Good occlusal practice in the provision of implant borne prostheses

Occlusal changes on implant-supported single crowns with one year follow-up after loading: A systematic review and meta-analysis

OBJECTIVE

This systematic review evaluated the occlusal changes after loading with implant-supported single crowns.

SOURCES

An electronic literature search was conducted in PubMed, Embase and Cochrane library for randomized (RCTs) or non-randomized controlled clinical trials (CCTs), with a minimum of 10 patients.

STUDY SELECTION

Studies reporting the occlusal force changes on implant-supported single crowns - with natural teeth as antagonist - measured at baseline and after loading periods were included. 4 CCTs including 133 ISCs in posterior sites were included for meta-analysis. All analyzed ISCs had no contact at a light bite and a light contact at a heavy bite in MIP at loading (baseline).

DATA

The relative occlusal forces (ROFs) of each implant-supported single crown (ISC) or control tooth (CT) were extracted. ROFs were defined as percentage of the total occlusal force of the entire dentition at maximum intercuspal position (MIP). A meta-analysis was conducted to compare the ROF changes at different follow-up periods and the weighted mean differences in ROF between ISCs and CTs were pooled and analyzed. The amount of change in ROF was significantly lower in 6 to 12 months after loading comparing the follow-up period between baseline and 6 month (p < 0.05). At baseline and 3-month follow-up, CTs presented significant higher ROF than ISCs (p < 0.05), while no significant difference was found after half year following.

CONCLUSIONS

This study showed that the ROF changes significantly over time after loading of ISCs. It might prove that the occlusal concept defined at the time of prosthetic delivery changes or adapts naturally over time.

CLINICAL SIGNIFICANCE

The function of specific implant occlusal concept (no contact at a light bite and a light contact at a heavy bite in MIP) is limited over time and careful monitoring and occlusal adjustments should be recommendable during the first-year follow-up.

Evaluation of two different occlusal patterns on single posterior implant-supported crowns: A 12-month prospective study of occlusal analysis

STATEMENT OF PROBLEM

According to the concept of implant-protected occlusion, light occlusion and late contact could prevent implants from occlusal overload. However, clinical data demonstrating how light occlusion differs from normal occlusion are lacking.

PURPOSE

The purpose of this prospective clinical study was to characterize the occlusal variation of single posterior implant-supported crowns with or without light occlusion.

MATERIAL AND METHODS

Participants with a single missing posterior maxillary or mandibular molar who were to receive implant-supported zirconia ceramic crowns were enrolled. The participants were divided into a light occlusion group, in which a 12-μm articulating film could be removed from the implant-supported crown and opposing natural teeth under the intercuspal position, and a normal occlusion group, in which the articulating film could not be removed. All participants underwent occlusal examinations using the T-scan III system, answered a satisfaction questionnaire using a visual analog scale (VAS), and received regular follow-ups. The participants were evaluated at 0.5, 3, 6, and 12 months after implant-supported crown delivery. The relative occlusal force of the implant-supported crowns, mesial teeth, control teeth (corresponding natural tooth on the dentition contralateral to each implant), and the occlusal contact time of implant-supported crowns were recorded. Moreover, the asymmetry index of the occlusal force and the VAS score were calculated. Two independent-sample tests were used to compare the 2 groups. The Wilcoxon rank sum and Mann‒Whitney tests were used to compare nonnormally distributed data (α=.001).

RESULTS

Fifty study participants with a mean ±standard deviation age of 36.97 ±7.34 years (23 men and 27 women aged 20 to 50 years) were followed for 0.5 to 12 months. No obvious complications of overloading were observed in either group. The mean ±standard deviation of the relative occlusal force of implant-supported crowns in the light occlusion group (from 4.91 ±3.52% to 10.34 ±4.35%) was always lower than that in the normal occlusion group (from 10.45 ±4.32% to 18.15 ±4.80%), while the mean ±standard deviation of the occlusal contact time in the light occlusion group (from 0.38 ±0.26 seconds to 0.10 ±0.07 seconds) was significantly later than that in the normal occlusion group (from 0.12 ±0.08 seconds to 0.04 ±0.02 seconds) (P<.001). The value of the asymmetry index of occlusal force remained within the normal range (10%). The VAS score in the normal occlusion group was significantly higher than that in the light occlusion group (P<.001).

CONCLUSIONS

Providing light occlusion to reduce occlusal force and delay the contact time was not stable over time. The relative occlusal force and occlusal contact time showed a similar development trend in both groups, and no obvious signs of occlusal overloading were observed in this study. Long-term follow-up is necessary for implant-supported prostheses because of the continuous increase in occlusal force.

Evaluation of a Technique for Reducing Chairside Occlusal Adjustment of Crowns

PURPOSE

To assess whether the occlusion of metal-ceramic crowns, as received from the laboratory, and the time taken to adjust the occlusion of crowns not deemed acceptable, can be reduced by fabricating the crowns with controlled amounts of infra-occlusion during the laboratory phase.

MATERIAL AND METHODS

An opposing set of typodonts, articulated in maximum intercuspal position served as the patient in an in vitro simulation. Seventy-five metal-ceramic crowns were fabricated for the mandibular right second molar with three different occlusal contact specifications: A, control group had occlusal contacts shared evenly by the crown and the neighboring teeth (n = 25); B, first experimental group had the occlusion relieved until 2 shimstock foils were able to be pulled from between the crown and the opposing tooth without tugging (n = 25); C, second experimental group had the occlusion relieved until 4 shimstock foils were able to be pulled from between the crown and the opposing tooth without tugging (n = 25). The occlusion of each crown, as received from the laboratory, was assessed using one of three categories (Excellent, Acceptable, and Poor). Chi-square analysis was used to test the differences in occlusal outcomes between the three study groups. For all of those rated "Acceptable," the time taken to adjust each crown to proper occlusion was recorded. One-way analysis of variance (ANOVA) and Bonferroni tests were carried out to compare the adjustment times across the three study groups.

RESULTS

The 2-shim group had the best outcome, with 56% of the crowns rated as "Excellent" (p = 0.001). In addition, there were statistically significant differences in adjustment times between the control group (A) and the 2-shim (B) and the 4-shim (C) groups (p = 0.0001), but not between the 2-shim (B) and 4-shim (C) groups (p = 0.08).

CONCLUSIONS

Metal-ceramic crowns fabricated with controlled interocclusal relief of 2- and 4-shims each required less time for chairside occlusal adjustment than crowns fabricated in the laboratory to conventional occlusal contact. However, the overall superior outcome, in terms of the possibility for immediate insertion as received from the laboratory as well as favorable chairside adjustment time, for the 2-shim prespacing suggests that this dimension is the preferred option over 4-shim prespacing to reduce occlusal inaccuracies of indirect restorations.

Initial management and long-term follow up after the rehabilitation of a patient with severe dentoalveolar trauma: A case report

Dental trauma is common and for patients who suffer significant oral injuries, rehabilitation can be challenging to the clinical team. This case report describes the successful prosthetic replacement of multiple missing teeth lost due to severe dentoalveolar trauma, using iliac crest bone grafting, an implant-retained removable dental prosthesis and implant-supported crowns. Good functionality and aesthetic outcome were achieved.

Factors affecting the complexity of dental implant restoration - what is the current evidence and guidance?

Objectives The aim of this paper is to identify the factors that affect the complexity of implant restoration and to explore the indices that help us to assess it. With this knowledge the growing number of clinicians restoring dental implants will have a better understanding of the available guidance and evidence base, and the differing levels of competence required.Study design A literature review was conducted. The selection of publications reporting on complexity was based on predetermined criteria and was agreed upon by the authors. After title and abstract screening 17 articles were reviewed. The articles that were utilised to form the ITI SAC tool and Cologne Risk Assessment we also included.Assessing complexity Two key guides are available: International Team for Implantology's Straight-forward Advanced Complex tool and the Cologne ABC risk score. While these guides help identify treatment complexity they do not provide a strong enough evidence base from which to solely base clinical decisions. The key patient factors are expectation, communication, the oral environment, aesthetic outcome, occlusion, soft tissue profile and the intra-arch distance, whereas the key technical factors are impression taking, type of retention, loading protocol and the need for provisional restorations. Human factors also have a significant effect on complexity, specifically, the experience and training of the clinician, team communication and the work environment.Conclusions There are many interconnecting factors that affect the complexity of dental implant restoration. Furthermore the two widely used indices for the assessment of complexity have been investigated, and although these offer a good guideline as to the level of complexity, there is a lack evidence to support their use. The development of evidence-based treatment and protocols is necessary to develop the current indices further, and these need to be expanded to include other critical areas, such as human factors. A practical guide to aid practitioners in reducing complexity has been proposed.

Prosthetic Consideration in Implant-supported Prosthesis: A Review of Literature

Modern dentistry has changed tremendously with implant therapy. For the successful implant therapy, making a proper treatment plan considering both surgical and prosthetic part in mind is the key of success. Often practitioners tend to create a treatment plan overlooking the basic principles of prosthetic part. This present review has discussed various prosthetic consideration of implant-supported prosthesis. A step-by-step detailed prosthetic option with their indications has been discussed to help all dental implant practitioners in making of an optimal treatment plan for each case.

Combined Implant and Tooth Support: An Up-to-Date Comprehensive Overview

Objectives. This article presents a review on the concerned topics and some considerations related to the concept of splinting teeth and implants in the rehabilitation of partial edentulism. Study Selection. An electronic PubMed/MEDLINE and manual search of identified articles and reviews as well as clinical, laboratory, and finite element studies was performed in this project. Due to the shortage in within-subject, long term, randomized, controlled clinical trials regarding the subject a meta-analysis was not possible. Results. Although surrounded with some controversy, joining teeth and implants during the rehabilitation of partial edentulism provides the clinicians with more treatment options where proprioception and bone volume are maintained and distal cantilevers and free end saddles are eliminated. It makes the treatment less complex, of less cost, and more acceptable for the patient. Conclusions. Whenever suitable and justified, combining implant and tooth support might be recommended as an alternative during rehabilitation of partial edentulism. Based on the literature, clinical tips and suggestions were recommended to increase the success of this treatment.

Full mouth rehabilitation with maxillary tooth supported and mandibular tooth and implant supported combination prostheses: a 4-year case report

The primary objectives of successful prosthetic rehabilitation are to provide function, esthetics and comfort to the patient. Combination prosthesis is one which is supported by both natural teeth and implant. The periodontal ligament and osseointegrated interface distribute force differently to the supporting bone. Therefore problems can develop when tooth and implants are combined in the same prosthesis. However, clinicians can apply biomechanical principles, to negate the deleterious leverages exerted by the fixed prosthesis by using non rigid components and to equalize the stress applied by the prosthesis on implant and teeth. A case of partially edentulous situation was rehabilitated successfully with a combination of prostheses. Maxillary arch was restored to function with crowns, fixed dental prosthesis and with an extra coronal castable attachment prosthesis and the mandibular arch with a combination of tooth and implant supported attachment prosthesis. The clinical and laboratory steps for the fabrication of these prostheses are explained in this report.

Clinical and radiological classification of the jawbone anatomy in endosseous dental implant treatment

Objectives

The purpose of present article was to review the classifications suggested for assessment of the jawbone anatomy, to evaluate the diagnostic possibilities of mandibular canal identification and risk of inferior alveolar nerve injury, aesthetic considerations in aesthetic zone, as well as to suggest new classification system of the jawbone anatomy in endosseous dental implant treatment.

Material and Methods

Literature was selected through a search of PubMed, Embase and Cochrane electronic databases. The keywords used for search were mandible; mandibular canal; alveolar nerve, inferior; anatomy, cross-sectional; dental implants; classification. The search was restricted to English language articles, published from 1972 to March 2013. Additionally, a manual search in the major anatomy and oral surgery books were performed. The publications there selected by including clinical and human anatomy studies.

Results

In total 109 literature sources were obtained and reviewed. The classifications suggested for assessment of the jawbone anatomy, diagnostic possibilities of mandibular canal identification and risk of inferior alveolar nerve injury, aesthetic considerations in aesthetic zone were discussed. New classification system of the jawbone anatomy in endosseous dental implant treatment based on anatomical and radiologic findings and literature review results was suggested.

Conclusions

The classification system proposed here based on anatomical and radiological jawbone quantity and quality evaluation is a helpful tool for planning of treatment strategy and collaboration among specialists. Further clinical studies should be conducted for new classification validation and reliability evaluation.

Prototyping artificial jaws for the robotic dental testing simulator

This paper presents a robot periphery prototyped for the six-degrees-of-freedom robotic dental testing simulator, simulating the wear of materials on dental components, such as individual teeth, crowns, bridges, or a full set of teeth. The robot periphery consists of the artificial jaws and compliance module. The jaws have been reverse engineered and represent a human-like mandible and maxilla with artificial teeth. Each clinically fabricated tooth consists of a crown and glass ceramic roots which are connected using resin cement. Normal clinical occlusion of the artificial jaws assembly was emulated by a dental articulator based on 'Andrew's six keys to occlusion'. The radii of the von Spee curve, the Monson curve, and the Wilson curve were also measured as important jaw characteristic indicators to aid normal occlusion. A compliance module had to be built between the lower jaw and the robot platform to sustain the fluctuating forces that occur during normal chewing in the occlusal contact areas, where these high bite forces are major causes of dental component failure. A strain gauge force transducer has been integrated into the machined lower jaw, underneath the second molars, to measure axial biting forces applied to the posterior teeth. The experiments conducted have shown that the sensor is able to sense small changes in the compression force satisfactorily, when applied perpendicular to the occlusal surfaces of the teeth.

Immediate function in the atrophic maxilla using zygoma implants: a preliminary study

STATEMENT OF PROBLEM

Oral rehabilitation of the edentulous atrophic maxilla to allow placement of a fixed dental prosthesis remains a challenge, especially if immediate function is provided.

PURPOSE

The aim of this retrospective, preliminary study was to evaluate, after a period of a 6 to 29 months' follow-up of prosthetic loading, the survival rate of 36 immediately loaded zygomatic implants placed in 18 atrophied maxillae.

MATERIAL AND METHODS

Eighteen consecutive patients (6 men and 12 women), with an average age of 58 years (range of 44-74 years), were followed up to 29 months (average of 14 months). The clinical criteria included stability of the implants and the prosthesis, resonance frequency analysis (RFA), and evaluation of swelling, pain, or discomfort. Radiographic analysis was completed for conventional implants, but not for zygoma implants. All patients had a fixed prosthesis screwed onto implants within 48 hours after implant placement. Descriptive statistics were used to analyze the data.

RESULTS

No zygomatic implants were lost over the observation period. Survival rate was 100% over an average 14-month observation period. Three conventional implants were lost, resulting in a survival rate of 95.6%. All the provisional prostheses were stable, and no relevant complications were noted.

CONCLUSIONS

The use of zygoma implants, together with conventional implants, in severely resorbed maxilla, appears to be a reliable technique for providing immediate function to patients.