Original study - ZZI 02/2013

Immediately and conventionally loaded implants in the edentulous mandible

M. Lorenzoni1 , M. Stopper2, S. Vogl1, WA Wegscheider1

Objective: The aim of this current investigation was to evaluate clinical outcomes of conventional and immediate loaded implants and Dolder bars in the interforaminal region of the lower jaw after 5 years of clinical function.

Materials and methods: 160 implants were inserted in the interforaminal region. 20 patients of the control group were treated after a healing period of 3 months and 20 patients of test group were loaded within one week with Dolder bars and overdentures. Annual radiographic bone resorption, Periotest values and survival rates were recorded and evaluated.

Results: All implants (160 implants) were placed with an insertion torque of more than 20 Ncm. The evaluated mean coronal bone loss increased from 0.56 mm to 1.91 mm after five years of clinical function in the control group and from 0.55 mm to 1.98 mm in the test group. The median Periotest value was between –4 and –5 for the immediately loaded and the conventionally restored implants. After an observation period of 5 years the survival rate was 100 % in both groups.

Conclusion: These results after 5 years of loading suggest that interforaminal implants can be treated conventionally and immediately and restored with Dolder bars with clinically predictable outcomes with stable coronal bone levels.

Keywords: immediate and conventional loading; edentulous mandible; Dolder bars; overdentures


Lorenzoni M, Stopper M, Vogl S, Wegscheider WA: Immediately and conventionally loaded implants in the edentulous mandible. Z Zahnärtzl Implantol 2013;29:130?138

DOI 10.3238/ZZI.2013.0130?0138


Removable full overdentures supported by at least 4 implants have been proven clinically for decades [19, 32]. Bars are the most frequent means of coupling the implants with the removable overdentures [1, 15, 16, 18, 20, 24]. The advantage of bar constructions with a distal extension is that the prosthesis is supported fully by the implants. The posterior parts of the jaw are not loaded by the prosthesis and further atrophy is prevented. Implant-supported bars with a distal extension are therefore preferable if massive atrophy is already present [33]. Atrophy of one or both jaws leads to an increase in the intermaxillary distance, which has to be compensated by the denture. Compared with fixed implant-borne prostheses, removable dentures offer certain advantages. The peri-implant areas are easier to clean. Fewer problems occur with phonetics and adverse aesthetic effects [16, 25, 27].

The time of loading does not depend on the type of prosthetic restoration. The classical delayed loading treatment protocol provides for closed implant healing for at least 2 months in the mandible [12]. This method is time-consuming and means at least 2 surgical procedures for the patient. For this reason, Ledermann developed the concept of immediate implant restoration [21]. This protocol can today be regarded as standard and is supported by numerous publications (see discussion).

The aim of this study was to compare implant-supported bar prostheses after immediate and conventional restoration with implants (Dentsply Friadent, Germany). The survival rate and crestal bone atrophy were investigated after up to 5 years of clinical function.


Materials and methods


Patients who took part in this study had to meet the following conditions:

  • completely edentulous mandible with healed extraction wounds,
  • adult women and men (age: 18–99 years),
  • adequate residual bone height to allow insertion of a standard implant (> 10 mm),
  • general physical and psychological condition that allowed the surgical procedures and restoration process.


The following patients were excluded:

  • heavy smokers (> 10 cigarettes/day as reported by the patient),
  • patients with uncontrolled diabetes mellitus or disorders of bone metabolism,
  • pregnant women,
  • patients with parafunctions,
  • patients on bisphosphonate therapy,
  • patients with previous radiotherapy or chemotherapy in the head and neck region,
  • patients who could not attend for regular follow-up.


40 patients in total (21 men, 19 women) with an average age of 59.4 years (29 to 82 years) were selected.

In the period from 2006 to 2011 a total of 160 XiVE S plus implants of different diameters and lengths were inserted. Four implants per patient were placed interforaminally in positions 32, 34, 42 and 44. The study design was already described in 15, 16 and 16a.


Prosthetic planning

Planning was based on cephalic articulated study models, a digital orthopantomograph and the clinical findings. The opposing teeth and vertical dimension were considered in particular. If the patient had a full lower denture adapted to the anatomical and physiological situation, this was left. Otherwise a new one was fabricated. A duplicate of each full denture was fabricated out of transparent plastic (Palapress clear; Heraeus Kulzer, Hanau, Germany) and relieved in the anterior region from 35 to 45. This duplicate acted as implant template.


Surgical procedure

In all patients, the implants were placed 6 months at the earliest after the last extraction under local anesthesia (Ultracain Dental forte, Sanovi-Aventis, Germany) and without concurrent regenerative procedures. All patients were given antibiotics and anti-inflammatories for 4 days. The antibiotic was started one day preoperatively.

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