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32 Implant dentistry today June 2008 Volume 2 Number 2

Single tooth replacementLiviu Steier, Giovanni Dicran Meghighian and Gabriela Steier explain the clinical possibilities

Figure 1: Preoperative x-ray of the patient

Figure 2: Postoperative x-ray showing the implant in situ

Figure 3: Picture showing gum healing two weeks after II stage reentry and temporisation

Figure 4: Pick up impression performed with a polyether material

Dr Steier is currently Visiting Professor at Florence Dental School, Tufts School of Dental Medicine - Boston and Honorary Clinical Associate Professor at Warwick Medical School.He has been in private practice since 1985, and has been working at MSDentistry since 2006. He is currently the President of the British Academy of Oral Bone Grafting and is can be reached via www.msdentistry.co.uk

IntroductionThis article describes the variety of clinical possibilities for the patient and clinical challenges for the dentist in a classical presentation: a missing mandibular right first molar. The solution chosen in this clinical case is a single tooth implant restoration with flapless surgery. Here we explain why.

Single tooth replacement epidemiological dataMissing molars is a frequent occurrence in patients aged over 30 in developed countries (Palmqvist et al 2000, 2001). In a 10-year follow-up study of the population of Turku in Finland (Hiidenkari et al 1996) the mean number of lost teeth was 1.5 and the median one tooth. Among the 30-39 year age group, there has been a considerable improvement in retention of natural teeth during the 10-year interval. However, amongst the middle-aged and elderly population, reduced dentition was common. Mack et al (2006) analysed the prevalence of single tooth gaps in a German population of 3989 subjects aged 20-74.

The tooth missing most in all age groups was the first molar. The maxilla showed more single-tooth gaps than the mandible, with no significant differences in gender. The highest frequency of single-tooth gaps was present in medium education subjects and the lowest frequency was found in high education subjects. One single-tooth gap was found in 25% of the sample; 16% of all subjects had two single-tooth gaps. The prevalence of one single-tooth gap was between 3.8 and 13.1%.

Single-tooth replacement: Fixed partial denture (FPD)The traditional treatment for a single empty space between teeth is a fixed partial denture (FPD)(Shillingburg et al 1981). The need of extensive tooth reduction and the need of RCT of adjacent abutments (pillars of the bridge) makes this choice less desirable by patients who fear the early loss of abutments. This might be justified in the past. Schwartz et al (1970) estimated a longevity of 8.3 years, and Walton (1986) estimated a longevity of 10.3 years. The improvement of techniques, materials and trainings can explain the increased longevity of three units PFD. In 20 years, a retrospective study at Ghent University, Belgium (De Backer et al 2006), the overall survival rate of three units PFD produced by undergraduate students, as part of their curricula was 73.1% after 20 years. A statistically significant difference (P = .036) between the survival rates in the mandible for the vital group (96.3%) versus the root canal-treated group (69.3%) was found. Comparing the survival rate in the vital group for the restorations in the maxilla (70.2%) versus the mandible (96.3%), there is a statistically significant difference (P = .045). The survival rate after 20 years for the three-unit FPDs (73.1%) was significantly different

from that of the FPDs with more than three units (61.5%) (P = .026). The main reason for failure was caries (38.1%).

The single-tooth replacement was a resin-bonded fixed partial denture (RBFPD). Rochette introduced resin-bonded bridges concepts in 1973 as a periodontal splint improvement. Different techniques and materials are available. Metal, metal ceramic, metal composite, all ceramic, fibres reinforced composite are viable options available today.

Whatever the material used, the design of the retainers remains the key to avoid fractures or de-bonding. For those interested the scientific literature is filled with data and facts.

The advantages of RBFPD are basically its minimal invasive nature; the retainers can substitute existing restorations in the adjacent teeth, avoiding at all the destruction of remaining tooth tissues. If the adjacent teeth are sound, the more conservative approach is an alternative to conventional FPD. Secondly it is a very fast technique in the hands of an experienced dentist. A bridge can be delivered in two appointments. If the patient needs to fill the gap but cannot wait, this might be the right option. In regard to the survival rate, many studies are available.

Hussey et al (1991) reports a de-bonding rate of 25% over a period of 2.7 years. Ketabi et al (2004) reports a mean functional survival rate of 83% in 13 years. Audenino et al in (2006) suggest an estimated

survival probability for the first de-bonding or failure of 85% after five years and 71% after 10 years.

Single-tooth replacement: Implant-supported restorationThe use of single implants restorations is well established since the first data were published (Scheller 1998, Laney et al 1994).

Levine et al (2006a) report a 92.5% survival rate in areas with bone augmentation, and 93.1% in the non-augmented areas. Longer implants showed similar survival rates as shorter implants. Implant width showed no differences. A significant difference in implant longevity is related to the anatomic zone of placement and the maxillary premolar area showed the highest survival rate (96.2%). Implants have always involved a long treatment plan.

Levine et al (2006b) report a survival rate of 92.6% in single molar restoration with single implants.New surgical techniques and implant design have been developed to shorten the clinical time required and to create a better comfort for the patient.

Flapless implant surgery is a minimally invasive technique, where the bone is not exposed before drilling the socket to receive the implant. It reduces the healing time and is associated to immediate loading of the implant, or with shorter time span before loading.

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Figure 7: Ceramic abutment cut to desired length

Figure 8: Abutment screwed in on the master model ready for futher adjustments

Figure 9: Abutment prepared in laboratory using a parallelometer

Figure 10: A Procera coping was performed using Cad Cam technology

Figure 5: Full ceramic abutment (original NobelBiocare)

Figure 6: Ceramic abutment mounted on the master model

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34 Implant dentistry today June 2008 Volume 2 Number 2

Figure 11: Try in of the coping of the master model

Figure 12: To be seated in the mouth, a Pattern Resin key is performed for the individualised full ceramic abutment

Figure 13: The definitive shape of the full ceramic Zirconia crown is tried in on the master model

Figure 14: Occlusal view of the Zirconia crown showing the perfected relief

As Campelo and Camara (2002) assert that, since flapless implant surgery is a ‘blind ‘ technique, care must be taken in selecting the patients and the appropriate width of bone assessed. The risk of perforating the cortical bone associated with such procedure in virtually eliminated by adopting a surgical stent to guide the drilling.

Because the technique requires a smaller amount of time than conventional flap surgery the advantages for both the patient and the dentist are minimal bleeding, fast implant placement, and no need for sutures.

Clinical caseThe patient, a 46-year-old Caucasian female, expressed her concern about the missing lower right first molar, which was missing since she was 25 (Figure 1). Because of her previous dental experience with missing premolars in the maxilla and the RCT in the adjacent premolars to the missing 3.6 and the aesthetic consequences involved, she expressed the demand for long lasting restoration which would not involve the premolars on the right side.

The patient’s medical history was checked focusing on oral (mucosal) diseases, blood dyscrasias, non-controlled diabetes, drugs and medications, irradiation of maxillae, psychoses, substance abuse (tobacco, alcohol, drugs). Indication for antibiotic cover was negative. An OPG x-ray examination was done to assess the dental status.

The possible alternatives have been discussed with the patient. A conventional FPD was excluded as too invasive. A RBFPD was an option, especially because the both the abutments 4.7 and 4.5 had fillings that would have been replaced by the retainers. Nonetheless a better stability would have required the preparation of 4.4, which the patient did not agree with. A conventional implant option, with flap surgery appeared too invasive to the patient, and the time of recovery before receiving the final crown too long.

A flapless surgery with a groovy implant to speed up the integration process was proposed. The patient asked to know more about the procedure, and she was informed of any complications. She discussed

the treatment plan and an informed consent was signed.

Accepted treatment planImplant retained full ceramic crown.

Step by step treatmentAt the first appointment impressions were taken for a lab made surgical stent. At the following appointment implant placement was performed using local anesthesia, raising a full flap and the corect drilling protocol. The wound was sutred using GoreTex suture material. Fourteen days later the sutures were removed. The healing process occured without any problems. The second stage was performed three months later. The implant was exposed using locator and punch and an acrylic temporary was performed for two weeks. After 14 days an impression was taken and sent to the laboratory. Seven days later the coronal rehabiliation could be seated in local anesthesia. Further details regarding the seating are described in the pictures attached. Two recall sessions were organised to check the occlusal fitting as well as the gum. Two years after the performed treatment the patient was happy with the results.

Implant selectionSelected implant = Nobel Speedy Replace. Beautiful Teeth Now™ is delivered by flapless surgery. The NobelSpeedy™ implant enables dentists to achieve primary stability at time of implant placement, and is specially designed to circumvent compromised bone conditions. Its TiUnite® surface provides accelerated osseointegration over machined surface implants and natural gum contours, while its narrow tip makes it perfect for flapless surgery – shortening treatment time and speeding recovery as a result. NobelSpeedy™ features:- Parallel walled implant- Slightly tapered design- Internal/External abutment connections.

The implant for flapless surgeryImmediate Function™

Increased initial stability in soft boneOptimal Emergence Profile and EstheticsTiUnite® ‘all the way up’Healing time = 12 weeks

ReferencesAudenino G, Giannella G, Morello GM, Ceccarelli M, Carossa S, Bassi F. Resin-bonded fixed partial dentures: ten-year follow-up. Int J Prosthodont. 2006 Jan-Feb;19(1):22-3.Campelo LD, Camara JR. Flapless implant surgery: a 10-year clinical retrospective analysis. Int J Oral Maxillofac Implants. 2002 Mar-Apr;17(2):271-6.De Backer H, Van Maele G, De Moor N, Van den Berghe L. Single-tooth replacement: is a 3-unit fixed partial denture still an option? A 20-year retrospective study. Int J Prosthodont. 2006 Nov-Dec;19(6):567-73.Hiidenkari T, Parvinen T, Helenius H. Missing teeth and lost teeth of adults aged 30 years and over in south-western Finland. Community Dent Health. 1996 Dec;13(4):215-22.Hussey DL, Pagni C, Linden GL. Performance of 400 adhesive bridges fitted in a restorative dentistry department. J Dent 1991; 19:221-5.Ketabi AR, Kaus T, Herdach F, Groten M, Axmann-Krcmar D, Probster L, Weber H. Thirteen-year follow-up study of resin-bonded fixed partial dentures. Quintessence Int. 2004 May;35(5):407-10.Laney WR, Jemt T, Harris D, Henry PJ, Krogh PH, Polizzi, G, and others. Osseointegrated implants for single-tooth replacement: progress report from a multicenter prospective study after 3 years. Int J Oral Maxillofac Implants 1994; 9:49-54.Levin L, Laviv A, Schwartz-Arad D. Long-term success of implants replacing a single molar. J Periodontol. 2006 Sep;77(9):1528-32.Levin L, Sadet P, Grossmann Y. A retrospective evaluation of 1,387

single-tooth implants: a 6-year follow-up. J Periodontol. 2006 Dec;77(12):2080-3.Mack F, Samietz SA, Mundt T, Proff P, Gedrange T, Kocher T, Biffar R. Prevalence of single-tooth gaps in a population-based study and the potential for dental implants--data from the Study of Health in Pomerania (SHIP-0). J Craniomaxillofac Surg. 2006 Sep;34 Suppl 2:82-5.Palmqvist S, Söderfeldt B, Vigild M, Kihl J. Dental conditions in middle-aged and older people in Denmark and Sweden: a comparative study of the influence of socioeconomic and attitudinal factors. Acta Odontol Scand. 2000 Jun;58(3):113-8.Palmqvist S, Söderfeldt B, Vigild M. Influence of dental care systems on dental status. A comparison between two countries with different systems but similar living standards. Community Dent Health. 2001 Mar;18(1):16-9.Rochette AL. Attachment of a splint to enamel of lower anterior teeth. J Prosthet Dent 1973; 30:418-23.Scheller H, Urgell J, Kultje C, Klineberg I, Goldberg PV, Stevenson-Moore P, and others. A 5-year multicenter study on implant-supported single crown restorations. Int J Oral Maxillofac Implants 1998; 13:212-8.Schwartz NL, Whitsett LD, Berry TG, Stewart JL. Unserviceable crowns and fixed partial dentures: life-span and causes for loss of serviceability. J Am Dent Assoc 1970; 81:1395-401.Shillingburg HT, Hobo S, Whitsett LD. Fundamentals of fixed prosthodontics. 2nd ed. Chicago (IL): Quintessence Publishing Co.; 1981. p. 115-9Walton JN, Gardner FM, Agar JR. A survey of crown and fixed partial denture failures: length of service and reasons for replacement. J Prosthet Dent 1986; 56:416-21.

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Figure 15: Picture showing the needed prerquisite for seating the abutment and the crown in the mouth

Clinical

Figure 18: Picture showing the new restoration in full occlusal contact

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Figure 16: X ray control of the seated abutment - fit check

Figure 19: X-ray control of the fitted restoration

Figure 17: The abutment is mounted on the implant using the Pattern Resin key