SD = 0.54 mm). Patients' satisfaction for patients with implants still in function after 5 years was 91.7% (IQR = [90.5%-97.3%]), indicating satisfaction with the treatment. Pooled satisfaction in patients with successful implants after 5 years was significantly higher than patients' expressed expectations before treatment. None of the crowns failed, and no interventions were required.

CONCLUSION AND CLINICAL IMPLICATIONS

Survival rate of these particular ZV3 implants in our study was lower than expected and clinically not acceptable. Hence, ZV3 implant placement as applied in this study cannot be recommended for clinical practice. Further research on the different appearances of mechanical failure in ZrO2 implants would be highly recommended before a larger prospective randomized clinical trial is conducted to evaluate treatment with custom-made ZrO2 dental implants.

Risk factors contributing to interproximal contact loss between an implant crown and a natural tooth

PURPOSE

Interproximal contact loss (ICL) is considered a prevalent complication for a tooth abutting an implant restoration. While numerous potential causes for ICL have been presented, there is no consensus. A review of the current literature with a focus on possible risk factors was performed.

MATERIALS AND METHODS

A PubMed search using keywords "implant OR dental implants OR implant supported prosthesis AND proximal contact loss OR ICL OR loss of interproximal contact OR open contact OR interproximal open contact OR adjacent natural teeth" resulted in 81 citations, 9 of which were relevant to the focus question. Additional references were culled from the reference lists in the identified articles. Systematic reviews, case series, and case reports were reviewed with a focus on causation, association, or correlation.

RESULTS

Eight systematic reviews and 14 case series were reviewed. The prevalence of ICL has been reported to be as low as 16% and as high as 66%. ICL was more common on the mesial side of implants and when a tooth abuts a splinted implant restoration. The absence of a uniform definition to accurately describe an interproximal (IP) contact and an open IP contact is demonstrated in the literature. A lack of standardized measurement strategies that relate to a needed consensus definition further exacerbates the broad range of reported results regarding ICL. The lack of controls for almost all the ICL literature makes it difficult to draw conclusions and comparisons to unrestored, natural tooth IP contacts and the prevalence of ICL in this patient population. As a result, the available studies are inadequate to support a causal theory and the potential risk factors associated with ICL.

CONCLUSIONS

There is a large range of reported prevalence for IP contact loss. ICL is more common when a natural tooth abuts a splinted implant restoration. ICL is more common on the mesial, as opposed to the distal, of an implant retained restoration. Consensus in the definition and measurement strategies for ICL needs to be established to provide standardized terminology and methodology. Potential risk factors such as occlusion, restorative material, and tooth contact area need to be investigated.

Navigating Esthetic Challenges: Immediate Implant Placement and Comprehensive Restorative Solutions-A Clinical Case With 2-Year Follow-Up Study

Introduction: The esthetics of immediate implant dentistry can be challenging. Clinical considerations for immediate implant placement have demonstrated long-term success rates comparable to traditional delayed implant protocols. However, it is a sensitive technique that requires proper treatment planning as well as meticulous execution to be predictable and successful in the long term. Methods: This clinical situation demands extensive knowledge of soft and hard tissue management for atraumatic tooth extraction followed by implant therapy, along with an understanding of the available materials to meet esthetic needs. This case report features a female patient with the chief complaint of needing to replace an anterior crown due to loss of retention. After a comprehensive oral assessment and cone beam computed tomography (CBCT) radiographic examination, it was determined that the crown on Tooth #9 was fractured at the subgingival level. Furthermore, gingival zenith positions displayed differences at the keratinized mucosa level in Teeth #7, #8, and #9, and the metal marginal areas of the porcelain-fused-to-metal (PFM) crowns in the anterior area of Teeth #5, #7, #8, #9, and #10 were apparent. The procedure involved atraumatic extraction of Tooth #9, followed by immediate implant placement. Crowns on Teeth #5, #7, #8, and #10 were replaced, and veneers on Teeth #6 and #11 were fabricated using press lithium disilicate-reinforced ceramic. Connective tissue graft (CTG) was contoured before final implant restorations. Results: The final implant crown was restored using a prefabricated abutment with a titanium base and lithium disilicate ceramic dental material. A well-planned combined treatment, including atraumatic tooth extractions for immediate implants and ideal contouring of soft tissues, can significantly impact the outcome of esthetic restorations. Conclusions: Single immediate implant-supported crowns in the esthetic zone were able to fulfill the patient's esthetic expectations.

Radiographic assessment of the peri-implant site

While peri-implant mucositis relies solely on clinical parameters, radiological assessment becomes indispensable for diagnosing peri-implantitis. Intraoral radiography, with its simplicity of application, low radiation exposure, and adequate representation of peri-implant structures, stands out as the standard of care for both immediate and follow-up assessments. Standardization by custom-made radiologic splints allows for excellent comparability with previous images and allows for the determination of even small changes in contour and density of the peri-implant bone. Furthermore, other radiographic modalities like panoramic radiography and cone beam computed tomography (CBCT) may provide useful features for specific patients and clinical cases while also showing innate limitations. Beyond the assessment of the marginal peri-implant bone level as the crucial parameter of clinical relevance, radiologic assessment may reveal various other findings related to the prosthetic restoration itself, the precision of its fit to the implant, and the peri-implant soft and hard tissues. Since such findings can be crucial for the assessment of peri-implant health and the implants' prognosis, a systematic diagnostic evaluation pathway for a thorough assessment is recommended to extract all relevant information from radiologic imaging. This article also provides an overview of the clinical and chronological indications for different imaging modalities in peri-implant issues.

Proposal regarding potential causes related to certain complications with dental implants and adjacent natural teeth: Physics applied to prosthodontics

PURPOSE

Complications can and do occur with implants and their restorations with causes having been proposed for some single implant complications but not for others.

METHODS

A review of pertinent literature was conducted. A PubMed search of vibration, movement, and dentistry had 175 citations, while stress waves, movement, and dentistry had zero citations as did stress waves, movement. This paper discusses the physics of vibration, elastic and inelastic collision, and stress waves as potentially causative factors related to clinical complications.

RESULTS

Multiple potential causes for interproximal contact loss have been presented, but it has not been fully understood. Likewise, theories have been suggested regarding the intrusion of natural teeth when they are connected to an implant as part of a fixed partial denture as well as intrusion when a tooth is located between adjacent implants, but the process of intrusion, and resultant extrusion, is not fully understood. A third complication with single implants and their crowns is abutment screw loosening with several of the clinical characteristics having been discussed but without determining the underlying process(es).

CONCLUSIONS

Interproximal contact loss, natural tooth intrusion, and abutment screw loosening are common complications that occur with implant retained restorations. Occlusion is a significant confounding variable. The hypothesis is that vibration, or possibly stress waves, generated from occlusal impact forces on implant crowns and transmitted to adjacent teeth, are the causative factors in these events. Since occlusion appears to play a role in these complications, it is recommended that occlusal contacts provide centralized stability on implant crowns and not be located on any inclined surfaces that transmit lateral forces that could be transmitted to an adjacent tooth and cause interproximal contact loss or intrusion. The intensity, form, and location of proximal contacts between a natural tooth located between adjacent single implant crowns seem to play a role in the intrusion of the natural tooth. Currently, there is a lack of information about the underlying mechanisms related to these occurrences and research is needed to define any confounding variables.