Immediate Loading of Narrow-Diameter Implants With Overdentures in Severely Atrophic Mandibles

Sang-Choon Cho, DDS; Stuart Froum, DDS; Chih - Han Tai, DDS, Young Sung Cho, DDS; Nicolas Elian, DDS; Dennis P. Tarnow, DDS

Oral rehabilitation using two to four implants to support mandibular overdenturet hat been shown to hove success rates of approximately 96% with implants placed in a one- or two-stage procedure. The purpose of this study is to evaluate 10 con­secutive cases of immediately loaded, narrow-diameter implants \NDls) as support for overdentures in severely atrophic mandibles, and report on implant 'prosthetic survival rates and patient satisfaction. Overall implant and prosthetic survival rates were 94.1% and 100%, respectively.

Learning Objectives

This article discusses the implant/prosthetic survival rates and patient satisfac-lion For immediately loaded, narrow-diameter implants |NDIs| Upon reading this article, the reader should

1. Better understand how to evaluate NDIs as support for overdentures.
2. Become more familiar with determining whether NDIs are more efficient,
   as opposed to standard-diameter implants, for a specific case.

Key Words: narrow-diameter, implant, immediate loading, overdenture, edentulous
'   Clinical Aissitant Professor Department of Pwiodonto/ogv and tinpiant Dentistry. New Votli University College oi Dentistry, New York, NY
I    Clinical ProfeiKv, Deparhnenl ol Periadootatogy and Implan! Dentistry, New York
University College of Dentistry, Nr* York, NY, private practice. New York, NV
t Former Rendenl, Department of Penodontohgy and Implont Dentistry. New Hwi
University College of Dentistry, New York. NY § Former Resident, DopaDmenl of Periodontology and Implant Dentistry. New York
University CoOege at Dentistry, New York, NY, private practice. Ar>|oo, South Korea
II   Asiiitant Professor Division Hiod ol Implant Dentistry, Deportment of Perbdonlology and
Implant Dentistry, New YoA University College ol Denhttiy. New York. NY.
"■ Professor and Chair. Department of Penodontohgy und Implant Dentistry New Yoik
University College of Dertisfy, New York  NY private practice. New York  NY Stuart J. Fiwnr, DOS, K, ) 7 West 54th Strwt, SM. IC/D, New York, NY 10019tml: 1212) 586-4209 • Email: smile@dntvorifrtwm.com

Conventional mandibuar dentures for patients with severely atrophic mandibles often present retention, phonetic, and functional complications, as well as patient discomfort due lo instability.: Endosseous implants have been successfully used to restore edentulous mandibles with impbnt-supppported fixed partial dentures, hybrid pros­thetic dentures, and removable overdenture prostheses.' Oral rehab dilation using two to four implonts lo support mondibulof overdentures has been shown to have suc­cess rates of approximately 96% with implants placed in a one- or Iwo slage procedure.1' Numerous authors also have addressed patient satisfaction with mandibu-lar impbnt-supported overdentures.8' Meijer et al reported thai patients with mandibulon overdetilures sup-potted by two implants had higher satisfaction scores than patients who hod complete denture treatment.

Atrophy of edentulous jaws may. however, limil implant placemenl in the mandible In addition, anatonic limitations ond resorbed alveolar ridges may compro­mise implant number, length, and position '' The use of slandard-diameter implants to support an overdenture often requires ridge augmentation in order to ensure suf­ficient bone volume. In addition, in patients of advanced oge with serious medical problems or using anlicoogu-lant therapy, the placement of more than one stondaid impant has been shown to have a statistically significant increased risk of surgical com plications." NDIs placed with Ibpless surgery lo support pre-existing conventional denlures present a method ot restoring patients with atrophic mondibles. Advantages of this procedure include implanl placement witnout any bone augmentation surgery, minimally invasive surgery resulting in little bleed­ing, decreosed pain, and reduced patient expense

Narrow-diametei |ie, 1.8 mm) implants were origi­nally introduced and used to support provisional restora-tions in a single-stage suigery; these implants were then immediately loaded.11 ' White transitonal implants were generally removed ot the end of the provisinolization period. NDIs became osseoinlegrated with similar per centages of bone-to-implant contact, as was achieved with conventional machined-surface implants. **" A novel line of titanium alloy NDIs (ie. Atlas, Dentatus USA, New York. NY| was recently introduced and approved for use as conventional implants These were designed as single-piece implants composed of screw retained or cement-retained attachment superstructures. These implants have □ self-threading, tapered screw design with diameters o( 1.8 mm to 2.4 mm and embedded lengths of 7 mm, 10 mm, or 14 mm.

The purpose of the current study was to evaluate 10 consecutive coses of immediately boded NDIs as support for overdentures in severely atrophic mandibles and report on the implant/prosthetic survival rotes and patient satisfaction.

Materials and Methods

Clinical data were obtained retrospectively from on Implant Dentistry Database |IDD| at the Department of Periodontology and Implant Dentistry. New York University College of Dentistry (NYUCD) Kriser Dental Center This data set was extracted as de-identified information horn the clinical information obtained from the routine treat men! of patients. The IDD was certified by the Office oi Quality Assurance at NYUCD. This study was in com­pliance with the Health Insurance Portability and Accountability Act (HIPAA| requirements.

Between 2004 and 2007, 10 patients (ie, 3 males, 7 (females), mean age of 58.25 (ie, range 30 to 83|, received atotal of 34 NOIs |ie, 2.4 mm, Atlas, DontoJus USA, New York, NY] (Figures 1 through 10). Inclusion cri­teria consisted of patients who were dissatisfied with their conventional mandibular dentures due to lack of stability in function, and in whom there were no contraindications for implant placement Panoramic radiographs were obtained, and two to four narrowdiameter. one-piece dometype implants were placed in the mandibular anle-ricx area between the foramina using a Hapless surgical procedure The patient's preexisting mandibular denture was then relined with o resilient silicone material (ie, Tuf-Link Silicone Material, Dentalus USA, New York, NY| la establish adequate retention and allow immediate func­tion A patient interview wilh sub|ective evaluation was performed two months postoperatively This interview also included the patient's evaluation of his or her previous den­tures. In he present study, a patient satisfaction question­naire |PSQ| was used to evaluate ond compare the satisfaction of parents who had previously worn conven­tional dentures (CD) and who now function with narrow diameter, implant-supported overdentures.

Results

A total of 34 implants were placed in 10 patients Two of these implants failed within two monlhs of loading All 10 patients functioned with their NDISOs throughout the entire study period This represents on overall implant survival rate ol 94.1% and prosthetic survival rale of 100% (Table 1| Patient satisfaction questionnaire saves reported that NDISO resulted in improvement ,n func­tion (Ql |, stability (Ql), comfort |Q2), fitness (Q3 and Q4), occlusion |Q4|, satisfaction \Q5, Q8), speedi |Q6 and Q7), and social life (Q9| compared to the weor-ing o* CD (Tablei 2 and 3)

Discussion

Mandibular overdentures with different attachment designs supported by two to four implants have shown high implant survival rates wild various implant systems using submerged, norn-submerged, and immediately boded protocols. These clinical trials ranged from six months to 10 years (Tables 4 and 5).

The present study is the first to present longitudinal results , range 14 to 36 months of immediately boded, non-splinted NDIs used b support overdentures. with a resulting 94 1 % implanl survival rale The NDt survival iate lie, two failures ol 34 pbced implants) over a 14-to 36 month period is similar to the 96.4% success rate reported in a study of conventional unsplinted implants immediately loaded with ovedenlures in 10 patients over a 12- to 30month period." Park et ol leported on the long-term survival of NDls lie. 1 8 mm) with an over-all survival rate of 85 9%." The survival rate .n the mandible (93%] was greater than that in the maxilla (79 4%) 36 months following immediate boding '' Simon and Caputo evaluated the removal torque of immediately loaded tran-sitional endosseous implants in humans and reported that values were significantly higher in tie mandible |ie. 24.0 ± 7.3 Ncm) than in the maxilla |ie, 16 1 ± 4.8 ^kTn|;' These studies demonstrated that stronger integration occurred in the mandible with higher survival rates of NDis compared b those placed in the maxilla In the present study two to four NDls were inserted in severely atrophic mondible in order to support preexisling dentues.

The dentures, which were relined with a silicon material and immediately loaded, functioned with an implant survival rate of 94% which is slightly higher but similar to the study for the mandible by Park et al.

Two NDIs failed in two patients. The first NDI failure occured two months following immediate loading. This may have been the result of misalignment, which induced excessive forces during the initial healing phase. The use of the three remaining NDIs placed in the patient,however, allowed the prosthesis to maintain adequate function. Two monlhs following the removal of the failed NDI It was replaced by an NDI of similar size wilh flapless surgeiy and immediale loadmg. The other NDI that failed was placed into a fresh extraction socket Failure occurred one month Following placement This might have been The result of irnplanf micromovement
and loss of init ial stability during the first three weeks of socket bone remodeling. To dater there has been 100% prostheses survival rate in Ihe 10 reported cases.

Reconstruction of o severely resorbed mandible wilh standard implant placernent may require multiple grafting procedures prior to, or in conjunction with, implant placement. In the presenl study, NDIs placed with flapless sugery in severely athrophic mandibles resulted in limited bleeding during the surgery and minimal post operative discomfort and swelling. The surgery was expedient, and ridge augmentation procedure were avoided. The procedures represented a reduced risk to patienls Who were advanced in age (ie, 3 of 10 patients], had serious medical problems (ier I of 10
patients). or were using anticoligulant therapy (i.e 1 of 10 patients)Patients were also able to maintain the same vertical dimension of occlusian by using ihe preexisting denture supported by rhe NDI that was placed with
flapless surgery.

Flapless implant placement also decreased the post surgical dentuie shifting that is oflen caused by healing of □ sutured flap. immediate loading in function was acchieved with ihe palients denture at the time of implanl surgery.

Use of low prolile ball attachments (ie. 3 mm] decreased the risk of later overbading forces in the initial healing phase of the loaded implants. The procedure utilized less expensive implants with flapless surgery and therefore resulted in reduced cosl of treatment.

The patient satisfaction questionnaires indicated that following two months of immediate function with NDISOs. patients cleaned their dentures very well, three times a day, and removed them at night Patients reported wearing the NDISO for longer periods of time than the CD during the day There was also a significant increase in patient sat isfaction with improved denture retention during function and improved patient comfort compared to CDs. There was a higher satisfaction level reported with the occlusion ot lo© proslheses, as well as an improvement in reported ability to understand fhe patient's speech with NDISOs The dot) from the present study also showed that patients nod a significant increase in comfort and confidence with the NDISO as compared lo complete dentures

Conclusion

In this study, full mandibular dentures supported by non-splinted, domeshoped NDIs provided immediate occlusal loading and function with high survival rotes of both the NDIs(ie, 94.1*) and prostheses (ie, 100%).

When asked to evaluate and compare the NDISOs and CDs, patients reported an increase in comfort, func­tion, stability, fit, occlusion, satisfaction, phonetics, and social life over on average of 22.8 months (ie, range 14 to 36 months! To dale, the use of immediately placed NDIs to support removable overdentures in the mandible has shown excellent results. Further studies are required lo determine long term success and predictability of this treatment modality and possible applicability for NDI-supported maxilary overdentures

Acknowledgement

The authors declare no financia/ jnterest in any of the prod-ucts referenced here in. for a complete list of feferences cited in fables 4 and 5, please contact the oulkors. The authors mention ibeir gratitude to SangHee Potk. Sang-Jong Cha, Mchets lonaWl, Yung-Sang Park, and lae-Sung Kim for then ossulonce in tfie case freo'menf.

References

1. vanWaas MAJ, The influence of clinical variables on patients' satisfaction with complete dentures. J Prosthet Dent 1990;69(3); 307-310.
2. Adell R, Lekholm U, Bockler B, Branemark P-l, A 15 - year study of osseointergrated implants in the trteatment of edentulous jaw. Int J. Oral Surg 1981;10(6);387-416.
3. Batenburg RHK, Meijer HIA, Raghoebar GM, Vissink A. Treatment concept for mandibular overdentures supported by endosseous implants; A literature review, Int J Oral Maxillofac Impl 1998;1-3(4);539-545
4. Mericske-Stern R, Schaffner TS, Marti P, Geering AH, Peri-implant mucosal aspects lTl implants supporting overdenture. Clin Oral Impl Res 1994;5(1); 9-18.
5. Heydenrijk K, Raghoebar GM, Meijer HJA, et al. Two-Stage IMZ implants and lTl implants inserted in a single-stage procedure. A prospective comparative study. CLin Oral Impl Res 2002; 13(4);371-380.
6. Jemt T, Chai J, Harnett J, et al. A 5-year prospective multicenter follow-up report on overdentures supported by osseointergrated implants, Int J Oral Maxillofac Impl 1996;11(3);291-298
7. Naert IE, Gizani S, Vuylsteke M, van Steenberghe D, A 5-year prospective randomized clinical trail on the influence of splinted and unsplinted oral implants retaining a mandibular overdenture; Prosthetic Aspects and patient satisfaction. J Oral Rehab 1999;26(3); 195-202.
8. Burns DR, Unger JW, Elswick RK Jr, Beck DA. Prospective clinical evaluation of mandibular implant overdentures; Part retention, stability, and tissue response. J Prosthet Dent. 1994; 73(4); 354-363.
9. de Albuquerque Jr RF, Lund JP, Tang L, et al. Within-subject comparison of maxillary long-bar implant-retained prostheses with and without palatal coverage; Patient-based outcomes, Clin Oral Impl Res 2000;11(6); 555-565.
10. Wismeijer D, Vermeeren JIJH, van Waas MAJ, Patient satisfaction with overdentures supported by one-stage TPS implants, Int J. Oral Maxillofac Impl Res 1999;10(3); 238-244.
11. Meijer HJA, Raghoebar GM, Van't Hof MA, et al. Implant-retained mandibular overdentures compared with complete dentures; A 5-years follow-up study of clinical aspects and patient satisfaction, Clin Oral Impl Res 1999;10(3);238-244.
12. Harle TJ, Anderson JD. Patient satisfaction with implant - supported prostheses, Int J Prosthodont 1993;6(2); 153-162.
13. Sadowsky SJ, Mandibular implant-retained overdentures: A literature reveiw. J Prosthet Dent 2001; 86(5);468-473
14. Smith RA, Berger R. Risk factors associated with dental implants in healthy and medically compromised patients. Int J Oral Maxillofac Impl 1992;7(3);367-372
15. Petrungaro PS. Fixed temparization and bone-augumentes ridge stabilization with transitional implants. Pract Periodont Aesthet Dent 1997;9(9);1071-1078
16. el Altar MS, el Shazly D, Osman S, et al. Study of the effect of using mini-transitional implants as temporary abutments in implant overdenture cases. Impl Dent 1999;8(2); 152-157
17. Bohsali K, Simon H, Kan JYK, Redd M. Modular transitional implants to support the interim maxillary overdenture. Compend Cont Educ Dent 1999;20(10);975-983.
18. Petrungaro PS. Reconstruction of severely resorbed atrophic maxillae and management with transitionsl implants. Impl Dent 2000;9(3);271-277
19. Bichacho N, Landsberg CJ, Rohrer M, Davidovich Y, Immediate fixed transitional restoration in implant therapy, Pract Periodont Aesthet Dent 1999;11(1); 45-51.
20. Zubery Y, Bichacho N, Moses O, Tal H, Immediate loading of modular transitional implants; A histologic and histomorphometric study in dogs, Int. J Periodont Rest Dent 1999;19(4); 434-453
21. Froum SJ, Simon HH, Cho SC, et al, Histological evaluation of immediately loaded transitional implants after 6 to 27 months.
22. Simon H, Caputo AA, Removal torque of immediately loaded transitional endosseous implants in human subjects. Int J Oral maxillofac Impl 2002; 17(6);839-845
23. Ormianer Z, Garg AK, Palti A, Immediate loading of implant overdentures using modified loading protocol, Impl Dent 2006;15(1);3540
24. Park SH, Choi SJ, Galasso D, et al. Long term survival of small diameter implants [poster presentation]. Orlando Fl; 20th Academy of Osseointergration Annual Meeting; 2005.