For patients missing all their teeth in one or both arches, there have never been more options available for replacing those teeth than today. The literature and clinical experiences are full of reports of positive patient outcomes utilizing dental implants to improve comfort, function, and appearance.

A variety of prosthetic options exist to aid in supporting our patients with one or both edentulous arches—but there is no universal implant number or position that will work for every one of these designs. Therefore, the prosthetic planning must be well thought out before the dental implants are placed.

With the wide range of prosthetic options available come many questions. Some of those questions are specific to sequencing the treatment with a particular design while other questions may be more general in nature. A question that one could ask for any of the designs here that utilize implants is this: How soon can you load implant overdentures?

Patient looking in mirror smiling

This is a great question in a practice landscape where patients may be expecting “teeth in a day”! Let's explore this question in-depth.

Defining loading protocols

The original Branemark loading concepts suggested leaving dental implants submerged for between three and six months before uncovering the fixtures and attaching them to a dental prosthesis.

This conservative concept was conceived largely empirically and was designed to avoid micromotion of the still-integrating implants and the resulting introduction of a connective tissue layer at the implant-bone interface (i.e. failure to osseointegrate).

Modern loading protocols have evolved along with implant design and surface technology. While some discussion remains regarding loading protocols, many researchers and clinicians follow these general guidelines for describing the timing of implant loading:

Conventional loading

Prosthesis attached to dental implants 2 months or more after implant placement.

Immediate loading

Prosthesis attached to dental implants one week or less following implant placement.

Early loading

Prosthesis attached to dental implants between one week and two months following implant placement.

This patient has recently been edentulated. If implants are going to be used how soon can they be “loaded”, or attached to the dental prosthesis?
Figure 2: This patient has recently been edentulated. If implants are going to be used how soon can they be “loaded”, or attached to the dental prosthesis? Is the timing different if the prosthesis is fixed instead of removable? Is the timing the same in the maxilla as it is in the mandible?

Fixed vs. removable

Immediate loading is well documented (Papaspyridakos et al. 2014) in both the maxilla and the mandible when using a fixed dental prosthesis. The cross-arch stabilization of the fixed prosthesis appears to be effective in sufficiently reducing micromovement of the integrating implants. As a result, immediate loading is an approach that should be considered for a fixed reconstruction on dental implants.

Far less is understood regarding the influence of implant loading protocols when implant overdentures are being utilized. Confusion about appropriate loading times with overdentures is understandable within the context of the risk to osseointegration from micromovement, considering that the implants will be subject to significant loading both under function and when the prosthesis is removed and inserted. The confusion is then amplified when the heterogeneity of overdenture design is considered.

As a result, the question to ask is: “Which loading protocol should be utilized when the dental implants will be attached to a removable prosthesis, or overdenture?”

To answer that, the current literature is quite helpful.

Loading protocols for implant overdentures—a systematic review

In a 2021 systematic review and meta-analysis, Borges et al. looked at long-term outcomes of different loading protocols when implant overdentures were used to replace missing teeth in the mandible.

The authors concluded that when compared to conventional loading, both immediate loading and early loading protocols demonstrated similar levels of implant survival and implant success in the mandible. Further, given the benefits of shortened overall treatment time, immediate and early loading protocols should be considered in clinical practice.

In another systematic review and meta-analysis, Cao et al. (in press) reported similar findings when evaluating conventional loading against immediate loading protocols with mandibular two-implant overdentures. In this paper, the number of implant failures reported was higher with immediate loading protocols, but the increase was not statistically significant.

Neither of these papers reported on the influence of the prosthetic design of the mandibular overdentures utilized. Is there a difference in implant success or survival when a passive fitting tissue bar is used rather than resilient individual attachments, like Locator or spherical attachments? An article from Elsyad et al. (2021) sheds light on this question by comparing overdentures with immediately loaded implants and “resilient stud” Locator attachments and a bar attachment. In this study, 4 implants were used in the mandible. At one year, the authors report implant survival as 96.6% for the Locator and 98.3% for the passive fitting bar — no statistical difference.

Intraoral view showing a tissue bar fabricated in one week or less, shown both with and without the bar connection.
Figure 3: Surprisingly, there is literature support to immediately load each of these mandibular overdentures under the right clinical circumstances. Considering the logistical difficulty in having a tissue bar (right) fabricated in one week or less, early loading may be a more realistic approach, and conventional loading is always an option as well.

These recent articles further support ITI consensus statements published by Gallucci et al. in 2014 regarding implant loading protocols for implant overdentures in edentulous jaws. According to this paper:

  1. “Current clinical research supports high survival with the use of threaded, microtextured implants with a minimum diameter of 3 mm for the support of overdenture prostheses when used with immediate, early, or conventional loading protocols. Limited evidence exists for immediate loading of implants supporting overdentures in the maxilla.” 4
  2. “Descriptive material from the review in this group for immediate loading by Schimmel et al lists inclusion criteria of: insertion torque (≥ 30 Ncm), ISQ value (≥ 60), two or more implants in the mandible, or four or more implants in the maxilla.”4
  3. “Splinting of implants and the type of attachment system had no effect on 1-year survival rate compared to freestanding implants.”4
Side by side intraoral and prothesis image to show final prothesis placement.
Figure 4: This patient's lost two implants from underneath a maxillary overdenture. While immediate loading for fixed reconstructions on implants in the maxilla are well documented, the literature remains unclear about how implant loading influences longevity in the maxilla when overdentures are being utilized.

The article then goes on to provide guidelines for clinical practice:

  1. “The intended loading protocol should be selected considering implant-prosthodontic parameters as well as functional, psychosocial, and financial aspects and patient preference.” 4
  2. “Early loading represents a satisfactory treatment modality in the management of the edentulous jaw, when using implants to support/retain an overdenture prosthesis and can be recommended as routine in the absence of modifying factors.” 4
  3. “Immediate loading protocols in implant-supported/ retained overdentures appear predictable. The available research arbitrarily uses an insertion torque of 30 Ncm or greater and/or an ISQ value of 60 or greater. The evidence for immediate implant loading in the maxilla is less compelling. However, there is no reliable pre-treatment predictor that has determined conclusively that the clinician can perform an immediate loading procedure.” 4
  4. “Given the lack of research, the use of a single implant in an immediately loaded fashion may not be indicated for support/retention of overdenture prostheses.” 4

In practice, I have found these clinical guidelines incredibly helpful and a great conversation starter with our interdisciplinary team.

Conclusions and final thoughts

For overdentures in the mandible, immediate, early, and conventional loading protocols are all worth consideration.

For overdentures in the maxilla, the literature is unclear and conventional loading may be the most predictable approach. Other clinical variables, such as low insertion torque values or patient history of bruxism may alter the approach to implant loading with overdentures.

I hope you find the information helpful in treating your own patients and I look forward to hearing your thoughts about loading protocols and overdentures on Spear Talk and at your next visit to Spear campus.


Darin Dichter, D.M.D., is a member of Spear Resident Faculty.

References:

  1. Borges GA, Costa RC, Nagay Bruna Egumi, Magno MB, Maia LC, Barao VAR, Mesquita MF. Long-term outcomes of different loading protocols for implant-supported mandibular overdentures: A systematic review and meta-analysis. J Prosthet Dent 2021;125:732-745.
  2. Cao ZL, Li Xiao, Lin LJ, Chen YH. Immediate or delayed loading protocols for two-implant mandibular overdentures: A systematic review and meta-analysis of randomized controlled trials. J Prosthet Dent 2020; in press.
  3. Elsyad MA, Alsabri, AM, Elgamal M, Youssef Al-Tonbary G. Resilient Stud Versus Bar Attachments for immediately loaded Implants supporting mandibular overdentures: 1-year randomized controlled clinical trial. Int J Oral Maxillofac Implants 2021;36:346-354.
  4. Galluci GO, Benic GI, Eckert SE, Papasyridakos P, Schimmel M, Schrott A. Consensus statements and clinical recommendations for implant loading protocols. I J Oral Maxillofac Implants 2014;29 Suppl:287-290.
  5. Liu W, Cai H, Zhang J, Wang J, Sui L. Effects of immediate and delayed loading protocols on marginal bone loss around implants in unsplinted mandibular implant-retained overdentures: a systematic review and meta-analysis. BMC Oral Health 2021;21:online.
  6. Papaspyridakos P, Chen CJ, Chuang SK, Weber HP. Implant loading protocols for edentulous patients with fixed prostheses: a systematic review and meta-analysis. Int J Oral Maxillofac Implants 2014;29 Suppl:256-70.

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