Utilizing digital occlusal indicators to increase occlusal accuracy and decrease complications in implant-supported cases

Table of Contents

Introduction

Modern implant rehabilitation has become a computer-driven process, where CBCT imaging, surgical planning and prosthetic design software all allow the implementation of a digital workflow (Lerner et al. 2021). This workflow does not only help the practitioner execute the planned implant easily , but also increases the predictability and clinical success of osseointegration. It also aid in immediate loading protocols along the biological developments of fusing implant surfaces to grafted bone and peri-implant supporting structures (Adell et al. 1981; Albrektsson et al. 1986).

Nevertheless, at the end of this digital process, all the intended prosthetic design elements cannot account for the occlusal loads that occur during function on a newly installed, rigid, immobile, and unforgiving implant-supported prosthesis. Complication rates in implant prosthodontics exceed those of traditional tooth-supported restorations (Sailer et al. 2018), which necessitates following an occlusal scheme to combat destructive occlusal forces that often damage implant restorations.

Generally, applied occlusal forces are controlled through pulpal and periodontal ligament (PDL) mechanoreception and proprioception, and are somewhat neutralized by the periodontal structures (Madani et al. 2017; Dario 1995). Unlike natural teeth, the absorption of masticatory forces through osseoperception is reduced with implant-supported prostheses, due to the absence of a periodontal ligament (Madani et al. 2017; Dario 1995). While teeth can move apically within the socket about 50 to 100 µm, apical implant movement is limited to only 3 to 5 µm (Roque 2017). Hence, the occlusal material on an implant-supported crown bears the entire applied occlusal force, and can affect the structural integrity of both the abutment and implant body, as well.

Typically, an implant-supported prosthesis is delivered with an implant-protective occlusal scheme (IPO), developed with shim stock and very thin articulating paper. The implant occlusal surface is theoretically sub-occluded from the opposing occlusal surface by 25 µm, to prevent occlusal force overload during a normal strength mandibular closure into maximum intercuspation (Bozhkova 2016; Chaithanya et al. 2019; Luo et al. 2020).

Despite the widespread belief that an IPO provides adequate control over occlusal forces, occlusion related mechanical complications in implant-supported prosthesis remain common (Elemek et al. 2020; Papaspyridakos et al. 2020; Lerner et al. 2020; Sailer et al. 2018; Shen et al. 2018; Pjetursson et al. 2018; Drago 2016; Wittneben et al. 2014; Fischer et al. 2013; Pjetursson et al. 2012; Bozini et al. 2011; Jemt 2006), as long term survival studies indicate that mechanical complication rates in implant -supported prosthesis supersede those of natural teeth. (Elemek et al. 2020; Papaspyridakos et al. 2020; Lerner et al. 2020; Sailer et al. 2018; Shen et al. 2018; Pjetursson et al. 2018; Drago 2016; Wittneben et al. 2014; Fischer et al. 2013; Pjetursson et al. 2012; Bozini et al. 2011; Jemt 2006). Therefore, compared to tooth-supported prosthesis, implant rehabilitations require meticulously adapted occlusion because the implant-supported prosthesis lacks resiliency, elasticity, and forgiveness (Lerner 2020).

There are many known types of implant complications that result from increased occlusal overload (Adell et al. 1981; Albrektsson et al. 1986; Esposito et al. 1998; Balshi 1996), which can elevate peri-implant crevicular fluid levels, compromising peri-implant tissue health while leading to possible bone loss. The frequent mechanical complications include:

  1. Screw loosening
  2. Screw fracture
  3. Occlusal material failure (Fig. 1)
  4. Prosthesis substructure fracture (Fig. 2)
  5. Abutment fracture
  6. Peri-implant bone loss
  7. Difficult patient occlusal acceptance of the prosthetic occlusal contacts
  8. Occasionally, in severe cases, an implant body itself can fracture (Fig. 3)

A major contributor to a common occlusion-related mechanical complications is the clinical use of analog traditional occlusal indicators, such as articulating paper/foil/strips/horeshoes, shim stock “hold”, occlusal wax imprints, silicone imprints, and articulated casts (both stone and virtual) (Qadeer & Sarinnaphakorn 2020) . Studies have shown that articulating paper specifically, is incapable of measuring occlusal forces (Balshi 1996; Qadeer et al. 2012; Saad et al. 2008; Carey et al. 2007; Bozhkova 2020), leaving the clinician to adjust occlusion by “subjectively interpreting” the articulating paper marks. Unfortunately, this contact selection method is highly prone to error and fails to reliably control force levels (Basson et al. 2020; Sutter 2017; Kerstein & Radke 2013). Studies have shown that by relying on the visual detection of articulating paper marks, dentists select incorrect contacts 87-95% of the time (Basson et al. 2020; Sutter 2017; Kerstein & Radke 2013).

Utilizing digital occlusal indicators in implant-supported prosthesis

Adding computerized occlusal analysis (T-Scan 10 Novus, Tekscan, Inc., Norwood, MA, USA) when adjusting occlusion in cases definitive implant restorations or in cases of immediate loading, helps ensure a predictable targeting of problematic occlusal loads when adjusting occlusion (Lerner 2020). These problematic occlusal loads include premature contacts and excessive contact forces that can de-stabilize an implant restoration. Several digital occlusal tools exist that can aid in occlusal adjustments like Accura (Dmetec Co, Ltd, Seoul, South Korea) , Occlusense (Gmbh Bausch, Germany), and T-Scan , the latter being the most clinically tested device (Sutter 2019).

Many studies have been conducted on T-Scan (Qadeer et al. 2020) that have verified its accuracy in detecting occlusal problems (Koos et al. 2010), its force reproducibility (Harty et al. 2006; Koos et al. 2010; da Silva Martins et al. 2014; Kerstein & Radke, 2022), its time quantification (Koos et al. 2012), and its clinical effectiveness in many areas of patient occlusal care (Qadeer et. al. 2020). Many digital occlusion T-Scan protocols exist in Prosthodontics, Dental Implants, the Digital Workflow, TMD, Posturology, Orthodontics, Periodontics, Occlusal Diagnosis, Aesthetic Dentistry, Tooth Hypersensitivity, Mandibular Orthosis, Occlusal Adjustments, and Patient Education (Kerstein 2020).

Digital occlusal indicators like T-Scan dynamically records and displays the occlusion time (OT), disclusion time (DT), the relative force % distribution, the intensity of 256 relative occlusal forces and their duration, and the timing order of all occlusal contacts, as they each occur inter-occlusally during functional mandibular movements (Kerstein 2020).Such indicators bring objective data to the process of occlusally adjusting an implant restoration, whether the case is full-arch implant supported prosthesis, a removable overdenture, a segmental implant restoration, or a single unit (Aradya et al. 2022; Mangano et al. 2021; Kuder et al. 2017; Ma et al. 2016; Cotruţă et al. 2015). Regardless of the clinician’s desired occlusal scheme (Implant Protected; Anterior Guided, or Balanced), the digital indicator can guide the contacts selected for corrective adjustment where the case installation outcomes are quantifiably improved compared to those obtained with subjectively interpreted, non-digital occlusal indicators (Fig. 5) (Qadeer et al. 2020; Andrus et al. 2019).

How digital occlusal indicators work?

Functional occlusal data sets are recorded intraorally with an ultra-thin, Mylar-encased 100-um thick electronic printed circuit sensor, shaped in the form of a dental arch (Novus HD sensor, Tekscan Inc. S. Norwood, MA, USA) (Figs 6 – 7) that is placed between the patient’s teeth, as they occlude into maximum intercuspation or make lateral excursive movements. The HD sensor sits in the Novus recording handpiece that connects to a computer workstation via a USB interface, and transmits a stream of digital occlusal contact information to the software for presentation to the dentist on the T-Scan 10 desktop.

When a patient occludes upon an HD sensor, the opposing teeth make approximating contact that compresses together the upper and lower sensor surfaces, which results in a change in the electrical resistance in each of the compressed 1-mm2 force measurers (the sensors contain between 1500-2200 force measurers). These resistance changes are then measured by the T-Scan’s hardware electronics as a change in digital output voltage (DO). When the contact force applied is higher, it produces larger resistance changes, and lower occlusal contact force produces lesser resistance changes. A map in the T-Scan 10 software receives a stream of changing sensel digital output voltage values (from the recording handpiece) and organizes them in the same orientation the sensels have within the sensor matrix. These contact-induced voltage changes are presented to the implantologist in a multi-colored, 2- and 3-dimensional dynamic video playback graphical display (Fig. 8a) (Kerstein 2020).

The digital indicator system detects whether an occlusal force on one set of contacting opposing teeth or implants is greater, equal to, or less than the occlusal forces occurring on other contacting teeth throughout the dental arches. This aids the implantologist in diagnosing excessively high occlusal force concentrations, while simultaneously diagnosing where there is little, moderate, low, or no occlusal force present in other areas of the same occlusion (Kerstein 2020). Determining where excessive relative forces are concentrated on implant prostheses can accurately diagnose their location for precisely targeted computer-guided time-based and force-based occlusal adjustments.

An example of this computer-guided closure into MIP force control that develops improved occlusal force balance in a patient with 3 isolated single implants crowns can be seen in Figures 8a and b. The maxillary 2nd molar implant #I-17 is holding excessive and intense contact forces (32.7% of the entire occlusion), which set off an overloaded implant warning (red stop sign), while also causing the patient significant bite discomfort since this crown was initially placed 2 years prior. Excess occlusal force was also detected on implant #I-26, setting off another overloaded implant warning. By using the T-Scan technology to target these 2 overloaded implant crowns with computer-guided occlusal adjustments, widespread, low force occlusal balance was established that did not raise any implant warnings (Fig. 8b). Then, following closure and balance corrections, excursive lateral and protrusive movements were optimized.

Limitations of digital occlusal indicators

Digital occlusal indicators can increase chair time when performing computer-guided occlusal treatment, because it requires the clinician to meet high-telorance occlusal metrics to measurably establish a low-force and balanced outcome (Fig. 8b). Also, digital sensors do not mark the occlusal contacts which means that an articulating paper is still needed, but only to “mark” contacts. Its appearance is not “judged subjectively” for perceived force content because the digital indicator data targets the specific contacts for adjustment. Another limitation is that these indicators do not measure absolute force in engineering units (Kerstein 2020). Finally, there is a definite learning curve required of clinicians (involving didactic amd clinical training), to develop the chairside skills required for optimal computer-guided diagnostic and treatment effectiveness (Afrashtehfar & Qadeer, 2016).

Advantages of digital occlusal indicators

a. Clinician related advantages
There are many clinical advantages for the clinician when using this technolgy compared to using traditional occlusal indicators (Qadeer, 2020) including:

  • Quantifiable time-sequencing and force-mapping guides diagnosis and treatment
  • Precise, targeted occlusal adjustments  made based on objective, metric data
  • Increased accuracy and clinical results when performing occlusal adjustments
  • Cost savings related to fewer material and prosthesis failures

b. Patient related advantages
There are also a number of patient advantages to T-Scan, as well (Qadeer 2020) that also include:

  • A visual aid that offers comprehensive insight and understanding to the patient’s occlusal status
  • Minimally invasive treatment is rendered because occlusal measurements replace the compromised subjective paper mark method
  • Improved prosthesis occlusal outcomes  with less overload sequelae
  • Reduced number of follow-up adjustment appointments needed for occlusal adaptation

Conclusion

The deleterious consequences of choosing the wrong contact to adjust occlusion are potentially many, because undetected high force contacts are left in place and eventually cause cyclic overload of an implant prosthesis, while healthy undetected low-force contacts may be inadvertently adjusted away. Contact selection subjectivity certainly plays a definitive role in the high rates of occlusal and implant material complications that occur with dental implant restorations. This is the main reason installing implant prostheses with the objective force and timing metrics of the digital occlusal indicator technology like T-Scan helps aid in both long-term implant component material survival and peri-implant biomechanical health.


Disclosure
Dr. Robert Kerstein is a Clinical Consultant for Tekscan Inc., Norwood MA, USA. He receives no compensation for sales of any Tekscan products

Authors

Robert B. Kerstein
Dr. Kerstein, DMD, graduated in Prosthodontics at the Tufts University School of Dental Medicine, where he also received his D.M.D. He maintained an active appointment at Tufts as a clinical professor teaching fixed and removable prosthodontics in the Department of Restorative Dentistry from 1985 to 1998. He began publishing about the original T-Scan I technology and has since then published many research papers on T-Scan II, T-Scan III, T-Scan VII, T-Scan 8, T-Scan 9, and the present-day version, the T-Scan 10 technology.

Adell R, Lekholm U, Rockler B, Branemark PI. A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg. 1981;10:387-416.

Afrashtehfar KI, Qadeer S. Computerized occlusal analysis as an alternative occlusal indicator. Jour Craniomandibular Sleep Pract. 2016;34:52–7

Albrektsson T, Zarb G, Worthington P, Eriksson AR. The long-term efficacy of currently used dental implants: a review and proposed criteria of success. Int J Oral Maxillofac Implants. 1986;1:11-25

Andrus R, Quian F, Weir D, Schneider R, Huber L, Kerstein RB. Comparison of results of traditional occlusal adjustment technique w/ computer-aided occlusal adjustment technique. Advanced Technologies and Techniques, 2019;1(2):43-53.

Aradya A, Nagarajagowda RS, Basavaraju RM, Srinivas S, Kumararama SS. Influence of T-Scan System on Occlusion Correction of Implant Supported Prostheses: A Systematic Review. Jour Contemp Dent Pract 2022; 23(1):105-117.

Balshi TJ. An analysis and management of fractured implants: a clinical report. Int J Oral Maxillofac Implants. 1996;11:660-666.

Basson E, Kerstein RB, Radke J. Ability to Correctly Select High Force Occlusal Contacts from Articulating Paper Markings. Adv Dent Tech. 2020;2(1):101-10.

 

Bozhkova TP. Comparative study of occlusal contact marking indicators. Folia Med (Plovdiv) 2020;62(1):180-4. doi: 10.3897/ folmed.62.e48018.

Bozhkova TP. The T-SCAN System in Evaluating Occlusal Contacts. Folia Med (Plovdiv). 2016;58:122-130.

Bozini T, Petridis H, Garefis K, Garefis P. A meta-analysis of prosthodontic complication rates of implant-supported fixed dental prostheses in edentulous patients after an observation period of at least 5 years.  Int J Oral Maxillofac Implants. 2011;26(2):304-18

Carey JP, Craig M, Kerstein RB, Radke J. Determining a relationship between applied occlusal load and articulating paper mark area. The Open Dentistry Journal. 2007;1:1-7.

Chaithanya R, Sajjan S, Raju AVR. A study of change in occlusal contacts and force dynamics after fixed prosthetic treatment and after equilibration – Using Tekscan III. J Indian Prosthodont Soc. 2019;19:9-19.

Cotruţă AM, Mihăescu CS, Tănăsescu LA, et al. Analyzing the morphology and intensity of occlusal contacts in implant-prosthetic restorations using T-Scan system. Rom Jour Morphol Embryol 2015;56(1):277–281.

Dario LJ. How occlusal forces change in implant patients: a clinical research report. J Am Dent Assoc.1995;126:1130-1133.

da Silva Martins MJ, Caramelo FJ, Ramalho da Fonseca JA, Gomes Nicolau PM. In vitro study on the sensibility and reproducibility of the new T-Scan® III HD system. Revista Portuguesa de Estomatologia, Medicina Dentária e Cirurgia Maxilofacial. 2014;55:14-22. doi:10.1016/j.rpemd.2014.01.001

Drago C. Frequency and type of prosthetic complications associated with interim, immediately loaded full-arch prostheses: A 2-year retrospective chart review. J Prosthodont 2016;25(6):433-9.  doi: 10.1111/jopr.12343. Epub 2015 Sep 15.

Elemek E, Agrali OB, Kuru B, Kuru L. Peri-implantitis and Severity Level. Eur J Dent 2020;14(1):24-30.    doi: 10.1055/s-0040-1701162.  Epub 2020 Mar 13.  PMID:  32168529 PMCID:

Esposito M, Hirsch JM, Lekholm U, et al. Biological factors contributing to failures of osseointegrated oral implants. Eur J Oral Sci. 1998;106:721-764.

Fischer K, Stenberg T. Prospective 10-year cohort study based on a randomized, controlled trial (RCT) on implant-supported full-arch maxillary prostheses. Part II: prosthetic outcomes and maintenance. Clin Implant Dent Related Res 2013;15:498-508

Jemt T, Johansson J. Implant treatment in the edentulous maxillae: a 15-year follow-up study on 76 consecutive patients provided with fixed prostheses.  Clin Implant Dent Relat Res. 2006;8(2):61-9. doi: 10.1111/j.1708-8208.2006.00003.x. PMID: 16774591

Kerstein RB, Radke J. Clinician accuracy when subjectively interpreting articulating paper markings. Jour Craniomandibular Sleep Pract. 2013;32(1):13-23.

Kerstein RB, Radke J. In-vitro consistency testing of the T-Scan 10 relative force measurement system. Advanced Dental Technologies & Techniques. 2022;4(2):47-58. Epub

Kerstein RB. Handbook of Research on Clinical Applications of Computerized Occlusal Analysis in Dental Medicine. Hershey, PA: IGI Global, 2020. Pp. 1-1550. http://doi:10.4018/978-1-5225-9254-9

Kerstein RB. Digital occlusal analysis of the final implant restorations. In Digital Dentistry Science & Clinics. Mangano C, Lerner H. Mouhyi, J Luongo G. (Eds.). Youssef Impressions, Marrakesh, Morocco 2021; Pp. 307-365.

Khuder T, Yunus N, Sulaiman E, et al. Association between occlusal force distribution in implant overdenture prostheses and residual ridge resorption. Jour Oral Rehabil. 2017;44(5):398–404.

Koos B, Holler J, Schille C, & Godt A. Time-dependent analysis and representation of force distribution and occlusion contact in the masticatory cycle. Journal of Orofacial Orthopedics. 2012;73:204-14.

Koos B, Holler J, Schille C, & Goz G. Precision of an instrumentation-based method of analyzing occlusion and its resulting distribution of forces in the dental arch. Journal of Orofacial Orthopedics. 2010;71:403-10.

Lee W, Kwon HB, Kim MJ, & Lim YJ. Determination of the reliability and repeatability of aquantitative occlusal analyzer by using a piezoelectric film sensor: An in vitro study. Jour of Prosthetic Dentistry. 2022;127(2):331-337.  doi: 10.1016/j.prosdent.2020.07.024. Epub 2020 Nov 26.

Lerner H, Hauschild U, Sader R, Ghanaati S. Complete arch fixed reconstruction by means of guided surgery and immediate loading: a retrospective clinical study on 12 patients with 1 year follow up. BMC Oral Health. 2020;20:15   https://doi.org/10.1186/s12903-019-0941-z

Lerner, H. Digital Occlusion in the Workflow of Implant Rehabilitations. In Kerstein RB. (Ed). Handbook of Research on Clinical Applications of Computerized Occlusal Analysis in Dental Medicine. Hershey, PA: IGI Global, 2020; 945-995. http://doi:10.4018/978-1-5225-9254-9

Lowe, M., Harty, M., Kerstein, R.B., Radke, J A Force reproduction analysis of two recording sensors of a computerized occlusal analysis system. Jour Craniomandibular Practice. 2006;24(1):15-24.

Luo Q, Ding Q, Zhang L, Xie Q. Analyzing the occlusion variation of single posterior implant-supported fixed prostheses by using the T-Scan system: A prospective 3-year follow-up study. J Prosthet Dent. 2020;123:79-84.

Ma FF, Lin Y, Di P, et al. All-on-4 occlusion study: using T-Scan III occlusal analysis system. Chin Jour Stomatol 2016;51(9):517–520.

Madani AS, Nakhaei M, Alami M, Haghi HR, Moazzami SM. Post-insertion Posterior Single-implant Occlusion Changes at Different Intervals: A T-Scan Computerized Occlusal Analysis. J Contemp Dent Pract.2017;18:927-932.

Papaspyridakos P, Barizan Bordin T,  Kim YJ,  El-Rafie K, Pagni SENatto ZS,  Teixeira ER, Chochlidakis K, Weber HP. Technical complications and prosthesis survival rates with implant-supported fixed complete dental prostheses: A retrospective study with 1- to 12-year follow-up.  J Prosthodont 2020;29(1):3-11.  doi: 10.1111/jopr.13119. Epub 2019 Nov 21.

Pjetursson BE, Thoma D, Jung R, Zwahlen M, Zembic A et al. A systematic review of the survival and complication rates of implant-supported fixed dental prostheses (FDPs) after a mean observation period of at least 5 years. Clin Oral Implants Res. 2012;23 Suppl 6:22-38. doi: 10.1111/j.1600-0501.2012.02546.x.

Pjetursson BE, Valente NA, Strasding M, Zwahlen M, Liu S, Sailer I, Pjetursson BE, et al. A systematic review of the survival and complication rates of zirconia-ceramic and metal-ceraic single crowns.  Clin Oral Implants Res. 2018;29 Suppl 16:199-214. doi: 10.1111/clr.13306. PMID: 30328190

Qadeer S, Kerstein RB, Yung Kim RJ, Huh JB, Shin SW. Relationship between articulation paper mark size and percentage of force measured with computerized occlusal analysis. Journal of Advanced Prosthodontics, 2012;4:1-6.

Qadeer S, Özcan M, Edelhoff D, Van Pelt H. Accuracy, reliability and clinical implications of static compared to quantifiable occlusal indicators. Eur J Prosthodont and Restor Dent. 2020;28:1-1235.

Qadeer S, Sarinnaphakorn L. Comparing the force and timing limitations of traditional non digital occlusal indicators to the T-Scan  computerized occlusa analysis technology. In Kerstein RB. (Ed). Handbook of Research on Clinical Applications of Computerized Occlusal Analysis in Dental Medicine. Hershey, PA: IGI Global, 2020; Pp. 55-99. http://doi:10.4018/978-1-5225-9254-9

Roque MA, Gallucci GO, Lee SJ. Occlusal Pressure Redistribution with Single Implant Restorations. J Prosthodont. 2017;26:275-279.

Saad MN, Weiner G, Ehrenberg D, Weiner S. Effect of load and indicator type upon occlusal contact markings. Journal of Biomedical Materials Research, Part B, Applied Biomaterials, 2008;85(1):18-22.

Sailer I, Strasding MValente NAZwahlen M, Liu S, Pjetursson BE. A Systematic Review of the Survival and Complication Rates of Zirconia-Ceramic and Metal-Ceramic Multiple-Unit Fixed Dental Prostheses. Clin Oral Implants Res Actions. 2018;29 (Suppl 16):184-198. doi: 10.1111/clr.13277

Shen HD, Di P, Li JH, Luo J, Zhang Y, Lin Y. Complications of implant-supported full-arch immediate prosthesis: a retrospective analysis of 114 cases. Zhonghua Kou Qiang Yi Xue Za Zhi. 2018 5;(4):236-242.    doi: 10.3760/cma.j.issn.1002-0098.2018.04.005.

Sutter, B.A. (2017) A digital poll of dentists testing the accuracy of paper mark subjective interpretation. CRANIO. 2017;36(6): 96-403. doi: 10.1080/08869634.2017.1362786.

Sutter, B.A.  Digital Occlusion Analyzers: A product review of T-Scan 10 and Occlusense. Advanced Dental Technologies & Techniques 2019;2(1):1-31.

Wittneben JG, Buser D, Salvi GE, Bürgin W, Hicklin S, Brägger U. Complication and failure rates with implant-supported fixed dental prostheses and single crowns: a 10-year retrospective study. Clin Implant Dent Related Res, 2014;16(3):356-64.  doi: 10.1111/cid.12066. Epub 2013 Apr 2.

Share on facebook
Share on twitter
Share on linkedin
Share on whatsapp
Clinical insights

Interocclusal space assessment for full-arch implant-supported prostheses

Introduction Even though new technologies and techniques have dramatically improved the treatment of edentulous patients over the years, clinicians still need to be aware of the challenges when managing these patients during treatment planning. The main reason is that, when implant-related treatments are involved, certain site-specific anatomic characteristics should be

Read More »
sustainability
News

Living up to our values

Everything we do at the ITI is guided by our values. These include social responsibility and good stewardship, i.e. responsibility towards society as well as economic, social and environmental sustainability. We take our values seriously and do our best to translate them into tangible benefits for the global society at large. We

Read More »
Practice development

An esthetic choice

Anyone landing on the website for Marisa Zenha’s practice based in Porto, Portugal, for the first time might be forgiven for being a little confused. There is not a single white coat in sight and instead the practice staff on the welcome page look ready for an evening at the

Read More »